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| #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; | |
| } | |
| 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 struct object_id *hash1, const struct object_id *hash2) | |
| { | |
| struct tree_desc one; | |
| struct tree_desc two; | |
| void *one_buf = fill_tree_desc_strict(&one, hash1); | |
| void *two_buf = fill_tree_desc_strict(&two, hash2); | |
| int score = 0; | |
| 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 (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 */ | |
| 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(e1.mode, e1.path); | |
| else if (cmp > 0) | |
| /* path2 does not appear in one */ | |
| score += score_missing(e2.mode, e2.path); | |
| else if (oidcmp(e1.oid, e2.oid)) | |
| /* they are different */ | |
| score += score_differs(e1.mode, e2.mode, e1.path); | |
| else | |
| /* same subtree or blob */ | |
| score += score_matches(e1.mode, e2.mode, e1.path); | |
| } | |
| 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 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 = fill_tree_desc_strict(&one, hash1); | |
| while (one.size) { | |
| const char *path; | |
| const struct object_id *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) { | |
| free(*best_match); | |
| *best_match = xstrfmt("%s%s", base, path); | |
| *best_score = score; | |
| } | |
| if (recurse_limit) { | |
| char *newbase = xstrfmt("%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, | |
| const 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 = strchrnul(prefix, '/'); | |
| toplen = subpath - prefix; | |
| if (*subpath) | |
| 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 struct object_id *oid; | |
| 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 *) oid->hash; | |
| 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 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); | |
| /* | |
| * 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 */ | |
| oidcpy(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->hash, del_prefix, shifted->hash, &mode)) | |
| die("cannot find path %s in tree %s", | |
| del_prefix, oid_to_hex(hash2)); | |
| return; | |
| } | |
| if (!*add_prefix) | |
| return; | |
| 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); | |
| } |