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-rw-r--r--.gitignore2
-rw-r--r--Makefile10
-rw-r--r--cache.h3
-rwxr-xr-xgit-merge.sh4
-rw-r--r--match-trees.c304
-rw-r--r--merge-recursive.c29
-rw-r--r--test-match-trees.c24
7 files changed, 373 insertions, 3 deletions
diff --git a/.gitignore b/.gitignore
index b39f78f..9229e91 100644
--- a/.gitignore
+++ b/.gitignore
@@ -77,6 +77,7 @@ git-merge-ours
git-merge-recursive
git-merge-resolve
git-merge-stupid
+git-merge-subtree
git-mergetool
git-mktag
git-mktree
@@ -148,6 +149,7 @@ test-chmtime
test-date
test-delta
test-dump-cache-tree
+test-match-trees
common-cmds.h
*.tar.gz
*.dsc
diff --git a/Makefile b/Makefile
index ac29c62..a77d31d 100644
--- a/Makefile
+++ b/Makefile
@@ -251,6 +251,8 @@ BUILT_INS = \
# what 'all' will build and 'install' will install, in gitexecdir
ALL_PROGRAMS = $(PROGRAMS) $(SCRIPTS)
+ALL_PROGRAMS += git-merge-subtree$X
+
# what 'all' will build but not install in gitexecdir
OTHER_PROGRAMS = git$X gitweb/gitweb.cgi
ifndef NO_TCLTK
@@ -299,7 +301,7 @@ LIB_OBJS = \
server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \
tag.o tree.o usage.o config.o environment.o ctype.o copy.o \
revision.o pager.o tree-walk.o xdiff-interface.o \
- write_or_die.o trace.o list-objects.o grep.o \
+ write_or_die.o trace.o list-objects.o grep.o match-trees.o \
alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS) \
color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \
convert.o
@@ -725,6 +727,9 @@ git$X: git.c common-cmds.h $(BUILTIN_OBJS) $(GITLIBS) GIT-CFLAGS
help.o: common-cmds.h
+git-merge-subtree$X: git-merge-recursive$X
+ rm -f $@ && ln git-merge-recursive$X $@
+
$(BUILT_INS): git$X
$(QUIET_BUILT_IN)rm -f $@ && ln git$X $@
@@ -942,6 +947,9 @@ test-dump-cache-tree$X: dump-cache-tree.o $(GITLIBS)
test-sha1$X: test-sha1.o $(GITLIBS)
$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)
+test-match-trees$X: test-match-trees.o $(GITLIBS)
+ $(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)
+
test-chmtime$X: test-chmtime.c
$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $<
diff --git a/cache.h b/cache.h
index 1b50c32..eb57507 100644
--- a/cache.h
+++ b/cache.h
@@ -496,4 +496,7 @@ extern void trace_argv_printf(const char **argv, int count, const char *format,
extern int convert_to_git(const char *path, char **bufp, unsigned long *sizep);
extern int convert_to_working_tree(const char *path, char **bufp, unsigned long *sizep);
+/* match-trees.c */
+void shift_tree(const unsigned char *, const unsigned char *, unsigned char *, int);
+
#endif /* CACHE_H */
diff --git a/git-merge.sh b/git-merge.sh
index fa45891..7ebbce4 100755
--- a/git-merge.sh
+++ b/git-merge.sh
@@ -16,10 +16,10 @@ test -z "$(git ls-files -u)" ||
LF='
'
-all_strategies='recur recursive octopus resolve stupid ours'
+all_strategies='recur recursive octopus resolve stupid ours subtree'
default_twohead_strategies='recursive'
default_octopus_strategies='octopus'
-no_trivial_merge_strategies='ours'
+no_trivial_merge_strategies='ours subtree'
use_strategies=
index_merge=t
diff --git a/match-trees.c b/match-trees.c
new file mode 100644
index 0000000..23cafe4
--- /dev/null
+++ b/match-trees.c
@@ -0,0 +1,304 @@
+#include "cache.h"
+#include "tree.h"
+#include "tree-walk.h"
+
+static int score_missing(unsigned mode, const char *path)
+{
+ int score;
+
+ if (S_ISDIR(mode))
+ score = -1000;
+ else if (S_ISLNK(mode))
+ score = -500;
+ else
+ score = -50;
+ return score;
+}
+
+static int score_differs(unsigned mode1, unsigned mode2, const char *path)
+{
+ int score;
+
+ if (S_ISDIR(mode1) != S_ISDIR(mode2))
+ score = -100;
+ else if (S_ISLNK(mode1) != S_ISLNK(mode2))
+ score = -50;
+ else
+ score = -5;
+ return score;
+}
+
+static int score_matches(unsigned mode1, unsigned mode2, const char *path)
+{
+ int score;
+
+ /* Heh, we found SHA-1 collisions between different kind of objects */
+ if (S_ISDIR(mode1) != S_ISDIR(mode2))
+ score = -100;
+ else if (S_ISLNK(mode1) != S_ISLNK(mode2))
+ score = -50;
+
+ else if (S_ISDIR(mode1))
+ score = 1000;
+ else if (S_ISLNK(mode1))
+ score = 500;
+ else
+ score = 250;
+ return score;
+}
+
+/*
+ * Inspect two trees, and give a score that tells how similar they are.
+ */
+static int score_trees(const unsigned char *hash1, const unsigned char *hash2)
+{
+ struct tree_desc one;
+ struct tree_desc two;
+ void *one_buf, *two_buf;
+ int score = 0;
+ enum object_type type;
+ unsigned long size;
+
+ one_buf = read_sha1_file(hash1, &type, &size);
+ if (!one_buf)
+ die("unable to read tree (%s)", sha1_to_hex(hash1));
+ if (type != OBJ_TREE)
+ die("%s is not a tree", sha1_to_hex(hash1));
+ init_tree_desc(&one, one_buf, size);
+ two_buf = read_sha1_file(hash2, &type, &size);
+ if (!two_buf)
+ die("unable to read tree (%s)", sha1_to_hex(hash2));
+ if (type != OBJ_TREE)
+ die("%s is not a tree", sha1_to_hex(hash2));
+ init_tree_desc(&two, two_buf, size);
+ while (one.size | two.size) {
+ const unsigned char *elem1 = elem1;
+ const unsigned char *elem2 = elem2;
+ const char *path1 = path1;
+ const char *path2 = path2;
+ unsigned mode1 = mode1;
+ unsigned mode2 = mode2;
+ int cmp;
+
+ if (one.size)
+ elem1 = tree_entry_extract(&one, &path1, &mode1);
+ if (two.size)
+ elem2 = tree_entry_extract(&two, &path2, &mode2);
+
+ if (!one.size) {
+ /* two has more entries */
+ score += score_missing(mode2, path2);
+ update_tree_entry(&two);
+ continue;
+ }
+ if (!two.size) {
+ /* two lacks this entry */
+ score += score_missing(mode1, path1);
+ update_tree_entry(&one);
+ continue;
+ }
+ cmp = base_name_compare(path1, strlen(path1), mode1,
+ path2, strlen(path2), mode2);
+ if (cmp < 0) {
+ /* path1 does not appear in two */
+ score += score_missing(mode1, path1);
+ update_tree_entry(&one);
+ continue;
+ }
+ else if (cmp > 0) {
+ /* path2 does not appear in one */
+ score += score_missing(mode2, path2);
+ update_tree_entry(&two);
+ continue;
+ }
+ else if (hashcmp(elem1, elem2))
+ /* they are different */
+ score += score_differs(mode1, mode2, path1);
+ else
+ /* same subtree or blob */
+ score += score_matches(mode1, mode2, path1);
+ update_tree_entry(&one);
+ update_tree_entry(&two);
+ }
+ free(one_buf);
+ free(two_buf);
+ return score;
+}
+
+/*
+ * Match one itself and its subtrees with two and pick the best match.
+ */
+static void match_trees(const unsigned char *hash1,
+ const unsigned char *hash2,
+ int *best_score,
+ char **best_match,
+ char *base,
+ int recurse_limit)
+{
+ struct tree_desc one;
+ void *one_buf;
+ enum object_type type;
+ unsigned long size;
+
+ one_buf = read_sha1_file(hash1, &type, &size);
+ if (!one_buf)
+ die("unable to read tree (%s)", sha1_to_hex(hash1));
+ if (type != OBJ_TREE)
+ die("%s is not a tree", sha1_to_hex(hash1));
+ init_tree_desc(&one, one_buf, size);
+
+ while (one.size) {
+ const char *path;
+ const unsigned char *elem;
+ unsigned mode;
+ int score;
+
+ elem = tree_entry_extract(&one, &path, &mode);
+ if (!S_ISDIR(mode))
+ goto next;
+ score = score_trees(elem, hash2);
+ if (*best_score < score) {
+ char *newpath;
+ newpath = xmalloc(strlen(base) + strlen(path) + 1);
+ sprintf(newpath, "%s%s", base, path);
+ free(*best_match);
+ *best_match = newpath;
+ *best_score = score;
+ }
+ if (recurse_limit) {
+ char *newbase;
+ newbase = xmalloc(strlen(base) + strlen(path) + 2);
+ sprintf(newbase, "%s%s/", base, path);
+ match_trees(elem, hash2, best_score, best_match,
+ newbase, recurse_limit - 1);
+ free(newbase);
+ }
+
+ next:
+ update_tree_entry(&one);
+ }
+ free(one_buf);
+}
+
+/*
+ * A tree "hash1" has a subdirectory at "prefix". Come up with a
+ * tree object by replacing it with another tree "hash2".
+ */
+static int splice_tree(const unsigned char *hash1,
+ char *prefix,
+ const unsigned char *hash2,
+ unsigned char *result)
+{
+ char *subpath;
+ int toplen;
+ char *buf;
+ unsigned long sz;
+ struct tree_desc desc;
+ unsigned char *rewrite_here;
+ const unsigned char *rewrite_with;
+ unsigned char subtree[20];
+ enum object_type type;
+ int status;
+
+ subpath = strchr(prefix, '/');
+ if (!subpath)
+ toplen = strlen(prefix);
+ else {
+ toplen = subpath - prefix;
+ subpath++;
+ }
+
+ buf = read_sha1_file(hash1, &type, &sz);
+ if (!buf)
+ die("cannot read tree %s", sha1_to_hex(hash1));
+ init_tree_desc(&desc, buf, sz);
+
+ rewrite_here = NULL;
+ while (desc.size) {
+ const char *name;
+ unsigned mode;
+ const unsigned char *sha1;
+
+ sha1 = tree_entry_extract(&desc, &name, &mode);
+ if (strlen(name) == toplen &&
+ !memcmp(name, prefix, toplen)) {
+ if (!S_ISDIR(mode))
+ die("entry %s in tree %s is not a tree",
+ name, sha1_to_hex(hash1));
+ rewrite_here = (unsigned char *) sha1;
+ break;
+ }
+ update_tree_entry(&desc);
+ }
+ if (!rewrite_here)
+ die("entry %.*s not found in tree %s",
+ toplen, prefix, sha1_to_hex(hash1));
+ if (subpath) {
+ status = splice_tree(rewrite_here, subpath, hash2, subtree);
+ if (status)
+ return status;
+ rewrite_with = subtree;
+ }
+ else
+ rewrite_with = hash2;
+ hashcpy(rewrite_here, rewrite_with);
+ status = write_sha1_file(buf, sz, tree_type, result);
+ free(buf);
+ return status;
+}
+
+/*
+ * We are trying to come up with a merge between one and two that
+ * results in a tree shape similar to one. The tree two might
+ * correspond to a subtree of one, in which case it needs to be
+ * shifted down by prefixing otherwise empty directories. On the
+ * other hand, it could cover tree one and we might need to pick a
+ * subtree of it.
+ */
+void shift_tree(const unsigned char *hash1,
+ const unsigned char *hash2,
+ unsigned char *shifted,
+ int depth_limit)
+{
+ char *add_prefix;
+ char *del_prefix;
+ int add_score, del_score;
+
+ add_score = del_score = score_trees(hash1, hash2);
+ add_prefix = xcalloc(1, 1);
+ del_prefix = xcalloc(1, 1);
+
+ /*
+ * See if one's subtree resembles two; if so we need to prefix
+ * two with a few fake trees to match the prefix.
+ */
+ match_trees(hash1, hash2, &add_score, &add_prefix, "", depth_limit);
+
+ /*
+ * See if two's subtree resembles one; if so we need to
+ * pick only subtree of two.
+ */
+ match_trees(hash2, hash1, &del_score, &del_prefix, "", depth_limit);
+
+ /* Assume we do not have to do any shifting */
+ hashcpy(shifted, hash2);
+
+ if (add_score < del_score) {
+ /* We need to pick a subtree of two */
+ unsigned mode;
+
+ if (!*del_prefix)
+ return;
+
+ if (get_tree_entry(hash2, del_prefix, shifted, &mode))
+ die("cannot find path %s in tree %s",
+ del_prefix, sha1_to_hex(hash2));
+ return;
+ }
+
+ if (!*add_prefix)
+ return;
+
+ splice_tree(hash1, add_prefix, hash2, shifted);
+}
+
diff --git a/merge-recursive.c b/merge-recursive.c
index 2b614b6..3096594 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -16,6 +16,22 @@
#include "path-list.h"
#include "xdiff-interface.h"
+static int subtree_merge;
+
+static struct tree *shift_tree_object(struct tree *one, struct tree *two)
+{
+ unsigned char shifted[20];
+
+ /*
+ * NEEDSWORK: this limits the recursion depth to hardcoded
+ * value '2' to avoid excessive overhead.
+ */
+ shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
+ if (!hashcmp(two->object.sha1, shifted))
+ return two;
+ return lookup_tree(shifted);
+}
+
/*
* A virtual commit has
* - (const char *)commit->util set to the name, and
@@ -1137,6 +1153,12 @@ static int merge_trees(struct tree *head,
struct tree **result)
{
int code, clean;
+
+ if (subtree_merge) {
+ merge = shift_tree_object(head, merge);
+ common = shift_tree_object(head, common);
+ }
+
if (sha_eq(common->object.sha1, merge->object.sha1)) {
output(0, "Already uptodate!");
*result = head;
@@ -1342,6 +1364,13 @@ int main(int argc, char *argv[])
struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
int index_fd;
+ if (argv[0]) {
+ int namelen = strlen(argv[0]);
+ if (8 < namelen &&
+ !strcmp(argv[0] + namelen - 8, "-subtree"))
+ subtree_merge = 1;
+ }
+
git_config(merge_config);
if (getenv("GIT_MERGE_VERBOSITY"))
verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
diff --git a/test-match-trees.c b/test-match-trees.c
new file mode 100644
index 0000000..a3c4688
--- /dev/null
+++ b/test-match-trees.c
@@ -0,0 +1,24 @@
+#include "cache.h"
+#include "tree.h"
+
+int main(int ac, char **av)
+{
+ unsigned char hash1[20], hash2[20], shifted[20];
+ struct tree *one, *two;
+
+ if (get_sha1(av[1], hash1))
+ die("cannot parse %s as an object name", av[1]);
+ if (get_sha1(av[2], hash2))
+ die("cannot parse %s as an object name", av[2]);
+ one = parse_tree_indirect(hash1);
+ if (!one)
+ die("not a treeish %s", av[1]);
+ two = parse_tree_indirect(hash2);
+ if (!two)
+ die("not a treeish %s", av[2]);
+
+ shift_tree(one->object.sha1, two->object.sha1, shifted, -1);
+ printf("shifted: %s\n", sha1_to_hex(shifted));
+
+ exit(0);
+}