Merge branch 'dt/refs-backend-pre-vtable'

Code preparation for pluggable ref backends.

* dt/refs-backend-pre-vtable:
  refs: break out ref conflict checks
  files_log_ref_write: new function
  initdb: make safe_create_dir public
  refs: split filesystem-based refs code into a new file
  refs/refs-internal.h: new header file
  refname_is_safe(): improve docstring
  pack_if_possible_fn(): use ref_type() instead of is_per_worktree_ref()
  copy_msg(): rename to copy_reflog_msg()
  verify_refname_available(): new function
  verify_refname_available(): rename function

7 files changed, 3776 insertions, 3682 deletions

diff --git a/Makefile b/Makefile
index bce79a1..fd19b54 100644
--- a/Makefile
+++ b/Makefile
@@ -772,6 +772,7 @@ LIB_OBJS += reachable.o
 LIB_OBJS += read-cache.o
 LIB_OBJS += reflog-walk.o
 LIB_OBJS += refs.o
+LIB_OBJS += refs/files-backend.o
 LIB_OBJS += ref-filter.o
 LIB_OBJS += remote.o
 LIB_OBJS += replace_object.o
@@ -2432,7 +2433,7 @@ profile-clean:
 	$(RM) $(addsuffix *.gcno,$(addprefix $(PROFILE_DIR)/, $(object_dirs)))
 
 clean: profile-clean coverage-clean
-	$(RM) *.o *.res block-sha1/*.o ppc/*.o compat/*.o compat/*/*.o
+	$(RM) *.o *.res refs/*.o block-sha1/*.o ppc/*.o compat/*.o compat/*/*.o
 	$(RM) xdiff/*.o vcs-svn/*.o ewah/*.o builtin/*.o
 	$(RM) $(LIB_FILE) $(XDIFF_LIB) $(VCSSVN_LIB)
 	$(RM) $(ALL_PROGRAMS) $(SCRIPT_LIB) $(BUILT_INS) git$X
diff --git a/builtin/init-db.c b/builtin/init-db.c
index f59f407..07229d6 100644
--- a/builtin/init-db.c
+++ b/builtin/init-db.c
@@ -24,18 +24,6 @@ static int init_shared_repository = -1;
 static const char *init_db_template_dir;
 static const char *git_link;
 
-static void safe_create_dir(const char *dir, int share)
-{
-	if (mkdir(dir, 0777) < 0) {
-		if (errno != EEXIST) {
-			perror(dir);
-			exit(1);
-		}
-	}
-	else if (share && adjust_shared_perm(dir))
-		die(_("Could not make %s writable by group"), dir);
-}
-
 static void copy_templates_1(struct strbuf *path, struct strbuf *template,
 			     DIR *dir)
 {
diff --git a/cache.h b/cache.h
index 2a9e902..c3b196e 100644
--- a/cache.h
+++ b/cache.h
@@ -1768,4 +1768,12 @@ void stat_validity_update(struct stat_validity *sv, int fd);
 int versioncmp(const char *s1, const char *s2);
 void sleep_millisec(int millisec);
 
+/*
+ * Create a directory and (if share is nonzero) adjust its permissions
+ * according to the shared_repository setting. Only use this for
+ * directories under $GIT_DIR.  Don't use it for working tree
+ * directories.
+ */
+void safe_create_dir(const char *dir, int share);
+
 #endif /* CACHE_H */
diff --git a/path.c b/path.c
index f28ace2..3cd155e 100644
--- a/path.c
+++ b/path.c
@@ -740,6 +740,18 @@ int adjust_shared_perm(const char *path)
 	return 0;
 }
 
+void safe_create_dir(const char *dir, int share)
+{
+	if (mkdir(dir, 0777) < 0) {
+		if (errno != EEXIST) {
+			perror(dir);
+			exit(1);
+		}
+	}
+	else if (share && adjust_shared_perm(dir))
+		die(_("Could not make %s writable by group"), dir);
+}
+
 static int have_same_root(const char *path1, const char *path2)
 {
 	int is_abs1, is_abs2;
diff --git a/refs.c b/refs.c
index bab92d7..0f7628d 100644
--- a/refs.c
+++ b/refs.c
@@ -1,17 +1,13 @@
+/*
+ * The backend-independent part of the reference module.
+ */
+
 #include "cache.h"
 #include "lockfile.h"
 #include "refs.h"
+#include "refs/refs-internal.h"
 #include "object.h"
 #include "tag.h"
-#include "dir.h"
-#include "string-list.h"
-
-struct ref_lock {
-	char *ref_name;
-	char *orig_ref_name;
-	struct lock_file *lk;
-	struct object_id old_oid;
-};
 
 /*
  * How to handle various characters in refnames:
@@ -35,41 +31,6 @@ static unsigned char refname_disposition[256] = {
 };
 
 /*
- * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
- * refs (i.e., because the reference is about to be deleted anyway).
- */
-#define REF_DELETING	0x02
-
-/*
- * Used as a flag in ref_update::flags when a loose ref is being
- * pruned.
- */
-#define REF_ISPRUNING	0x04
-
-/*
- * Used as a flag in ref_update::flags when the reference should be
- * updated to new_sha1.
- */
-#define REF_HAVE_NEW	0x08
-
-/*
- * Used as a flag in ref_update::flags when old_sha1 should be
- * checked.
- */
-#define REF_HAVE_OLD	0x10
-
-/*
- * Used as a flag in ref_update::flags when the lockfile needs to be
- * committed.
- */
-#define REF_NEEDS_COMMIT 0x20
-
-/*
- * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
- * value to ref_update::flags
- */
-
-/*
  * Try to read one refname component from the front of refname.
  * Return the length of the component found, or -1 if the component is
  * not legal.  It is legal if it is something reasonable to have under
@@ -157,199 +118,7 @@ int check_refname_format(const char *refname, int flags)
 	return 0;
 }
 
-struct ref_entry;
-
-/*
- * Information used (along with the information in ref_entry) to
- * describe a single cached reference.  This data structure only
- * occurs embedded in a union in struct ref_entry, and only when
- * (ref_entry->flag & REF_DIR) is zero.
- */
-struct ref_value {
-	/*
-	 * The name of the object to which this reference resolves
-	 * (which may be a tag object).  If REF_ISBROKEN, this is
-	 * null.  If REF_ISSYMREF, then this is the name of the object
-	 * referred to by the last reference in the symlink chain.
-	 */
-	struct object_id oid;
-
-	/*
-	 * If REF_KNOWS_PEELED, then this field holds the peeled value
-	 * of this reference, or null if the reference is known not to
-	 * be peelable.  See the documentation for peel_ref() for an
-	 * exact definition of "peelable".
-	 */
-	struct object_id peeled;
-};
-
-struct ref_cache;
-
-/*
- * Information used (along with the information in ref_entry) to
- * describe a level in the hierarchy of references.  This data
- * structure only occurs embedded in a union in struct ref_entry, and
- * only when (ref_entry.flag & REF_DIR) is set.  In that case,
- * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
- * in the directory have already been read:
- *
- *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
- *         or packed references, already read.
- *
- *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
- *         references that hasn't been read yet (nor has any of its
- *         subdirectories).
- *
- * Entries within a directory are stored within a growable array of
- * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
- * sorted are sorted by their component name in strcmp() order and the
- * remaining entries are unsorted.
- *
- * Loose references are read lazily, one directory at a time.  When a
- * directory of loose references is read, then all of the references
- * in that directory are stored, and REF_INCOMPLETE stubs are created
- * for any subdirectories, but the subdirectories themselves are not
- * read.  The reading is triggered by get_ref_dir().
- */
-struct ref_dir {
-	int nr, alloc;
-
-	/*
-	 * Entries with index 0 <= i < sorted are sorted by name.  New
-	 * entries are appended to the list unsorted, and are sorted
-	 * only when required; thus we avoid the need to sort the list
-	 * after the addition of every reference.
-	 */
-	int sorted;
-
-	/* A pointer to the ref_cache that contains this ref_dir. */
-	struct ref_cache *ref_cache;
-
-	struct ref_entry **entries;
-};
-
-/*
- * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
- * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
- * public values; see refs.h.
- */
-
-/*
- * The field ref_entry->u.value.peeled of this value entry contains
- * the correct peeled value for the reference, which might be
- * null_sha1 if the reference is not a tag or if it is broken.
- */
-#define REF_KNOWS_PEELED 0x10
-
-/* ref_entry represents a directory of references */
-#define REF_DIR 0x20
-
-/*
- * Entry has not yet been read from disk (used only for REF_DIR
- * entries representing loose references)
- */
-#define REF_INCOMPLETE 0x40
-
-/*
- * A ref_entry represents either a reference or a "subdirectory" of
- * references.
- *
- * Each directory in the reference namespace is represented by a
- * ref_entry with (flags & REF_DIR) set and containing a subdir member
- * that holds the entries in that directory that have been read so
- * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
- * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
- * used for loose reference directories.
- *
- * References are represented by a ref_entry with (flags & REF_DIR)
- * unset and a value member that describes the reference's value.  The
- * flag member is at the ref_entry level, but it is also needed to
- * interpret the contents of the value field (in other words, a
- * ref_value object is not very much use without the enclosing
- * ref_entry).
- *
- * Reference names cannot end with slash and directories' names are
- * always stored with a trailing slash (except for the top-level
- * directory, which is always denoted by "").  This has two nice
- * consequences: (1) when the entries in each subdir are sorted
- * lexicographically by name (as they usually are), the references in
- * a whole tree can be generated in lexicographic order by traversing
- * the tree in left-to-right, depth-first order; (2) the names of
- * references and subdirectories cannot conflict, and therefore the
- * presence of an empty subdirectory does not block the creation of a
- * similarly-named reference.  (The fact that reference names with the
- * same leading components can conflict *with each other* is a
- * separate issue that is regulated by verify_refname_available().)
- *
- * Please note that the name field contains the fully-qualified
- * reference (or subdirectory) name.  Space could be saved by only
- * storing the relative names.  But that would require the full names
- * to be generated on the fly when iterating in do_for_each_ref(), and
- * would break callback functions, who have always been able to assume
- * that the name strings that they are passed will not be freed during
- * the iteration.
- */
-struct ref_entry {
-	unsigned char flag; /* ISSYMREF? ISPACKED? */
-	union {
-		struct ref_value value; /* if not (flags&REF_DIR) */
-		struct ref_dir subdir; /* if (flags&REF_DIR) */
-	} u;
-	/*
-	 * The full name of the reference (e.g., "refs/heads/master")
-	 * or the full name of the directory with a trailing slash
-	 * (e.g., "refs/heads/"):
-	 */
-	char name[FLEX_ARRAY];
-};
-
-static void read_loose_refs(const char *dirname, struct ref_dir *dir);
-static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
-static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
-					  const char *dirname, size_t len,
-					  int incomplete);
-static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
-
-static struct ref_dir *get_ref_dir(struct ref_entry *entry)
-{
-	struct ref_dir *dir;
-	assert(entry->flag & REF_DIR);
-	dir = &entry->u.subdir;
-	if (entry->flag & REF_INCOMPLETE) {
-		read_loose_refs(entry->name, dir);
-
-		/*
-		 * Manually add refs/bisect, which, being
-		 * per-worktree, might not appear in the directory
-		 * listing for refs/ in the main repo.
-		 */
-		if (!strcmp(entry->name, "refs/")) {
-			int pos = search_ref_dir(dir, "refs/bisect/", 12);
-			if (pos < 0) {
-				struct ref_entry *child_entry;
-				child_entry = create_dir_entry(dir->ref_cache,
-							       "refs/bisect/",
-							       12, 1);
-				add_entry_to_dir(dir, child_entry);
-				read_loose_refs("refs/bisect",
-						&child_entry->u.subdir);
-			}
-		}
-		entry->flag &= ~REF_INCOMPLETE;
-	}
-	return dir;
-}
-
-/*
- * Check if a refname is safe.
- * For refs that start with "refs/" we consider it safe as long they do
- * not try to resolve to outside of refs/.
- *
- * For all other refs we only consider them safe iff they only contain
- * upper case characters and '_' (like "HEAD" AND "MERGE_HEAD", and not like
- * "config").
- */
-static int refname_is_safe(const char *refname)
+int refname_is_safe(const char *refname)
 {
 	if (starts_with(refname, "refs/")) {
 		char *buf;
@@ -373,1422 +142,6 @@ static int refname_is_safe(const char *refname)
 	return 1;
 }
 
-static struct ref_entry *create_ref_entry(const char *refname,
-					  const unsigned char *sha1, int flag,
-					  int check_name)
-{
-	int len;
-	struct ref_entry *ref;
-
-	if (check_name &&
-	    check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
-		die("Reference has invalid format: '%s'", refname);
-	len = strlen(refname) + 1;
-	ref = xmalloc(sizeof(struct ref_entry) + len);
-	hashcpy(ref->u.value.oid.hash, sha1);
-	oidclr(&ref->u.value.peeled);
-	memcpy(ref->name, refname, len);
-	ref->flag = flag;
-	return ref;
-}
-
-static void clear_ref_dir(struct ref_dir *dir);
-
-static void free_ref_entry(struct ref_entry *entry)
-{
-	if (entry->flag & REF_DIR) {
-		/*
-		 * Do not use get_ref_dir() here, as that might
-		 * trigger the reading of loose refs.
-		 */
-		clear_ref_dir(&entry->u.subdir);
-	}
-	free(entry);
-}
-
-/*
- * Add a ref_entry to the end of dir (unsorted).  Entry is always
- * stored directly in dir; no recursion into subdirectories is
- * done.
- */
-static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
-{
-	ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
-	dir->entries[dir->nr++] = entry;
-	/* optimize for the case that entries are added in order */
-	if (dir->nr == 1 ||
-	    (dir->nr == dir->sorted + 1 &&
-	     strcmp(dir->entries[dir->nr - 2]->name,
-		    dir->entries[dir->nr - 1]->name) < 0))
-		dir->sorted = dir->nr;
-}
-
-/*
- * Clear and free all entries in dir, recursively.
- */
-static void clear_ref_dir(struct ref_dir *dir)
-{
-	int i;
-	for (i = 0; i < dir->nr; i++)
-		free_ref_entry(dir->entries[i]);
-	free(dir->entries);
-	dir->sorted = dir->nr = dir->alloc = 0;
-	dir->entries = NULL;
-}
-
-/*
- * Create a struct ref_entry object for the specified dirname.
- * dirname is the name of the directory with a trailing slash (e.g.,
- * "refs/heads/") or "" for the top-level directory.
- */
-static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
-					  const char *dirname, size_t len,
-					  int incomplete)
-{
-	struct ref_entry *direntry;
-	direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
-	memcpy(direntry->name, dirname, len);
-	direntry->name[len] = '\0';
-	direntry->u.subdir.ref_cache = ref_cache;
-	direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
-	return direntry;
-}
-
-static int ref_entry_cmp(const void *a, const void *b)
-{
-	struct ref_entry *one = *(struct ref_entry **)a;
-	struct ref_entry *two = *(struct ref_entry **)b;
-	return strcmp(one->name, two->name);
-}
-
-static void sort_ref_dir(struct ref_dir *dir);
-
-struct string_slice {
-	size_t len;
-	const char *str;
-};
-
-static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
-{
-	const struct string_slice *key = key_;
-	const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
-	int cmp = strncmp(key->str, ent->name, key->len);
-	if (cmp)
-		return cmp;
-	return '\0' - (unsigned char)ent->name[key->len];
-}
-
-/*
- * Return the index of the entry with the given refname from the
- * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
- * no such entry is found.  dir must already be complete.
- */
-static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
-{
-	struct ref_entry **r;
-	struct string_slice key;
-
-	if (refname == NULL || !dir->nr)
-		return -1;
-
-	sort_ref_dir(dir);
-	key.len = len;
-	key.str = refname;
-	r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
-		    ref_entry_cmp_sslice);
-
-	if (r == NULL)
-		return -1;
-
-	return r - dir->entries;
-}
-
-/*
- * Search for a directory entry directly within dir (without
- * recursing).  Sort dir if necessary.  subdirname must be a directory
- * name (i.e., end in '/').  If mkdir is set, then create the
- * directory if it is missing; otherwise, return NULL if the desired
- * directory cannot be found.  dir must already be complete.
- */
-static struct ref_dir *search_for_subdir(struct ref_dir *dir,
-					 const char *subdirname, size_t len,
-					 int mkdir)
-{
-	int entry_index = search_ref_dir(dir, subdirname, len);
-	struct ref_entry *entry;
-	if (entry_index == -1) {
-		if (!mkdir)
-			return NULL;
-		/*
-		 * Since dir is complete, the absence of a subdir
-		 * means that the subdir really doesn't exist;
-		 * therefore, create an empty record for it but mark
-		 * the record complete.
-		 */
-		entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
-		add_entry_to_dir(dir, entry);
-	} else {
-		entry = dir->entries[entry_index];
-	}
-	return get_ref_dir(entry);
-}
-
-/*
- * If refname is a reference name, find the ref_dir within the dir
- * tree that should hold refname.  If refname is a directory name
- * (i.e., ends in '/'), then return that ref_dir itself.  dir must
- * represent the top-level directory and must already be complete.
- * Sort ref_dirs and recurse into subdirectories as necessary.  If
- * mkdir is set, then create any missing directories; otherwise,
- * return NULL if the desired directory cannot be found.
- */
-static struct ref_dir *find_containing_dir(struct ref_dir *dir,
-					   const char *refname, int mkdir)
-{
-	const char *slash;
-	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
-		size_t dirnamelen = slash - refname + 1;
-		struct ref_dir *subdir;
-		subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
-		if (!subdir) {
-			dir = NULL;
-			break;
-		}
-		dir = subdir;
-	}
-
-	return dir;
-}
-
-/*
- * Find the value entry with the given name in dir, sorting ref_dirs
- * and recursing into subdirectories as necessary.  If the name is not
- * found or it corresponds to a directory entry, return NULL.
- */
-static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
-{
-	int entry_index;
-	struct ref_entry *entry;
-	dir = find_containing_dir(dir, refname, 0);
-	if (!dir)
-		return NULL;
-	entry_index = search_ref_dir(dir, refname, strlen(refname));
-	if (entry_index == -1)
-		return NULL;
-	entry = dir->entries[entry_index];
-	return (entry->flag & REF_DIR) ? NULL : entry;
-}
-
-/*
- * Remove the entry with the given name from dir, recursing into
- * subdirectories as necessary.  If refname is the name of a directory
- * (i.e., ends with '/'), then remove the directory and its contents.
- * If the removal was successful, return the number of entries
- * remaining in the directory entry that contained the deleted entry.
- * If the name was not found, return -1.  Please note that this
- * function only deletes the entry from the cache; it does not delete
- * it from the filesystem or ensure that other cache entries (which
- * might be symbolic references to the removed entry) are updated.
- * Nor does it remove any containing dir entries that might be made
- * empty by the removal.  dir must represent the top-level directory
- * and must already be complete.
- */
-static int remove_entry(struct ref_dir *dir, const char *refname)
-{
-	int refname_len = strlen(refname);
-	int entry_index;
-	struct ref_entry *entry;
-	int is_dir = refname[refname_len - 1] == '/';
-	if (is_dir) {
-		/*
-		 * refname represents a reference directory.  Remove
-		 * the trailing slash; otherwise we will get the
-		 * directory *representing* refname rather than the
-		 * one *containing* it.
-		 */
-		char *dirname = xmemdupz(refname, refname_len - 1);
-		dir = find_containing_dir(dir, dirname, 0);
-		free(dirname);
-	} else {
-		dir = find_containing_dir(dir, refname, 0);
-	}
-	if (!dir)
-		return -1;
-	entry_index = search_ref_dir(dir, refname, refname_len);
-	if (entry_index == -1)
-		return -1;
-	entry = dir->entries[entry_index];
-
-	memmove(&dir->entries[entry_index],
-		&dir->entries[entry_index + 1],
-		(dir->nr - entry_index - 1) * sizeof(*dir->entries)
-		);
-	dir->nr--;
-	if (dir->sorted > entry_index)
-		dir->sorted--;
-	free_ref_entry(entry);
-	return dir->nr;
-}
-
-/*
- * Add a ref_entry to the ref_dir (unsorted), recursing into
- * subdirectories as necessary.  dir must represent the top-level
- * directory.  Return 0 on success.
- */
-static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
-{
-	dir = find_containing_dir(dir, ref->name, 1);
-	if (!dir)
-		return -1;
-	add_entry_to_dir(dir, ref);
-	return 0;
-}
-
-/*
- * Emit a warning and return true iff ref1 and ref2 have the same name
- * and the same sha1.  Die if they have the same name but different
- * sha1s.
- */
-static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
-{
-	if (strcmp(ref1->name, ref2->name))
-		return 0;
-
-	/* Duplicate name; make sure that they don't conflict: */
-
-	if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
-		/* This is impossible by construction */
-		die("Reference directory conflict: %s", ref1->name);
-
-	if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
-		die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
-
-	warning("Duplicated ref: %s", ref1->name);
-	return 1;
-}
-
-/*
- * Sort the entries in dir non-recursively (if they are not already
- * sorted) and remove any duplicate entries.
- */
-static void sort_ref_dir(struct ref_dir *dir)
-{
-	int i, j;
-	struct ref_entry *last = NULL;
-
-	/*
-	 * This check also prevents passing a zero-length array to qsort(),
-	 * which is a problem on some platforms.
-	 */
-	if (dir->sorted == dir->nr)
-		return;
-
-	qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
-
-	/* Remove any duplicates: */
-	for (i = 0, j = 0; j < dir->nr; j++) {
-		struct ref_entry *entry = dir->entries[j];
-		if (last && is_dup_ref(last, entry))
-			free_ref_entry(entry);
-		else
-			last = dir->entries[i++] = entry;
-	}
-	dir->sorted = dir->nr = i;
-}
-
-/* Include broken references in a do_for_each_ref*() iteration: */
-#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
-
-/*
- * Return true iff the reference described by entry can be resolved to
- * an object in the database.  Emit a warning if the referred-to
- * object does not exist.
- */
-static int ref_resolves_to_object(struct ref_entry *entry)
-{
-	if (entry->flag & REF_ISBROKEN)
-		return 0;
-	if (!has_sha1_file(entry->u.value.oid.hash)) {
-		error("%s does not point to a valid object!", entry->name);
-		return 0;
-	}
-	return 1;
-}
-
-/*
- * current_ref is a performance hack: when iterating over references
- * using the for_each_ref*() functions, current_ref is set to the
- * current reference's entry before calling the callback function.  If
- * the callback function calls peel_ref(), then peel_ref() first
- * checks whether the reference to be peeled is the current reference
- * (it usually is) and if so, returns that reference's peeled version
- * if it is available.  This avoids a refname lookup in a common case.
- */
-static struct ref_entry *current_ref;
-
-typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
-
-struct ref_entry_cb {
-	const char *base;
-	int trim;
-	int flags;
-	each_ref_fn *fn;
-	void *cb_data;
-};
-
-/*
- * Handle one reference in a do_for_each_ref*()-style iteration,
- * calling an each_ref_fn for each entry.
- */
-static int do_one_ref(struct ref_entry *entry, void *cb_data)
-{
-	struct ref_entry_cb *data = cb_data;
-	struct ref_entry *old_current_ref;
-	int retval;
-
-	if (!starts_with(entry->name, data->base))
-		return 0;
-
-	if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
-	      !ref_resolves_to_object(entry))
-		return 0;
-
-	/* Store the old value, in case this is a recursive call: */
-	old_current_ref = current_ref;
-	current_ref = entry;
-	retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
-			  entry->flag, data->cb_data);
-	current_ref = old_current_ref;
-	return retval;
-}
-
-/*
- * Call fn for each reference in dir that has index in the range
- * offset <= index < dir->nr.  Recurse into subdirectories that are in
- * that index range, sorting them before iterating.  This function
- * does not sort dir itself; it should be sorted beforehand.  fn is
- * called for all references, including broken ones.
- */
-static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
-				    each_ref_entry_fn fn, void *cb_data)
-{
-	int i;
-	assert(dir->sorted == dir->nr);
-	for (i = offset; i < dir->nr; i++) {
-		struct ref_entry *entry = dir->entries[i];
-		int retval;
-		if (entry->flag & REF_DIR) {
-			struct ref_dir *subdir = get_ref_dir(entry);
-			sort_ref_dir(subdir);
-			retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
-		} else {
-			retval = fn(entry, cb_data);
-		}
-		if (retval)
-			return retval;
-	}
-	return 0;
-}
-
-/*
- * Call fn for each reference in the union of dir1 and dir2, in order
- * by refname.  Recurse into subdirectories.  If a value entry appears
- * in both dir1 and dir2, then only process the version that is in
- * dir2.  The input dirs must already be sorted, but subdirs will be
- * sorted as needed.  fn is called for all references, including
- * broken ones.
- */
-static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
-				     struct ref_dir *dir2,
-				     each_ref_entry_fn fn, void *cb_data)
-{
-	int retval;
-	int i1 = 0, i2 = 0;
-
-	assert(dir1->sorted == dir1->nr);
-	assert(dir2->sorted == dir2->nr);
-	while (1) {
-		struct ref_entry *e1, *e2;
-		int cmp;
-		if (i1 == dir1->nr) {
-			return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
-		}
-		if (i2 == dir2->nr) {
-			return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
-		}
-		e1 = dir1->entries[i1];
-		e2 = dir2->entries[i2];
-		cmp = strcmp(e1->name, e2->name);
-		if (cmp == 0) {
-			if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
-				/* Both are directories; descend them in parallel. */
-				struct ref_dir *subdir1 = get_ref_dir(e1);
-				struct ref_dir *subdir2 = get_ref_dir(e2);
-				sort_ref_dir(subdir1);
-				sort_ref_dir(subdir2);
-				retval = do_for_each_entry_in_dirs(
-						subdir1, subdir2, fn, cb_data);
-				i1++;
-				i2++;
-			} else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
-				/* Both are references; ignore the one from dir1. */
-				retval = fn(e2, cb_data);
-				i1++;
-				i2++;
-			} else {
-				die("conflict between reference and directory: %s",
-				    e1->name);
-			}
-		} else {
-			struct ref_entry *e;
-			if (cmp < 0) {
-				e = e1;
-				i1++;
-			} else {
-				e = e2;
-				i2++;
-			}
-			if (e->flag & REF_DIR) {
-				struct ref_dir *subdir = get_ref_dir(e);
-				sort_ref_dir(subdir);
-				retval = do_for_each_entry_in_dir(
-						subdir, 0, fn, cb_data);
-			} else {
-				retval = fn(e, cb_data);
-			}
-		}
-		if (retval)
-			return retval;
-	}
-}
-
-/*
- * Load all of the refs from the dir into our in-memory cache. The hard work
- * of loading loose refs is done by get_ref_dir(), so we just need to recurse
- * through all of the sub-directories. We do not even need to care about
- * sorting, as traversal order does not matter to us.
- */
-static void prime_ref_dir(struct ref_dir *dir)
-{
-	int i;
-	for (i = 0; i < dir->nr; i++) {
-		struct ref_entry *entry = dir->entries[i];
-		if (entry->flag & REF_DIR)
-			prime_ref_dir(get_ref_dir(entry));
-	}
-}
-
-struct nonmatching_ref_data {
-	const struct string_list *skip;
-	const char *conflicting_refname;
-};
-
-static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
-{
-	struct nonmatching_ref_data *data = vdata;
-
-	if (data->skip && string_list_has_string(data->skip, entry->name))
-		return 0;
-
-	data->conflicting_refname = entry->name;
-	return 1;
-}
-
-/*
- * Return 0 if a reference named refname could be created without
- * conflicting with the name of an existing reference in dir.
- * Otherwise, return a negative value and write an explanation to err.
- * If extras is non-NULL, it is a list of additional refnames with
- * which refname is not allowed to conflict. If skip is non-NULL,
- * ignore potential conflicts with refs in skip (e.g., because they
- * are scheduled for deletion in the same operation). Behavior is
- * undefined if the same name is listed in both extras and skip.
- *
- * Two reference names conflict if one of them exactly matches the
- * leading components of the other; e.g., "refs/foo/bar" conflicts
- * with both "refs/foo" and with "refs/foo/bar/baz" but not with
- * "refs/foo/bar" or "refs/foo/barbados".
- *
- * extras and skip must be sorted.
- */
-static int verify_refname_available(const char *refname,
-				    const struct string_list *extras,
-				    const struct string_list *skip,
-				    struct ref_dir *dir,
-				    struct strbuf *err)
-{
-	const char *slash;
-	int pos;
-	struct strbuf dirname = STRBUF_INIT;
-	int ret = -1;
-
-	/*
-	 * For the sake of comments in this function, suppose that
-	 * refname is "refs/foo/bar".
-	 */
-
-	assert(err);
-
-	strbuf_grow(&dirname, strlen(refname) + 1);
-	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
-		/* Expand dirname to the new prefix, not including the trailing slash: */
-		strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
-
-		/*
-		 * We are still at a leading dir of the refname (e.g.,
-		 * "refs/foo"; if there is a reference with that name,
-		 * it is a conflict, *unless* it is in skip.
-		 */
-		if (dir) {
-			pos = search_ref_dir(dir, dirname.buf, dirname.len);
-			if (pos >= 0 &&
-			    (!skip || !string_list_has_string(skip, dirname.buf))) {
-				/*
-				 * We found a reference whose name is
-				 * a proper prefix of refname; e.g.,
-				 * "refs/foo", and is not in skip.
-				 */
-				strbuf_addf(err, "'%s' exists; cannot create '%s'",
-					    dirname.buf, refname);
-				goto cleanup;
-			}
-		}
-
-		if (extras && string_list_has_string(extras, dirname.buf) &&
-		    (!skip || !string_list_has_string(skip, dirname.buf))) {
-			strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
-				    refname, dirname.buf);
-			goto cleanup;
-		}
-
-		/*
-		 * Otherwise, we can try to continue our search with
-		 * the next component. So try to look up the
-		 * directory, e.g., "refs/foo/". If we come up empty,
-		 * we know there is nothing under this whole prefix,
-		 * but even in that case we still have to continue the
-		 * search for conflicts with extras.
-		 */
-		strbuf_addch(&dirname, '/');
-		if (dir) {
-			pos = search_ref_dir(dir, dirname.buf, dirname.len);
-			if (pos < 0) {
-				/*
-				 * There was no directory "refs/foo/",
-				 * so there is nothing under this
-				 * whole prefix. So there is no need
-				 * to continue looking for conflicting
-				 * references. But we need to continue
-				 * looking for conflicting extras.
-				 */
-				dir = NULL;
-			} else {
-				dir = get_ref_dir(dir->entries[pos]);
-			}
-		}
-	}
-
-	/*
-	 * We are at the leaf of our refname (e.g., "refs/foo/bar").
-	 * There is no point in searching for a reference with that
-	 * name, because a refname isn't considered to conflict with
-	 * itself. But we still need to check for references whose
-	 * names are in the "refs/foo/bar/" namespace, because they
-	 * *do* conflict.
-	 */
-	strbuf_addstr(&dirname, refname + dirname.len);
-	strbuf_addch(&dirname, '/');
-
-	if (dir) {
-		pos = search_ref_dir(dir, dirname.buf, dirname.len);
-
-		if (pos >= 0) {
-			/*
-			 * We found a directory named "$refname/"
-			 * (e.g., "refs/foo/bar/"). It is a problem
-			 * iff it contains any ref that is not in
-			 * "skip".
-			 */
-			struct nonmatching_ref_data data;
-
-			data.skip = skip;
-			data.conflicting_refname = NULL;
-			dir = get_ref_dir(dir->entries[pos]);
-			sort_ref_dir(dir);
-			if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
-				strbuf_addf(err, "'%s' exists; cannot create '%s'",
-					    data.conflicting_refname, refname);
-				goto cleanup;
-			}
-		}
-	}
-
-	if (extras) {
-		/*
-		 * Check for entries in extras that start with
-		 * "$refname/". We do that by looking for the place
-		 * where "$refname/" would be inserted in extras. If
-		 * there is an entry at that position that starts with
-		 * "$refname/" and is not in skip, then we have a
-		 * conflict.
-		 */
-		for (pos = string_list_find_insert_index(extras, dirname.buf, 0);
-		     pos < extras->nr; pos++) {
-			const char *extra_refname = extras->items[pos].string;
-
-			if (!starts_with(extra_refname, dirname.buf))
-				break;
-
-			if (!skip || !string_list_has_string(skip, extra_refname)) {
-				strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
-					    refname, extra_refname);
-				goto cleanup;
-			}
-		}
-	}
-
-	/* No conflicts were found */
-	ret = 0;
-
-cleanup:
-	strbuf_release(&dirname);
-	return ret;
-}
-
-struct packed_ref_cache {
-	struct ref_entry *root;
-
-	/*
-	 * Count of references to the data structure in this instance,
-	 * including the pointer from ref_cache::packed if any.  The
-	 * data will not be freed as long as the reference count is
-	 * nonzero.
-	 */
-	unsigned int referrers;
-
-	/*
-	 * Iff the packed-refs file associated with this instance is
-	 * currently locked for writing, this points at the associated
-	 * lock (which is owned by somebody else).  The referrer count
-	 * is also incremented when the file is locked and decremented
-	 * when it is unlocked.
-	 */
-	struct lock_file *lock;
-
-	/* The metadata from when this packed-refs cache was read */
-	struct stat_validity validity;
-};
-
-/*
- * Future: need to be in "struct repository"
- * when doing a full libification.
- */
-static struct ref_cache {
-	struct ref_cache *next;
-	struct ref_entry *loose;
-	struct packed_ref_cache *packed;
-	/*
-	 * The submodule name, or "" for the main repo.  We allocate
-	 * length 1 rather than FLEX_ARRAY so that the main ref_cache
-	 * is initialized correctly.
-	 */
-	char name[1];
-} ref_cache, *submodule_ref_caches;
-
-/* Lock used for the main packed-refs file: */
-static struct lock_file packlock;
-
-/*
- * Increment the reference count of *packed_refs.
- */
-static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
-{
-	packed_refs->referrers++;
-}
-
-/*
- * Decrease the reference count of *packed_refs.  If it goes to zero,
- * free *packed_refs and return true; otherwise return false.
- */
-static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
-{
-	if (!--packed_refs->referrers) {
-		free_ref_entry(packed_refs->root);
-		stat_validity_clear(&packed_refs->validity);
-		free(packed_refs);
-		return 1;
-	} else {
-		return 0;
-	}
-}
-
-static void clear_packed_ref_cache(struct ref_cache *refs)
-{
-	if (refs->packed) {
-		struct packed_ref_cache *packed_refs = refs->packed;
-
-		if (packed_refs->lock)
-			die("internal error: packed-ref cache cleared while locked");
-		refs->packed = NULL;
-		release_packed_ref_cache(packed_refs);
-	}
-}
-
-static void clear_loose_ref_cache(struct ref_cache *refs)
-{
-	if (refs->loose) {
-		free_ref_entry(refs->loose);
-		refs->loose = NULL;
-	}
-}
-
-static struct ref_cache *create_ref_cache(const char *submodule)
-{
-	int len;
-	struct ref_cache *refs;
-	if (!submodule)
-		submodule = "";
-	len = strlen(submodule) + 1;
-	refs = xcalloc(1, sizeof(struct ref_cache) + len);
-	memcpy(refs->name, submodule, len);
-	return refs;
-}
-
-/*
- * Return a pointer to a ref_cache for the specified submodule. For
- * the main repository, use submodule==NULL. The returned structure
- * will be allocated and initialized but not necessarily populated; it
- * should not be freed.
- */
-static struct ref_cache *get_ref_cache(const char *submodule)
-{
-	struct ref_cache *refs;
-
-	if (!submodule || !*submodule)
-		return &ref_cache;
-
-	for (refs = submodule_ref_caches; refs; refs = refs->next)
-		if (!strcmp(submodule, refs->name))
-			return refs;
-
-	refs = create_ref_cache(submodule);
-	refs->next = submodule_ref_caches;
-	submodule_ref_caches = refs;
-	return refs;
-}
-
-/* The length of a peeled reference line in packed-refs, including EOL: */
-#define PEELED_LINE_LENGTH 42
-
-/*
- * The packed-refs header line that we write out.  Perhaps other
- * traits will be added later.  The trailing space is required.
- */
-static const char PACKED_REFS_HEADER[] =
-	"# pack-refs with: peeled fully-peeled \n";
-
-/*
- * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
- * Return a pointer to the refname within the line (null-terminated),
- * or NULL if there was a problem.
- */
-static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
-{
-	const char *ref;
-
-	/*
-	 * 42: the answer to everything.
-	 *
-	 * In this case, it happens to be the answer to
-	 *  40 (length of sha1 hex representation)
-	 *  +1 (space in between hex and name)
-	 *  +1 (newline at the end of the line)
-	 */
-	if (line->len <= 42)
-		return NULL;
-
-	if (get_sha1_hex(line->buf, sha1) < 0)
-		return NULL;
-	if (!isspace(line->buf[40]))
-		return NULL;
-
-	ref = line->buf + 41;
-	if (isspace(*ref))
-		return NULL;
-
-	if (line->buf[line->len - 1] != '\n')
-		return NULL;
-	line->buf[--line->len] = 0;
-
-	return ref;
-}
-
-/*
- * Read f, which is a packed-refs file, into dir.
- *
- * A comment line of the form "# pack-refs with: " may contain zero or
- * more traits. We interpret the traits as follows:
- *
- *   No traits:
- *
- *      Probably no references are peeled. But if the file contains a
- *      peeled value for a reference, we will use it.
- *
- *   peeled:
- *
- *      References under "refs/tags/", if they *can* be peeled, *are*
- *      peeled in this file. References outside of "refs/tags/" are
- *      probably not peeled even if they could have been, but if we find
- *      a peeled value for such a reference we will use it.
- *
- *   fully-peeled:
- *
- *      All references in the file that can be peeled are peeled.
- *      Inversely (and this is more important), any references in the
- *      file for which no peeled value is recorded is not peelable. This
- *      trait should typically be written alongside "peeled" for
- *      compatibility with older clients, but we do not require it
- *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
- */
-static void read_packed_refs(FILE *f, struct ref_dir *dir)
-{
-	struct ref_entry *last = NULL;
-	struct strbuf line = STRBUF_INIT;
-	enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
-
-	while (strbuf_getwholeline(&line, f, '\n') != EOF) {
-		unsigned char sha1[20];
-		const char *refname;
-		const char *traits;
-
-		if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
-			if (strstr(traits, " fully-peeled "))
-				peeled = PEELED_FULLY;
-			else if (strstr(traits, " peeled "))
-				peeled = PEELED_TAGS;
-			/* perhaps other traits later as well */
-			continue;
-		}
-
-		refname = parse_ref_line(&line, sha1);
-		if (refname) {
-			int flag = REF_ISPACKED;
-
-			if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
-				if (!refname_is_safe(refname))
-					die("packed refname is dangerous: %s", refname);
-				hashclr(sha1);
-				flag |= REF_BAD_NAME | REF_ISBROKEN;
-			}
-			last = create_ref_entry(refname, sha1, flag, 0);
-			if (peeled == PEELED_FULLY ||
-			    (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
-				last->flag |= REF_KNOWS_PEELED;
-			add_ref(dir, last);
-			continue;
-		}
-		if (last &&
-		    line.buf[0] == '^' &&
-		    line.len == PEELED_LINE_LENGTH &&
-		    line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
-		    !get_sha1_hex(line.buf + 1, sha1)) {
-			hashcpy(last->u.value.peeled.hash, sha1);
-			/*
-			 * Regardless of what the file header said,
-			 * we definitely know the value of *this*
-			 * reference:
-			 */
-			last->flag |= REF_KNOWS_PEELED;
-		}
-	}
-
-	strbuf_release(&line);
-}
-
-/*
- * Get the packed_ref_cache for the specified ref_cache, creating it
- * if necessary.
- */
-static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
-{
-	char *packed_refs_file;
-
-	if (*refs->name)
-		packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
-	else
-		packed_refs_file = git_pathdup("packed-refs");
-
-	if (refs->packed &&
-	    !stat_validity_check(&refs->packed->validity, packed_refs_file))
-		clear_packed_ref_cache(refs);
-
-	if (!refs->packed) {
-		FILE *f;
-
-		refs->packed = xcalloc(1, sizeof(*refs->packed));
-		acquire_packed_ref_cache(refs->packed);
-		refs->packed->root = create_dir_entry(refs, "", 0, 0);
-		f = fopen(packed_refs_file, "r");
-		if (f) {
-			stat_validity_update(&refs->packed->validity, fileno(f));
-			read_packed_refs(f, get_ref_dir(refs->packed->root));
-			fclose(f);
-		}
-	}
-	free(packed_refs_file);
-	return refs->packed;
-}
-
-static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
-{
-	return get_ref_dir(packed_ref_cache->root);
-}
-
-static struct ref_dir *get_packed_refs(struct ref_cache *refs)
-{
-	return get_packed_ref_dir(get_packed_ref_cache(refs));
-}
-
-/*
- * Add a reference to the in-memory packed reference cache.  This may
- * only be called while the packed-refs file is locked (see
- * lock_packed_refs()).  To actually write the packed-refs file, call
- * commit_packed_refs().
- */
-static void add_packed_ref(const char *refname, const unsigned char *sha1)
-{
-	struct packed_ref_cache *packed_ref_cache =
-		get_packed_ref_cache(&ref_cache);
-
-	if (!packed_ref_cache->lock)
-		die("internal error: packed refs not locked");
-	add_ref(get_packed_ref_dir(packed_ref_cache),
-		create_ref_entry(refname, sha1, REF_ISPACKED, 1));
-}
-
-/*
- * Read the loose references from the namespace dirname into dir
- * (without recursing).  dirname must end with '/'.  dir must be the
- * directory entry corresponding to dirname.
- */
-static void read_loose_refs(const char *dirname, struct ref_dir *dir)
-{
-	struct ref_cache *refs = dir->ref_cache;
-	DIR *d;
-	struct dirent *de;
-	int dirnamelen = strlen(dirname);
-	struct strbuf refname;
-	struct strbuf path = STRBUF_INIT;
-	size_t path_baselen;
-
-	if (*refs->name)
-		strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
-	else
-		strbuf_git_path(&path, "%s", dirname);
-	path_baselen = path.len;
-
-	d = opendir(path.buf);
-	if (!d) {
-		strbuf_release(&path);
-		return;
-	}
-
-	strbuf_init(&refname, dirnamelen + 257);
-	strbuf_add(&refname, dirname, dirnamelen);
-
-	while ((de = readdir(d)) != NULL) {
-		unsigned char sha1[20];
-		struct stat st;
-		int flag;
-
-		if (de->d_name[0] == '.')
-			continue;
-		if (ends_with(de->d_name, ".lock"))
-			continue;
-		strbuf_addstr(&refname, de->d_name);
-		strbuf_addstr(&path, de->d_name);
-		if (stat(path.buf, &st) < 0) {
-			; /* silently ignore */
-		} else if (S_ISDIR(st.st_mode)) {
-			strbuf_addch(&refname, '/');
-			add_entry_to_dir(dir,
-					 create_dir_entry(refs, refname.buf,
-							  refname.len, 1));
-		} else {
-			int read_ok;
-
-			if (*refs->name) {
-				hashclr(sha1);
-				flag = 0;
-				read_ok = !resolve_gitlink_ref(refs->name,
-							       refname.buf, sha1);
-			} else {
-				read_ok = !read_ref_full(refname.buf,
-							 RESOLVE_REF_READING,
-							 sha1, &flag);
-			}
-
-			if (!read_ok) {
-				hashclr(sha1);
-				flag |= REF_ISBROKEN;
-			} else if (is_null_sha1(sha1)) {
-				/*
-				 * It is so astronomically unlikely
-				 * that NULL_SHA1 is the SHA-1 of an
-				 * actual object that we consider its
-				 * appearance in a loose reference
-				 * file to be repo corruption
-				 * (probably due to a software bug).
-				 */
-				flag |= REF_ISBROKEN;
-			}
-
-			if (check_refname_format(refname.buf,
-						 REFNAME_ALLOW_ONELEVEL)) {
-				if (!refname_is_safe(refname.buf))
-					die("loose refname is dangerous: %s", refname.buf);
-				hashclr(sha1);
-				flag |= REF_BAD_NAME | REF_ISBROKEN;
-			}
-			add_entry_to_dir(dir,
-					 create_ref_entry(refname.buf, sha1, flag, 0));
-		}
-		strbuf_setlen(&refname, dirnamelen);
-		strbuf_setlen(&path, path_baselen);
-	}
-	strbuf_release(&refname);
-	strbuf_release(&path);
-	closedir(d);
-}
-
-static struct ref_dir *get_loose_refs(struct ref_cache *refs)
-{
-	if (!refs->loose) {
-		/*
-		 * Mark the top-level directory complete because we
-		 * are about to read the only subdirectory that can
-		 * hold references:
-		 */
-		refs->loose = create_dir_entry(refs, "", 0, 0);
-		/*
-		 * Create an incomplete entry for "refs/":
-		 */
-		add_entry_to_dir(get_ref_dir(refs->loose),
-				 create_dir_entry(refs, "refs/", 5, 1));
-	}
-	return get_ref_dir(refs->loose);
-}
-
-/* We allow "recursive" symbolic refs. Only within reason, though */
-#define MAXDEPTH 5
-#define MAXREFLEN (1024)
-
-/*
- * Called by resolve_gitlink_ref_recursive() after it failed to read
- * from the loose refs in ref_cache refs. Find <refname> in the
- * packed-refs file for the submodule.
- */
-static int resolve_gitlink_packed_ref(struct ref_cache *refs,
-				      const char *refname, unsigned char *sha1)
-{
-	struct ref_entry *ref;
-	struct ref_dir *dir = get_packed_refs(refs);
-
-	ref = find_ref(dir, refname);
-	if (ref == NULL)
-		return -1;
-
-	hashcpy(sha1, ref->u.value.oid.hash);
-	return 0;
-}
-
-static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
-					 const char *refname, unsigned char *sha1,
-					 int recursion)
-{
-	int fd, len;
-	char buffer[128], *p;
-	char *path;
-
-	if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
-		return -1;
-	path = *refs->name
-		? git_pathdup_submodule(refs->name, "%s", refname)
-		: git_pathdup("%s", refname);
-	fd = open(path, O_RDONLY);
-	free(path);
-	if (fd < 0)
-		return resolve_gitlink_packed_ref(refs, refname, sha1);
-
-	len = read(fd, buffer, sizeof(buffer)-1);
-	close(fd);
-	if (len < 0)
-		return -1;
-	while (len && isspace(buffer[len-1]))
-		len--;
-	buffer[len] = 0;
-
-	/* Was it a detached head or an old-fashioned symlink? */
-	if (!get_sha1_hex(buffer, sha1))
-		return 0;
-
-	/* Symref? */
-	if (strncmp(buffer, "ref:", 4))
-		return -1;
-	p = buffer + 4;
-	while (isspace(*p))
-		p++;
-
-	return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
-}
-
-int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
-{
-	int len = strlen(path), retval;
-	char *submodule;
-	struct ref_cache *refs;
-
-	while (len && path[len-1] == '/')
-		len--;
-	if (!len)
-		return -1;
-	submodule = xstrndup(path, len);
-	refs = get_ref_cache(submodule);
-	free(submodule);
-
-	retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
-	return retval;
-}
-
-/*
- * Return the ref_entry for the given refname from the packed
- * references.  If it does not exist, return NULL.
- */
-static struct ref_entry *get_packed_ref(const char *refname)
-{
-	return find_ref(get_packed_refs(&ref_cache), refname);
-}
-
-/*
- * A loose ref file doesn't exist; check for a packed ref.  The
- * options are forwarded from resolve_safe_unsafe().
- */
-static int resolve_missing_loose_ref(const char *refname,
-				     int resolve_flags,
-				     unsigned char *sha1,
-				     int *flags)
-{
-	struct ref_entry *entry;
-
-	/*
-	 * The loose reference file does not exist; check for a packed
-	 * reference.
-	 */
-	entry = get_packed_ref(refname);
-	if (entry) {
-		hashcpy(sha1, entry->u.value.oid.hash);
-		if (flags)
-			*flags |= REF_ISPACKED;
-		return 0;
-	}
-	/* The reference is not a packed reference, either. */
-	if (resolve_flags & RESOLVE_REF_READING) {
-		errno = ENOENT;
-		return -1;
-	} else {
-		hashclr(sha1);
-		return 0;
-	}
-}
-
-/* This function needs to return a meaningful errno on failure */
-static const char *resolve_ref_1(const char *refname,
-				 int resolve_flags,
-				 unsigned char *sha1,
-				 int *flags,
-				 struct strbuf *sb_refname,
-				 struct strbuf *sb_path,
-				 struct strbuf *sb_contents)
-{
-	int depth = MAXDEPTH;
-	int bad_name = 0;
-
-	if (flags)
-		*flags = 0;
-
-	if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
-		if (flags)
-			*flags |= REF_BAD_NAME;
-
-		if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
-		    !refname_is_safe(refname)) {
-			errno = EINVAL;
-			return NULL;
-		}
-		/*
-		 * dwim_ref() uses REF_ISBROKEN to distinguish between
-		 * missing refs and refs that were present but invalid,
-		 * to complain about the latter to stderr.
-		 *
-		 * We don't know whether the ref exists, so don't set
-		 * REF_ISBROKEN yet.
-		 */
-		bad_name = 1;
-	}
-	for (;;) {
-		const char *path;
-		struct stat st;
-		char *buf;
-		int fd;
-
-		if (--depth < 0) {
-			errno = ELOOP;
-			return NULL;
-		}
-
-		strbuf_reset(sb_path);
-		strbuf_git_path(sb_path, "%s", refname);
-		path = sb_path->buf;
-
-		/*
-		 * We might have to loop back here to avoid a race
-		 * condition: first we lstat() the file, then we try
-		 * to read it as a link or as a file.  But if somebody
-		 * changes the type of the file (file <-> directory
-		 * <-> symlink) between the lstat() and reading, then
-		 * we don't want to report that as an error but rather
-		 * try again starting with the lstat().
-		 */
-	stat_ref:
-		if (lstat(path, &st) < 0) {
-			if (errno != ENOENT)
-				return NULL;
-			if (resolve_missing_loose_ref(refname, resolve_flags,
-						      sha1, flags))
-				return NULL;
-			if (bad_name) {
-				hashclr(sha1);
-				if (flags)
-					*flags |= REF_ISBROKEN;
-			}
-			return refname;
-		}
-
-		/* Follow "normalized" - ie "refs/.." symlinks by hand */
-		if (S_ISLNK(st.st_mode)) {
-			strbuf_reset(sb_contents);
-			if (strbuf_readlink(sb_contents, path, 0) < 0) {
-				if (errno == ENOENT || errno == EINVAL)
-					/* inconsistent with lstat; retry */
-					goto stat_ref;
-				else
-					return NULL;
-			}
-			if (starts_with(sb_contents->buf, "refs/") &&
-			    !check_refname_format(sb_contents->buf, 0)) {
-				strbuf_swap(sb_refname, sb_contents);
-				refname = sb_refname->buf;
-				if (flags)
-					*flags |= REF_ISSYMREF;
-				if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
-					hashclr(sha1);
-					return refname;
-				}
-				continue;
-			}
-		}
-
-		/* Is it a directory? */
-		if (S_ISDIR(st.st_mode)) {
-			errno = EISDIR;
-			return NULL;
-		}
-
-		/*
-		 * Anything else, just open it and try to use it as
-		 * a ref
-		 */
-		fd = open(path, O_RDONLY);
-		if (fd < 0) {
-			if (errno == ENOENT)
-				/* inconsistent with lstat; retry */
-				goto stat_ref;
-			else
-				return NULL;
-		}
-		strbuf_reset(sb_contents);
-		if (strbuf_read(sb_contents, fd, 256) < 0) {
-			int save_errno = errno;
-			close(fd);
-			errno = save_errno;
-			return NULL;
-		}
-		close(fd);
-		strbuf_rtrim(sb_contents);
-
-		/*
-		 * Is it a symbolic ref?
-		 */
-		if (!starts_with(sb_contents->buf, "ref:")) {
-			/*
-			 * Please note that FETCH_HEAD has a second
-			 * line containing other data.
-			 */
-			if (get_sha1_hex(sb_contents->buf, sha1) ||
-			    (sb_contents->buf[40] != '\0' && !isspace(sb_contents->buf[40]))) {
-				if (flags)
-					*flags |= REF_ISBROKEN;
-				errno = EINVAL;
-				return NULL;
-			}
-			if (bad_name) {
-				hashclr(sha1);
-				if (flags)
-					*flags |= REF_ISBROKEN;
-			}
-			return refname;
-		}
-		if (flags)
-			*flags |= REF_ISSYMREF;
-		buf = sb_contents->buf + 4;
-		while (isspace(*buf))
-			buf++;
-		strbuf_reset(sb_refname);
-		strbuf_addstr(sb_refname, buf);
-		refname = sb_refname->buf;
-		if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
-			hashclr(sha1);
-			return refname;
-		}
-		if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
-			if (flags)
-				*flags |= REF_ISBROKEN;
-
-			if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
-			    !refname_is_safe(buf)) {
-				errno = EINVAL;
-				return NULL;
-			}
-			bad_name = 1;
-		}
-	}
-}
-
-const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
-			       unsigned char *sha1, int *flags)
-{
-	static struct strbuf sb_refname = STRBUF_INIT;
-	struct strbuf sb_contents = STRBUF_INIT;
-	struct strbuf sb_path = STRBUF_INIT;
-	const char *ret;
-
-	ret = resolve_ref_1(refname, resolve_flags, sha1, flags,
-			    &sb_refname, &sb_path, &sb_contents);
-	strbuf_release(&sb_path);
-	strbuf_release(&sb_contents);
-	return ret;
-}
-
 char *resolve_refdup(const char *refname, int resolve_flags,
 		     unsigned char *sha1, int *flags)
 {
@@ -1831,39 +184,7 @@ static int filter_refs(const char *refname, const struct object_id *oid,
 	return filter->fn(refname, oid, flags, filter->cb_data);
 }
 
-enum peel_status {
-	/* object was peeled successfully: */
-	PEEL_PEELED = 0,
-
-	/*
-	 * object cannot be peeled because the named object (or an
-	 * object referred to by a tag in the peel chain), does not
-	 * exist.
-	 */
-	PEEL_INVALID = -1,
-
-	/* object cannot be peeled because it is not a tag: */
-	PEEL_NON_TAG = -2,
-
-	/* ref_entry contains no peeled value because it is a symref: */
-	PEEL_IS_SYMREF = -3,
-
-	/*
-	 * ref_entry cannot be peeled because it is broken (i.e., the
-	 * symbolic reference cannot even be resolved to an object
-	 * name):
-	 */
-	PEEL_BROKEN = -4
-};
-
-/*
- * Peel the named object; i.e., if the object is a tag, resolve the
- * tag recursively until a non-tag is found.  If successful, store the
- * result to sha1 and return PEEL_PEELED.  If the object is not a tag
- * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
- * and leave sha1 unchanged.
- */
-static enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
+enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 {
 	struct object *o = lookup_unknown_object(name);
 
@@ -1884,78 +205,6 @@ static enum peel_status peel_object(const unsigned char *name, unsigned char *sh
 	return PEEL_PEELED;
 }
 
-/*
- * Peel the entry (if possible) and return its new peel_status.  If
- * repeel is true, re-peel the entry even if there is an old peeled
- * value that is already stored in it.
- *
- * It is OK to call this function with a packed reference entry that
- * might be stale and might even refer to an object that has since
- * been garbage-collected.  In such a case, if the entry has
- * REF_KNOWS_PEELED then leave the status unchanged and return
- * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
- */
-static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
-{
-	enum peel_status status;
-
-	if (entry->flag & REF_KNOWS_PEELED) {
-		if (repeel) {
-			entry->flag &= ~REF_KNOWS_PEELED;
-			oidclr(&entry->u.value.peeled);
-		} else {
-			return is_null_oid(&entry->u.value.peeled) ?
-				PEEL_NON_TAG : PEEL_PEELED;
-		}
-	}
-	if (entry->flag & REF_ISBROKEN)
-		return PEEL_BROKEN;
-	if (entry->flag & REF_ISSYMREF)
-		return PEEL_IS_SYMREF;
-
-	status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
-	if (status == PEEL_PEELED || status == PEEL_NON_TAG)
-		entry->flag |= REF_KNOWS_PEELED;
-	return status;
-}
-
-int peel_ref(const char *refname, unsigned char *sha1)
-{
-	int flag;
-	unsigned char base[20];
-
-	if (current_ref && (current_ref->name == refname
-			    || !strcmp(current_ref->name, refname))) {
-		if (peel_entry(current_ref, 0))
-			return -1;
-		hashcpy(sha1, current_ref->u.value.peeled.hash);
-		return 0;
-	}
-
-	if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
-		return -1;
-
-	/*
-	 * If the reference is packed, read its ref_entry from the
-	 * cache in the hope that we already know its peeled value.
-	 * We only try this optimization on packed references because
-	 * (a) forcing the filling of the loose reference cache could
-	 * be expensive and (b) loose references anyway usually do not
-	 * have REF_KNOWS_PEELED.
-	 */
-	if (flag & REF_ISPACKED) {
-		struct ref_entry *r = get_packed_ref(refname);
-		if (r) {
-			if (peel_entry(r, 0))
-				return -1;
-			hashcpy(sha1, r->u.value.peeled.hash);
-			return 0;
-		}
-	}
-
-	return peel_object(base, sha1);
-}
-
 struct warn_if_dangling_data {
 	FILE *fp;
 	const char *refname;
@@ -2008,147 +257,6 @@ void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_li
 	for_each_rawref(warn_if_dangling_symref, &data);
 }
 
-/*
- * Call fn for each reference in the specified ref_cache, omitting
- * references not in the containing_dir of base.  fn is called for all
- * references, including broken ones.  If fn ever returns a non-zero
- * value, stop the iteration and return that value; otherwise, return
- * 0.
- */
-static int do_for_each_entry(struct ref_cache *refs, const char *base,
-			     each_ref_entry_fn fn, void *cb_data)
-{
-	struct packed_ref_cache *packed_ref_cache;
-	struct ref_dir *loose_dir;
-	struct ref_dir *packed_dir;
-	int retval = 0;
-
-	/*
-	 * We must make sure that all loose refs are read before accessing the
-	 * packed-refs file; this avoids a race condition in which loose refs
-	 * are migrated to the packed-refs file by a simultaneous process, but
-	 * our in-memory view is from before the migration. get_packed_ref_cache()
-	 * takes care of making sure our view is up to date with what is on
-	 * disk.
-	 */
-	loose_dir = get_loose_refs(refs);
-	if (base && *base) {
-		loose_dir = find_containing_dir(loose_dir, base, 0);
-	}
-	if (loose_dir)
-		prime_ref_dir(loose_dir);
-
-	packed_ref_cache = get_packed_ref_cache(refs);
-	acquire_packed_ref_cache(packed_ref_cache);
-	packed_dir = get_packed_ref_dir(packed_ref_cache);
-	if (base && *base) {
-		packed_dir = find_containing_dir(packed_dir, base, 0);
-	}
-
-	if (packed_dir && loose_dir) {
-		sort_ref_dir(packed_dir);
-		sort_ref_dir(loose_dir);
-		retval = do_for_each_entry_in_dirs(
-				packed_dir, loose_dir, fn, cb_data);
-	} else if (packed_dir) {
-		sort_ref_dir(packed_dir);
-		retval = do_for_each_entry_in_dir(
-				packed_dir, 0, fn, cb_data);
-	} else if (loose_dir) {
-		sort_ref_dir(loose_dir);
-		retval = do_for_each_entry_in_dir(
-				loose_dir, 0, fn, cb_data);
-	}
-
-	release_packed_ref_cache(packed_ref_cache);
-	return retval;
-}
-
-/*
- * Call fn for each reference in the specified ref_cache for which the
- * refname begins with base.  If trim is non-zero, then trim that many
- * characters off the beginning of each refname before passing the
- * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
- * broken references in the iteration.  If fn ever returns a non-zero
- * value, stop the iteration and return that value; otherwise, return
- * 0.
- */
-static int do_for_each_ref(struct ref_cache *refs, const char *base,
-			   each_ref_fn fn, int trim, int flags, void *cb_data)
-{
-	struct ref_entry_cb data;
-	data.base = base;
-	data.trim = trim;
-	data.flags = flags;
-	data.fn = fn;
-	data.cb_data = cb_data;
-
-	if (ref_paranoia < 0)
-		ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
-	if (ref_paranoia)
-		data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
-
-	return do_for_each_entry(refs, base, do_one_ref, &data);
-}
-
-static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-	struct object_id oid;
-	int flag;
-
-	if (submodule) {
-		if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
-			return fn("HEAD", &oid, 0, cb_data);
-
-		return 0;
-	}
-
-	if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
-		return fn("HEAD", &oid, flag, cb_data);
-
-	return 0;
-}
-
-int head_ref(each_ref_fn fn, void *cb_data)
-{
-	return do_head_ref(NULL, fn, cb_data);
-}
-
-int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-	return do_head_ref(submodule, fn, cb_data);
-}
-
-int for_each_ref(each_ref_fn fn, void *cb_data)
-{
-	return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
-}
-
-int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
-{
-	return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
-}
-
-int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
-{
-	return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
-}
-
-int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
-{
-	unsigned int flag = 0;
-
-	if (broken)
-		flag = DO_FOR_EACH_INCLUDE_BROKEN;
-	return do_for_each_ref(&ref_cache, prefix, fn, 0, flag, cb_data);
-}
-
-int for_each_ref_in_submodule(const char *submodule, const char *prefix,
-		each_ref_fn fn, void *cb_data)
-{
-	return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
-}
-
 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 {
 	return for_each_ref_in("refs/tags/", fn, cb_data);
@@ -2179,12 +287,6 @@ int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *c
 	return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 }
 
-int for_each_replace_ref(each_ref_fn fn, void *cb_data)
-{
-	return do_for_each_ref(&ref_cache, git_replace_ref_base, fn,
-			       strlen(git_replace_ref_base), 0, cb_data);
-}
-
 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 {
 	struct strbuf buf = STRBUF_INIT;
@@ -2200,16 +302,6 @@ int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 	return ret;
 }
 
-int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
-{
-	struct strbuf buf = STRBUF_INIT;
-	int ret;
-	strbuf_addf(&buf, "%srefs/", get_git_namespace());
-	ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
-	strbuf_release(&buf);
-	return ret;
-}
-
 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 	const char *prefix, void *cb_data)
 {
@@ -2244,12 +336,6 @@ int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 	return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 }
 
-int for_each_rawref(each_ref_fn fn, void *cb_data)
-{
-	return do_for_each_ref(&ref_cache, "", fn, 0,
-			       DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
-}
-
 const char *prettify_refname(const char *name)
 {
 	return name + (
@@ -2283,57 +369,6 @@ int refname_match(const char *abbrev_name, const char *full_name)
 	return 0;
 }
 
-static void unlock_ref(struct ref_lock *lock)
-{
-	/* Do not free lock->lk -- atexit() still looks at them */
-	if (lock->lk)
-		rollback_lock_file(lock->lk);
-	free(lock->ref_name);
-	free(lock->orig_ref_name);
-	free(lock);
-}
-
-/*
- * Verify that the reference locked by lock has the value old_sha1.
- * Fail if the reference doesn't exist and mustexist is set. Return 0
- * on success. On error, write an error message to err, set errno, and
- * return a negative value.
- */
-static int verify_lock(struct ref_lock *lock,
-		       const unsigned char *old_sha1, int mustexist,
-		       struct strbuf *err)
-{
-	assert(err);
-
-	if (read_ref_full(lock->ref_name,
-			  mustexist ? RESOLVE_REF_READING : 0,
-			  lock->old_oid.hash, NULL)) {
-		int save_errno = errno;
-		strbuf_addf(err, "can't verify ref %s", lock->ref_name);
-		errno = save_errno;
-		return -1;
-	}
-	if (hashcmp(lock->old_oid.hash, old_sha1)) {
-		strbuf_addf(err, "ref %s is at %s but expected %s",
-			    lock->ref_name,
-			    sha1_to_hex(lock->old_oid.hash),
-			    sha1_to_hex(old_sha1));
-		errno = EBUSY;
-		return -1;
-	}
-	return 0;
-}
-
-static int remove_empty_directories(struct strbuf *path)
-{
-	/*
-	 * we want to create a file but there is a directory there;
-	 * if that is an empty directory (or a directory that contains
-	 * only empty directories), remove them.
-	 */
-	return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
-}
-
 /*
  * *string and *len will only be substituted, and *string returned (for
  * later free()ing) if the string passed in is a magic short-hand form
@@ -2420,480 +455,6 @@ int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 	return logs_found;
 }
 
-/*
- * Locks a ref returning the lock on success and NULL on failure.
- * On failure errno is set to something meaningful.
- */
-static struct ref_lock *lock_ref_sha1_basic(const char *refname,
-					    const unsigned char *old_sha1,
-					    const struct string_list *extras,
-					    const struct string_list *skip,
-					    unsigned int flags, int *type_p,
-					    struct strbuf *err)
-{
-	struct strbuf ref_file = STRBUF_INIT;
-	struct strbuf orig_ref_file = STRBUF_INIT;
-	const char *orig_refname = refname;
-	struct ref_lock *lock;
-	int last_errno = 0;
-	int type, lflags;
-	int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
-	int resolve_flags = 0;
-	int attempts_remaining = 3;
-
-	assert(err);
-
-	lock = xcalloc(1, sizeof(struct ref_lock));
-
-	if (mustexist)
-		resolve_flags |= RESOLVE_REF_READING;
-	if (flags & REF_DELETING) {
-		resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
-		if (flags & REF_NODEREF)
-			resolve_flags |= RESOLVE_REF_NO_RECURSE;
-	}
-
-	refname = resolve_ref_unsafe(refname, resolve_flags,
-				     lock->old_oid.hash, &type);
-	if (!refname && errno == EISDIR) {
-		/*
-		 * we are trying to lock foo but we used to
-		 * have foo/bar which now does not exist;
-		 * it is normal for the empty directory 'foo'
-		 * to remain.
-		 */
-		strbuf_git_path(&orig_ref_file, "%s", orig_refname);
-		if (remove_empty_directories(&orig_ref_file)) {
-			last_errno = errno;
-			if (!verify_refname_available(orig_refname, extras, skip,
-						      get_loose_refs(&ref_cache), err))
-				strbuf_addf(err, "there are still refs under '%s'",
-					    orig_refname);
-			goto error_return;
-		}
-		refname = resolve_ref_unsafe(orig_refname, resolve_flags,
-					     lock->old_oid.hash, &type);
-	}
-	if (type_p)
-	    *type_p = type;
-	if (!refname) {
-		last_errno = errno;
-		if (last_errno != ENOTDIR ||
-		    !verify_refname_available(orig_refname, extras, skip,
-					      get_loose_refs(&ref_cache), err))
-			strbuf_addf(err, "unable to resolve reference %s: %s",
-				    orig_refname, strerror(last_errno));
-
-		goto error_return;
-	}
-	/*
-	 * If the ref did not exist and we are creating it, make sure
-	 * there is no existing packed ref whose name begins with our
-	 * refname, nor a packed ref whose name is a proper prefix of
-	 * our refname.
-	 */
-	if (is_null_oid(&lock->old_oid) &&
-	    verify_refname_available(refname, extras, skip,
-				     get_packed_refs(&ref_cache), err)) {
-		last_errno = ENOTDIR;
-		goto error_return;
-	}
-
-	lock->lk = xcalloc(1, sizeof(struct lock_file));
-
-	lflags = 0;
-	if (flags & REF_NODEREF) {
-		refname = orig_refname;
-		lflags |= LOCK_NO_DEREF;
-	}
-	lock->ref_name = xstrdup(refname);
-	lock->orig_ref_name = xstrdup(orig_refname);
-	strbuf_git_path(&ref_file, "%s", refname);
-
- retry:
-	switch (safe_create_leading_directories_const(ref_file.buf)) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_VANISHED:
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
-		last_errno = errno;
-		strbuf_addf(err, "unable to create directory for %s",
-			    ref_file.buf);
-		goto error_return;
-	}
-
-	if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
-		last_errno = errno;
-		if (errno == ENOENT && --attempts_remaining > 0)
-			/*
-			 * Maybe somebody just deleted one of the
-			 * directories leading to ref_file.  Try
-			 * again:
-			 */
-			goto retry;
-		else {
-			unable_to_lock_message(ref_file.buf, errno, err);
-			goto error_return;
-		}
-	}
-	if (old_sha1 && verify_lock(lock, old_sha1, mustexist, err)) {
-		last_errno = errno;
-		goto error_return;
-	}
-	goto out;
-
- error_return:
-	unlock_ref(lock);
-	lock = NULL;
-
- out:
-	strbuf_release(&ref_file);
-	strbuf_release(&orig_ref_file);
-	errno = last_errno;
-	return lock;
-}
-
-/*
- * Write an entry to the packed-refs file for the specified refname.
- * If peeled is non-NULL, write it as the entry's peeled value.
- */
-static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
-			       unsigned char *peeled)
-{
-	fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
-	if (peeled)
-		fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
-}
-
-/*
- * An each_ref_entry_fn that writes the entry to a packed-refs file.
- */
-static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
-{
-	enum peel_status peel_status = peel_entry(entry, 0);
-
-	if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
-		error("internal error: %s is not a valid packed reference!",
-		      entry->name);
-	write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
-			   peel_status == PEEL_PEELED ?
-			   entry->u.value.peeled.hash : NULL);
-	return 0;
-}
-
-/*
- * Lock the packed-refs file for writing. Flags is passed to
- * hold_lock_file_for_update(). Return 0 on success. On errors, set
- * errno appropriately and return a nonzero value.
- */
-static int lock_packed_refs(int flags)
-{
-	static int timeout_configured = 0;
-	static int timeout_value = 1000;
-
-	struct packed_ref_cache *packed_ref_cache;
-
-	if (!timeout_configured) {
-		git_config_get_int("core.packedrefstimeout", &timeout_value);
-		timeout_configured = 1;
-	}
-
-	if (hold_lock_file_for_update_timeout(
-			    &packlock, git_path("packed-refs"),
-			    flags, timeout_value) < 0)
-		return -1;
-	/*
-	 * Get the current packed-refs while holding the lock.  If the
-	 * packed-refs file has been modified since we last read it,
-	 * this will automatically invalidate the cache and re-read
-	 * the packed-refs file.
-	 */
-	packed_ref_cache = get_packed_ref_cache(&ref_cache);
-	packed_ref_cache->lock = &packlock;
-	/* Increment the reference count to prevent it from being freed: */
-	acquire_packed_ref_cache(packed_ref_cache);
-	return 0;
-}
-
-/*
- * Write the current version of the packed refs cache from memory to
- * disk. The packed-refs file must already be locked for writing (see
- * lock_packed_refs()). Return zero on success. On errors, set errno
- * and return a nonzero value
- */
-static int commit_packed_refs(void)
-{
-	struct packed_ref_cache *packed_ref_cache =
-		get_packed_ref_cache(&ref_cache);
-	int error = 0;
-	int save_errno = 0;
-	FILE *out;
-
-	if (!packed_ref_cache->lock)
-		die("internal error: packed-refs not locked");
-
-	out = fdopen_lock_file(packed_ref_cache->lock, "w");
-	if (!out)
-		die_errno("unable to fdopen packed-refs descriptor");
-
-	fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
-	do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
-				 0, write_packed_entry_fn, out);
-
-	if (commit_lock_file(packed_ref_cache->lock)) {
-		save_errno = errno;
-		error = -1;
-	}
-	packed_ref_cache->lock = NULL;
-	release_packed_ref_cache(packed_ref_cache);
-	errno = save_errno;
-	return error;
-}
-
-/*
- * Rollback the lockfile for the packed-refs file, and discard the
- * in-memory packed reference cache.  (The packed-refs file will be
- * read anew if it is needed again after this function is called.)
- */
-static void rollback_packed_refs(void)
-{
-	struct packed_ref_cache *packed_ref_cache =
-		get_packed_ref_cache(&ref_cache);
-
-	if (!packed_ref_cache->lock)
-		die("internal error: packed-refs not locked");
-	rollback_lock_file(packed_ref_cache->lock);
-	packed_ref_cache->lock = NULL;
-	release_packed_ref_cache(packed_ref_cache);
-	clear_packed_ref_cache(&ref_cache);
-}
-
-struct ref_to_prune {
-	struct ref_to_prune *next;
-	unsigned char sha1[20];
-	char name[FLEX_ARRAY];
-};
-
-struct pack_refs_cb_data {
-	unsigned int flags;
-	struct ref_dir *packed_refs;
-	struct ref_to_prune *ref_to_prune;
-};
-
-static int is_per_worktree_ref(const char *refname);
-
-/*
- * An each_ref_entry_fn that is run over loose references only.  If
- * the loose reference can be packed, add an entry in the packed ref
- * cache.  If the reference should be pruned, also add it to
- * ref_to_prune in the pack_refs_cb_data.
- */
-static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
-{
-	struct pack_refs_cb_data *cb = cb_data;
-	enum peel_status peel_status;
-	struct ref_entry *packed_entry;
-	int is_tag_ref = starts_with(entry->name, "refs/tags/");
-
-	/* Do not pack per-worktree refs: */
-	if (is_per_worktree_ref(entry->name))
-		return 0;
-
-	/* ALWAYS pack tags */
-	if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
-		return 0;
-
-	/* Do not pack symbolic or broken refs: */
-	if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
-		return 0;
-
-	/* Add a packed ref cache entry equivalent to the loose entry. */
-	peel_status = peel_entry(entry, 1);
-	if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
-		die("internal error peeling reference %s (%s)",
-		    entry->name, oid_to_hex(&entry->u.value.oid));
-	packed_entry = find_ref(cb->packed_refs, entry->name);
-	if (packed_entry) {
-		/* Overwrite existing packed entry with info from loose entry */
-		packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
-		oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
-	} else {
-		packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
-						REF_ISPACKED | REF_KNOWS_PEELED, 0);
-		add_ref(cb->packed_refs, packed_entry);
-	}
-	oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
-
-	/* Schedule the loose reference for pruning if requested. */
-	if ((cb->flags & PACK_REFS_PRUNE)) {
-		int namelen = strlen(entry->name) + 1;
-		struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
-		hashcpy(n->sha1, entry->u.value.oid.hash);
-		memcpy(n->name, entry->name, namelen); /* includes NUL */
-		n->next = cb->ref_to_prune;
-		cb->ref_to_prune = n;
-	}
-	return 0;
-}
-
-/*
- * Remove empty parents, but spare refs/ and immediate subdirs.
- * Note: munges *name.
- */
-static void try_remove_empty_parents(char *name)
-{
-	char *p, *q;
-	int i;
-	p = name;
-	for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
-		while (*p && *p != '/')
-			p++;
-		/* tolerate duplicate slashes; see check_refname_format() */
-		while (*p == '/')
-			p++;
-	}
-	for (q = p; *q; q++)
-		;
-	while (1) {
-		while (q > p && *q != '/')
-			q--;
-		while (q > p && *(q-1) == '/')
-			q--;
-		if (q == p)
-			break;
-		*q = '\0';
-		if (rmdir(git_path("%s", name)))
-			break;
-	}
-}
-
-/* make sure nobody touched the ref, and unlink */
-static void prune_ref(struct ref_to_prune *r)
-{
-	struct ref_transaction *transaction;
-	struct strbuf err = STRBUF_INIT;
-
-	if (check_refname_format(r->name, 0))
-		return;
-
-	transaction = ref_transaction_begin(&err);
-	if (!transaction ||
-	    ref_transaction_delete(transaction, r->name, r->sha1,
-				   REF_ISPRUNING, NULL, &err) ||
-	    ref_transaction_commit(transaction, &err)) {
-		ref_transaction_free(transaction);
-		error("%s", err.buf);
-		strbuf_release(&err);
-		return;
-	}
-	ref_transaction_free(transaction);
-	strbuf_release(&err);
-	try_remove_empty_parents(r->name);
-}
-
-static void prune_refs(struct ref_to_prune *r)
-{
-	while (r) {
-		prune_ref(r);
-		r = r->next;
-	}
-}
-
-int pack_refs(unsigned int flags)
-{
-	struct pack_refs_cb_data cbdata;
-
-	memset(&cbdata, 0, sizeof(cbdata));
-	cbdata.flags = flags;
-
-	lock_packed_refs(LOCK_DIE_ON_ERROR);
-	cbdata.packed_refs = get_packed_refs(&ref_cache);
-
-	do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
-				 pack_if_possible_fn, &cbdata);
-
-	if (commit_packed_refs())
-		die_errno("unable to overwrite old ref-pack file");
-
-	prune_refs(cbdata.ref_to_prune);
-	return 0;
-}
-
-/*
- * Rewrite the packed-refs file, omitting any refs listed in
- * 'refnames'. On error, leave packed-refs unchanged, write an error
- * message to 'err', and return a nonzero value.
- *
- * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
- */
-static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
-{
-	struct ref_dir *packed;
-	struct string_list_item *refname;
-	int ret, needs_repacking = 0, removed = 0;
-
-	assert(err);
-
-	/* Look for a packed ref */
-	for_each_string_list_item(refname, refnames) {
-		if (get_packed_ref(refname->string)) {
-			needs_repacking = 1;
-			break;
-		}
-	}
-
-	/* Avoid locking if we have nothing to do */
-	if (!needs_repacking)
-		return 0; /* no refname exists in packed refs */
-
-	if (lock_packed_refs(0)) {
-		unable_to_lock_message(git_path("packed-refs"), errno, err);
-		return -1;
-	}
-	packed = get_packed_refs(&ref_cache);
-
-	/* Remove refnames from the cache */
-	for_each_string_list_item(refname, refnames)
-		if (remove_entry(packed, refname->string) != -1)
-			removed = 1;
-	if (!removed) {
-		/*
-		 * All packed entries disappeared while we were
-		 * acquiring the lock.
-		 */
-		rollback_packed_refs();
-		return 0;
-	}
-
-	/* Write what remains */
-	ret = commit_packed_refs();
-	if (ret)
-		strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
-			    strerror(errno));
-	return ret;
-}
-
-static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
-{
-	assert(err);
-
-	if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
-		/*
-		 * loose.  The loose file name is the same as the
-		 * lockfile name, minus ".lock":
-		 */
-		char *loose_filename = get_locked_file_path(lock->lk);
-		int res = unlink_or_msg(loose_filename, err);
-		free(loose_filename);
-		if (res)
-			return 1;
-	}
-	return 0;
-}
-
 static int is_per_worktree_ref(const char *refname)
 {
 	return !strcmp(refname, "HEAD") ||
@@ -3021,254 +582,7 @@ int delete_ref(const char *refname, const unsigned char *old_sha1,
 	return 0;
 }
 
-int delete_refs(struct string_list *refnames)
-{
-	struct strbuf err = STRBUF_INIT;
-	int i, result = 0;
-
-	if (!refnames->nr)
-		return 0;
-
-	result = repack_without_refs(refnames, &err);
-	if (result) {
-		/*
-		 * If we failed to rewrite the packed-refs file, then
-		 * it is unsafe to try to remove loose refs, because
-		 * doing so might expose an obsolete packed value for
-		 * a reference that might even point at an object that
-		 * has been garbage collected.
-		 */
-		if (refnames->nr == 1)
-			error(_("could not delete reference %s: %s"),
-			      refnames->items[0].string, err.buf);
-		else
-			error(_("could not delete references: %s"), err.buf);
-
-		goto out;
-	}
-
-	for (i = 0; i < refnames->nr; i++) {
-		const char *refname = refnames->items[i].string;
-
-		if (delete_ref(refname, NULL, 0))
-			result |= error(_("could not remove reference %s"), refname);
-	}
-
-out:
-	strbuf_release(&err);
-	return result;
-}
-
-/*
- * People using contrib's git-new-workdir have .git/logs/refs ->
- * /some/other/path/.git/logs/refs, and that may live on another device.
- *
- * IOW, to avoid cross device rename errors, the temporary renamed log must
- * live into logs/refs.
- */
-#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
-
-static int rename_tmp_log(const char *newrefname)
-{
-	int attempts_remaining = 4;
-	struct strbuf path = STRBUF_INIT;
-	int ret = -1;
-
- retry:
-	strbuf_reset(&path);
-	strbuf_git_path(&path, "logs/%s", newrefname);
-	switch (safe_create_leading_directories_const(path.buf)) {
-	case SCLD_OK:
-		break; /* success */
-	case SCLD_VANISHED:
-		if (--attempts_remaining > 0)
-			goto retry;
-		/* fall through */
-	default:
-		error("unable to create directory for %s", newrefname);
-		goto out;
-	}
-
-	if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
-		if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
-			/*
-			 * rename(a, b) when b is an existing
-			 * directory ought to result in ISDIR, but
-			 * Solaris 5.8 gives ENOTDIR.  Sheesh.
-			 */
-			if (remove_empty_directories(&path)) {
-				error("Directory not empty: logs/%s", newrefname);
-				goto out;
-			}
-			goto retry;
-		} else if (errno == ENOENT && --attempts_remaining > 0) {
-			/*
-			 * Maybe another process just deleted one of
-			 * the directories in the path to newrefname.
-			 * Try again from the beginning.
-			 */
-			goto retry;
-		} else {
-			error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
-				newrefname, strerror(errno));
-			goto out;
-		}
-	}
-	ret = 0;
-out:
-	strbuf_release(&path);
-	return ret;
-}
-
-static int rename_ref_available(const char *oldname, const char *newname)
-{
-	struct string_list skip = STRING_LIST_INIT_NODUP;
-	struct strbuf err = STRBUF_INIT;
-	int ret;
-
-	string_list_insert(&skip, oldname);
-	ret = !verify_refname_available(newname, NULL, &skip,
-					get_packed_refs(&ref_cache), &err)
-		&& !verify_refname_available(newname, NULL, &skip,
-					     get_loose_refs(&ref_cache), &err);
-	if (!ret)
-		error("%s", err.buf);
-
-	string_list_clear(&skip, 0);
-	strbuf_release(&err);
-	return ret;
-}
-
-static int write_ref_to_lockfile(struct ref_lock *lock,
-				 const unsigned char *sha1, struct strbuf *err);
-static int commit_ref_update(struct ref_lock *lock,
-			     const unsigned char *sha1, const char *logmsg,
-			     int flags, struct strbuf *err);
-
-int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
-{
-	unsigned char sha1[20], orig_sha1[20];
-	int flag = 0, logmoved = 0;
-	struct ref_lock *lock;
-	struct stat loginfo;
-	int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
-	const char *symref = NULL;
-	struct strbuf err = STRBUF_INIT;
-
-	if (log && S_ISLNK(loginfo.st_mode))
-		return error("reflog for %s is a symlink", oldrefname);
-
-	symref = resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING,
-				    orig_sha1, &flag);
-	if (flag & REF_ISSYMREF)
-		return error("refname %s is a symbolic ref, renaming it is not supported",
-			oldrefname);
-	if (!symref)
-		return error("refname %s not found", oldrefname);
-
-	if (!rename_ref_available(oldrefname, newrefname))
-		return 1;
-
-	if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
-		return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-
-	if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
-		error("unable to delete old %s", oldrefname);
-		goto rollback;
-	}
-
-	if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
-	    delete_ref(newrefname, sha1, REF_NODEREF)) {
-		if (errno==EISDIR) {
-			struct strbuf path = STRBUF_INIT;
-			int result;
-
-			strbuf_git_path(&path, "%s", newrefname);
-			result = remove_empty_directories(&path);
-			strbuf_release(&path);
-
-			if (result) {
-				error("Directory not empty: %s", newrefname);
-				goto rollback;
-			}
-		} else {
-			error("unable to delete existing %s", newrefname);
-			goto rollback;
-		}
-	}
-
-	if (log && rename_tmp_log(newrefname))
-		goto rollback;
-
-	logmoved = log;
-
-	lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, 0, NULL, &err);
-	if (!lock) {
-		error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
-		strbuf_release(&err);
-		goto rollback;
-	}
-	hashcpy(lock->old_oid.hash, orig_sha1);
-
-	if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-	    commit_ref_update(lock, orig_sha1, logmsg, 0, &err)) {
-		error("unable to write current sha1 into %s: %s", newrefname, err.buf);
-		strbuf_release(&err);
-		goto rollback;
-	}
-
-	return 0;
-
- rollback:
-	lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, 0, NULL, &err);
-	if (!lock) {
-		error("unable to lock %s for rollback: %s", oldrefname, err.buf);
-		strbuf_release(&err);
-		goto rollbacklog;
-	}
-
-	flag = log_all_ref_updates;
-	log_all_ref_updates = 0;
-	if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
-	    commit_ref_update(lock, orig_sha1, NULL, 0, &err)) {
-		error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
-		strbuf_release(&err);
-	}
-	log_all_ref_updates = flag;
-
- rollbacklog:
-	if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from %s: %s",
-			oldrefname, newrefname, strerror(errno));
-	if (!logmoved && log &&
-	    rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
-		error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
-			oldrefname, strerror(errno));
-
-	return 1;
-}
-
-static int close_ref(struct ref_lock *lock)
-{
-	if (close_lock_file(lock->lk))
-		return -1;
-	return 0;
-}
-
-static int commit_ref(struct ref_lock *lock)
-{
-	if (commit_lock_file(lock->lk))
-		return -1;
-	return 0;
-}
-
-/*
- * copy the reflog message msg to buf, which has been allocated sufficiently
- * large, while cleaning up the whitespaces.  Especially, convert LF to space,
- * because reflog file is one line per entry.
- */
-static int copy_msg(char *buf, const char *msg)
+int copy_reflog_msg(char *buf, const char *msg)
 {
 	char *cp = buf;
 	char c;
@@ -3289,7 +603,7 @@ static int copy_msg(char *buf, const char *msg)
 	return cp - buf;
 }
 
-static int should_autocreate_reflog(const char *refname)
+int should_autocreate_reflog(const char *refname)
 {
 	if (!log_all_ref_updates)
 		return 0;
@@ -3299,305 +613,11 @@ static int should_autocreate_reflog(const char *refname)
 		!strcmp(refname, "HEAD");
 }
 
-/*
- * Create a reflog for a ref.  If force_create = 0, the reflog will
- * only be created for certain refs (those for which
- * should_autocreate_reflog returns non-zero.  Otherwise, create it
- * regardless of the ref name.  Fill in *err and return -1 on failure.
- */
-static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
-{
-	int logfd, oflags = O_APPEND | O_WRONLY;
-
-	strbuf_git_path(logfile, "logs/%s", refname);
-	if (force_create || should_autocreate_reflog(refname)) {
-		if (safe_create_leading_directories(logfile->buf) < 0) {
-			strbuf_addf(err, "unable to create directory for %s: "
-				    "%s", logfile->buf, strerror(errno));
-			return -1;
-		}
-		oflags |= O_CREAT;
-	}
-
-	logfd = open(logfile->buf, oflags, 0666);
-	if (logfd < 0) {
-		if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
-			return 0;
-
-		if (errno == EISDIR) {
-			if (remove_empty_directories(logfile)) {
-				strbuf_addf(err, "There are still logs under "
-					    "'%s'", logfile->buf);
-				return -1;
-			}
-			logfd = open(logfile->buf, oflags, 0666);
-		}
-
-		if (logfd < 0) {
-			strbuf_addf(err, "unable to append to %s: %s",
-				    logfile->buf, strerror(errno));
-			return -1;
-		}
-	}
-
-	adjust_shared_perm(logfile->buf);
-	close(logfd);
-	return 0;
-}
-
-
-int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
-{
-	int ret;
-	struct strbuf sb = STRBUF_INIT;
-
-	ret = log_ref_setup(refname, &sb, err, force_create);
-	strbuf_release(&sb);
-	return ret;
-}
-
-static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
-			    const unsigned char *new_sha1,
-			    const char *committer, const char *msg)
-{
-	int msglen, written;
-	unsigned maxlen, len;
-	char *logrec;
-
-	msglen = msg ? strlen(msg) : 0;
-	maxlen = strlen(committer) + msglen + 100;
-	logrec = xmalloc(maxlen);
-	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
-			sha1_to_hex(old_sha1),
-			sha1_to_hex(new_sha1),
-			committer);
-	if (msglen)
-		len += copy_msg(logrec + len - 1, msg) - 1;
-
-	written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
-	free(logrec);
-	if (written != len)
-		return -1;
-
-	return 0;
-}
-
-static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
-			   const unsigned char *new_sha1, const char *msg,
-			   struct strbuf *logfile, int flags,
-			   struct strbuf *err)
-{
-	int logfd, result, oflags = O_APPEND | O_WRONLY;
-
-	if (log_all_ref_updates < 0)
-		log_all_ref_updates = !is_bare_repository();
-
-	result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
-
-	if (result)
-		return result;
-
-	logfd = open(logfile->buf, oflags);
-	if (logfd < 0)
-		return 0;
-	result = log_ref_write_fd(logfd, old_sha1, new_sha1,
-				  git_committer_info(0), msg);
-	if (result) {
-		strbuf_addf(err, "unable to append to %s: %s", logfile->buf,
-			    strerror(errno));
-		close(logfd);
-		return -1;
-	}
-	if (close(logfd)) {
-		strbuf_addf(err, "unable to append to %s: %s", logfile->buf,
-			    strerror(errno));
-		return -1;
-	}
-	return 0;
-}
-
-static int log_ref_write(const char *refname, const unsigned char *old_sha1,
-			 const unsigned char *new_sha1, const char *msg,
-			 int flags, struct strbuf *err)
-{
-	struct strbuf sb = STRBUF_INIT;
-	int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
-				  err);
-	strbuf_release(&sb);
-	return ret;
-}
-
 int is_branch(const char *refname)
 {
 	return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 }
 
-/*
- * Write sha1 into the open lockfile, then close the lockfile. On
- * errors, rollback the lockfile, fill in *err and
- * return -1.
- */
-static int write_ref_to_lockfile(struct ref_lock *lock,
-				 const unsigned char *sha1, struct strbuf *err)
-{
-	static char term = '\n';
-	struct object *o;
-	int fd;
-
-	o = parse_object(sha1);
-	if (!o) {
-		strbuf_addf(err,
-			    "Trying to write ref %s with nonexistent object %s",
-			    lock->ref_name, sha1_to_hex(sha1));
-		unlock_ref(lock);
-		return -1;
-	}
-	if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
-		strbuf_addf(err,
-			    "Trying to write non-commit object %s to branch %s",
-			    sha1_to_hex(sha1), lock->ref_name);
-		unlock_ref(lock);
-		return -1;
-	}
-	fd = get_lock_file_fd(lock->lk);
-	if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
-	    write_in_full(fd, &term, 1) != 1 ||
-	    close_ref(lock) < 0) {
-		strbuf_addf(err,
-			    "Couldn't write %s", get_lock_file_path(lock->lk));
-		unlock_ref(lock);
-		return -1;
-	}
-	return 0;
-}
-
-/*
- * Commit a change to a loose reference that has already been written
- * to the loose reference lockfile. Also update the reflogs if
- * necessary, using the specified lockmsg (which can be NULL).
- */
-static int commit_ref_update(struct ref_lock *lock,
-			     const unsigned char *sha1, const char *logmsg,
-			     int flags, struct strbuf *err)
-{
-	clear_loose_ref_cache(&ref_cache);
-	if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0 ||
-	    (strcmp(lock->ref_name, lock->orig_ref_name) &&
-	     log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0)) {
-		char *old_msg = strbuf_detach(err, NULL);
-		strbuf_addf(err, "Cannot update the ref '%s': %s",
-			    lock->ref_name, old_msg);
-		free(old_msg);
-		unlock_ref(lock);
-		return -1;
-	}
-	if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
-		/*
-		 * Special hack: If a branch is updated directly and HEAD
-		 * points to it (may happen on the remote side of a push
-		 * for example) then logically the HEAD reflog should be
-		 * updated too.
-		 * A generic solution implies reverse symref information,
-		 * but finding all symrefs pointing to the given branch
-		 * would be rather costly for this rare event (the direct
-		 * update of a branch) to be worth it.  So let's cheat and
-		 * check with HEAD only which should cover 99% of all usage
-		 * scenarios (even 100% of the default ones).
-		 */
-		unsigned char head_sha1[20];
-		int head_flag;
-		const char *head_ref;
-		head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
-					      head_sha1, &head_flag);
-		if (head_ref && (head_flag & REF_ISSYMREF) &&
-		    !strcmp(head_ref, lock->ref_name)) {
-			struct strbuf log_err = STRBUF_INIT;
-			if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
-					  logmsg, 0, &log_err)) {
-				error("%s", log_err.buf);
-				strbuf_release(&log_err);
-			}
-		}
-	}
-	if (commit_ref(lock)) {
-		error("Couldn't set %s", lock->ref_name);
-		unlock_ref(lock);
-		return -1;
-	}
-
-	unlock_ref(lock);
-	return 0;
-}
-
-int create_symref(const char *ref_target, const char *refs_heads_master,
-		  const char *logmsg)
-{
-	char *lockpath = NULL;
-	char ref[1000];
-	int fd, len, written;
-	char *git_HEAD = git_pathdup("%s", ref_target);
-	unsigned char old_sha1[20], new_sha1[20];
-	struct strbuf err = STRBUF_INIT;
-
-	if (logmsg && read_ref(ref_target, old_sha1))
-		hashclr(old_sha1);
-
-	if (safe_create_leading_directories(git_HEAD) < 0)
-		return error("unable to create directory for %s", git_HEAD);
-
-#ifndef NO_SYMLINK_HEAD
-	if (prefer_symlink_refs) {
-		unlink(git_HEAD);
-		if (!symlink(refs_heads_master, git_HEAD))
-			goto done;
-		fprintf(stderr, "no symlink - falling back to symbolic ref\n");
-	}
-#endif
-
-	len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
-	if (sizeof(ref) <= len) {
-		error("refname too long: %s", refs_heads_master);
-		goto error_free_return;
-	}
-	lockpath = mkpathdup("%s.lock", git_HEAD);
-	fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
-	if (fd < 0) {
-		error("Unable to open %s for writing", lockpath);
-		goto error_free_return;
-	}
-	written = write_in_full(fd, ref, len);
-	if (close(fd) != 0 || written != len) {
-		error("Unable to write to %s", lockpath);
-		goto error_unlink_return;
-	}
-	if (rename(lockpath, git_HEAD) < 0) {
-		error("Unable to create %s", git_HEAD);
-		goto error_unlink_return;
-	}
-	if (adjust_shared_perm(git_HEAD)) {
-		error("Unable to fix permissions on %s", lockpath);
-	error_unlink_return:
-		unlink_or_warn(lockpath);
-	error_free_return:
-		free(lockpath);
-		free(git_HEAD);
-		return -1;
-	}
-	free(lockpath);
-
-#ifndef NO_SYMLINK_HEAD
-	done:
-#endif
-	if (logmsg && !read_ref(refs_heads_master, new_sha1) &&
-		log_ref_write(ref_target, old_sha1, new_sha1, logmsg, 0, &err)) {
-		error("%s", err.buf);
-		strbuf_release(&err);
-	}
-
-	free(git_HEAD);
-	return 0;
-}
-
 struct read_ref_at_cb {
 	const char *refname;
 	unsigned long at_time;
@@ -3716,287 +736,6 @@ int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time,
 	return 1;
 }
 
-int reflog_exists(const char *refname)
-{
-	struct stat st;
-
-	return !lstat(git_path("logs/%s", refname), &st) &&
-		S_ISREG(st.st_mode);
-}
-
-int delete_reflog(const char *refname)
-{
-	return remove_path(git_path("logs/%s", refname));
-}
-
-static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
-{
-	unsigned char osha1[20], nsha1[20];
-	char *email_end, *message;
-	unsigned long timestamp;
-	int tz;
-
-	/* old SP new SP name <email> SP time TAB msg LF */
-	if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
-	    get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
-	    get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
-	    !(email_end = strchr(sb->buf + 82, '>')) ||
-	    email_end[1] != ' ' ||
-	    !(timestamp = strtoul(email_end + 2, &message, 10)) ||
-	    !message || message[0] != ' ' ||
-	    (message[1] != '+' && message[1] != '-') ||
-	    !isdigit(message[2]) || !isdigit(message[3]) ||
-	    !isdigit(message[4]) || !isdigit(message[5]))
-		return 0; /* corrupt? */
-	email_end[1] = '\0';
-	tz = strtol(message + 1, NULL, 10);
-	if (message[6] != '\t')
-		message += 6;
-	else
-		message += 7;
-	return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
-}
-
-static char *find_beginning_of_line(char *bob, char *scan)
-{
-	while (bob < scan && *(--scan) != '\n')
-		; /* keep scanning backwards */
-	/*
-	 * Return either beginning of the buffer, or LF at the end of
-	 * the previous line.
-	 */
-	return scan;
-}
-
-int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
-{
-	struct strbuf sb = STRBUF_INIT;
-	FILE *logfp;
-	long pos;
-	int ret = 0, at_tail = 1;
-
-	logfp = fopen(git_path("logs/%s", refname), "r");
-	if (!logfp)
-		return -1;
-
-	/* Jump to the end */
-	if (fseek(logfp, 0, SEEK_END) < 0)
-		return error("cannot seek back reflog for %s: %s",
-			     refname, strerror(errno));
-	pos = ftell(logfp);
-	while (!ret && 0 < pos) {
-		int cnt;
-		size_t nread;
-		char buf[BUFSIZ];
-		char *endp, *scanp;
-
-		/* Fill next block from the end */
-		cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
-		if (fseek(logfp, pos - cnt, SEEK_SET))
-			return error("cannot seek back reflog for %s: %s",
-				     refname, strerror(errno));
-		nread = fread(buf, cnt, 1, logfp);
-		if (nread != 1)
-			return error("cannot read %d bytes from reflog for %s: %s",
-				     cnt, refname, strerror(errno));
-		pos -= cnt;
-
-		scanp = endp = buf + cnt;
-		if (at_tail && scanp[-1] == '\n')
-			/* Looking at the final LF at the end of the file */
-			scanp--;
-		at_tail = 0;
-
-		while (buf < scanp) {
-			/*
-			 * terminating LF of the previous line, or the beginning
-			 * of the buffer.
-			 */
-			char *bp;
-
-			bp = find_beginning_of_line(buf, scanp);
-
-			if (*bp == '\n') {
-				/*
-				 * The newline is the end of the previous line,
-				 * so we know we have complete line starting
-				 * at (bp + 1). Prefix it onto any prior data
-				 * we collected for the line and process it.
-				 */
-				strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
-				scanp = bp;
-				endp = bp + 1;
-				ret = show_one_reflog_ent(&sb, fn, cb_data);
-				strbuf_reset(&sb);
-				if (ret)
-					break;
-			} else if (!pos) {
-				/*
-				 * We are at the start of the buffer, and the
-				 * start of the file; there is no previous
-				 * line, and we have everything for this one.
-				 * Process it, and we can end the loop.
-				 */
-				strbuf_splice(&sb, 0, 0, buf, endp - buf);
-				ret = show_one_reflog_ent(&sb, fn, cb_data);
-				strbuf_reset(&sb);
-				break;
-			}
-
-			if (bp == buf) {
-				/*
-				 * We are at the start of the buffer, and there
-				 * is more file to read backwards. Which means
-				 * we are in the middle of a line. Note that we
-				 * may get here even if *bp was a newline; that
-				 * just means we are at the exact end of the
-				 * previous line, rather than some spot in the
-				 * middle.
-				 *
-				 * Save away what we have to be combined with
-				 * the data from the next read.
-				 */
-				strbuf_splice(&sb, 0, 0, buf, endp - buf);
-				break;
-			}
-		}
-
-	}
-	if (!ret && sb.len)
-		die("BUG: reverse reflog parser had leftover data");
-
-	fclose(logfp);
-	strbuf_release(&sb);
-	return ret;
-}
-
-int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
-{
-	FILE *logfp;
-	struct strbuf sb = STRBUF_INIT;
-	int ret = 0;
-
-	logfp = fopen(git_path("logs/%s", refname), "r");
-	if (!logfp)
-		return -1;
-
-	while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
-		ret = show_one_reflog_ent(&sb, fn, cb_data);
-	fclose(logfp);
-	strbuf_release(&sb);
-	return ret;
-}
-/*
- * Call fn for each reflog in the namespace indicated by name.  name
- * must be empty or end with '/'.  Name will be used as a scratch
- * space, but its contents will be restored before return.
- */
-static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
-{
-	DIR *d = opendir(git_path("logs/%s", name->buf));
-	int retval = 0;
-	struct dirent *de;
-	int oldlen = name->len;
-
-	if (!d)
-		return name->len ? errno : 0;
-
-	while ((de = readdir(d)) != NULL) {
-		struct stat st;
-
-		if (de->d_name[0] == '.')
-			continue;
-		if (ends_with(de->d_name, ".lock"))
-			continue;
-		strbuf_addstr(name, de->d_name);
-		if (stat(git_path("logs/%s", name->buf), &st) < 0) {
-			; /* silently ignore */
-		} else {
-			if (S_ISDIR(st.st_mode)) {
-				strbuf_addch(name, '/');
-				retval = do_for_each_reflog(name, fn, cb_data);
-			} else {
-				struct object_id oid;
-
-				if (read_ref_full(name->buf, 0, oid.hash, NULL))
-					retval = error("bad ref for %s", name->buf);
-				else
-					retval = fn(name->buf, &oid, 0, cb_data);
-			}
-			if (retval)
-				break;
-		}
-		strbuf_setlen(name, oldlen);
-	}
-	closedir(d);
-	return retval;
-}
-
-int for_each_reflog(each_ref_fn fn, void *cb_data)
-{
-	int retval;
-	struct strbuf name;
-	strbuf_init(&name, PATH_MAX);
-	retval = do_for_each_reflog(&name, fn, cb_data);
-	strbuf_release(&name);
-	return retval;
-}
-
-/**
- * Information needed for a single ref update. Set new_sha1 to the new
- * value or to null_sha1 to delete the ref. To check the old value
- * while the ref is locked, set (flags & REF_HAVE_OLD) and set
- * old_sha1 to the old value, or to null_sha1 to ensure the ref does
- * not exist before update.
- */
-struct ref_update {
-	/*
-	 * If (flags & REF_HAVE_NEW), set the reference to this value:
-	 */
-	unsigned char new_sha1[20];
-	/*
-	 * If (flags & REF_HAVE_OLD), check that the reference
-	 * previously had this value:
-	 */
-	unsigned char old_sha1[20];
-	/*
-	 * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
-	 * REF_DELETING, and REF_ISPRUNING:
-	 */
-	unsigned int flags;
-	struct ref_lock *lock;
-	int type;
-	char *msg;
-	const char refname[FLEX_ARRAY];
-};
-
-/*
- * Transaction states.
- * OPEN:   The transaction is in a valid state and can accept new updates.
- *         An OPEN transaction can be committed.
- * CLOSED: A closed transaction is no longer active and no other operations
- *         than free can be used on it in this state.
- *         A transaction can either become closed by successfully committing
- *         an active transaction or if there is a failure while building
- *         the transaction thus rendering it failed/inactive.
- */
-enum ref_transaction_state {
-	REF_TRANSACTION_OPEN   = 0,
-	REF_TRANSACTION_CLOSED = 1
-};
-
-/*
- * Data structure for holding a reference transaction, which can
- * consist of checks and updates to multiple references, carried out
- * as atomically as possible.  This structure is opaque to callers.
- */
-struct ref_transaction {
-	struct ref_update **updates;
-	size_t alloc;
-	size_t nr;
-	enum ref_transaction_state state;
-};
-
 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 {
 	assert(err);
@@ -4147,274 +886,6 @@ int update_ref(const char *msg, const char *refname,
 	return 0;
 }
 
-static int ref_update_reject_duplicates(struct string_list *refnames,
-					struct strbuf *err)
-{
-	int i, n = refnames->nr;
-
-	assert(err);
-
-	for (i = 1; i < n; i++)
-		if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
-			strbuf_addf(err,
-				    "Multiple updates for ref '%s' not allowed.",
-				    refnames->items[i].string);
-			return 1;
-		}
-	return 0;
-}
-
-int ref_transaction_commit(struct ref_transaction *transaction,
-			   struct strbuf *err)
-{
-	int ret = 0, i;
-	int n = transaction->nr;
-	struct ref_update **updates = transaction->updates;
-	struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
-	struct string_list_item *ref_to_delete;
-	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
-
-	assert(err);
-
-	if (transaction->state != REF_TRANSACTION_OPEN)
-		die("BUG: commit called for transaction that is not open");
-
-	if (!n) {
-		transaction->state = REF_TRANSACTION_CLOSED;
-		return 0;
-	}
-
-	/* Fail if a refname appears more than once in the transaction: */
-	for (i = 0; i < n; i++)
-		string_list_append(&affected_refnames, updates[i]->refname);
-	string_list_sort(&affected_refnames);
-	if (ref_update_reject_duplicates(&affected_refnames, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-	/*
-	 * Acquire all locks, verify old values if provided, check
-	 * that new values are valid, and write new values to the
-	 * lockfiles, ready to be activated. Only keep one lockfile
-	 * open at a time to avoid running out of file descriptors.
-	 */
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if ((update->flags & REF_HAVE_NEW) &&
-		    is_null_sha1(update->new_sha1))
-			update->flags |= REF_DELETING;
-		update->lock = lock_ref_sha1_basic(
-				update->refname,
-				((update->flags & REF_HAVE_OLD) ?
-				 update->old_sha1 : NULL),
-				&affected_refnames, NULL,
-				update->flags,
-				&update->type,
-				err);
-		if (!update->lock) {
-			char *reason;
-
-			ret = (errno == ENOTDIR)
-				? TRANSACTION_NAME_CONFLICT
-				: TRANSACTION_GENERIC_ERROR;
-			reason = strbuf_detach(err, NULL);
-			strbuf_addf(err, "cannot lock ref '%s': %s",
-				    update->refname, reason);
-			free(reason);
-			goto cleanup;
-		}
-		if ((update->flags & REF_HAVE_NEW) &&
-		    !(update->flags & REF_DELETING)) {
-			int overwriting_symref = ((update->type & REF_ISSYMREF) &&
-						  (update->flags & REF_NODEREF));
-
-			if (!overwriting_symref &&
-			    !hashcmp(update->lock->old_oid.hash, update->new_sha1)) {
-				/*
-				 * The reference already has the desired
-				 * value, so we don't need to write it.
-				 */
-			} else if (write_ref_to_lockfile(update->lock,
-							 update->new_sha1,
-							 err)) {
-				char *write_err = strbuf_detach(err, NULL);
-
-				/*
-				 * The lock was freed upon failure of
-				 * write_ref_to_lockfile():
-				 */
-				update->lock = NULL;
-				strbuf_addf(err,
-					    "cannot update the ref '%s': %s",
-					    update->refname, write_err);
-				free(write_err);
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			} else {
-				update->flags |= REF_NEEDS_COMMIT;
-			}
-		}
-		if (!(update->flags & REF_NEEDS_COMMIT)) {
-			/*
-			 * We didn't have to write anything to the lockfile.
-			 * Close it to free up the file descriptor:
-			 */
-			if (close_ref(update->lock)) {
-				strbuf_addf(err, "Couldn't close %s.lock",
-					    update->refname);
-				goto cleanup;
-			}
-		}
-	}
-
-	/* Perform updates first so live commits remain referenced */
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if (update->flags & REF_NEEDS_COMMIT) {
-			if (commit_ref_update(update->lock,
-					      update->new_sha1, update->msg,
-					      update->flags, err)) {
-				/* freed by commit_ref_update(): */
-				update->lock = NULL;
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			} else {
-				/* freed by commit_ref_update(): */
-				update->lock = NULL;
-			}
-		}
-	}
-
-	/* Perform deletes now that updates are safely completed */
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if (update->flags & REF_DELETING) {
-			if (delete_ref_loose(update->lock, update->type, err)) {
-				ret = TRANSACTION_GENERIC_ERROR;
-				goto cleanup;
-			}
-
-			if (!(update->flags & REF_ISPRUNING))
-				string_list_append(&refs_to_delete,
-						   update->lock->ref_name);
-		}
-	}
-
-	if (repack_without_refs(&refs_to_delete, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-	for_each_string_list_item(ref_to_delete, &refs_to_delete)
-		unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
-	clear_loose_ref_cache(&ref_cache);
-
-cleanup:
-	transaction->state = REF_TRANSACTION_CLOSED;
-
-	for (i = 0; i < n; i++)
-		if (updates[i]->lock)
-			unlock_ref(updates[i]->lock);
-	string_list_clear(&refs_to_delete, 0);
-	string_list_clear(&affected_refnames, 0);
-	return ret;
-}
-
-static int ref_present(const char *refname,
-		       const struct object_id *oid, int flags, void *cb_data)
-{
-	struct string_list *affected_refnames = cb_data;
-
-	return string_list_has_string(affected_refnames, refname);
-}
-
-int initial_ref_transaction_commit(struct ref_transaction *transaction,
-				   struct strbuf *err)
-{
-	struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
-	struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
-	int ret = 0, i;
-	int n = transaction->nr;
-	struct ref_update **updates = transaction->updates;
-	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
-
-	assert(err);
-
-	if (transaction->state != REF_TRANSACTION_OPEN)
-		die("BUG: commit called for transaction that is not open");
-
-	/* Fail if a refname appears more than once in the transaction: */
-	for (i = 0; i < n; i++)
-		string_list_append(&affected_refnames, updates[i]->refname);
-	string_list_sort(&affected_refnames);
-	if (ref_update_reject_duplicates(&affected_refnames, err)) {
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-	/*
-	 * It's really undefined to call this function in an active
-	 * repository or when there are existing references: we are
-	 * only locking and changing packed-refs, so (1) any
-	 * simultaneous processes might try to change a reference at
-	 * the same time we do, and (2) any existing loose versions of
-	 * the references that we are setting would have precedence
-	 * over our values. But some remote helpers create the remote
-	 * "HEAD" and "master" branches before calling this function,
-	 * so here we really only check that none of the references
-	 * that we are creating already exists.
-	 */
-	if (for_each_rawref(ref_present, &affected_refnames))
-		die("BUG: initial ref transaction called with existing refs");
-
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if ((update->flags & REF_HAVE_OLD) &&
-		    !is_null_sha1(update->old_sha1))
-			die("BUG: initial ref transaction with old_sha1 set");
-		if (verify_refname_available(update->refname,
-					     &affected_refnames, NULL,
-					     loose_refs, err) ||
-		    verify_refname_available(update->refname,
-					     &affected_refnames, NULL,
-					     packed_refs, err)) {
-			ret = TRANSACTION_NAME_CONFLICT;
-			goto cleanup;
-		}
-	}
-
-	if (lock_packed_refs(0)) {
-		strbuf_addf(err, "unable to lock packed-refs file: %s",
-			    strerror(errno));
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-	for (i = 0; i < n; i++) {
-		struct ref_update *update = updates[i];
-
-		if ((update->flags & REF_HAVE_NEW) &&
-		    !is_null_sha1(update->new_sha1))
-			add_packed_ref(update->refname, update->new_sha1);
-	}
-
-	if (commit_packed_refs()) {
-		strbuf_addf(err, "unable to commit packed-refs file: %s",
-			    strerror(errno));
-		ret = TRANSACTION_GENERIC_ERROR;
-		goto cleanup;
-	}
-
-cleanup:
-	transaction->state = REF_TRANSACTION_CLOSED;
-	string_list_clear(&affected_refnames, 0);
-	return ret;
-}
-
 char *shorten_unambiguous_ref(const char *refname, int strict)
 {
 	int i;
@@ -4568,144 +1039,46 @@ int ref_is_hidden(const char *refname, const char *refname_full)
 	return 0;
 }
 
-struct expire_reflog_cb {
-	unsigned int flags;
-	reflog_expiry_should_prune_fn *should_prune_fn;
-	void *policy_cb;
-	FILE *newlog;
-	unsigned char last_kept_sha1[20];
-};
-
-static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
-			     const char *email, unsigned long timestamp, int tz,
-			     const char *message, void *cb_data)
+const char *find_descendant_ref(const char *dirname,
+				const struct string_list *extras,
+				const struct string_list *skip)
 {
-	struct expire_reflog_cb *cb = cb_data;
-	struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
-
-	if (cb->flags & EXPIRE_REFLOGS_REWRITE)
-		osha1 = cb->last_kept_sha1;
-
-	if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
-				   message, policy_cb)) {
-		if (!cb->newlog)
-			printf("would prune %s", message);
-		else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-			printf("prune %s", message);
-	} else {
-		if (cb->newlog) {
-			fprintf(cb->newlog, "%s %s %s %lu %+05d\t%s",
-				sha1_to_hex(osha1), sha1_to_hex(nsha1),
-				email, timestamp, tz, message);
-			hashcpy(cb->last_kept_sha1, nsha1);
-		}
-		if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
-			printf("keep %s", message);
-	}
-	return 0;
-}
-
-int reflog_expire(const char *refname, const unsigned char *sha1,
-		 unsigned int flags,
-		 reflog_expiry_prepare_fn prepare_fn,
-		 reflog_expiry_should_prune_fn should_prune_fn,
-		 reflog_expiry_cleanup_fn cleanup_fn,
-		 void *policy_cb_data)
-{
-	static struct lock_file reflog_lock;
-	struct expire_reflog_cb cb;
-	struct ref_lock *lock;
-	char *log_file;
-	int status = 0;
-	int type;
-	struct strbuf err = STRBUF_INIT;
+	int pos;
 
-	memset(&cb, 0, sizeof(cb));
-	cb.flags = flags;
-	cb.policy_cb = policy_cb_data;
-	cb.should_prune_fn = should_prune_fn;
+	if (!extras)
+		return NULL;
 
 	/*
-	 * The reflog file is locked by holding the lock on the
-	 * reference itself, plus we might need to update the
-	 * reference if --updateref was specified:
+	 * Look at the place where dirname would be inserted into
+	 * extras. If there is an entry at that position that starts
+	 * with dirname (remember, dirname includes the trailing
+	 * slash) and is not in skip, then we have a conflict.
 	 */
-	lock = lock_ref_sha1_basic(refname, sha1, NULL, NULL, 0, &type, &err);
-	if (!lock) {
-		error("cannot lock ref '%s': %s", refname, err.buf);
-		strbuf_release(&err);
-		return -1;
-	}
-	if (!reflog_exists(refname)) {
-		unlock_ref(lock);
-		return 0;
-	}
+	for (pos = string_list_find_insert_index(extras, dirname, 0);
+	     pos < extras->nr; pos++) {
+		const char *extra_refname = extras->items[pos].string;
 
-	log_file = git_pathdup("logs/%s", refname);
-	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
-		/*
-		 * Even though holding $GIT_DIR/logs/$reflog.lock has
-		 * no locking implications, we use the lock_file
-		 * machinery here anyway because it does a lot of the
-		 * work we need, including cleaning up if the program
-		 * exits unexpectedly.
-		 */
-		if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
-			struct strbuf err = STRBUF_INIT;
-			unable_to_lock_message(log_file, errno, &err);
-			error("%s", err.buf);
-			strbuf_release(&err);
-			goto failure;
-		}
-		cb.newlog = fdopen_lock_file(&reflog_lock, "w");
-		if (!cb.newlog) {
-			error("cannot fdopen %s (%s)",
-			      get_lock_file_path(&reflog_lock), strerror(errno));
-			goto failure;
-		}
+		if (!starts_with(extra_refname, dirname))
+			break;
+
+		if (!skip || !string_list_has_string(skip, extra_refname))
+			return extra_refname;
 	}
+	return NULL;
+}
 
-	(*prepare_fn)(refname, sha1, cb.policy_cb);
-	for_each_reflog_ent(refname, expire_reflog_ent, &cb);
-	(*cleanup_fn)(cb.policy_cb);
+int rename_ref_available(const char *oldname, const char *newname)
+{
+	struct string_list skip = STRING_LIST_INIT_NODUP;
+	struct strbuf err = STRBUF_INIT;
+	int ret;
 
-	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
-		/*
-		 * It doesn't make sense to adjust a reference pointed
-		 * to by a symbolic ref based on expiring entries in
-		 * the symbolic reference's reflog. Nor can we update
-		 * a reference if there are no remaining reflog
-		 * entries.
-		 */
-		int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
-			!(type & REF_ISSYMREF) &&
-			!is_null_sha1(cb.last_kept_sha1);
-
-		if (close_lock_file(&reflog_lock)) {
-			status |= error("couldn't write %s: %s", log_file,
-					strerror(errno));
-		} else if (update &&
-			   (write_in_full(get_lock_file_fd(lock->lk),
-				sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
-			    write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
-			    close_ref(lock) < 0)) {
-			status |= error("couldn't write %s",
-					get_lock_file_path(lock->lk));
-			rollback_lock_file(&reflog_lock);
-		} else if (commit_lock_file(&reflog_lock)) {
-			status |= error("unable to commit reflog '%s' (%s)",
-					log_file, strerror(errno));
-		} else if (update && commit_ref(lock)) {
-			status |= error("couldn't set %s", lock->ref_name);
-		}
-	}
-	free(log_file);
-	unlock_ref(lock);
-	return status;
-
- failure:
-	rollback_lock_file(&reflog_lock);
-	free(log_file);
-	unlock_ref(lock);
-	return -1;
+	string_list_insert(&skip, oldname);
+	ret = !verify_refname_available(newname, NULL, &skip, &err);
+	if (!ret)
+		error("%s", err.buf);
+
+	string_list_clear(&skip, 0);
+	strbuf_release(&err);
+	return ret;
 }
diff --git a/refs/files-backend.c b/refs/files-backend.c
new file mode 100644
index 0000000..4db3e36
--- /dev/null
+++ b/refs/files-backend.c
@@ -0,0 +1,3512 @@
+#include "../cache.h"
+#include "../refs.h"
+#include "refs-internal.h"
+#include "../lockfile.h"
+#include "../object.h"
+#include "../dir.h"
+
+struct ref_lock {
+	char *ref_name;
+	char *orig_ref_name;
+	struct lock_file *lk;
+	struct object_id old_oid;
+};
+
+struct ref_entry;
+
+/*
+ * Information used (along with the information in ref_entry) to
+ * describe a single cached reference.  This data structure only
+ * occurs embedded in a union in struct ref_entry, and only when
+ * (ref_entry->flag & REF_DIR) is zero.
+ */
+struct ref_value {
+	/*
+	 * The name of the object to which this reference resolves
+	 * (which may be a tag object).  If REF_ISBROKEN, this is
+	 * null.  If REF_ISSYMREF, then this is the name of the object
+	 * referred to by the last reference in the symlink chain.
+	 */
+	struct object_id oid;
+
+	/*
+	 * If REF_KNOWS_PEELED, then this field holds the peeled value
+	 * of this reference, or null if the reference is known not to
+	 * be peelable.  See the documentation for peel_ref() for an
+	 * exact definition of "peelable".
+	 */
+	struct object_id peeled;
+};
+
+struct ref_cache;
+
+/*
+ * Information used (along with the information in ref_entry) to
+ * describe a level in the hierarchy of references.  This data
+ * structure only occurs embedded in a union in struct ref_entry, and
+ * only when (ref_entry.flag & REF_DIR) is set.  In that case,
+ * (ref_entry.flag & REF_INCOMPLETE) determines whether the references
+ * in the directory have already been read:
+ *
+ *     (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
+ *         or packed references, already read.
+ *
+ *     (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
+ *         references that hasn't been read yet (nor has any of its
+ *         subdirectories).
+ *
+ * Entries within a directory are stored within a growable array of
+ * pointers to ref_entries (entries, nr, alloc).  Entries 0 <= i <
+ * sorted are sorted by their component name in strcmp() order and the
+ * remaining entries are unsorted.
+ *
+ * Loose references are read lazily, one directory at a time.  When a
+ * directory of loose references is read, then all of the references
+ * in that directory are stored, and REF_INCOMPLETE stubs are created
+ * for any subdirectories, but the subdirectories themselves are not
+ * read.  The reading is triggered by get_ref_dir().
+ */
+struct ref_dir {
+	int nr, alloc;
+
+	/*
+	 * Entries with index 0 <= i < sorted are sorted by name.  New
+	 * entries are appended to the list unsorted, and are sorted
+	 * only when required; thus we avoid the need to sort the list
+	 * after the addition of every reference.
+	 */
+	int sorted;
+
+	/* A pointer to the ref_cache that contains this ref_dir. */
+	struct ref_cache *ref_cache;
+
+	struct ref_entry **entries;
+};
+
+/*
+ * Bit values for ref_entry::flag.  REF_ISSYMREF=0x01,
+ * REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
+ * public values; see refs.h.
+ */
+
+/*
+ * The field ref_entry->u.value.peeled of this value entry contains
+ * the correct peeled value for the reference, which might be
+ * null_sha1 if the reference is not a tag or if it is broken.
+ */
+#define REF_KNOWS_PEELED 0x10
+
+/* ref_entry represents a directory of references */
+#define REF_DIR 0x20
+
+/*
+ * Entry has not yet been read from disk (used only for REF_DIR
+ * entries representing loose references)
+ */
+#define REF_INCOMPLETE 0x40
+
+/*
+ * A ref_entry represents either a reference or a "subdirectory" of
+ * references.
+ *
+ * Each directory in the reference namespace is represented by a
+ * ref_entry with (flags & REF_DIR) set and containing a subdir member
+ * that holds the entries in that directory that have been read so
+ * far.  If (flags & REF_INCOMPLETE) is set, then the directory and
+ * its subdirectories haven't been read yet.  REF_INCOMPLETE is only
+ * used for loose reference directories.
+ *
+ * References are represented by a ref_entry with (flags & REF_DIR)
+ * unset and a value member that describes the reference's value.  The
+ * flag member is at the ref_entry level, but it is also needed to
+ * interpret the contents of the value field (in other words, a
+ * ref_value object is not very much use without the enclosing
+ * ref_entry).
+ *
+ * Reference names cannot end with slash and directories' names are
+ * always stored with a trailing slash (except for the top-level
+ * directory, which is always denoted by "").  This has two nice
+ * consequences: (1) when the entries in each subdir are sorted
+ * lexicographically by name (as they usually are), the references in
+ * a whole tree can be generated in lexicographic order by traversing
+ * the tree in left-to-right, depth-first order; (2) the names of
+ * references and subdirectories cannot conflict, and therefore the
+ * presence of an empty subdirectory does not block the creation of a
+ * similarly-named reference.  (The fact that reference names with the
+ * same leading components can conflict *with each other* is a
+ * separate issue that is regulated by verify_refname_available().)
+ *
+ * Please note that the name field contains the fully-qualified
+ * reference (or subdirectory) name.  Space could be saved by only
+ * storing the relative names.  But that would require the full names
+ * to be generated on the fly when iterating in do_for_each_ref(), and
+ * would break callback functions, who have always been able to assume
+ * that the name strings that they are passed will not be freed during
+ * the iteration.
+ */
+struct ref_entry {
+	unsigned char flag; /* ISSYMREF? ISPACKED? */
+	union {
+		struct ref_value value; /* if not (flags&REF_DIR) */
+		struct ref_dir subdir; /* if (flags&REF_DIR) */
+	} u;
+	/*
+	 * The full name of the reference (e.g., "refs/heads/master")
+	 * or the full name of the directory with a trailing slash
+	 * (e.g., "refs/heads/"):
+	 */
+	char name[FLEX_ARRAY];
+};
+
+static void read_loose_refs(const char *dirname, struct ref_dir *dir);
+static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
+static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
+					  const char *dirname, size_t len,
+					  int incomplete);
+static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
+
+static struct ref_dir *get_ref_dir(struct ref_entry *entry)
+{
+	struct ref_dir *dir;
+	assert(entry->flag & REF_DIR);
+	dir = &entry->u.subdir;
+	if (entry->flag & REF_INCOMPLETE) {
+		read_loose_refs(entry->name, dir);
+
+		/*
+		 * Manually add refs/bisect, which, being
+		 * per-worktree, might not appear in the directory
+		 * listing for refs/ in the main repo.
+		 */
+		if (!strcmp(entry->name, "refs/")) {
+			int pos = search_ref_dir(dir, "refs/bisect/", 12);
+			if (pos < 0) {
+				struct ref_entry *child_entry;
+				child_entry = create_dir_entry(dir->ref_cache,
+							       "refs/bisect/",
+							       12, 1);
+				add_entry_to_dir(dir, child_entry);
+				read_loose_refs("refs/bisect",
+						&child_entry->u.subdir);
+			}
+		}
+		entry->flag &= ~REF_INCOMPLETE;
+	}
+	return dir;
+}
+
+static struct ref_entry *create_ref_entry(const char *refname,
+					  const unsigned char *sha1, int flag,
+					  int check_name)
+{
+	int len;
+	struct ref_entry *ref;
+
+	if (check_name &&
+	    check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
+		die("Reference has invalid format: '%s'", refname);
+	len = strlen(refname) + 1;
+	ref = xmalloc(sizeof(struct ref_entry) + len);
+	hashcpy(ref->u.value.oid.hash, sha1);
+	oidclr(&ref->u.value.peeled);
+	memcpy(ref->name, refname, len);
+	ref->flag = flag;
+	return ref;
+}
+
+static void clear_ref_dir(struct ref_dir *dir);
+
+static void free_ref_entry(struct ref_entry *entry)
+{
+	if (entry->flag & REF_DIR) {
+		/*
+		 * Do not use get_ref_dir() here, as that might
+		 * trigger the reading of loose refs.
+		 */
+		clear_ref_dir(&entry->u.subdir);
+	}
+	free(entry);
+}
+
+/*
+ * Add a ref_entry to the end of dir (unsorted).  Entry is always
+ * stored directly in dir; no recursion into subdirectories is
+ * done.
+ */
+static void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
+{
+	ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
+	dir->entries[dir->nr++] = entry;
+	/* optimize for the case that entries are added in order */
+	if (dir->nr == 1 ||
+	    (dir->nr == dir->sorted + 1 &&
+	     strcmp(dir->entries[dir->nr - 2]->name,
+		    dir->entries[dir->nr - 1]->name) < 0))
+		dir->sorted = dir->nr;
+}
+
+/*
+ * Clear and free all entries in dir, recursively.
+ */
+static void clear_ref_dir(struct ref_dir *dir)
+{
+	int i;
+	for (i = 0; i < dir->nr; i++)
+		free_ref_entry(dir->entries[i]);
+	free(dir->entries);
+	dir->sorted = dir->nr = dir->alloc = 0;
+	dir->entries = NULL;
+}
+
+/*
+ * Create a struct ref_entry object for the specified dirname.
+ * dirname is the name of the directory with a trailing slash (e.g.,
+ * "refs/heads/") or "" for the top-level directory.
+ */
+static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
+					  const char *dirname, size_t len,
+					  int incomplete)
+{
+	struct ref_entry *direntry;
+	direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
+	memcpy(direntry->name, dirname, len);
+	direntry->name[len] = '\0';
+	direntry->u.subdir.ref_cache = ref_cache;
+	direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
+	return direntry;
+}
+
+static int ref_entry_cmp(const void *a, const void *b)
+{
+	struct ref_entry *one = *(struct ref_entry **)a;
+	struct ref_entry *two = *(struct ref_entry **)b;
+	return strcmp(one->name, two->name);
+}
+
+static void sort_ref_dir(struct ref_dir *dir);
+
+struct string_slice {
+	size_t len;
+	const char *str;
+};
+
+static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
+{
+	const struct string_slice *key = key_;
+	const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
+	int cmp = strncmp(key->str, ent->name, key->len);
+	if (cmp)
+		return cmp;
+	return '\0' - (unsigned char)ent->name[key->len];
+}
+
+/*
+ * Return the index of the entry with the given refname from the
+ * ref_dir (non-recursively), sorting dir if necessary.  Return -1 if
+ * no such entry is found.  dir must already be complete.
+ */
+static int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
+{
+	struct ref_entry **r;
+	struct string_slice key;
+
+	if (refname == NULL || !dir->nr)
+		return -1;
+
+	sort_ref_dir(dir);
+	key.len = len;
+	key.str = refname;
+	r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
+		    ref_entry_cmp_sslice);
+
+	if (r == NULL)
+		return -1;
+
+	return r - dir->entries;
+}
+
+/*
+ * Search for a directory entry directly within dir (without
+ * recursing).  Sort dir if necessary.  subdirname must be a directory
+ * name (i.e., end in '/').  If mkdir is set, then create the
+ * directory if it is missing; otherwise, return NULL if the desired
+ * directory cannot be found.  dir must already be complete.
+ */
+static struct ref_dir *search_for_subdir(struct ref_dir *dir,
+					 const char *subdirname, size_t len,
+					 int mkdir)
+{
+	int entry_index = search_ref_dir(dir, subdirname, len);
+	struct ref_entry *entry;
+	if (entry_index == -1) {
+		if (!mkdir)
+			return NULL;
+		/*
+		 * Since dir is complete, the absence of a subdir
+		 * means that the subdir really doesn't exist;
+		 * therefore, create an empty record for it but mark
+		 * the record complete.
+		 */
+		entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
+		add_entry_to_dir(dir, entry);
+	} else {
+		entry = dir->entries[entry_index];
+	}
+	return get_ref_dir(entry);
+}
+
+/*
+ * If refname is a reference name, find the ref_dir within the dir
+ * tree that should hold refname.  If refname is a directory name
+ * (i.e., ends in '/'), then return that ref_dir itself.  dir must
+ * represent the top-level directory and must already be complete.
+ * Sort ref_dirs and recurse into subdirectories as necessary.  If
+ * mkdir is set, then create any missing directories; otherwise,
+ * return NULL if the desired directory cannot be found.
+ */
+static struct ref_dir *find_containing_dir(struct ref_dir *dir,
+					   const char *refname, int mkdir)
+{
+	const char *slash;
+	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+		size_t dirnamelen = slash - refname + 1;
+		struct ref_dir *subdir;
+		subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
+		if (!subdir) {
+			dir = NULL;
+			break;
+		}
+		dir = subdir;
+	}
+
+	return dir;
+}
+
+/*
+ * Find the value entry with the given name in dir, sorting ref_dirs
+ * and recursing into subdirectories as necessary.  If the name is not
+ * found or it corresponds to a directory entry, return NULL.
+ */
+static struct ref_entry *find_ref(struct ref_dir *dir, const char *refname)
+{
+	int entry_index;
+	struct ref_entry *entry;
+	dir = find_containing_dir(dir, refname, 0);
+	if (!dir)
+		return NULL;
+	entry_index = search_ref_dir(dir, refname, strlen(refname));
+	if (entry_index == -1)
+		return NULL;
+	entry = dir->entries[entry_index];
+	return (entry->flag & REF_DIR) ? NULL : entry;
+}
+
+/*
+ * Remove the entry with the given name from dir, recursing into
+ * subdirectories as necessary.  If refname is the name of a directory
+ * (i.e., ends with '/'), then remove the directory and its contents.
+ * If the removal was successful, return the number of entries
+ * remaining in the directory entry that contained the deleted entry.
+ * If the name was not found, return -1.  Please note that this
+ * function only deletes the entry from the cache; it does not delete
+ * it from the filesystem or ensure that other cache entries (which
+ * might be symbolic references to the removed entry) are updated.
+ * Nor does it remove any containing dir entries that might be made
+ * empty by the removal.  dir must represent the top-level directory
+ * and must already be complete.
+ */
+static int remove_entry(struct ref_dir *dir, const char *refname)
+{
+	int refname_len = strlen(refname);
+	int entry_index;
+	struct ref_entry *entry;
+	int is_dir = refname[refname_len - 1] == '/';
+	if (is_dir) {
+		/*
+		 * refname represents a reference directory.  Remove
+		 * the trailing slash; otherwise we will get the
+		 * directory *representing* refname rather than the
+		 * one *containing* it.
+		 */
+		char *dirname = xmemdupz(refname, refname_len - 1);
+		dir = find_containing_dir(dir, dirname, 0);
+		free(dirname);
+	} else {
+		dir = find_containing_dir(dir, refname, 0);
+	}
+	if (!dir)
+		return -1;
+	entry_index = search_ref_dir(dir, refname, refname_len);
+	if (entry_index == -1)
+		return -1;
+	entry = dir->entries[entry_index];
+
+	memmove(&dir->entries[entry_index],
+		&dir->entries[entry_index + 1],
+		(dir->nr - entry_index - 1) * sizeof(*dir->entries)
+		);
+	dir->nr--;
+	if (dir->sorted > entry_index)
+		dir->sorted--;
+	free_ref_entry(entry);
+	return dir->nr;
+}
+
+/*
+ * Add a ref_entry to the ref_dir (unsorted), recursing into
+ * subdirectories as necessary.  dir must represent the top-level
+ * directory.  Return 0 on success.
+ */
+static int add_ref(struct ref_dir *dir, struct ref_entry *ref)
+{
+	dir = find_containing_dir(dir, ref->name, 1);
+	if (!dir)
+		return -1;
+	add_entry_to_dir(dir, ref);
+	return 0;
+}
+
+/*
+ * Emit a warning and return true iff ref1 and ref2 have the same name
+ * and the same sha1.  Die if they have the same name but different
+ * sha1s.
+ */
+static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
+{
+	if (strcmp(ref1->name, ref2->name))
+		return 0;
+
+	/* Duplicate name; make sure that they don't conflict: */
+
+	if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
+		/* This is impossible by construction */
+		die("Reference directory conflict: %s", ref1->name);
+
+	if (oidcmp(&ref1->u.value.oid, &ref2->u.value.oid))
+		die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
+
+	warning("Duplicated ref: %s", ref1->name);
+	return 1;
+}
+
+/*
+ * Sort the entries in dir non-recursively (if they are not already
+ * sorted) and remove any duplicate entries.
+ */
+static void sort_ref_dir(struct ref_dir *dir)
+{
+	int i, j;
+	struct ref_entry *last = NULL;
+
+	/*
+	 * This check also prevents passing a zero-length array to qsort(),
+	 * which is a problem on some platforms.
+	 */
+	if (dir->sorted == dir->nr)
+		return;
+
+	qsort(dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
+
+	/* Remove any duplicates: */
+	for (i = 0, j = 0; j < dir->nr; j++) {
+		struct ref_entry *entry = dir->entries[j];
+		if (last && is_dup_ref(last, entry))
+			free_ref_entry(entry);
+		else
+			last = dir->entries[i++] = entry;
+	}
+	dir->sorted = dir->nr = i;
+}
+
+/* Include broken references in a do_for_each_ref*() iteration: */
+#define DO_FOR_EACH_INCLUDE_BROKEN 0x01
+
+/*
+ * Return true iff the reference described by entry can be resolved to
+ * an object in the database.  Emit a warning if the referred-to
+ * object does not exist.
+ */
+static int ref_resolves_to_object(struct ref_entry *entry)
+{
+	if (entry->flag & REF_ISBROKEN)
+		return 0;
+	if (!has_sha1_file(entry->u.value.oid.hash)) {
+		error("%s does not point to a valid object!", entry->name);
+		return 0;
+	}
+	return 1;
+}
+
+/*
+ * current_ref is a performance hack: when iterating over references
+ * using the for_each_ref*() functions, current_ref is set to the
+ * current reference's entry before calling the callback function.  If
+ * the callback function calls peel_ref(), then peel_ref() first
+ * checks whether the reference to be peeled is the current reference
+ * (it usually is) and if so, returns that reference's peeled version
+ * if it is available.  This avoids a refname lookup in a common case.
+ */
+static struct ref_entry *current_ref;
+
+typedef int each_ref_entry_fn(struct ref_entry *entry, void *cb_data);
+
+struct ref_entry_cb {
+	const char *base;
+	int trim;
+	int flags;
+	each_ref_fn *fn;
+	void *cb_data;
+};
+
+/*
+ * Handle one reference in a do_for_each_ref*()-style iteration,
+ * calling an each_ref_fn for each entry.
+ */
+static int do_one_ref(struct ref_entry *entry, void *cb_data)
+{
+	struct ref_entry_cb *data = cb_data;
+	struct ref_entry *old_current_ref;
+	int retval;
+
+	if (!starts_with(entry->name, data->base))
+		return 0;
+
+	if (!(data->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
+	      !ref_resolves_to_object(entry))
+		return 0;
+
+	/* Store the old value, in case this is a recursive call: */
+	old_current_ref = current_ref;
+	current_ref = entry;
+	retval = data->fn(entry->name + data->trim, &entry->u.value.oid,
+			  entry->flag, data->cb_data);
+	current_ref = old_current_ref;
+	return retval;
+}
+
+/*
+ * Call fn for each reference in dir that has index in the range
+ * offset <= index < dir->nr.  Recurse into subdirectories that are in
+ * that index range, sorting them before iterating.  This function
+ * does not sort dir itself; it should be sorted beforehand.  fn is
+ * called for all references, including broken ones.
+ */
+static int do_for_each_entry_in_dir(struct ref_dir *dir, int offset,
+				    each_ref_entry_fn fn, void *cb_data)
+{
+	int i;
+	assert(dir->sorted == dir->nr);
+	for (i = offset; i < dir->nr; i++) {
+		struct ref_entry *entry = dir->entries[i];
+		int retval;
+		if (entry->flag & REF_DIR) {
+			struct ref_dir *subdir = get_ref_dir(entry);
+			sort_ref_dir(subdir);
+			retval = do_for_each_entry_in_dir(subdir, 0, fn, cb_data);
+		} else {
+			retval = fn(entry, cb_data);
+		}
+		if (retval)
+			return retval;
+	}
+	return 0;
+}
+
+/*
+ * Call fn for each reference in the union of dir1 and dir2, in order
+ * by refname.  Recurse into subdirectories.  If a value entry appears
+ * in both dir1 and dir2, then only process the version that is in
+ * dir2.  The input dirs must already be sorted, but subdirs will be
+ * sorted as needed.  fn is called for all references, including
+ * broken ones.
+ */
+static int do_for_each_entry_in_dirs(struct ref_dir *dir1,
+				     struct ref_dir *dir2,
+				     each_ref_entry_fn fn, void *cb_data)
+{
+	int retval;
+	int i1 = 0, i2 = 0;
+
+	assert(dir1->sorted == dir1->nr);
+	assert(dir2->sorted == dir2->nr);
+	while (1) {
+		struct ref_entry *e1, *e2;
+		int cmp;
+		if (i1 == dir1->nr) {
+			return do_for_each_entry_in_dir(dir2, i2, fn, cb_data);
+		}
+		if (i2 == dir2->nr) {
+			return do_for_each_entry_in_dir(dir1, i1, fn, cb_data);
+		}
+		e1 = dir1->entries[i1];
+		e2 = dir2->entries[i2];
+		cmp = strcmp(e1->name, e2->name);
+		if (cmp == 0) {
+			if ((e1->flag & REF_DIR) && (e2->flag & REF_DIR)) {
+				/* Both are directories; descend them in parallel. */
+				struct ref_dir *subdir1 = get_ref_dir(e1);
+				struct ref_dir *subdir2 = get_ref_dir(e2);
+				sort_ref_dir(subdir1);
+				sort_ref_dir(subdir2);
+				retval = do_for_each_entry_in_dirs(
+						subdir1, subdir2, fn, cb_data);
+				i1++;
+				i2++;
+			} else if (!(e1->flag & REF_DIR) && !(e2->flag & REF_DIR)) {
+				/* Both are references; ignore the one from dir1. */
+				retval = fn(e2, cb_data);
+				i1++;
+				i2++;
+			} else {
+				die("conflict between reference and directory: %s",
+				    e1->name);
+			}
+		} else {
+			struct ref_entry *e;
+			if (cmp < 0) {
+				e = e1;
+				i1++;
+			} else {
+				e = e2;
+				i2++;
+			}
+			if (e->flag & REF_DIR) {
+				struct ref_dir *subdir = get_ref_dir(e);
+				sort_ref_dir(subdir);
+				retval = do_for_each_entry_in_dir(
+						subdir, 0, fn, cb_data);
+			} else {
+				retval = fn(e, cb_data);
+			}
+		}
+		if (retval)
+			return retval;
+	}
+}
+
+/*
+ * Load all of the refs from the dir into our in-memory cache. The hard work
+ * of loading loose refs is done by get_ref_dir(), so we just need to recurse
+ * through all of the sub-directories. We do not even need to care about
+ * sorting, as traversal order does not matter to us.
+ */
+static void prime_ref_dir(struct ref_dir *dir)
+{
+	int i;
+	for (i = 0; i < dir->nr; i++) {
+		struct ref_entry *entry = dir->entries[i];
+		if (entry->flag & REF_DIR)
+			prime_ref_dir(get_ref_dir(entry));
+	}
+}
+
+struct nonmatching_ref_data {
+	const struct string_list *skip;
+	const char *conflicting_refname;
+};
+
+static int nonmatching_ref_fn(struct ref_entry *entry, void *vdata)
+{
+	struct nonmatching_ref_data *data = vdata;
+
+	if (data->skip && string_list_has_string(data->skip, entry->name))
+		return 0;
+
+	data->conflicting_refname = entry->name;
+	return 1;
+}
+
+/*
+ * Return 0 if a reference named refname could be created without
+ * conflicting with the name of an existing reference in dir.
+ * See verify_refname_available for more information.
+ */
+static int verify_refname_available_dir(const char *refname,
+					const struct string_list *extras,
+					const struct string_list *skip,
+					struct ref_dir *dir,
+					struct strbuf *err)
+{
+	const char *slash;
+	const char *extra_refname;
+	int pos;
+	struct strbuf dirname = STRBUF_INIT;
+	int ret = -1;
+
+	/*
+	 * For the sake of comments in this function, suppose that
+	 * refname is "refs/foo/bar".
+	 */
+
+	assert(err);
+
+	strbuf_grow(&dirname, strlen(refname) + 1);
+	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+		/* Expand dirname to the new prefix, not including the trailing slash: */
+		strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
+
+		/*
+		 * We are still at a leading dir of the refname (e.g.,
+		 * "refs/foo"; if there is a reference with that name,
+		 * it is a conflict, *unless* it is in skip.
+		 */
+		if (dir) {
+			pos = search_ref_dir(dir, dirname.buf, dirname.len);
+			if (pos >= 0 &&
+			    (!skip || !string_list_has_string(skip, dirname.buf))) {
+				/*
+				 * We found a reference whose name is
+				 * a proper prefix of refname; e.g.,
+				 * "refs/foo", and is not in skip.
+				 */
+				strbuf_addf(err, "'%s' exists; cannot create '%s'",
+					    dirname.buf, refname);
+				goto cleanup;
+			}
+		}
+
+		if (extras && string_list_has_string(extras, dirname.buf) &&
+		    (!skip || !string_list_has_string(skip, dirname.buf))) {
+			strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
+				    refname, dirname.buf);
+			goto cleanup;
+		}
+
+		/*
+		 * Otherwise, we can try to continue our search with
+		 * the next component. So try to look up the
+		 * directory, e.g., "refs/foo/". If we come up empty,
+		 * we know there is nothing under this whole prefix,
+		 * but even in that case we still have to continue the
+		 * search for conflicts with extras.
+		 */
+		strbuf_addch(&dirname, '/');
+		if (dir) {
+			pos = search_ref_dir(dir, dirname.buf, dirname.len);
+			if (pos < 0) {
+				/*
+				 * There was no directory "refs/foo/",
+				 * so there is nothing under this
+				 * whole prefix. So there is no need
+				 * to continue looking for conflicting
+				 * references. But we need to continue
+				 * looking for conflicting extras.
+				 */
+				dir = NULL;
+			} else {
+				dir = get_ref_dir(dir->entries[pos]);
+			}
+		}
+	}
+
+	/*
+	 * We are at the leaf of our refname (e.g., "refs/foo/bar").
+	 * There is no point in searching for a reference with that
+	 * name, because a refname isn't considered to conflict with
+	 * itself. But we still need to check for references whose
+	 * names are in the "refs/foo/bar/" namespace, because they
+	 * *do* conflict.
+	 */
+	strbuf_addstr(&dirname, refname + dirname.len);
+	strbuf_addch(&dirname, '/');
+
+	if (dir) {
+		pos = search_ref_dir(dir, dirname.buf, dirname.len);
+
+		if (pos >= 0) {
+			/*
+			 * We found a directory named "$refname/"
+			 * (e.g., "refs/foo/bar/"). It is a problem
+			 * iff it contains any ref that is not in
+			 * "skip".
+			 */
+			struct nonmatching_ref_data data;
+
+			data.skip = skip;
+			data.conflicting_refname = NULL;
+			dir = get_ref_dir(dir->entries[pos]);
+			sort_ref_dir(dir);
+			if (do_for_each_entry_in_dir(dir, 0, nonmatching_ref_fn, &data)) {
+				strbuf_addf(err, "'%s' exists; cannot create '%s'",
+					    data.conflicting_refname, refname);
+				goto cleanup;
+			}
+		}
+	}
+
+	extra_refname = find_descendant_ref(dirname.buf, extras, skip);
+	if (extra_refname)
+		strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
+			    refname, extra_refname);
+	else
+		ret = 0;
+
+cleanup:
+	strbuf_release(&dirname);
+	return ret;
+}
+
+struct packed_ref_cache {
+	struct ref_entry *root;
+
+	/*
+	 * Count of references to the data structure in this instance,
+	 * including the pointer from ref_cache::packed if any.  The
+	 * data will not be freed as long as the reference count is
+	 * nonzero.
+	 */
+	unsigned int referrers;
+
+	/*
+	 * Iff the packed-refs file associated with this instance is
+	 * currently locked for writing, this points at the associated
+	 * lock (which is owned by somebody else).  The referrer count
+	 * is also incremented when the file is locked and decremented
+	 * when it is unlocked.
+	 */
+	struct lock_file *lock;
+
+	/* The metadata from when this packed-refs cache was read */
+	struct stat_validity validity;
+};
+
+/*
+ * Future: need to be in "struct repository"
+ * when doing a full libification.
+ */
+static struct ref_cache {
+	struct ref_cache *next;
+	struct ref_entry *loose;
+	struct packed_ref_cache *packed;
+	/*
+	 * The submodule name, or "" for the main repo.  We allocate
+	 * length 1 rather than FLEX_ARRAY so that the main ref_cache
+	 * is initialized correctly.
+	 */
+	char name[1];
+} ref_cache, *submodule_ref_caches;
+
+/* Lock used for the main packed-refs file: */
+static struct lock_file packlock;
+
+/*
+ * Increment the reference count of *packed_refs.
+ */
+static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
+{
+	packed_refs->referrers++;
+}
+
+/*
+ * Decrease the reference count of *packed_refs.  If it goes to zero,
+ * free *packed_refs and return true; otherwise return false.
+ */
+static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
+{
+	if (!--packed_refs->referrers) {
+		free_ref_entry(packed_refs->root);
+		stat_validity_clear(&packed_refs->validity);
+		free(packed_refs);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+static void clear_packed_ref_cache(struct ref_cache *refs)
+{
+	if (refs->packed) {
+		struct packed_ref_cache *packed_refs = refs->packed;
+
+		if (packed_refs->lock)
+			die("internal error: packed-ref cache cleared while locked");
+		refs->packed = NULL;
+		release_packed_ref_cache(packed_refs);
+	}
+}
+
+static void clear_loose_ref_cache(struct ref_cache *refs)
+{
+	if (refs->loose) {
+		free_ref_entry(refs->loose);
+		refs->loose = NULL;
+	}
+}
+
+static struct ref_cache *create_ref_cache(const char *submodule)
+{
+	int len;
+	struct ref_cache *refs;
+	if (!submodule)
+		submodule = "";
+	len = strlen(submodule) + 1;
+	refs = xcalloc(1, sizeof(struct ref_cache) + len);
+	memcpy(refs->name, submodule, len);
+	return refs;
+}
+
+/*
+ * Return a pointer to a ref_cache for the specified submodule. For
+ * the main repository, use submodule==NULL. The returned structure
+ * will be allocated and initialized but not necessarily populated; it
+ * should not be freed.
+ */
+static struct ref_cache *get_ref_cache(const char *submodule)
+{
+	struct ref_cache *refs;
+
+	if (!submodule || !*submodule)
+		return &ref_cache;
+
+	for (refs = submodule_ref_caches; refs; refs = refs->next)
+		if (!strcmp(submodule, refs->name))
+			return refs;
+
+	refs = create_ref_cache(submodule);
+	refs->next = submodule_ref_caches;
+	submodule_ref_caches = refs;
+	return refs;
+}
+
+/* The length of a peeled reference line in packed-refs, including EOL: */
+#define PEELED_LINE_LENGTH 42
+
+/*
+ * The packed-refs header line that we write out.  Perhaps other
+ * traits will be added later.  The trailing space is required.
+ */
+static const char PACKED_REFS_HEADER[] =
+	"# pack-refs with: peeled fully-peeled \n";
+
+/*
+ * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
+ * Return a pointer to the refname within the line (null-terminated),
+ * or NULL if there was a problem.
+ */
+static const char *parse_ref_line(struct strbuf *line, unsigned char *sha1)
+{
+	const char *ref;
+
+	/*
+	 * 42: the answer to everything.
+	 *
+	 * In this case, it happens to be the answer to
+	 *  40 (length of sha1 hex representation)
+	 *  +1 (space in between hex and name)
+	 *  +1 (newline at the end of the line)
+	 */
+	if (line->len <= 42)
+		return NULL;
+
+	if (get_sha1_hex(line->buf, sha1) < 0)
+		return NULL;
+	if (!isspace(line->buf[40]))
+		return NULL;
+
+	ref = line->buf + 41;
+	if (isspace(*ref))
+		return NULL;
+
+	if (line->buf[line->len - 1] != '\n')
+		return NULL;
+	line->buf[--line->len] = 0;
+
+	return ref;
+}
+
+/*
+ * Read f, which is a packed-refs file, into dir.
+ *
+ * A comment line of the form "# pack-refs with: " may contain zero or
+ * more traits. We interpret the traits as follows:
+ *
+ *   No traits:
+ *
+ *      Probably no references are peeled. But if the file contains a
+ *      peeled value for a reference, we will use it.
+ *
+ *   peeled:
+ *
+ *      References under "refs/tags/", if they *can* be peeled, *are*
+ *      peeled in this file. References outside of "refs/tags/" are
+ *      probably not peeled even if they could have been, but if we find
+ *      a peeled value for such a reference we will use it.
+ *
+ *   fully-peeled:
+ *
+ *      All references in the file that can be peeled are peeled.
+ *      Inversely (and this is more important), any references in the
+ *      file for which no peeled value is recorded is not peelable. This
+ *      trait should typically be written alongside "peeled" for
+ *      compatibility with older clients, but we do not require it
+ *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
+ */
+static void read_packed_refs(FILE *f, struct ref_dir *dir)
+{
+	struct ref_entry *last = NULL;
+	struct strbuf line = STRBUF_INIT;
+	enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
+
+	while (strbuf_getwholeline(&line, f, '\n') != EOF) {
+		unsigned char sha1[20];
+		const char *refname;
+		const char *traits;
+
+		if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
+			if (strstr(traits, " fully-peeled "))
+				peeled = PEELED_FULLY;
+			else if (strstr(traits, " peeled "))
+				peeled = PEELED_TAGS;
+			/* perhaps other traits later as well */
+			continue;
+		}
+
+		refname = parse_ref_line(&line, sha1);
+		if (refname) {
+			int flag = REF_ISPACKED;
+
+			if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+				if (!refname_is_safe(refname))
+					die("packed refname is dangerous: %s", refname);
+				hashclr(sha1);
+				flag |= REF_BAD_NAME | REF_ISBROKEN;
+			}
+			last = create_ref_entry(refname, sha1, flag, 0);
+			if (peeled == PEELED_FULLY ||
+			    (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
+				last->flag |= REF_KNOWS_PEELED;
+			add_ref(dir, last);
+			continue;
+		}
+		if (last &&
+		    line.buf[0] == '^' &&
+		    line.len == PEELED_LINE_LENGTH &&
+		    line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
+		    !get_sha1_hex(line.buf + 1, sha1)) {
+			hashcpy(last->u.value.peeled.hash, sha1);
+			/*
+			 * Regardless of what the file header said,
+			 * we definitely know the value of *this*
+			 * reference:
+			 */
+			last->flag |= REF_KNOWS_PEELED;
+		}
+	}
+
+	strbuf_release(&line);
+}
+
+/*
+ * Get the packed_ref_cache for the specified ref_cache, creating it
+ * if necessary.
+ */
+static struct packed_ref_cache *get_packed_ref_cache(struct ref_cache *refs)
+{
+	char *packed_refs_file;
+
+	if (*refs->name)
+		packed_refs_file = git_pathdup_submodule(refs->name, "packed-refs");
+	else
+		packed_refs_file = git_pathdup("packed-refs");
+
+	if (refs->packed &&
+	    !stat_validity_check(&refs->packed->validity, packed_refs_file))
+		clear_packed_ref_cache(refs);
+
+	if (!refs->packed) {
+		FILE *f;
+
+		refs->packed = xcalloc(1, sizeof(*refs->packed));
+		acquire_packed_ref_cache(refs->packed);
+		refs->packed->root = create_dir_entry(refs, "", 0, 0);
+		f = fopen(packed_refs_file, "r");
+		if (f) {
+			stat_validity_update(&refs->packed->validity, fileno(f));
+			read_packed_refs(f, get_ref_dir(refs->packed->root));
+			fclose(f);
+		}
+	}
+	free(packed_refs_file);
+	return refs->packed;
+}
+
+static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
+{
+	return get_ref_dir(packed_ref_cache->root);
+}
+
+static struct ref_dir *get_packed_refs(struct ref_cache *refs)
+{
+	return get_packed_ref_dir(get_packed_ref_cache(refs));
+}
+
+/*
+ * Add a reference to the in-memory packed reference cache.  This may
+ * only be called while the packed-refs file is locked (see
+ * lock_packed_refs()).  To actually write the packed-refs file, call
+ * commit_packed_refs().
+ */
+static void add_packed_ref(const char *refname, const unsigned char *sha1)
+{
+	struct packed_ref_cache *packed_ref_cache =
+		get_packed_ref_cache(&ref_cache);
+
+	if (!packed_ref_cache->lock)
+		die("internal error: packed refs not locked");
+	add_ref(get_packed_ref_dir(packed_ref_cache),
+		create_ref_entry(refname, sha1, REF_ISPACKED, 1));
+}
+
+/*
+ * Read the loose references from the namespace dirname into dir
+ * (without recursing).  dirname must end with '/'.  dir must be the
+ * directory entry corresponding to dirname.
+ */
+static void read_loose_refs(const char *dirname, struct ref_dir *dir)
+{
+	struct ref_cache *refs = dir->ref_cache;
+	DIR *d;
+	struct dirent *de;
+	int dirnamelen = strlen(dirname);
+	struct strbuf refname;
+	struct strbuf path = STRBUF_INIT;
+	size_t path_baselen;
+
+	if (*refs->name)
+		strbuf_git_path_submodule(&path, refs->name, "%s", dirname);
+	else
+		strbuf_git_path(&path, "%s", dirname);
+	path_baselen = path.len;
+
+	d = opendir(path.buf);
+	if (!d) {
+		strbuf_release(&path);
+		return;
+	}
+
+	strbuf_init(&refname, dirnamelen + 257);
+	strbuf_add(&refname, dirname, dirnamelen);
+
+	while ((de = readdir(d)) != NULL) {
+		unsigned char sha1[20];
+		struct stat st;
+		int flag;
+
+		if (de->d_name[0] == '.')
+			continue;
+		if (ends_with(de->d_name, ".lock"))
+			continue;
+		strbuf_addstr(&refname, de->d_name);
+		strbuf_addstr(&path, de->d_name);
+		if (stat(path.buf, &st) < 0) {
+			; /* silently ignore */
+		} else if (S_ISDIR(st.st_mode)) {
+			strbuf_addch(&refname, '/');
+			add_entry_to_dir(dir,
+					 create_dir_entry(refs, refname.buf,
+							  refname.len, 1));
+		} else {
+			int read_ok;
+
+			if (*refs->name) {
+				hashclr(sha1);
+				flag = 0;
+				read_ok = !resolve_gitlink_ref(refs->name,
+							       refname.buf, sha1);
+			} else {
+				read_ok = !read_ref_full(refname.buf,
+							 RESOLVE_REF_READING,
+							 sha1, &flag);
+			}
+
+			if (!read_ok) {
+				hashclr(sha1);
+				flag |= REF_ISBROKEN;
+			} else if (is_null_sha1(sha1)) {
+				/*
+				 * It is so astronomically unlikely
+				 * that NULL_SHA1 is the SHA-1 of an
+				 * actual object that we consider its
+				 * appearance in a loose reference
+				 * file to be repo corruption
+				 * (probably due to a software bug).
+				 */
+				flag |= REF_ISBROKEN;
+			}
+
+			if (check_refname_format(refname.buf,
+						 REFNAME_ALLOW_ONELEVEL)) {
+				if (!refname_is_safe(refname.buf))
+					die("loose refname is dangerous: %s", refname.buf);
+				hashclr(sha1);
+				flag |= REF_BAD_NAME | REF_ISBROKEN;
+			}
+			add_entry_to_dir(dir,
+					 create_ref_entry(refname.buf, sha1, flag, 0));
+		}
+		strbuf_setlen(&refname, dirnamelen);
+		strbuf_setlen(&path, path_baselen);
+	}
+	strbuf_release(&refname);
+	strbuf_release(&path);
+	closedir(d);
+}
+
+static struct ref_dir *get_loose_refs(struct ref_cache *refs)
+{
+	if (!refs->loose) {
+		/*
+		 * Mark the top-level directory complete because we
+		 * are about to read the only subdirectory that can
+		 * hold references:
+		 */
+		refs->loose = create_dir_entry(refs, "", 0, 0);
+		/*
+		 * Create an incomplete entry for "refs/":
+		 */
+		add_entry_to_dir(get_ref_dir(refs->loose),
+				 create_dir_entry(refs, "refs/", 5, 1));
+	}
+	return get_ref_dir(refs->loose);
+}
+
+/* We allow "recursive" symbolic refs. Only within reason, though */
+#define MAXDEPTH 5
+#define MAXREFLEN (1024)
+
+/*
+ * Called by resolve_gitlink_ref_recursive() after it failed to read
+ * from the loose refs in ref_cache refs. Find <refname> in the
+ * packed-refs file for the submodule.
+ */
+static int resolve_gitlink_packed_ref(struct ref_cache *refs,
+				      const char *refname, unsigned char *sha1)
+{
+	struct ref_entry *ref;
+	struct ref_dir *dir = get_packed_refs(refs);
+
+	ref = find_ref(dir, refname);
+	if (ref == NULL)
+		return -1;
+
+	hashcpy(sha1, ref->u.value.oid.hash);
+	return 0;
+}
+
+static int resolve_gitlink_ref_recursive(struct ref_cache *refs,
+					 const char *refname, unsigned char *sha1,
+					 int recursion)
+{
+	int fd, len;
+	char buffer[128], *p;
+	char *path;
+
+	if (recursion > MAXDEPTH || strlen(refname) > MAXREFLEN)
+		return -1;
+	path = *refs->name
+		? git_pathdup_submodule(refs->name, "%s", refname)
+		: git_pathdup("%s", refname);
+	fd = open(path, O_RDONLY);
+	free(path);
+	if (fd < 0)
+		return resolve_gitlink_packed_ref(refs, refname, sha1);
+
+	len = read(fd, buffer, sizeof(buffer)-1);
+	close(fd);
+	if (len < 0)
+		return -1;
+	while (len && isspace(buffer[len-1]))
+		len--;
+	buffer[len] = 0;
+
+	/* Was it a detached head or an old-fashioned symlink? */
+	if (!get_sha1_hex(buffer, sha1))
+		return 0;
+
+	/* Symref? */
+	if (strncmp(buffer, "ref:", 4))
+		return -1;
+	p = buffer + 4;
+	while (isspace(*p))
+		p++;
+
+	return resolve_gitlink_ref_recursive(refs, p, sha1, recursion+1);
+}
+
+int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
+{
+	int len = strlen(path), retval;
+	char *submodule;
+	struct ref_cache *refs;
+
+	while (len && path[len-1] == '/')
+		len--;
+	if (!len)
+		return -1;
+	submodule = xstrndup(path, len);
+	refs = get_ref_cache(submodule);
+	free(submodule);
+
+	retval = resolve_gitlink_ref_recursive(refs, refname, sha1, 0);
+	return retval;
+}
+
+/*
+ * Return the ref_entry for the given refname from the packed
+ * references.  If it does not exist, return NULL.
+ */
+static struct ref_entry *get_packed_ref(const char *refname)
+{
+	return find_ref(get_packed_refs(&ref_cache), refname);
+}
+
+/*
+ * A loose ref file doesn't exist; check for a packed ref.  The
+ * options are forwarded from resolve_safe_unsafe().
+ */
+static int resolve_missing_loose_ref(const char *refname,
+				     int resolve_flags,
+				     unsigned char *sha1,
+				     int *flags)
+{
+	struct ref_entry *entry;
+
+	/*
+	 * The loose reference file does not exist; check for a packed
+	 * reference.
+	 */
+	entry = get_packed_ref(refname);
+	if (entry) {
+		hashcpy(sha1, entry->u.value.oid.hash);
+		if (flags)
+			*flags |= REF_ISPACKED;
+		return 0;
+	}
+	/* The reference is not a packed reference, either. */
+	if (resolve_flags & RESOLVE_REF_READING) {
+		errno = ENOENT;
+		return -1;
+	} else {
+		hashclr(sha1);
+		return 0;
+	}
+}
+
+/* This function needs to return a meaningful errno on failure */
+static const char *resolve_ref_1(const char *refname,
+				 int resolve_flags,
+				 unsigned char *sha1,
+				 int *flags,
+				 struct strbuf *sb_refname,
+				 struct strbuf *sb_path,
+				 struct strbuf *sb_contents)
+{
+	int depth = MAXDEPTH;
+	int bad_name = 0;
+
+	if (flags)
+		*flags = 0;
+
+	if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
+		if (flags)
+			*flags |= REF_BAD_NAME;
+
+		if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
+		    !refname_is_safe(refname)) {
+			errno = EINVAL;
+			return NULL;
+		}
+		/*
+		 * dwim_ref() uses REF_ISBROKEN to distinguish between
+		 * missing refs and refs that were present but invalid,
+		 * to complain about the latter to stderr.
+		 *
+		 * We don't know whether the ref exists, so don't set
+		 * REF_ISBROKEN yet.
+		 */
+		bad_name = 1;
+	}
+	for (;;) {
+		const char *path;
+		struct stat st;
+		char *buf;
+		int fd;
+
+		if (--depth < 0) {
+			errno = ELOOP;
+			return NULL;
+		}
+
+		strbuf_reset(sb_path);
+		strbuf_git_path(sb_path, "%s", refname);
+		path = sb_path->buf;
+
+		/*
+		 * We might have to loop back here to avoid a race
+		 * condition: first we lstat() the file, then we try
+		 * to read it as a link or as a file.  But if somebody
+		 * changes the type of the file (file <-> directory
+		 * <-> symlink) between the lstat() and reading, then
+		 * we don't want to report that as an error but rather
+		 * try again starting with the lstat().
+		 */
+	stat_ref:
+		if (lstat(path, &st) < 0) {
+			if (errno != ENOENT)
+				return NULL;
+			if (resolve_missing_loose_ref(refname, resolve_flags,
+						      sha1, flags))
+				return NULL;
+			if (bad_name) {
+				hashclr(sha1);
+				if (flags)
+					*flags |= REF_ISBROKEN;
+			}
+			return refname;
+		}
+
+		/* Follow "normalized" - ie "refs/.." symlinks by hand */
+		if (S_ISLNK(st.st_mode)) {
+			strbuf_reset(sb_contents);
+			if (strbuf_readlink(sb_contents, path, 0) < 0) {
+				if (errno == ENOENT || errno == EINVAL)
+					/* inconsistent with lstat; retry */
+					goto stat_ref;
+				else
+					return NULL;
+			}
+			if (starts_with(sb_contents->buf, "refs/") &&
+			    !check_refname_format(sb_contents->buf, 0)) {
+				strbuf_swap(sb_refname, sb_contents);
+				refname = sb_refname->buf;
+				if (flags)
+					*flags |= REF_ISSYMREF;
+				if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+					hashclr(sha1);
+					return refname;
+				}
+				continue;
+			}
+		}
+
+		/* Is it a directory? */
+		if (S_ISDIR(st.st_mode)) {
+			errno = EISDIR;
+			return NULL;
+		}
+
+		/*
+		 * Anything else, just open it and try to use it as
+		 * a ref
+		 */
+		fd = open(path, O_RDONLY);
+		if (fd < 0) {
+			if (errno == ENOENT)
+				/* inconsistent with lstat; retry */
+				goto stat_ref;
+			else
+				return NULL;
+		}
+		strbuf_reset(sb_contents);
+		if (strbuf_read(sb_contents, fd, 256) < 0) {
+			int save_errno = errno;
+			close(fd);
+			errno = save_errno;
+			return NULL;
+		}
+		close(fd);
+		strbuf_rtrim(sb_contents);
+
+		/*
+		 * Is it a symbolic ref?
+		 */
+		if (!starts_with(sb_contents->buf, "ref:")) {
+			/*
+			 * Please note that FETCH_HEAD has a second
+			 * line containing other data.
+			 */
+			if (get_sha1_hex(sb_contents->buf, sha1) ||
+			    (sb_contents->buf[40] != '\0' && !isspace(sb_contents->buf[40]))) {
+				if (flags)
+					*flags |= REF_ISBROKEN;
+				errno = EINVAL;
+				return NULL;
+			}
+			if (bad_name) {
+				hashclr(sha1);
+				if (flags)
+					*flags |= REF_ISBROKEN;
+			}
+			return refname;
+		}
+		if (flags)
+			*flags |= REF_ISSYMREF;
+		buf = sb_contents->buf + 4;
+		while (isspace(*buf))
+			buf++;
+		strbuf_reset(sb_refname);
+		strbuf_addstr(sb_refname, buf);
+		refname = sb_refname->buf;
+		if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
+			hashclr(sha1);
+			return refname;
+		}
+		if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
+			if (flags)
+				*flags |= REF_ISBROKEN;
+
+			if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
+			    !refname_is_safe(buf)) {
+				errno = EINVAL;
+				return NULL;
+			}
+			bad_name = 1;
+		}
+	}
+}
+
+const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
+			       unsigned char *sha1, int *flags)
+{
+	static struct strbuf sb_refname = STRBUF_INIT;
+	struct strbuf sb_contents = STRBUF_INIT;
+	struct strbuf sb_path = STRBUF_INIT;
+	const char *ret;
+
+	ret = resolve_ref_1(refname, resolve_flags, sha1, flags,
+			    &sb_refname, &sb_path, &sb_contents);
+	strbuf_release(&sb_path);
+	strbuf_release(&sb_contents);
+	return ret;
+}
+
+/*
+ * Peel the entry (if possible) and return its new peel_status.  If
+ * repeel is true, re-peel the entry even if there is an old peeled
+ * value that is already stored in it.
+ *
+ * It is OK to call this function with a packed reference entry that
+ * might be stale and might even refer to an object that has since
+ * been garbage-collected.  In such a case, if the entry has
+ * REF_KNOWS_PEELED then leave the status unchanged and return
+ * PEEL_PEELED or PEEL_NON_TAG; otherwise, return PEEL_INVALID.
+ */
+static enum peel_status peel_entry(struct ref_entry *entry, int repeel)
+{
+	enum peel_status status;
+
+	if (entry->flag & REF_KNOWS_PEELED) {
+		if (repeel) {
+			entry->flag &= ~REF_KNOWS_PEELED;
+			oidclr(&entry->u.value.peeled);
+		} else {
+			return is_null_oid(&entry->u.value.peeled) ?
+				PEEL_NON_TAG : PEEL_PEELED;
+		}
+	}
+	if (entry->flag & REF_ISBROKEN)
+		return PEEL_BROKEN;
+	if (entry->flag & REF_ISSYMREF)
+		return PEEL_IS_SYMREF;
+
+	status = peel_object(entry->u.value.oid.hash, entry->u.value.peeled.hash);
+	if (status == PEEL_PEELED || status == PEEL_NON_TAG)
+		entry->flag |= REF_KNOWS_PEELED;
+	return status;
+}
+
+int peel_ref(const char *refname, unsigned char *sha1)
+{
+	int flag;
+	unsigned char base[20];
+
+	if (current_ref && (current_ref->name == refname
+			    || !strcmp(current_ref->name, refname))) {
+		if (peel_entry(current_ref, 0))
+			return -1;
+		hashcpy(sha1, current_ref->u.value.peeled.hash);
+		return 0;
+	}
+
+	if (read_ref_full(refname, RESOLVE_REF_READING, base, &flag))
+		return -1;
+
+	/*
+	 * If the reference is packed, read its ref_entry from the
+	 * cache in the hope that we already know its peeled value.
+	 * We only try this optimization on packed references because
+	 * (a) forcing the filling of the loose reference cache could
+	 * be expensive and (b) loose references anyway usually do not
+	 * have REF_KNOWS_PEELED.
+	 */
+	if (flag & REF_ISPACKED) {
+		struct ref_entry *r = get_packed_ref(refname);
+		if (r) {
+			if (peel_entry(r, 0))
+				return -1;
+			hashcpy(sha1, r->u.value.peeled.hash);
+			return 0;
+		}
+	}
+
+	return peel_object(base, sha1);
+}
+
+/*
+ * Call fn for each reference in the specified ref_cache, omitting
+ * references not in the containing_dir of base.  fn is called for all
+ * references, including broken ones.  If fn ever returns a non-zero
+ * value, stop the iteration and return that value; otherwise, return
+ * 0.
+ */
+static int do_for_each_entry(struct ref_cache *refs, const char *base,
+			     each_ref_entry_fn fn, void *cb_data)
+{
+	struct packed_ref_cache *packed_ref_cache;
+	struct ref_dir *loose_dir;
+	struct ref_dir *packed_dir;
+	int retval = 0;
+
+	/*
+	 * We must make sure that all loose refs are read before accessing the
+	 * packed-refs file; this avoids a race condition in which loose refs
+	 * are migrated to the packed-refs file by a simultaneous process, but
+	 * our in-memory view is from before the migration. get_packed_ref_cache()
+	 * takes care of making sure our view is up to date with what is on
+	 * disk.
+	 */
+	loose_dir = get_loose_refs(refs);
+	if (base && *base) {
+		loose_dir = find_containing_dir(loose_dir, base, 0);
+	}
+	if (loose_dir)
+		prime_ref_dir(loose_dir);
+
+	packed_ref_cache = get_packed_ref_cache(refs);
+	acquire_packed_ref_cache(packed_ref_cache);
+	packed_dir = get_packed_ref_dir(packed_ref_cache);
+	if (base && *base) {
+		packed_dir = find_containing_dir(packed_dir, base, 0);
+	}
+
+	if (packed_dir && loose_dir) {
+		sort_ref_dir(packed_dir);
+		sort_ref_dir(loose_dir);
+		retval = do_for_each_entry_in_dirs(
+				packed_dir, loose_dir, fn, cb_data);
+	} else if (packed_dir) {
+		sort_ref_dir(packed_dir);
+		retval = do_for_each_entry_in_dir(
+				packed_dir, 0, fn, cb_data);
+	} else if (loose_dir) {
+		sort_ref_dir(loose_dir);
+		retval = do_for_each_entry_in_dir(
+				loose_dir, 0, fn, cb_data);
+	}
+
+	release_packed_ref_cache(packed_ref_cache);
+	return retval;
+}
+
+/*
+ * Call fn for each reference in the specified ref_cache for which the
+ * refname begins with base.  If trim is non-zero, then trim that many
+ * characters off the beginning of each refname before passing the
+ * refname to fn.  flags can be DO_FOR_EACH_INCLUDE_BROKEN to include
+ * broken references in the iteration.  If fn ever returns a non-zero
+ * value, stop the iteration and return that value; otherwise, return
+ * 0.
+ */
+static int do_for_each_ref(struct ref_cache *refs, const char *base,
+			   each_ref_fn fn, int trim, int flags, void *cb_data)
+{
+	struct ref_entry_cb data;
+	data.base = base;
+	data.trim = trim;
+	data.flags = flags;
+	data.fn = fn;
+	data.cb_data = cb_data;
+
+	if (ref_paranoia < 0)
+		ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
+	if (ref_paranoia)
+		data.flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+
+	return do_for_each_entry(refs, base, do_one_ref, &data);
+}
+
+static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	struct object_id oid;
+	int flag;
+
+	if (submodule) {
+		if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
+			return fn("HEAD", &oid, 0, cb_data);
+
+		return 0;
+	}
+
+	if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
+		return fn("HEAD", &oid, flag, cb_data);
+
+	return 0;
+}
+
+int head_ref(each_ref_fn fn, void *cb_data)
+{
+	return do_head_ref(NULL, fn, cb_data);
+}
+
+int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	return do_head_ref(submodule, fn, cb_data);
+}
+
+int for_each_ref(each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(&ref_cache, "", fn, 0, 0, cb_data);
+}
+
+int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(get_ref_cache(submodule), "", fn, 0, 0, cb_data);
+}
+
+int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(&ref_cache, prefix, fn, strlen(prefix), 0, cb_data);
+}
+
+int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
+{
+	unsigned int flag = 0;
+
+	if (broken)
+		flag = DO_FOR_EACH_INCLUDE_BROKEN;
+	return do_for_each_ref(&ref_cache, prefix, fn, 0, flag, cb_data);
+}
+
+int for_each_ref_in_submodule(const char *submodule, const char *prefix,
+		each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(get_ref_cache(submodule), prefix, fn, strlen(prefix), 0, cb_data);
+}
+
+int for_each_replace_ref(each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(&ref_cache, git_replace_ref_base, fn,
+			       strlen(git_replace_ref_base), 0, cb_data);
+}
+
+int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int ret;
+	strbuf_addf(&buf, "%srefs/", get_git_namespace());
+	ret = do_for_each_ref(&ref_cache, buf.buf, fn, 0, 0, cb_data);
+	strbuf_release(&buf);
+	return ret;
+}
+
+int for_each_rawref(each_ref_fn fn, void *cb_data)
+{
+	return do_for_each_ref(&ref_cache, "", fn, 0,
+			       DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
+}
+
+static void unlock_ref(struct ref_lock *lock)
+{
+	/* Do not free lock->lk -- atexit() still looks at them */
+	if (lock->lk)
+		rollback_lock_file(lock->lk);
+	free(lock->ref_name);
+	free(lock->orig_ref_name);
+	free(lock);
+}
+
+/*
+ * Verify that the reference locked by lock has the value old_sha1.
+ * Fail if the reference doesn't exist and mustexist is set. Return 0
+ * on success. On error, write an error message to err, set errno, and
+ * return a negative value.
+ */
+static int verify_lock(struct ref_lock *lock,
+		       const unsigned char *old_sha1, int mustexist,
+		       struct strbuf *err)
+{
+	assert(err);
+
+	if (read_ref_full(lock->ref_name,
+			  mustexist ? RESOLVE_REF_READING : 0,
+			  lock->old_oid.hash, NULL)) {
+		int save_errno = errno;
+		strbuf_addf(err, "can't verify ref %s", lock->ref_name);
+		errno = save_errno;
+		return -1;
+	}
+	if (hashcmp(lock->old_oid.hash, old_sha1)) {
+		strbuf_addf(err, "ref %s is at %s but expected %s",
+			    lock->ref_name,
+			    sha1_to_hex(lock->old_oid.hash),
+			    sha1_to_hex(old_sha1));
+		errno = EBUSY;
+		return -1;
+	}
+	return 0;
+}
+
+static int remove_empty_directories(struct strbuf *path)
+{
+	/*
+	 * we want to create a file but there is a directory there;
+	 * if that is an empty directory (or a directory that contains
+	 * only empty directories), remove them.
+	 */
+	return remove_dir_recursively(path, REMOVE_DIR_EMPTY_ONLY);
+}
+
+/*
+ * Locks a ref returning the lock on success and NULL on failure.
+ * On failure errno is set to something meaningful.
+ */
+static struct ref_lock *lock_ref_sha1_basic(const char *refname,
+					    const unsigned char *old_sha1,
+					    const struct string_list *extras,
+					    const struct string_list *skip,
+					    unsigned int flags, int *type_p,
+					    struct strbuf *err)
+{
+	struct strbuf ref_file = STRBUF_INIT;
+	struct strbuf orig_ref_file = STRBUF_INIT;
+	const char *orig_refname = refname;
+	struct ref_lock *lock;
+	int last_errno = 0;
+	int type, lflags;
+	int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
+	int resolve_flags = 0;
+	int attempts_remaining = 3;
+
+	assert(err);
+
+	lock = xcalloc(1, sizeof(struct ref_lock));
+
+	if (mustexist)
+		resolve_flags |= RESOLVE_REF_READING;
+	if (flags & REF_DELETING) {
+		resolve_flags |= RESOLVE_REF_ALLOW_BAD_NAME;
+		if (flags & REF_NODEREF)
+			resolve_flags |= RESOLVE_REF_NO_RECURSE;
+	}
+
+	refname = resolve_ref_unsafe(refname, resolve_flags,
+				     lock->old_oid.hash, &type);
+	if (!refname && errno == EISDIR) {
+		/*
+		 * we are trying to lock foo but we used to
+		 * have foo/bar which now does not exist;
+		 * it is normal for the empty directory 'foo'
+		 * to remain.
+		 */
+		strbuf_git_path(&orig_ref_file, "%s", orig_refname);
+		if (remove_empty_directories(&orig_ref_file)) {
+			last_errno = errno;
+			if (!verify_refname_available_dir(orig_refname, extras, skip,
+							  get_loose_refs(&ref_cache), err))
+				strbuf_addf(err, "there are still refs under '%s'",
+					    orig_refname);
+			goto error_return;
+		}
+		refname = resolve_ref_unsafe(orig_refname, resolve_flags,
+					     lock->old_oid.hash, &type);
+	}
+	if (type_p)
+	    *type_p = type;
+	if (!refname) {
+		last_errno = errno;
+		if (last_errno != ENOTDIR ||
+		    !verify_refname_available_dir(orig_refname, extras, skip,
+						  get_loose_refs(&ref_cache), err))
+			strbuf_addf(err, "unable to resolve reference %s: %s",
+				    orig_refname, strerror(last_errno));
+
+		goto error_return;
+	}
+	/*
+	 * If the ref did not exist and we are creating it, make sure
+	 * there is no existing packed ref whose name begins with our
+	 * refname, nor a packed ref whose name is a proper prefix of
+	 * our refname.
+	 */
+	if (is_null_oid(&lock->old_oid) &&
+	    verify_refname_available_dir(refname, extras, skip,
+					 get_packed_refs(&ref_cache), err)) {
+		last_errno = ENOTDIR;
+		goto error_return;
+	}
+
+	lock->lk = xcalloc(1, sizeof(struct lock_file));
+
+	lflags = 0;
+	if (flags & REF_NODEREF) {
+		refname = orig_refname;
+		lflags |= LOCK_NO_DEREF;
+	}
+	lock->ref_name = xstrdup(refname);
+	lock->orig_ref_name = xstrdup(orig_refname);
+	strbuf_git_path(&ref_file, "%s", refname);
+
+ retry:
+	switch (safe_create_leading_directories_const(ref_file.buf)) {
+	case SCLD_OK:
+		break; /* success */
+	case SCLD_VANISHED:
+		if (--attempts_remaining > 0)
+			goto retry;
+		/* fall through */
+	default:
+		last_errno = errno;
+		strbuf_addf(err, "unable to create directory for %s",
+			    ref_file.buf);
+		goto error_return;
+	}
+
+	if (hold_lock_file_for_update(lock->lk, ref_file.buf, lflags) < 0) {
+		last_errno = errno;
+		if (errno == ENOENT && --attempts_remaining > 0)
+			/*
+			 * Maybe somebody just deleted one of the
+			 * directories leading to ref_file.  Try
+			 * again:
+			 */
+			goto retry;
+		else {
+			unable_to_lock_message(ref_file.buf, errno, err);
+			goto error_return;
+		}
+	}
+	if (old_sha1 && verify_lock(lock, old_sha1, mustexist, err)) {
+		last_errno = errno;
+		goto error_return;
+	}
+	goto out;
+
+ error_return:
+	unlock_ref(lock);
+	lock = NULL;
+
+ out:
+	strbuf_release(&ref_file);
+	strbuf_release(&orig_ref_file);
+	errno = last_errno;
+	return lock;
+}
+
+/*
+ * Write an entry to the packed-refs file for the specified refname.
+ * If peeled is non-NULL, write it as the entry's peeled value.
+ */
+static void write_packed_entry(FILE *fh, char *refname, unsigned char *sha1,
+			       unsigned char *peeled)
+{
+	fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
+	if (peeled)
+		fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
+}
+
+/*
+ * An each_ref_entry_fn that writes the entry to a packed-refs file.
+ */
+static int write_packed_entry_fn(struct ref_entry *entry, void *cb_data)
+{
+	enum peel_status peel_status = peel_entry(entry, 0);
+
+	if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
+		error("internal error: %s is not a valid packed reference!",
+		      entry->name);
+	write_packed_entry(cb_data, entry->name, entry->u.value.oid.hash,
+			   peel_status == PEEL_PEELED ?
+			   entry->u.value.peeled.hash : NULL);
+	return 0;
+}
+
+/*
+ * Lock the packed-refs file for writing. Flags is passed to
+ * hold_lock_file_for_update(). Return 0 on success. On errors, set
+ * errno appropriately and return a nonzero value.
+ */
+static int lock_packed_refs(int flags)
+{
+	static int timeout_configured = 0;
+	static int timeout_value = 1000;
+
+	struct packed_ref_cache *packed_ref_cache;
+
+	if (!timeout_configured) {
+		git_config_get_int("core.packedrefstimeout", &timeout_value);
+		timeout_configured = 1;
+	}
+
+	if (hold_lock_file_for_update_timeout(
+			    &packlock, git_path("packed-refs"),
+			    flags, timeout_value) < 0)
+		return -1;
+	/*
+	 * Get the current packed-refs while holding the lock.  If the
+	 * packed-refs file has been modified since we last read it,
+	 * this will automatically invalidate the cache and re-read
+	 * the packed-refs file.
+	 */
+	packed_ref_cache = get_packed_ref_cache(&ref_cache);
+	packed_ref_cache->lock = &packlock;
+	/* Increment the reference count to prevent it from being freed: */
+	acquire_packed_ref_cache(packed_ref_cache);
+	return 0;
+}
+
+/*
+ * Write the current version of the packed refs cache from memory to
+ * disk. The packed-refs file must already be locked for writing (see
+ * lock_packed_refs()). Return zero on success. On errors, set errno
+ * and return a nonzero value
+ */
+static int commit_packed_refs(void)
+{
+	struct packed_ref_cache *packed_ref_cache =
+		get_packed_ref_cache(&ref_cache);
+	int error = 0;
+	int save_errno = 0;
+	FILE *out;
+
+	if (!packed_ref_cache->lock)
+		die("internal error: packed-refs not locked");
+
+	out = fdopen_lock_file(packed_ref_cache->lock, "w");
+	if (!out)
+		die_errno("unable to fdopen packed-refs descriptor");
+
+	fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
+	do_for_each_entry_in_dir(get_packed_ref_dir(packed_ref_cache),
+				 0, write_packed_entry_fn, out);
+
+	if (commit_lock_file(packed_ref_cache->lock)) {
+		save_errno = errno;
+		error = -1;
+	}
+	packed_ref_cache->lock = NULL;
+	release_packed_ref_cache(packed_ref_cache);
+	errno = save_errno;
+	return error;
+}
+
+/*
+ * Rollback the lockfile for the packed-refs file, and discard the
+ * in-memory packed reference cache.  (The packed-refs file will be
+ * read anew if it is needed again after this function is called.)
+ */
+static void rollback_packed_refs(void)
+{
+	struct packed_ref_cache *packed_ref_cache =
+		get_packed_ref_cache(&ref_cache);
+
+	if (!packed_ref_cache->lock)
+		die("internal error: packed-refs not locked");
+	rollback_lock_file(packed_ref_cache->lock);
+	packed_ref_cache->lock = NULL;
+	release_packed_ref_cache(packed_ref_cache);
+	clear_packed_ref_cache(&ref_cache);
+}
+
+struct ref_to_prune {
+	struct ref_to_prune *next;
+	unsigned char sha1[20];
+	char name[FLEX_ARRAY];
+};
+
+struct pack_refs_cb_data {
+	unsigned int flags;
+	struct ref_dir *packed_refs;
+	struct ref_to_prune *ref_to_prune;
+};
+
+/*
+ * An each_ref_entry_fn that is run over loose references only.  If
+ * the loose reference can be packed, add an entry in the packed ref
+ * cache.  If the reference should be pruned, also add it to
+ * ref_to_prune in the pack_refs_cb_data.
+ */
+static int pack_if_possible_fn(struct ref_entry *entry, void *cb_data)
+{
+	struct pack_refs_cb_data *cb = cb_data;
+	enum peel_status peel_status;
+	struct ref_entry *packed_entry;
+	int is_tag_ref = starts_with(entry->name, "refs/tags/");
+
+	/* Do not pack per-worktree refs: */
+	if (ref_type(entry->name) != REF_TYPE_NORMAL)
+		return 0;
+
+	/* ALWAYS pack tags */
+	if (!(cb->flags & PACK_REFS_ALL) && !is_tag_ref)
+		return 0;
+
+	/* Do not pack symbolic or broken refs: */
+	if ((entry->flag & REF_ISSYMREF) || !ref_resolves_to_object(entry))
+		return 0;
+
+	/* Add a packed ref cache entry equivalent to the loose entry. */
+	peel_status = peel_entry(entry, 1);
+	if (peel_status != PEEL_PEELED && peel_status != PEEL_NON_TAG)
+		die("internal error peeling reference %s (%s)",
+		    entry->name, oid_to_hex(&entry->u.value.oid));
+	packed_entry = find_ref(cb->packed_refs, entry->name);
+	if (packed_entry) {
+		/* Overwrite existing packed entry with info from loose entry */
+		packed_entry->flag = REF_ISPACKED | REF_KNOWS_PEELED;
+		oidcpy(&packed_entry->u.value.oid, &entry->u.value.oid);
+	} else {
+		packed_entry = create_ref_entry(entry->name, entry->u.value.oid.hash,
+						REF_ISPACKED | REF_KNOWS_PEELED, 0);
+		add_ref(cb->packed_refs, packed_entry);
+	}
+	oidcpy(&packed_entry->u.value.peeled, &entry->u.value.peeled);
+
+	/* Schedule the loose reference for pruning if requested. */
+	if ((cb->flags & PACK_REFS_PRUNE)) {
+		int namelen = strlen(entry->name) + 1;
+		struct ref_to_prune *n = xcalloc(1, sizeof(*n) + namelen);
+		hashcpy(n->sha1, entry->u.value.oid.hash);
+		memcpy(n->name, entry->name, namelen); /* includes NUL */
+		n->next = cb->ref_to_prune;
+		cb->ref_to_prune = n;
+	}
+	return 0;
+}
+
+/*
+ * Remove empty parents, but spare refs/ and immediate subdirs.
+ * Note: munges *name.
+ */
+static void try_remove_empty_parents(char *name)
+{
+	char *p, *q;
+	int i;
+	p = name;
+	for (i = 0; i < 2; i++) { /* refs/{heads,tags,...}/ */
+		while (*p && *p != '/')
+			p++;
+		/* tolerate duplicate slashes; see check_refname_format() */
+		while (*p == '/')
+			p++;
+	}
+	for (q = p; *q; q++)
+		;
+	while (1) {
+		while (q > p && *q != '/')
+			q--;
+		while (q > p && *(q-1) == '/')
+			q--;
+		if (q == p)
+			break;
+		*q = '\0';
+		if (rmdir(git_path("%s", name)))
+			break;
+	}
+}
+
+/* make sure nobody touched the ref, and unlink */
+static void prune_ref(struct ref_to_prune *r)
+{
+	struct ref_transaction *transaction;
+	struct strbuf err = STRBUF_INIT;
+
+	if (check_refname_format(r->name, 0))
+		return;
+
+	transaction = ref_transaction_begin(&err);
+	if (!transaction ||
+	    ref_transaction_delete(transaction, r->name, r->sha1,
+				   REF_ISPRUNING, NULL, &err) ||
+	    ref_transaction_commit(transaction, &err)) {
+		ref_transaction_free(transaction);
+		error("%s", err.buf);
+		strbuf_release(&err);
+		return;
+	}
+	ref_transaction_free(transaction);
+	strbuf_release(&err);
+	try_remove_empty_parents(r->name);
+}
+
+static void prune_refs(struct ref_to_prune *r)
+{
+	while (r) {
+		prune_ref(r);
+		r = r->next;
+	}
+}
+
+int pack_refs(unsigned int flags)
+{
+	struct pack_refs_cb_data cbdata;
+
+	memset(&cbdata, 0, sizeof(cbdata));
+	cbdata.flags = flags;
+
+	lock_packed_refs(LOCK_DIE_ON_ERROR);
+	cbdata.packed_refs = get_packed_refs(&ref_cache);
+
+	do_for_each_entry_in_dir(get_loose_refs(&ref_cache), 0,
+				 pack_if_possible_fn, &cbdata);
+
+	if (commit_packed_refs())
+		die_errno("unable to overwrite old ref-pack file");
+
+	prune_refs(cbdata.ref_to_prune);
+	return 0;
+}
+
+/*
+ * Rewrite the packed-refs file, omitting any refs listed in
+ * 'refnames'. On error, leave packed-refs unchanged, write an error
+ * message to 'err', and return a nonzero value.
+ *
+ * The refs in 'refnames' needn't be sorted. `err` must not be NULL.
+ */
+static int repack_without_refs(struct string_list *refnames, struct strbuf *err)
+{
+	struct ref_dir *packed;
+	struct string_list_item *refname;
+	int ret, needs_repacking = 0, removed = 0;
+
+	assert(err);
+
+	/* Look for a packed ref */
+	for_each_string_list_item(refname, refnames) {
+		if (get_packed_ref(refname->string)) {
+			needs_repacking = 1;
+			break;
+		}
+	}
+
+	/* Avoid locking if we have nothing to do */
+	if (!needs_repacking)
+		return 0; /* no refname exists in packed refs */
+
+	if (lock_packed_refs(0)) {
+		unable_to_lock_message(git_path("packed-refs"), errno, err);
+		return -1;
+	}
+	packed = get_packed_refs(&ref_cache);
+
+	/* Remove refnames from the cache */
+	for_each_string_list_item(refname, refnames)
+		if (remove_entry(packed, refname->string) != -1)
+			removed = 1;
+	if (!removed) {
+		/*
+		 * All packed entries disappeared while we were
+		 * acquiring the lock.
+		 */
+		rollback_packed_refs();
+		return 0;
+	}
+
+	/* Write what remains */
+	ret = commit_packed_refs();
+	if (ret)
+		strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
+			    strerror(errno));
+	return ret;
+}
+
+static int delete_ref_loose(struct ref_lock *lock, int flag, struct strbuf *err)
+{
+	assert(err);
+
+	if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
+		/*
+		 * loose.  The loose file name is the same as the
+		 * lockfile name, minus ".lock":
+		 */
+		char *loose_filename = get_locked_file_path(lock->lk);
+		int res = unlink_or_msg(loose_filename, err);
+		free(loose_filename);
+		if (res)
+			return 1;
+	}
+	return 0;
+}
+
+int delete_refs(struct string_list *refnames)
+{
+	struct strbuf err = STRBUF_INIT;
+	int i, result = 0;
+
+	if (!refnames->nr)
+		return 0;
+
+	result = repack_without_refs(refnames, &err);
+	if (result) {
+		/*
+		 * If we failed to rewrite the packed-refs file, then
+		 * it is unsafe to try to remove loose refs, because
+		 * doing so might expose an obsolete packed value for
+		 * a reference that might even point at an object that
+		 * has been garbage collected.
+		 */
+		if (refnames->nr == 1)
+			error(_("could not delete reference %s: %s"),
+			      refnames->items[0].string, err.buf);
+		else
+			error(_("could not delete references: %s"), err.buf);
+
+		goto out;
+	}
+
+	for (i = 0; i < refnames->nr; i++) {
+		const char *refname = refnames->items[i].string;
+
+		if (delete_ref(refname, NULL, 0))
+			result |= error(_("could not remove reference %s"), refname);
+	}
+
+out:
+	strbuf_release(&err);
+	return result;
+}
+
+/*
+ * People using contrib's git-new-workdir have .git/logs/refs ->
+ * /some/other/path/.git/logs/refs, and that may live on another device.
+ *
+ * IOW, to avoid cross device rename errors, the temporary renamed log must
+ * live into logs/refs.
+ */
+#define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
+
+static int rename_tmp_log(const char *newrefname)
+{
+	int attempts_remaining = 4;
+	struct strbuf path = STRBUF_INIT;
+	int ret = -1;
+
+ retry:
+	strbuf_reset(&path);
+	strbuf_git_path(&path, "logs/%s", newrefname);
+	switch (safe_create_leading_directories_const(path.buf)) {
+	case SCLD_OK:
+		break; /* success */
+	case SCLD_VANISHED:
+		if (--attempts_remaining > 0)
+			goto retry;
+		/* fall through */
+	default:
+		error("unable to create directory for %s", newrefname);
+		goto out;
+	}
+
+	if (rename(git_path(TMP_RENAMED_LOG), path.buf)) {
+		if ((errno==EISDIR || errno==ENOTDIR) && --attempts_remaining > 0) {
+			/*
+			 * rename(a, b) when b is an existing
+			 * directory ought to result in ISDIR, but
+			 * Solaris 5.8 gives ENOTDIR.  Sheesh.
+			 */
+			if (remove_empty_directories(&path)) {
+				error("Directory not empty: logs/%s", newrefname);
+				goto out;
+			}
+			goto retry;
+		} else if (errno == ENOENT && --attempts_remaining > 0) {
+			/*
+			 * Maybe another process just deleted one of
+			 * the directories in the path to newrefname.
+			 * Try again from the beginning.
+			 */
+			goto retry;
+		} else {
+			error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
+				newrefname, strerror(errno));
+			goto out;
+		}
+	}
+	ret = 0;
+out:
+	strbuf_release(&path);
+	return ret;
+}
+
+int verify_refname_available(const char *newname,
+			     struct string_list *extras,
+			     struct string_list *skip,
+			     struct strbuf *err)
+{
+	struct ref_dir *packed_refs = get_packed_refs(&ref_cache);
+	struct ref_dir *loose_refs = get_loose_refs(&ref_cache);
+
+	if (verify_refname_available_dir(newname, extras, skip,
+					 packed_refs, err) ||
+	    verify_refname_available_dir(newname, extras, skip,
+					 loose_refs, err))
+		return -1;
+
+	return 0;
+}
+
+static int write_ref_to_lockfile(struct ref_lock *lock,
+				 const unsigned char *sha1, struct strbuf *err);
+static int commit_ref_update(struct ref_lock *lock,
+			     const unsigned char *sha1, const char *logmsg,
+			     int flags, struct strbuf *err);
+
+int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
+{
+	unsigned char sha1[20], orig_sha1[20];
+	int flag = 0, logmoved = 0;
+	struct ref_lock *lock;
+	struct stat loginfo;
+	int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
+	const char *symref = NULL;
+	struct strbuf err = STRBUF_INIT;
+
+	if (log && S_ISLNK(loginfo.st_mode))
+		return error("reflog for %s is a symlink", oldrefname);
+
+	symref = resolve_ref_unsafe(oldrefname, RESOLVE_REF_READING,
+				    orig_sha1, &flag);
+	if (flag & REF_ISSYMREF)
+		return error("refname %s is a symbolic ref, renaming it is not supported",
+			oldrefname);
+	if (!symref)
+		return error("refname %s not found", oldrefname);
+
+	if (!rename_ref_available(oldrefname, newrefname))
+		return 1;
+
+	if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
+		return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
+			oldrefname, strerror(errno));
+
+	if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
+		error("unable to delete old %s", oldrefname);
+		goto rollback;
+	}
+
+	if (!read_ref_full(newrefname, RESOLVE_REF_READING, sha1, NULL) &&
+	    delete_ref(newrefname, sha1, REF_NODEREF)) {
+		if (errno==EISDIR) {
+			struct strbuf path = STRBUF_INIT;
+			int result;
+
+			strbuf_git_path(&path, "%s", newrefname);
+			result = remove_empty_directories(&path);
+			strbuf_release(&path);
+
+			if (result) {
+				error("Directory not empty: %s", newrefname);
+				goto rollback;
+			}
+		} else {
+			error("unable to delete existing %s", newrefname);
+			goto rollback;
+		}
+	}
+
+	if (log && rename_tmp_log(newrefname))
+		goto rollback;
+
+	logmoved = log;
+
+	lock = lock_ref_sha1_basic(newrefname, NULL, NULL, NULL, 0, NULL, &err);
+	if (!lock) {
+		error("unable to rename '%s' to '%s': %s", oldrefname, newrefname, err.buf);
+		strbuf_release(&err);
+		goto rollback;
+	}
+	hashcpy(lock->old_oid.hash, orig_sha1);
+
+	if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
+	    commit_ref_update(lock, orig_sha1, logmsg, 0, &err)) {
+		error("unable to write current sha1 into %s: %s", newrefname, err.buf);
+		strbuf_release(&err);
+		goto rollback;
+	}
+
+	return 0;
+
+ rollback:
+	lock = lock_ref_sha1_basic(oldrefname, NULL, NULL, NULL, 0, NULL, &err);
+	if (!lock) {
+		error("unable to lock %s for rollback: %s", oldrefname, err.buf);
+		strbuf_release(&err);
+		goto rollbacklog;
+	}
+
+	flag = log_all_ref_updates;
+	log_all_ref_updates = 0;
+	if (write_ref_to_lockfile(lock, orig_sha1, &err) ||
+	    commit_ref_update(lock, orig_sha1, NULL, 0, &err)) {
+		error("unable to write current sha1 into %s: %s", oldrefname, err.buf);
+		strbuf_release(&err);
+	}
+	log_all_ref_updates = flag;
+
+ rollbacklog:
+	if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
+		error("unable to restore logfile %s from %s: %s",
+			oldrefname, newrefname, strerror(errno));
+	if (!logmoved && log &&
+	    rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
+		error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
+			oldrefname, strerror(errno));
+
+	return 1;
+}
+
+static int close_ref(struct ref_lock *lock)
+{
+	if (close_lock_file(lock->lk))
+		return -1;
+	return 0;
+}
+
+static int commit_ref(struct ref_lock *lock)
+{
+	if (commit_lock_file(lock->lk))
+		return -1;
+	return 0;
+}
+
+/*
+ * Create a reflog for a ref.  If force_create = 0, the reflog will
+ * only be created for certain refs (those for which
+ * should_autocreate_reflog returns non-zero.  Otherwise, create it
+ * regardless of the ref name.  Fill in *err and return -1 on failure.
+ */
+static int log_ref_setup(const char *refname, struct strbuf *logfile, struct strbuf *err, int force_create)
+{
+	int logfd, oflags = O_APPEND | O_WRONLY;
+
+	strbuf_git_path(logfile, "logs/%s", refname);
+	if (force_create || should_autocreate_reflog(refname)) {
+		if (safe_create_leading_directories(logfile->buf) < 0) {
+			strbuf_addf(err, "unable to create directory for %s: "
+				    "%s", logfile->buf, strerror(errno));
+			return -1;
+		}
+		oflags |= O_CREAT;
+	}
+
+	logfd = open(logfile->buf, oflags, 0666);
+	if (logfd < 0) {
+		if (!(oflags & O_CREAT) && (errno == ENOENT || errno == EISDIR))
+			return 0;
+
+		if (errno == EISDIR) {
+			if (remove_empty_directories(logfile)) {
+				strbuf_addf(err, "There are still logs under "
+					    "'%s'", logfile->buf);
+				return -1;
+			}
+			logfd = open(logfile->buf, oflags, 0666);
+		}
+
+		if (logfd < 0) {
+			strbuf_addf(err, "unable to append to %s: %s",
+				    logfile->buf, strerror(errno));
+			return -1;
+		}
+	}
+
+	adjust_shared_perm(logfile->buf);
+	close(logfd);
+	return 0;
+}
+
+
+int safe_create_reflog(const char *refname, int force_create, struct strbuf *err)
+{
+	int ret;
+	struct strbuf sb = STRBUF_INIT;
+
+	ret = log_ref_setup(refname, &sb, err, force_create);
+	strbuf_release(&sb);
+	return ret;
+}
+
+static int log_ref_write_fd(int fd, const unsigned char *old_sha1,
+			    const unsigned char *new_sha1,
+			    const char *committer, const char *msg)
+{
+	int msglen, written;
+	unsigned maxlen, len;
+	char *logrec;
+
+	msglen = msg ? strlen(msg) : 0;
+	maxlen = strlen(committer) + msglen + 100;
+	logrec = xmalloc(maxlen);
+	len = xsnprintf(logrec, maxlen, "%s %s %s\n",
+			sha1_to_hex(old_sha1),
+			sha1_to_hex(new_sha1),
+			committer);
+	if (msglen)
+		len += copy_reflog_msg(logrec + len - 1, msg) - 1;
+
+	written = len <= maxlen ? write_in_full(fd, logrec, len) : -1;
+	free(logrec);
+	if (written != len)
+		return -1;
+
+	return 0;
+}
+
+static int log_ref_write_1(const char *refname, const unsigned char *old_sha1,
+			   const unsigned char *new_sha1, const char *msg,
+			   struct strbuf *logfile, int flags,
+			   struct strbuf *err)
+{
+	int logfd, result, oflags = O_APPEND | O_WRONLY;
+
+	if (log_all_ref_updates < 0)
+		log_all_ref_updates = !is_bare_repository();
+
+	result = log_ref_setup(refname, logfile, err, flags & REF_FORCE_CREATE_REFLOG);
+
+	if (result)
+		return result;
+
+	logfd = open(logfile->buf, oflags);
+	if (logfd < 0)
+		return 0;
+	result = log_ref_write_fd(logfd, old_sha1, new_sha1,
+				  git_committer_info(0), msg);
+	if (result) {
+		strbuf_addf(err, "unable to append to %s: %s", logfile->buf,
+			    strerror(errno));
+		close(logfd);
+		return -1;
+	}
+	if (close(logfd)) {
+		strbuf_addf(err, "unable to append to %s: %s", logfile->buf,
+			    strerror(errno));
+		return -1;
+	}
+	return 0;
+}
+
+static int log_ref_write(const char *refname, const unsigned char *old_sha1,
+			 const unsigned char *new_sha1, const char *msg,
+			 int flags, struct strbuf *err)
+{
+	return files_log_ref_write(refname, old_sha1, new_sha1, msg, flags,
+				   err);
+}
+
+int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
+			const unsigned char *new_sha1, const char *msg,
+			int flags, struct strbuf *err)
+{
+	struct strbuf sb = STRBUF_INIT;
+	int ret = log_ref_write_1(refname, old_sha1, new_sha1, msg, &sb, flags,
+				  err);
+	strbuf_release(&sb);
+	return ret;
+}
+
+/*
+ * Write sha1 into the open lockfile, then close the lockfile. On
+ * errors, rollback the lockfile, fill in *err and
+ * return -1.
+ */
+static int write_ref_to_lockfile(struct ref_lock *lock,
+				 const unsigned char *sha1, struct strbuf *err)
+{
+	static char term = '\n';
+	struct object *o;
+	int fd;
+
+	o = parse_object(sha1);
+	if (!o) {
+		strbuf_addf(err,
+			    "Trying to write ref %s with nonexistent object %s",
+			    lock->ref_name, sha1_to_hex(sha1));
+		unlock_ref(lock);
+		return -1;
+	}
+	if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
+		strbuf_addf(err,
+			    "Trying to write non-commit object %s to branch %s",
+			    sha1_to_hex(sha1), lock->ref_name);
+		unlock_ref(lock);
+		return -1;
+	}
+	fd = get_lock_file_fd(lock->lk);
+	if (write_in_full(fd, sha1_to_hex(sha1), 40) != 40 ||
+	    write_in_full(fd, &term, 1) != 1 ||
+	    close_ref(lock) < 0) {
+		strbuf_addf(err,
+			    "Couldn't write %s", get_lock_file_path(lock->lk));
+		unlock_ref(lock);
+		return -1;
+	}
+	return 0;
+}
+
+/*
+ * Commit a change to a loose reference that has already been written
+ * to the loose reference lockfile. Also update the reflogs if
+ * necessary, using the specified lockmsg (which can be NULL).
+ */
+static int commit_ref_update(struct ref_lock *lock,
+			     const unsigned char *sha1, const char *logmsg,
+			     int flags, struct strbuf *err)
+{
+	clear_loose_ref_cache(&ref_cache);
+	if (log_ref_write(lock->ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0 ||
+	    (strcmp(lock->ref_name, lock->orig_ref_name) &&
+	     log_ref_write(lock->orig_ref_name, lock->old_oid.hash, sha1, logmsg, flags, err) < 0)) {
+		char *old_msg = strbuf_detach(err, NULL);
+		strbuf_addf(err, "Cannot update the ref '%s': %s",
+			    lock->ref_name, old_msg);
+		free(old_msg);
+		unlock_ref(lock);
+		return -1;
+	}
+	if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
+		/*
+		 * Special hack: If a branch is updated directly and HEAD
+		 * points to it (may happen on the remote side of a push
+		 * for example) then logically the HEAD reflog should be
+		 * updated too.
+		 * A generic solution implies reverse symref information,
+		 * but finding all symrefs pointing to the given branch
+		 * would be rather costly for this rare event (the direct
+		 * update of a branch) to be worth it.  So let's cheat and
+		 * check with HEAD only which should cover 99% of all usage
+		 * scenarios (even 100% of the default ones).
+		 */
+		unsigned char head_sha1[20];
+		int head_flag;
+		const char *head_ref;
+		head_ref = resolve_ref_unsafe("HEAD", RESOLVE_REF_READING,
+					      head_sha1, &head_flag);
+		if (head_ref && (head_flag & REF_ISSYMREF) &&
+		    !strcmp(head_ref, lock->ref_name)) {
+			struct strbuf log_err = STRBUF_INIT;
+			if (log_ref_write("HEAD", lock->old_oid.hash, sha1,
+					  logmsg, 0, &log_err)) {
+				error("%s", log_err.buf);
+				strbuf_release(&log_err);
+			}
+		}
+	}
+	if (commit_ref(lock)) {
+		error("Couldn't set %s", lock->ref_name);
+		unlock_ref(lock);
+		return -1;
+	}
+
+	unlock_ref(lock);
+	return 0;
+}
+
+int create_symref(const char *ref_target, const char *refs_heads_master,
+		  const char *logmsg)
+{
+	char *lockpath = NULL;
+	char ref[1000];
+	int fd, len, written;
+	char *git_HEAD = git_pathdup("%s", ref_target);
+	unsigned char old_sha1[20], new_sha1[20];
+	struct strbuf err = STRBUF_INIT;
+
+	if (logmsg && read_ref(ref_target, old_sha1))
+		hashclr(old_sha1);
+
+	if (safe_create_leading_directories(git_HEAD) < 0)
+		return error("unable to create directory for %s", git_HEAD);
+
+#ifndef NO_SYMLINK_HEAD
+	if (prefer_symlink_refs) {
+		unlink(git_HEAD);
+		if (!symlink(refs_heads_master, git_HEAD))
+			goto done;
+		fprintf(stderr, "no symlink - falling back to symbolic ref\n");
+	}
+#endif
+
+	len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
+	if (sizeof(ref) <= len) {
+		error("refname too long: %s", refs_heads_master);
+		goto error_free_return;
+	}
+	lockpath = mkpathdup("%s.lock", git_HEAD);
+	fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
+	if (fd < 0) {
+		error("Unable to open %s for writing", lockpath);
+		goto error_free_return;
+	}
+	written = write_in_full(fd, ref, len);
+	if (close(fd) != 0 || written != len) {
+		error("Unable to write to %s", lockpath);
+		goto error_unlink_return;
+	}
+	if (rename(lockpath, git_HEAD) < 0) {
+		error("Unable to create %s", git_HEAD);
+		goto error_unlink_return;
+	}
+	if (adjust_shared_perm(git_HEAD)) {
+		error("Unable to fix permissions on %s", lockpath);
+	error_unlink_return:
+		unlink_or_warn(lockpath);
+	error_free_return:
+		free(lockpath);
+		free(git_HEAD);
+		return -1;
+	}
+	free(lockpath);
+
+#ifndef NO_SYMLINK_HEAD
+	done:
+#endif
+	if (logmsg && !read_ref(refs_heads_master, new_sha1) &&
+		log_ref_write(ref_target, old_sha1, new_sha1, logmsg, 0, &err)) {
+		error("%s", err.buf);
+		strbuf_release(&err);
+	}
+
+	free(git_HEAD);
+	return 0;
+}
+
+int reflog_exists(const char *refname)
+{
+	struct stat st;
+
+	return !lstat(git_path("logs/%s", refname), &st) &&
+		S_ISREG(st.st_mode);
+}
+
+int delete_reflog(const char *refname)
+{
+	return remove_path(git_path("logs/%s", refname));
+}
+
+static int show_one_reflog_ent(struct strbuf *sb, each_reflog_ent_fn fn, void *cb_data)
+{
+	unsigned char osha1[20], nsha1[20];
+	char *email_end, *message;
+	unsigned long timestamp;
+	int tz;
+
+	/* old SP new SP name <email> SP time TAB msg LF */
+	if (sb->len < 83 || sb->buf[sb->len - 1] != '\n' ||
+	    get_sha1_hex(sb->buf, osha1) || sb->buf[40] != ' ' ||
+	    get_sha1_hex(sb->buf + 41, nsha1) || sb->buf[81] != ' ' ||
+	    !(email_end = strchr(sb->buf + 82, '>')) ||
+	    email_end[1] != ' ' ||
+	    !(timestamp = strtoul(email_end + 2, &message, 10)) ||
+	    !message || message[0] != ' ' ||
+	    (message[1] != '+' && message[1] != '-') ||
+	    !isdigit(message[2]) || !isdigit(message[3]) ||
+	    !isdigit(message[4]) || !isdigit(message[5]))
+		return 0; /* corrupt? */
+	email_end[1] = '\0';
+	tz = strtol(message + 1, NULL, 10);
+	if (message[6] != '\t')
+		message += 6;
+	else
+		message += 7;
+	return fn(osha1, nsha1, sb->buf + 82, timestamp, tz, message, cb_data);
+}
+
+static char *find_beginning_of_line(char *bob, char *scan)
+{
+	while (bob < scan && *(--scan) != '\n')
+		; /* keep scanning backwards */
+	/*
+	 * Return either beginning of the buffer, or LF at the end of
+	 * the previous line.
+	 */
+	return scan;
+}
+
+int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn, void *cb_data)
+{
+	struct strbuf sb = STRBUF_INIT;
+	FILE *logfp;
+	long pos;
+	int ret = 0, at_tail = 1;
+
+	logfp = fopen(git_path("logs/%s", refname), "r");
+	if (!logfp)
+		return -1;
+
+	/* Jump to the end */
+	if (fseek(logfp, 0, SEEK_END) < 0)
+		return error("cannot seek back reflog for %s: %s",
+			     refname, strerror(errno));
+	pos = ftell(logfp);
+	while (!ret && 0 < pos) {
+		int cnt;
+		size_t nread;
+		char buf[BUFSIZ];
+		char *endp, *scanp;
+
+		/* Fill next block from the end */
+		cnt = (sizeof(buf) < pos) ? sizeof(buf) : pos;
+		if (fseek(logfp, pos - cnt, SEEK_SET))
+			return error("cannot seek back reflog for %s: %s",
+				     refname, strerror(errno));
+		nread = fread(buf, cnt, 1, logfp);
+		if (nread != 1)
+			return error("cannot read %d bytes from reflog for %s: %s",
+				     cnt, refname, strerror(errno));
+		pos -= cnt;
+
+		scanp = endp = buf + cnt;
+		if (at_tail && scanp[-1] == '\n')
+			/* Looking at the final LF at the end of the file */
+			scanp--;
+		at_tail = 0;
+
+		while (buf < scanp) {
+			/*
+			 * terminating LF of the previous line, or the beginning
+			 * of the buffer.
+			 */
+			char *bp;
+
+			bp = find_beginning_of_line(buf, scanp);
+
+			if (*bp == '\n') {
+				/*
+				 * The newline is the end of the previous line,
+				 * so we know we have complete line starting
+				 * at (bp + 1). Prefix it onto any prior data
+				 * we collected for the line and process it.
+				 */
+				strbuf_splice(&sb, 0, 0, bp + 1, endp - (bp + 1));
+				scanp = bp;
+				endp = bp + 1;
+				ret = show_one_reflog_ent(&sb, fn, cb_data);
+				strbuf_reset(&sb);
+				if (ret)
+					break;
+			} else if (!pos) {
+				/*
+				 * We are at the start of the buffer, and the
+				 * start of the file; there is no previous
+				 * line, and we have everything for this one.
+				 * Process it, and we can end the loop.
+				 */
+				strbuf_splice(&sb, 0, 0, buf, endp - buf);
+				ret = show_one_reflog_ent(&sb, fn, cb_data);
+				strbuf_reset(&sb);
+				break;
+			}
+
+			if (bp == buf) {
+				/*
+				 * We are at the start of the buffer, and there
+				 * is more file to read backwards. Which means
+				 * we are in the middle of a line. Note that we
+				 * may get here even if *bp was a newline; that
+				 * just means we are at the exact end of the
+				 * previous line, rather than some spot in the
+				 * middle.
+				 *
+				 * Save away what we have to be combined with
+				 * the data from the next read.
+				 */
+				strbuf_splice(&sb, 0, 0, buf, endp - buf);
+				break;
+			}
+		}
+
+	}
+	if (!ret && sb.len)
+		die("BUG: reverse reflog parser had leftover data");
+
+	fclose(logfp);
+	strbuf_release(&sb);
+	return ret;
+}
+
+int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
+{
+	FILE *logfp;
+	struct strbuf sb = STRBUF_INIT;
+	int ret = 0;
+
+	logfp = fopen(git_path("logs/%s", refname), "r");
+	if (!logfp)
+		return -1;
+
+	while (!ret && !strbuf_getwholeline(&sb, logfp, '\n'))
+		ret = show_one_reflog_ent(&sb, fn, cb_data);
+	fclose(logfp);
+	strbuf_release(&sb);
+	return ret;
+}
+/*
+ * Call fn for each reflog in the namespace indicated by name.  name
+ * must be empty or end with '/'.  Name will be used as a scratch
+ * space, but its contents will be restored before return.
+ */
+static int do_for_each_reflog(struct strbuf *name, each_ref_fn fn, void *cb_data)
+{
+	DIR *d = opendir(git_path("logs/%s", name->buf));
+	int retval = 0;
+	struct dirent *de;
+	int oldlen = name->len;
+
+	if (!d)
+		return name->len ? errno : 0;
+
+	while ((de = readdir(d)) != NULL) {
+		struct stat st;
+
+		if (de->d_name[0] == '.')
+			continue;
+		if (ends_with(de->d_name, ".lock"))
+			continue;
+		strbuf_addstr(name, de->d_name);
+		if (stat(git_path("logs/%s", name->buf), &st) < 0) {
+			; /* silently ignore */
+		} else {
+			if (S_ISDIR(st.st_mode)) {
+				strbuf_addch(name, '/');
+				retval = do_for_each_reflog(name, fn, cb_data);
+			} else {
+				struct object_id oid;
+
+				if (read_ref_full(name->buf, 0, oid.hash, NULL))
+					retval = error("bad ref for %s", name->buf);
+				else
+					retval = fn(name->buf, &oid, 0, cb_data);
+			}
+			if (retval)
+				break;
+		}
+		strbuf_setlen(name, oldlen);
+	}
+	closedir(d);
+	return retval;
+}
+
+int for_each_reflog(each_ref_fn fn, void *cb_data)
+{
+	int retval;
+	struct strbuf name;
+	strbuf_init(&name, PATH_MAX);
+	retval = do_for_each_reflog(&name, fn, cb_data);
+	strbuf_release(&name);
+	return retval;
+}
+
+static int ref_update_reject_duplicates(struct string_list *refnames,
+					struct strbuf *err)
+{
+	int i, n = refnames->nr;
+
+	assert(err);
+
+	for (i = 1; i < n; i++)
+		if (!strcmp(refnames->items[i - 1].string, refnames->items[i].string)) {
+			strbuf_addf(err,
+				    "Multiple updates for ref '%s' not allowed.",
+				    refnames->items[i].string);
+			return 1;
+		}
+	return 0;
+}
+
+int ref_transaction_commit(struct ref_transaction *transaction,
+			   struct strbuf *err)
+{
+	int ret = 0, i;
+	int n = transaction->nr;
+	struct ref_update **updates = transaction->updates;
+	struct string_list refs_to_delete = STRING_LIST_INIT_NODUP;
+	struct string_list_item *ref_to_delete;
+	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+
+	assert(err);
+
+	if (transaction->state != REF_TRANSACTION_OPEN)
+		die("BUG: commit called for transaction that is not open");
+
+	if (!n) {
+		transaction->state = REF_TRANSACTION_CLOSED;
+		return 0;
+	}
+
+	/* Fail if a refname appears more than once in the transaction: */
+	for (i = 0; i < n; i++)
+		string_list_append(&affected_refnames, updates[i]->refname);
+	string_list_sort(&affected_refnames);
+	if (ref_update_reject_duplicates(&affected_refnames, err)) {
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+
+	/*
+	 * Acquire all locks, verify old values if provided, check
+	 * that new values are valid, and write new values to the
+	 * lockfiles, ready to be activated. Only keep one lockfile
+	 * open at a time to avoid running out of file descriptors.
+	 */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if ((update->flags & REF_HAVE_NEW) &&
+		    is_null_sha1(update->new_sha1))
+			update->flags |= REF_DELETING;
+		update->lock = lock_ref_sha1_basic(
+				update->refname,
+				((update->flags & REF_HAVE_OLD) ?
+				 update->old_sha1 : NULL),
+				&affected_refnames, NULL,
+				update->flags,
+				&update->type,
+				err);
+		if (!update->lock) {
+			char *reason;
+
+			ret = (errno == ENOTDIR)
+				? TRANSACTION_NAME_CONFLICT
+				: TRANSACTION_GENERIC_ERROR;
+			reason = strbuf_detach(err, NULL);
+			strbuf_addf(err, "cannot lock ref '%s': %s",
+				    update->refname, reason);
+			free(reason);
+			goto cleanup;
+		}
+		if ((update->flags & REF_HAVE_NEW) &&
+		    !(update->flags & REF_DELETING)) {
+			int overwriting_symref = ((update->type & REF_ISSYMREF) &&
+						  (update->flags & REF_NODEREF));
+
+			if (!overwriting_symref &&
+			    !hashcmp(update->lock->old_oid.hash, update->new_sha1)) {
+				/*
+				 * The reference already has the desired
+				 * value, so we don't need to write it.
+				 */
+			} else if (write_ref_to_lockfile(update->lock,
+							 update->new_sha1,
+							 err)) {
+				char *write_err = strbuf_detach(err, NULL);
+
+				/*
+				 * The lock was freed upon failure of
+				 * write_ref_to_lockfile():
+				 */
+				update->lock = NULL;
+				strbuf_addf(err,
+					    "cannot update the ref '%s': %s",
+					    update->refname, write_err);
+				free(write_err);
+				ret = TRANSACTION_GENERIC_ERROR;
+				goto cleanup;
+			} else {
+				update->flags |= REF_NEEDS_COMMIT;
+			}
+		}
+		if (!(update->flags & REF_NEEDS_COMMIT)) {
+			/*
+			 * We didn't have to write anything to the lockfile.
+			 * Close it to free up the file descriptor:
+			 */
+			if (close_ref(update->lock)) {
+				strbuf_addf(err, "Couldn't close %s.lock",
+					    update->refname);
+				goto cleanup;
+			}
+		}
+	}
+
+	/* Perform updates first so live commits remain referenced */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if (update->flags & REF_NEEDS_COMMIT) {
+			if (commit_ref_update(update->lock,
+					      update->new_sha1, update->msg,
+					      update->flags, err)) {
+				/* freed by commit_ref_update(): */
+				update->lock = NULL;
+				ret = TRANSACTION_GENERIC_ERROR;
+				goto cleanup;
+			} else {
+				/* freed by commit_ref_update(): */
+				update->lock = NULL;
+			}
+		}
+	}
+
+	/* Perform deletes now that updates are safely completed */
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if (update->flags & REF_DELETING) {
+			if (delete_ref_loose(update->lock, update->type, err)) {
+				ret = TRANSACTION_GENERIC_ERROR;
+				goto cleanup;
+			}
+
+			if (!(update->flags & REF_ISPRUNING))
+				string_list_append(&refs_to_delete,
+						   update->lock->ref_name);
+		}
+	}
+
+	if (repack_without_refs(&refs_to_delete, err)) {
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+	for_each_string_list_item(ref_to_delete, &refs_to_delete)
+		unlink_or_warn(git_path("logs/%s", ref_to_delete->string));
+	clear_loose_ref_cache(&ref_cache);
+
+cleanup:
+	transaction->state = REF_TRANSACTION_CLOSED;
+
+	for (i = 0; i < n; i++)
+		if (updates[i]->lock)
+			unlock_ref(updates[i]->lock);
+	string_list_clear(&refs_to_delete, 0);
+	string_list_clear(&affected_refnames, 0);
+	return ret;
+}
+
+static int ref_present(const char *refname,
+		       const struct object_id *oid, int flags, void *cb_data)
+{
+	struct string_list *affected_refnames = cb_data;
+
+	return string_list_has_string(affected_refnames, refname);
+}
+
+int initial_ref_transaction_commit(struct ref_transaction *transaction,
+				   struct strbuf *err)
+{
+	int ret = 0, i;
+	int n = transaction->nr;
+	struct ref_update **updates = transaction->updates;
+	struct string_list affected_refnames = STRING_LIST_INIT_NODUP;
+
+	assert(err);
+
+	if (transaction->state != REF_TRANSACTION_OPEN)
+		die("BUG: commit called for transaction that is not open");
+
+	/* Fail if a refname appears more than once in the transaction: */
+	for (i = 0; i < n; i++)
+		string_list_append(&affected_refnames, updates[i]->refname);
+	string_list_sort(&affected_refnames);
+	if (ref_update_reject_duplicates(&affected_refnames, err)) {
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+
+	/*
+	 * It's really undefined to call this function in an active
+	 * repository or when there are existing references: we are
+	 * only locking and changing packed-refs, so (1) any
+	 * simultaneous processes might try to change a reference at
+	 * the same time we do, and (2) any existing loose versions of
+	 * the references that we are setting would have precedence
+	 * over our values. But some remote helpers create the remote
+	 * "HEAD" and "master" branches before calling this function,
+	 * so here we really only check that none of the references
+	 * that we are creating already exists.
+	 */
+	if (for_each_rawref(ref_present, &affected_refnames))
+		die("BUG: initial ref transaction called with existing refs");
+
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if ((update->flags & REF_HAVE_OLD) &&
+		    !is_null_sha1(update->old_sha1))
+			die("BUG: initial ref transaction with old_sha1 set");
+		if (verify_refname_available(update->refname,
+					     &affected_refnames, NULL,
+					     err)) {
+			ret = TRANSACTION_NAME_CONFLICT;
+			goto cleanup;
+		}
+	}
+
+	if (lock_packed_refs(0)) {
+		strbuf_addf(err, "unable to lock packed-refs file: %s",
+			    strerror(errno));
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+
+	for (i = 0; i < n; i++) {
+		struct ref_update *update = updates[i];
+
+		if ((update->flags & REF_HAVE_NEW) &&
+		    !is_null_sha1(update->new_sha1))
+			add_packed_ref(update->refname, update->new_sha1);
+	}
+
+	if (commit_packed_refs()) {
+		strbuf_addf(err, "unable to commit packed-refs file: %s",
+			    strerror(errno));
+		ret = TRANSACTION_GENERIC_ERROR;
+		goto cleanup;
+	}
+
+cleanup:
+	transaction->state = REF_TRANSACTION_CLOSED;
+	string_list_clear(&affected_refnames, 0);
+	return ret;
+}
+
+struct expire_reflog_cb {
+	unsigned int flags;
+	reflog_expiry_should_prune_fn *should_prune_fn;
+	void *policy_cb;
+	FILE *newlog;
+	unsigned char last_kept_sha1[20];
+};
+
+static int expire_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
+			     const char *email, unsigned long timestamp, int tz,
+			     const char *message, void *cb_data)
+{
+	struct expire_reflog_cb *cb = cb_data;
+	struct expire_reflog_policy_cb *policy_cb = cb->policy_cb;
+
+	if (cb->flags & EXPIRE_REFLOGS_REWRITE)
+		osha1 = cb->last_kept_sha1;
+
+	if ((*cb->should_prune_fn)(osha1, nsha1, email, timestamp, tz,
+				   message, policy_cb)) {
+		if (!cb->newlog)
+			printf("would prune %s", message);
+		else if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
+			printf("prune %s", message);
+	} else {
+		if (cb->newlog) {
+			fprintf(cb->newlog, "%s %s %s %lu %+05d\t%s",
+				sha1_to_hex(osha1), sha1_to_hex(nsha1),
+				email, timestamp, tz, message);
+			hashcpy(cb->last_kept_sha1, nsha1);
+		}
+		if (cb->flags & EXPIRE_REFLOGS_VERBOSE)
+			printf("keep %s", message);
+	}
+	return 0;
+}
+
+int reflog_expire(const char *refname, const unsigned char *sha1,
+		 unsigned int flags,
+		 reflog_expiry_prepare_fn prepare_fn,
+		 reflog_expiry_should_prune_fn should_prune_fn,
+		 reflog_expiry_cleanup_fn cleanup_fn,
+		 void *policy_cb_data)
+{
+	static struct lock_file reflog_lock;
+	struct expire_reflog_cb cb;
+	struct ref_lock *lock;
+	char *log_file;
+	int status = 0;
+	int type;
+	struct strbuf err = STRBUF_INIT;
+
+	memset(&cb, 0, sizeof(cb));
+	cb.flags = flags;
+	cb.policy_cb = policy_cb_data;
+	cb.should_prune_fn = should_prune_fn;
+
+	/*
+	 * The reflog file is locked by holding the lock on the
+	 * reference itself, plus we might need to update the
+	 * reference if --updateref was specified:
+	 */
+	lock = lock_ref_sha1_basic(refname, sha1, NULL, NULL, 0, &type, &err);
+	if (!lock) {
+		error("cannot lock ref '%s': %s", refname, err.buf);
+		strbuf_release(&err);
+		return -1;
+	}
+	if (!reflog_exists(refname)) {
+		unlock_ref(lock);
+		return 0;
+	}
+
+	log_file = git_pathdup("logs/%s", refname);
+	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+		/*
+		 * Even though holding $GIT_DIR/logs/$reflog.lock has
+		 * no locking implications, we use the lock_file
+		 * machinery here anyway because it does a lot of the
+		 * work we need, including cleaning up if the program
+		 * exits unexpectedly.
+		 */
+		if (hold_lock_file_for_update(&reflog_lock, log_file, 0) < 0) {
+			struct strbuf err = STRBUF_INIT;
+			unable_to_lock_message(log_file, errno, &err);
+			error("%s", err.buf);
+			strbuf_release(&err);
+			goto failure;
+		}
+		cb.newlog = fdopen_lock_file(&reflog_lock, "w");
+		if (!cb.newlog) {
+			error("cannot fdopen %s (%s)",
+			      get_lock_file_path(&reflog_lock), strerror(errno));
+			goto failure;
+		}
+	}
+
+	(*prepare_fn)(refname, sha1, cb.policy_cb);
+	for_each_reflog_ent(refname, expire_reflog_ent, &cb);
+	(*cleanup_fn)(cb.policy_cb);
+
+	if (!(flags & EXPIRE_REFLOGS_DRY_RUN)) {
+		/*
+		 * It doesn't make sense to adjust a reference pointed
+		 * to by a symbolic ref based on expiring entries in
+		 * the symbolic reference's reflog. Nor can we update
+		 * a reference if there are no remaining reflog
+		 * entries.
+		 */
+		int update = (flags & EXPIRE_REFLOGS_UPDATE_REF) &&
+			!(type & REF_ISSYMREF) &&
+			!is_null_sha1(cb.last_kept_sha1);
+
+		if (close_lock_file(&reflog_lock)) {
+			status |= error("couldn't write %s: %s", log_file,
+					strerror(errno));
+		} else if (update &&
+			   (write_in_full(get_lock_file_fd(lock->lk),
+				sha1_to_hex(cb.last_kept_sha1), 40) != 40 ||
+			    write_str_in_full(get_lock_file_fd(lock->lk), "\n") != 1 ||
+			    close_ref(lock) < 0)) {
+			status |= error("couldn't write %s",
+					get_lock_file_path(lock->lk));
+			rollback_lock_file(&reflog_lock);
+		} else if (commit_lock_file(&reflog_lock)) {
+			status |= error("unable to commit reflog '%s' (%s)",
+					log_file, strerror(errno));
+		} else if (update && commit_ref(lock)) {
+			status |= error("couldn't set %s", lock->ref_name);
+		}
+	}
+	free(log_file);
+	unlock_ref(lock);
+	return status;
+
+ failure:
+	rollback_lock_file(&reflog_lock);
+	free(log_file);
+	unlock_ref(lock);
+	return -1;
+}
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
new file mode 100644
index 0000000..c7dded3
--- /dev/null
+++ b/refs/refs-internal.h
@@ -0,0 +1,200 @@
+#ifndef REFS_REFS_INTERNAL_H
+#define REFS_REFS_INTERNAL_H
+
+/*
+ * Data structures and functions for the internal use of the refs
+ * module. Code outside of the refs module should use only the public
+ * functions defined in "refs.h", and should *not* include this file.
+ */
+
+/*
+ * Flag passed to lock_ref_sha1_basic() telling it to tolerate broken
+ * refs (i.e., because the reference is about to be deleted anyway).
+ */
+#define REF_DELETING	0x02
+
+/*
+ * Used as a flag in ref_update::flags when a loose ref is being
+ * pruned.
+ */
+#define REF_ISPRUNING	0x04
+
+/*
+ * Used as a flag in ref_update::flags when the reference should be
+ * updated to new_sha1.
+ */
+#define REF_HAVE_NEW	0x08
+
+/*
+ * Used as a flag in ref_update::flags when old_sha1 should be
+ * checked.
+ */
+#define REF_HAVE_OLD	0x10
+
+/*
+ * Used as a flag in ref_update::flags when the lockfile needs to be
+ * committed.
+ */
+#define REF_NEEDS_COMMIT 0x20
+
+/*
+ * 0x40 is REF_FORCE_CREATE_REFLOG, so skip it if you're adding a
+ * value to ref_update::flags
+ */
+
+/*
+ * Return true iff refname is minimally safe. "Safe" here means that
+ * deleting a loose reference by this name will not do any damage, for
+ * example by causing a file that is not a reference to be deleted.
+ * This function does not check that the reference name is legal; for
+ * that, use check_refname_format().
+ *
+ * We consider a refname that starts with "refs/" to be safe as long
+ * as any ".." components that it might contain do not escape "refs/".
+ * Names that do not start with "refs/" are considered safe iff they
+ * consist entirely of upper case characters and '_' (like "HEAD" and
+ * "MERGE_HEAD" but not "config" or "FOO/BAR").
+ */
+int refname_is_safe(const char *refname);
+
+enum peel_status {
+	/* object was peeled successfully: */
+	PEEL_PEELED = 0,
+
+	/*
+	 * object cannot be peeled because the named object (or an
+	 * object referred to by a tag in the peel chain), does not
+	 * exist.
+	 */
+	PEEL_INVALID = -1,
+
+	/* object cannot be peeled because it is not a tag: */
+	PEEL_NON_TAG = -2,
+
+	/* ref_entry contains no peeled value because it is a symref: */
+	PEEL_IS_SYMREF = -3,
+
+	/*
+	 * ref_entry cannot be peeled because it is broken (i.e., the
+	 * symbolic reference cannot even be resolved to an object
+	 * name):
+	 */
+	PEEL_BROKEN = -4
+};
+
+/*
+ * Peel the named object; i.e., if the object is a tag, resolve the
+ * tag recursively until a non-tag is found.  If successful, store the
+ * result to sha1 and return PEEL_PEELED.  If the object is not a tag
+ * or is not valid, return PEEL_NON_TAG or PEEL_INVALID, respectively,
+ * and leave sha1 unchanged.
+ */
+enum peel_status peel_object(const unsigned char *name, unsigned char *sha1);
+
+/*
+ * Return 0 if a reference named refname could be created without
+ * conflicting with the name of an existing reference. Otherwise,
+ * return a negative value and write an explanation to err. If extras
+ * is non-NULL, it is a list of additional refnames with which refname
+ * is not allowed to conflict. If skip is non-NULL, ignore potential
+ * conflicts with refs in skip (e.g., because they are scheduled for
+ * deletion in the same operation). Behavior is undefined if the same
+ * name is listed in both extras and skip.
+ *
+ * Two reference names conflict if one of them exactly matches the
+ * leading components of the other; e.g., "foo/bar" conflicts with
+ * both "foo" and with "foo/bar/baz" but not with "foo/bar" or
+ * "foo/barbados".
+ *
+ * extras and skip must be sorted.
+ */
+int verify_refname_available(const char *newname,
+			     struct string_list *extras,
+			     struct string_list *skip,
+			     struct strbuf *err);
+
+/*
+ * Copy the reflog message msg to buf, which has been allocated sufficiently
+ * large, while cleaning up the whitespaces.  Especially, convert LF to space,
+ * because reflog file is one line per entry.
+ */
+int copy_reflog_msg(char *buf, const char *msg);
+
+int should_autocreate_reflog(const char *refname);
+
+/**
+ * Information needed for a single ref update. Set new_sha1 to the new
+ * value or to null_sha1 to delete the ref. To check the old value
+ * while the ref is locked, set (flags & REF_HAVE_OLD) and set
+ * old_sha1 to the old value, or to null_sha1 to ensure the ref does
+ * not exist before update.
+ */
+struct ref_update {
+	/*
+	 * If (flags & REF_HAVE_NEW), set the reference to this value:
+	 */
+	unsigned char new_sha1[20];
+	/*
+	 * If (flags & REF_HAVE_OLD), check that the reference
+	 * previously had this value:
+	 */
+	unsigned char old_sha1[20];
+	/*
+	 * One or more of REF_HAVE_NEW, REF_HAVE_OLD, REF_NODEREF,
+	 * REF_DELETING, and REF_ISPRUNING:
+	 */
+	unsigned int flags;
+	struct ref_lock *lock;
+	int type;
+	char *msg;
+	const char refname[FLEX_ARRAY];
+};
+
+/*
+ * Transaction states.
+ * OPEN:   The transaction is in a valid state and can accept new updates.
+ *         An OPEN transaction can be committed.
+ * CLOSED: A closed transaction is no longer active and no other operations
+ *         than free can be used on it in this state.
+ *         A transaction can either become closed by successfully committing
+ *         an active transaction or if there is a failure while building
+ *         the transaction thus rendering it failed/inactive.
+ */
+enum ref_transaction_state {
+	REF_TRANSACTION_OPEN   = 0,
+	REF_TRANSACTION_CLOSED = 1
+};
+
+/*
+ * Data structure for holding a reference transaction, which can
+ * consist of checks and updates to multiple references, carried out
+ * as atomically as possible.  This structure is opaque to callers.
+ */
+struct ref_transaction {
+	struct ref_update **updates;
+	size_t alloc;
+	size_t nr;
+	enum ref_transaction_state state;
+};
+
+int files_log_ref_write(const char *refname, const unsigned char *old_sha1,
+			const unsigned char *new_sha1, const char *msg,
+			int flags, struct strbuf *err);
+
+/*
+ * Check for entries in extras that are within the specified
+ * directory, where dirname is a reference directory name including
+ * the trailing slash (e.g., "refs/heads/foo/"). Ignore any
+ * conflicting references that are found in skip. If there is a
+ * conflicting reference, return its name.
+ *
+ * extras and skip must be sorted lists of reference names. Either one
+ * can be NULL, signifying the empty list.
+ */
+const char *find_descendant_ref(const char *dirname,
+				const struct string_list *extras,
+				const struct string_list *skip);
+
+int rename_ref_available(const char *oldname, const char *newname);
+
+#endif /* REFS_REFS_INTERNAL_H */