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-rw-r--r--match-trees.c229
1 files changed, 135 insertions, 94 deletions
diff --git a/match-trees.c b/match-trees.c
index 0fd6df7d6e..396b7338df 100644
--- a/match-trees.c
+++ b/match-trees.c
@@ -47,78 +47,69 @@ static int score_matches(unsigned mode1, unsigned mode2, const char *path)
return score;
}
+static void *fill_tree_desc_strict(struct tree_desc *desc,
+ const struct object_id *hash)
+{
+ void *buffer;
+ enum object_type type;
+ unsigned long size;
+
+ buffer = read_sha1_file(hash->hash, &type, &size);
+ if (!buffer)
+ die("unable to read tree (%s)", oid_to_hex(hash));
+ if (type != OBJ_TREE)
+ die("%s is not a tree", oid_to_hex(hash));
+ init_tree_desc(desc, buffer, size);
+ return buffer;
+}
+
+static int base_name_entries_compare(const struct name_entry *a,
+ const struct name_entry *b)
+{
+ return base_name_compare(a->path, tree_entry_len(a), a->mode,
+ b->path, tree_entry_len(b), b->mode);
+}
+
/*
* 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)
+static int score_trees(const struct object_id *hash1, const struct object_id *hash2)
{
struct tree_desc one;
struct tree_desc two;
- void *one_buf, *two_buf;
+ void *one_buf = fill_tree_desc_strict(&one, hash1);
+ void *two_buf = fill_tree_desc_strict(&two, hash2);
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;
+ for (;;) {
+ struct name_entry e1, e2;
+ int got_entry_from_one = tree_entry(&one, &e1);
+ int got_entry_from_two = tree_entry(&two, &e2);
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) {
+ if (got_entry_from_one && got_entry_from_two)
+ cmp = base_name_entries_compare(&e1, &e2);
+ else if (got_entry_from_one)
/* 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) {
+ cmp = -1;
+ else if (got_entry_from_two)
+ /* two has more entries */
+ cmp = 1;
+ else
+ break;
+
+ if (cmp < 0)
/* path1 does not appear in two */
- score += score_missing(mode1, path1);
- update_tree_entry(&one);
- continue;
- }
- else if (cmp > 0) {
+ score += score_missing(e1.mode, e1.path);
+ 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))
+ score += score_missing(e2.mode, e2.path);
+ else if (oidcmp(e1.oid, e2.oid))
/* they are different */
- score += score_differs(mode1, mode2, path1);
+ score += score_differs(e1.mode, e2.mode, e1.path);
else
/* same subtree or blob */
- score += score_matches(mode1, mode2, path1);
- update_tree_entry(&one);
- update_tree_entry(&two);
+ score += score_matches(e1.mode, e2.mode, e1.path);
}
free(one_buf);
free(two_buf);
@@ -128,28 +119,19 @@ static int score_trees(const unsigned char *hash1, const unsigned char *hash2)
/*
* 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,
+static void match_trees(const struct object_id *hash1,
+ const struct object_id *hash2,
int *best_score,
char **best_match,
const 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);
+ void *one_buf = fill_tree_desc_strict(&one, hash1);
while (one.size) {
const char *path;
- const unsigned char *elem;
+ const struct object_id *elem;
unsigned mode;
int score;
@@ -158,17 +140,12 @@ static void match_trees(const unsigned char *hash1,
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_match = xstrfmt("%s%s", base, path);
*best_score = score;
}
if (recurse_limit) {
- char *newbase;
- newbase = xmalloc(strlen(base) + strlen(path) + 2);
- sprintf(newbase, "%s%s/", base, path);
+ char *newbase = xstrfmt("%s%s/", base, path);
match_trees(elem, hash2, best_score, best_match,
newbase, recurse_limit - 1);
free(newbase);
@@ -185,7 +162,7 @@ static void match_trees(const unsigned char *hash1,
* tree object by replacing it with another tree "hash2".
*/
static int splice_tree(const unsigned char *hash1,
- char *prefix,
+ const char *prefix,
const unsigned char *hash2,
unsigned char *result)
{
@@ -200,13 +177,10 @@ static int splice_tree(const unsigned char *hash1,
enum object_type type;
int status;
- subpath = strchr(prefix, '/');
- if (!subpath)
- toplen = strlen(prefix);
- else {
- toplen = subpath - prefix;
+ subpath = strchrnul(prefix, '/');
+ toplen = subpath - prefix;
+ if (*subpath)
subpath++;
- }
buf = read_sha1_file(hash1, &type, &sz);
if (!buf)
@@ -217,15 +191,15 @@ static int splice_tree(const unsigned char *hash1,
while (desc.size) {
const char *name;
unsigned mode;
- const unsigned char *sha1;
+ const struct object_id *oid;
- sha1 = tree_entry_extract(&desc, &name, &mode);
+ oid = 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;
+ rewrite_here = (unsigned char *) oid->hash;
break;
}
update_tree_entry(&desc);
@@ -233,7 +207,7 @@ static int splice_tree(const unsigned char *hash1,
if (!rewrite_here)
die("entry %.*s not found in tree %s",
toplen, prefix, sha1_to_hex(hash1));
- if (subpath) {
+ if (*subpath) {
status = splice_tree(rewrite_here, subpath, hash2, subtree);
if (status)
return status;
@@ -255,15 +229,22 @@ static int splice_tree(const unsigned char *hash1,
* 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,
+void shift_tree(const struct object_id *hash1,
+ const struct object_id *hash2,
+ struct object_id *shifted,
int depth_limit)
{
char *add_prefix;
char *del_prefix;
int add_score, del_score;
+ /*
+ * NEEDSWORK: this limits the recursion depth to hardcoded
+ * value '2' to avoid excessive overhead.
+ */
+ if (!depth_limit)
+ depth_limit = 2;
+
add_score = del_score = score_trees(hash1, hash2);
add_prefix = xcalloc(1, 1);
del_prefix = xcalloc(1, 1);
@@ -281,7 +262,7 @@ void shift_tree(const unsigned char *hash1,
match_trees(hash2, hash1, &del_score, &del_prefix, "", depth_limit);
/* Assume we do not have to do any shifting */
- hashcpy(shifted, hash2);
+ oidcpy(shifted, hash2);
if (add_score < del_score) {
/* We need to pick a subtree of two */
@@ -290,14 +271,74 @@ void shift_tree(const unsigned char *hash1,
if (!*del_prefix)
return;
- if (get_tree_entry(hash2, del_prefix, shifted, &mode))
+ if (get_tree_entry(hash2->hash, del_prefix, shifted->hash, &mode))
die("cannot find path %s in tree %s",
- del_prefix, sha1_to_hex(hash2));
+ del_prefix, oid_to_hex(hash2));
return;
}
if (!*add_prefix)
return;
- splice_tree(hash1, add_prefix, hash2, shifted);
+ splice_tree(hash1->hash, add_prefix, hash2->hash, shifted->hash);
+}
+
+/*
+ * The user says the trees will be shifted by this much.
+ * Unfortunately we cannot fundamentally tell which one to
+ * be prefixed, as recursive merge can work in either direction.
+ */
+void shift_tree_by(const struct object_id *hash1,
+ const struct object_id *hash2,
+ struct object_id *shifted,
+ const char *shift_prefix)
+{
+ struct object_id sub1, sub2;
+ unsigned mode1, mode2;
+ unsigned candidate = 0;
+
+ /* Can hash2 be a tree at shift_prefix in tree hash1? */
+ if (!get_tree_entry(hash1->hash, shift_prefix, sub1.hash, &mode1) &&
+ S_ISDIR(mode1))
+ candidate |= 1;
+
+ /* Can hash1 be a tree at shift_prefix in tree hash2? */
+ if (!get_tree_entry(hash2->hash, shift_prefix, sub2.hash, &mode2) &&
+ S_ISDIR(mode2))
+ candidate |= 2;
+
+ if (candidate == 3) {
+ /* Both are plausible -- we need to evaluate the score */
+ int best_score = score_trees(hash1, hash2);
+ int score;
+
+ candidate = 0;
+ score = score_trees(&sub1, hash2);
+ if (score > best_score) {
+ candidate = 1;
+ best_score = score;
+ }
+ score = score_trees(&sub2, hash1);
+ if (score > best_score)
+ candidate = 2;
+ }
+
+ if (!candidate) {
+ /* Neither is plausible -- do not shift */
+ oidcpy(shifted, hash2);
+ return;
+ }
+
+ if (candidate == 1)
+ /*
+ * shift tree2 down by adding shift_prefix above it
+ * to match tree1.
+ */
+ splice_tree(hash1->hash, shift_prefix, hash2->hash, shifted->hash);
+ else
+ /*
+ * shift tree2 up by removing shift_prefix from it
+ * to match tree1.
+ */
+ oidcpy(shifted, &sub2);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-23 06:18:32 +0000