| #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, |
| 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); |
| |
| 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); |
| } |