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authorJunio C Hamano <gitster@pobox.com>2021-09-23 20:45:15 (GMT)
committerJunio C Hamano <gitster@pobox.com>2021-09-23 20:45:15 (GMT)
commit383ca01aeb6c922ca5135e880dd39239abbbe643 (patch)
tree12bba451df772231fc189e6000cd0dc8dcd228a4
parent5b0547fd25d66a50bfff2c546b8c36e3641ef65c (diff)
parent5b12e16bb134969747eaa983ab8d83d57f41e960 (diff)
downloadgit-383ca01aeb6c922ca5135e880dd39239abbbe643.zip
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Merge branch 'hn/refs-errno-cleanup' into jch
Futz with the way 'errno' is relied on in the refs API to carry the failure modes up the call chain. * hn/refs-errno-cleanup: refs: make errno output explicit for read_raw_ref_fn refs/files-backend: stop setting errno from lock_ref_oid_basic refs: remove EINVAL errno output from specification of read_raw_ref_fn refs file backend: move raceproof_create_file() here
-rw-r--r--cache.h43
-rw-r--r--object-file.c68
-rw-r--r--refs.c2
-rw-r--r--refs/debug.c7
-rw-r--r--refs/files-backend.c149
-rw-r--r--refs/packed-backend.c8
-rw-r--r--refs/refs-internal.h20
7 files changed, 146 insertions, 151 deletions
diff --git a/cache.h b/cache.h
index f6295f3..4a24b0c 100644
--- a/cache.h
+++ b/cache.h
@@ -1210,49 +1210,6 @@ enum scld_error safe_create_leading_directories(char *path);
enum scld_error safe_create_leading_directories_const(const char *path);
enum scld_error safe_create_leading_directories_no_share(char *path);
-/*
- * Callback function for raceproof_create_file(). This function is
- * expected to do something that makes dirname(path) permanent despite
- * the fact that other processes might be cleaning up empty
- * directories at the same time. Usually it will create a file named
- * path, but alternatively it could create another file in that
- * directory, or even chdir() into that directory. The function should
- * return 0 if the action was completed successfully. On error, it
- * should return a nonzero result and set errno.
- * raceproof_create_file() treats two errno values specially:
- *
- * - ENOENT -- dirname(path) does not exist. In this case,
- * raceproof_create_file() tries creating dirname(path)
- * (and any parent directories, if necessary) and calls
- * the function again.
- *
- * - EISDIR -- the file already exists and is a directory. In this
- * case, raceproof_create_file() removes the directory if
- * it is empty (and recursively any empty directories that
- * it contains) and calls the function again.
- *
- * Any other errno causes raceproof_create_file() to fail with the
- * callback's return value and errno.
- *
- * Obviously, this function should be OK with being called again if it
- * fails with ENOENT or EISDIR. In other scenarios it will not be
- * called again.
- */
-typedef int create_file_fn(const char *path, void *cb);
-
-/*
- * Create a file in dirname(path) by calling fn, creating leading
- * directories if necessary. Retry a few times in case we are racing
- * with another process that is trying to clean up the directory that
- * contains path. See the documentation for create_file_fn for more
- * details.
- *
- * Return the value and set the errno that resulted from the most
- * recent call of fn. fn is always called at least once, and will be
- * called more than once if it returns ENOENT or EISDIR.
- */
-int raceproof_create_file(const char *path, create_file_fn fn, void *cb);
-
int mkdir_in_gitdir(const char *path);
char *interpolate_path(const char *path, int real_home);
/* NEEDSWORK: remove this synonym once in-flight topics have migrated */
diff --git a/object-file.c b/object-file.c
index be4f94e..112d9b4 100644
--- a/object-file.c
+++ b/object-file.c
@@ -415,74 +415,6 @@ enum scld_error safe_create_leading_directories_const(const char *path)
return result;
}
-int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
-{
- /*
- * The number of times we will try to remove empty directories
- * in the way of path. This is only 1 because if another
- * process is racily creating directories that conflict with
- * us, we don't want to fight against them.
- */
- int remove_directories_remaining = 1;
-
- /*
- * The number of times that we will try to create the
- * directories containing path. We are willing to attempt this
- * more than once, because another process could be trying to
- * clean up empty directories at the same time as we are
- * trying to create them.
- */
- int create_directories_remaining = 3;
-
- /* A scratch copy of path, filled lazily if we need it: */
- struct strbuf path_copy = STRBUF_INIT;
-
- int ret, save_errno;
-
- /* Sanity check: */
- assert(*path);
-
-retry_fn:
- ret = fn(path, cb);
- save_errno = errno;
- if (!ret)
- goto out;
-
- if (errno == EISDIR && remove_directories_remaining-- > 0) {
- /*
- * A directory is in the way. Maybe it is empty; try
- * to remove it:
- */
- if (!path_copy.len)
- strbuf_addstr(&path_copy, path);
-
- if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
- goto retry_fn;
- } else if (errno == ENOENT && create_directories_remaining-- > 0) {
- /*
- * Maybe the containing directory didn't exist, or
- * maybe it was just deleted by a process that is
- * racing with us to clean up empty directories. Try
- * to create it:
- */
- enum scld_error scld_result;
-
- if (!path_copy.len)
- strbuf_addstr(&path_copy, path);
-
- do {
- scld_result = safe_create_leading_directories(path_copy.buf);
- if (scld_result == SCLD_OK)
- goto retry_fn;
- } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
- }
-
-out:
- strbuf_release(&path_copy);
- errno = save_errno;
- return ret;
-}
-
static void fill_loose_path(struct strbuf *buf, const struct object_id *oid)
{
int i;
diff --git a/refs.c b/refs.c
index 05944d8..da0cc82 100644
--- a/refs.c
+++ b/refs.c
@@ -1682,7 +1682,7 @@ int refs_read_raw_ref(struct ref_store *ref_store,
}
return ref_store->be->read_raw_ref(ref_store, refname, oid, referent,
- type);
+ type, &errno);
}
/* This function needs to return a meaningful errno on failure */
diff --git a/refs/debug.c b/refs/debug.c
index bf4a82b..8667c64 100644
--- a/refs/debug.c
+++ b/refs/debug.c
@@ -239,15 +239,14 @@ debug_ref_iterator_begin(struct ref_store *ref_store, const char *prefix,
static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
struct object_id *oid, struct strbuf *referent,
- unsigned int *type)
+ unsigned int *type, int *failure_errno)
{
struct debug_ref_store *drefs = (struct debug_ref_store *)ref_store;
int res = 0;
oidcpy(oid, null_oid());
- errno = 0;
res = drefs->refs->be->read_raw_ref(drefs->refs, refname, oid, referent,
- type);
+ type, failure_errno);
if (res == 0) {
trace_printf_key(&trace_refs, "read_raw_ref: %s: %s (=> %s) type %x: %d\n",
@@ -255,7 +254,7 @@ static int debug_read_raw_ref(struct ref_store *ref_store, const char *refname,
} else {
trace_printf_key(&trace_refs,
"read_raw_ref: %s: %d (errno %d)\n", refname,
- res, errno);
+ res, *failure_errno);
}
return res;
}
diff --git a/refs/files-backend.c b/refs/files-backend.c
index 2c8cac2..e461787 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -341,9 +341,9 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
return refs->loose;
}
-static int files_read_raw_ref(struct ref_store *ref_store,
- const char *refname, struct object_id *oid,
- struct strbuf *referent, unsigned int *type)
+static int files_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno)
{
struct files_ref_store *refs =
files_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
@@ -354,7 +354,6 @@ static int files_read_raw_ref(struct ref_store *ref_store,
struct stat st;
int fd;
int ret = -1;
- int save_errno;
int remaining_retries = 3;
*type = 0;
@@ -459,10 +458,9 @@ stat_ref:
ret = parse_loose_ref_contents(buf, oid, referent, type);
out:
- save_errno = errno;
+ *failure_errno = errno;
strbuf_release(&sb_path);
strbuf_release(&sb_contents);
- errno = save_errno;
return ret;
}
@@ -540,6 +538,7 @@ static int lock_raw_ref(struct files_ref_store *refs,
struct strbuf ref_file = STRBUF_INIT;
int attempts_remaining = 3;
int ret = TRANSACTION_GENERIC_ERROR;
+ int failure_errno;
assert(err);
files_assert_main_repository(refs, "lock_raw_ref");
@@ -610,7 +609,9 @@ retry:
if (hold_lock_file_for_update_timeout(
&lock->lk, ref_file.buf, LOCK_NO_DEREF,
get_files_ref_lock_timeout_ms()) < 0) {
- if (errno == ENOENT && --attempts_remaining > 0) {
+ int myerr = errno;
+ errno = 0;
+ if (myerr == ENOENT && --attempts_remaining > 0) {
/*
* Maybe somebody just deleted one of the
* directories leading to ref_file. Try
@@ -618,7 +619,7 @@ retry:
*/
goto retry;
} else {
- unable_to_lock_message(ref_file.buf, errno, err);
+ unable_to_lock_message(ref_file.buf, myerr, err);
goto error_return;
}
}
@@ -628,9 +629,9 @@ retry:
* fear that its value will change.
*/
- if (files_read_raw_ref(&refs->base, refname,
- &lock->old_oid, referent, type)) {
- if (errno == ENOENT) {
+ if (files_read_raw_ref(&refs->base, refname, &lock->old_oid, referent,
+ type, &failure_errno)) {
+ if (failure_errno == ENOENT) {
if (mustexist) {
/* Garden variety missing reference. */
strbuf_addf(err, "unable to resolve reference '%s'",
@@ -654,7 +655,7 @@ retry:
* reference named "refs/foo/bar/baz".
*/
}
- } else if (errno == EISDIR) {
+ } else if (failure_errno == EISDIR) {
/*
* There is a directory in the way. It might have
* contained references that have been deleted. If
@@ -692,13 +693,13 @@ retry:
goto error_return;
}
}
- } else if (errno == EINVAL && (*type & REF_ISBROKEN)) {
+ } else if (failure_errno == EINVAL && (*type & REF_ISBROKEN)) {
strbuf_addf(err, "unable to resolve reference '%s': "
"reference broken", refname);
goto error_return;
} else {
strbuf_addf(err, "unable to resolve reference '%s': %s",
- refname, strerror(errno));
+ refname, strerror(failure_errno));
goto error_return;
}
@@ -852,6 +853,115 @@ static struct ref_iterator *files_ref_iterator_begin(
return ref_iterator;
}
+/*
+ * Callback function for raceproof_create_file(). This function is
+ * expected to do something that makes dirname(path) permanent despite
+ * the fact that other processes might be cleaning up empty
+ * directories at the same time. Usually it will create a file named
+ * path, but alternatively it could create another file in that
+ * directory, or even chdir() into that directory. The function should
+ * return 0 if the action was completed successfully. On error, it
+ * should return a nonzero result and set errno.
+ * raceproof_create_file() treats two errno values specially:
+ *
+ * - ENOENT -- dirname(path) does not exist. In this case,
+ * raceproof_create_file() tries creating dirname(path)
+ * (and any parent directories, if necessary) and calls
+ * the function again.
+ *
+ * - EISDIR -- the file already exists and is a directory. In this
+ * case, raceproof_create_file() removes the directory if
+ * it is empty (and recursively any empty directories that
+ * it contains) and calls the function again.
+ *
+ * Any other errno causes raceproof_create_file() to fail with the
+ * callback's return value and errno.
+ *
+ * Obviously, this function should be OK with being called again if it
+ * fails with ENOENT or EISDIR. In other scenarios it will not be
+ * called again.
+ */
+typedef int create_file_fn(const char *path, void *cb);
+
+/*
+ * Create a file in dirname(path) by calling fn, creating leading
+ * directories if necessary. Retry a few times in case we are racing
+ * with another process that is trying to clean up the directory that
+ * contains path. See the documentation for create_file_fn for more
+ * details.
+ *
+ * Return the value and set the errno that resulted from the most
+ * recent call of fn. fn is always called at least once, and will be
+ * called more than once if it returns ENOENT or EISDIR.
+ */
+static int raceproof_create_file(const char *path, create_file_fn fn, void *cb)
+{
+ /*
+ * The number of times we will try to remove empty directories
+ * in the way of path. This is only 1 because if another
+ * process is racily creating directories that conflict with
+ * us, we don't want to fight against them.
+ */
+ int remove_directories_remaining = 1;
+
+ /*
+ * The number of times that we will try to create the
+ * directories containing path. We are willing to attempt this
+ * more than once, because another process could be trying to
+ * clean up empty directories at the same time as we are
+ * trying to create them.
+ */
+ int create_directories_remaining = 3;
+
+ /* A scratch copy of path, filled lazily if we need it: */
+ struct strbuf path_copy = STRBUF_INIT;
+
+ int ret, save_errno;
+
+ /* Sanity check: */
+ assert(*path);
+
+retry_fn:
+ ret = fn(path, cb);
+ save_errno = errno;
+ if (!ret)
+ goto out;
+
+ if (errno == EISDIR && remove_directories_remaining-- > 0) {
+ /*
+ * A directory is in the way. Maybe it is empty; try
+ * to remove it:
+ */
+ if (!path_copy.len)
+ strbuf_addstr(&path_copy, path);
+
+ if (!remove_dir_recursively(&path_copy, REMOVE_DIR_EMPTY_ONLY))
+ goto retry_fn;
+ } else if (errno == ENOENT && create_directories_remaining-- > 0) {
+ /*
+ * Maybe the containing directory didn't exist, or
+ * maybe it was just deleted by a process that is
+ * racing with us to clean up empty directories. Try
+ * to create it:
+ */
+ enum scld_error scld_result;
+
+ if (!path_copy.len)
+ strbuf_addstr(&path_copy, path);
+
+ do {
+ scld_result = safe_create_leading_directories(path_copy.buf);
+ if (scld_result == SCLD_OK)
+ goto retry_fn;
+ } while (scld_result == SCLD_VANISHED && create_directories_remaining-- > 0);
+ }
+
+out:
+ strbuf_release(&path_copy);
+ errno = save_errno;
+ return ret;
+}
+
static int remove_empty_directories(struct strbuf *path)
{
/*
@@ -873,7 +983,6 @@ static int create_reflock(const char *path, void *cb)
/*
* 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_oid_basic(struct files_ref_store *refs,
const char *refname, int *type,
@@ -881,7 +990,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
{
struct strbuf ref_file = STRBUF_INIT;
struct ref_lock *lock;
- int last_errno = 0;
files_assert_main_repository(refs, "lock_ref_oid_basic");
assert(err);
@@ -892,11 +1000,10 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
if (!refs_resolve_ref_unsafe(&refs->base, refname,
RESOLVE_REF_NO_RECURSE,
&lock->old_oid, type)) {
- last_errno = errno;
if (!refs_verify_refname_available(&refs->base, refname,
NULL, NULL, err))
strbuf_addf(err, "unable to resolve reference '%s': %s",
- refname, strerror(last_errno));
+ refname, strerror(errno));
goto error_return;
}
@@ -909,15 +1016,12 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
*/
if (is_null_oid(&lock->old_oid) &&
refs_verify_refname_available(refs->packed_ref_store, refname,
- NULL, NULL, err)) {
- last_errno = ENOTDIR;
+ NULL, NULL, err))
goto error_return;
- }
lock->ref_name = xstrdup(refname);
if (raceproof_create_file(ref_file.buf, create_reflock, &lock->lk)) {
- last_errno = errno;
unable_to_lock_message(ref_file.buf, errno, err);
goto error_return;
}
@@ -934,7 +1038,6 @@ static struct ref_lock *lock_ref_oid_basic(struct files_ref_store *refs,
out:
strbuf_release(&ref_file);
- errno = last_errno;
return lock;
}
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index 65ba421..47247a1 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -724,9 +724,9 @@ static struct snapshot *get_snapshot(struct packed_ref_store *refs)
return refs->snapshot;
}
-static int packed_read_raw_ref(struct ref_store *ref_store,
- const char *refname, struct object_id *oid,
- struct strbuf *referent, unsigned int *type)
+static int packed_read_raw_ref(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno)
{
struct packed_ref_store *refs =
packed_downcast(ref_store, REF_STORE_READ, "read_raw_ref");
@@ -739,7 +739,7 @@ static int packed_read_raw_ref(struct ref_store *ref_store,
if (!rec) {
/* refname is not a packed reference. */
- errno = ENOENT;
+ *failure_errno = ENOENT;
return -1;
}
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index d496c5e..ddd6d7f 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -620,11 +620,15 @@ typedef int reflog_expire_fn(struct ref_store *ref_store,
* properly-formatted or even safe reference name. NEITHER INPUT NOR
* OUTPUT REFERENCE NAMES ARE VALIDATED WITHIN THIS FUNCTION.
*
- * Return 0 on success. If the ref doesn't exist, set errno to ENOENT
- * and return -1. If the ref exists but is neither a symbolic ref nor
- * an object ID, it is broken; set REF_ISBROKEN in type, set errno to
- * EINVAL, and return -1. If there is another error reading the ref,
- * set errno appropriately and return -1.
+ * Return 0 on success, or -1 on failure. If the ref exists but is neither a
+ * symbolic ref nor an object ID, it is broken. In this case set REF_ISBROKEN in
+ * type, and return -1 (failure_errno should not be ENOENT)
+ *
+ * failure_errno provides errno codes that are interpreted beyond error
+ * reporting. The following error codes have special meaning:
+ * * ENOENT: the ref doesn't exist
+ * * EISDIR: ref name is a directory
+ * * ENOTDIR: ref prefix is not a directory
*
* Backend-specific flags might be set in type as well, regardless of
* outcome.
@@ -638,9 +642,9 @@ typedef int reflog_expire_fn(struct ref_store *ref_store,
* - in all other cases, referent will be untouched, and therefore
* refname will still be valid and unchanged.
*/
-typedef int read_raw_ref_fn(struct ref_store *ref_store,
- const char *refname, struct object_id *oid,
- struct strbuf *referent, unsigned int *type);
+typedef int read_raw_ref_fn(struct ref_store *ref_store, const char *refname,
+ struct object_id *oid, struct strbuf *referent,
+ unsigned int *type, int *failure_errno);
struct ref_storage_be {
struct ref_storage_be *next;