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303 lines
7.1 KiB
303 lines
7.1 KiB
#include "cache.h" |
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#include "tree.h" |
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#include "tree-walk.h" |
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static int score_missing(unsigned mode, const char *path) |
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{ |
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int score; |
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if (S_ISDIR(mode)) |
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score = -1000; |
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else if (S_ISLNK(mode)) |
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score = -500; |
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else |
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score = -50; |
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return score; |
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} |
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static int score_differs(unsigned mode1, unsigned mode2, const char *path) |
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{ |
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int score; |
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if (S_ISDIR(mode1) != S_ISDIR(mode2)) |
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score = -100; |
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else if (S_ISLNK(mode1) != S_ISLNK(mode2)) |
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score = -50; |
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else |
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score = -5; |
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return score; |
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} |
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static int score_matches(unsigned mode1, unsigned mode2, const char *path) |
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{ |
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int score; |
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/* Heh, we found SHA-1 collisions between different kind of objects */ |
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if (S_ISDIR(mode1) != S_ISDIR(mode2)) |
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score = -100; |
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else if (S_ISLNK(mode1) != S_ISLNK(mode2)) |
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score = -50; |
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else if (S_ISDIR(mode1)) |
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score = 1000; |
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else if (S_ISLNK(mode1)) |
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score = 500; |
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else |
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score = 250; |
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return score; |
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} |
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/* |
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* Inspect two trees, and give a score that tells how similar they are. |
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*/ |
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static int score_trees(const unsigned char *hash1, const unsigned char *hash2) |
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{ |
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struct tree_desc one; |
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struct tree_desc two; |
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void *one_buf, *two_buf; |
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int score = 0; |
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enum object_type type; |
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unsigned long size; |
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one_buf = read_sha1_file(hash1, &type, &size); |
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if (!one_buf) |
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die("unable to read tree (%s)", sha1_to_hex(hash1)); |
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if (type != OBJ_TREE) |
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die("%s is not a tree", sha1_to_hex(hash1)); |
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init_tree_desc(&one, one_buf, size); |
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two_buf = read_sha1_file(hash2, &type, &size); |
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if (!two_buf) |
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die("unable to read tree (%s)", sha1_to_hex(hash2)); |
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if (type != OBJ_TREE) |
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die("%s is not a tree", sha1_to_hex(hash2)); |
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init_tree_desc(&two, two_buf, size); |
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while (one.size | two.size) { |
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const unsigned char *elem1 = elem1; |
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const unsigned char *elem2 = elem2; |
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const char *path1 = path1; |
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const char *path2 = path2; |
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unsigned mode1 = mode1; |
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unsigned mode2 = mode2; |
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int cmp; |
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if (one.size) |
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elem1 = tree_entry_extract(&one, &path1, &mode1); |
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if (two.size) |
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elem2 = tree_entry_extract(&two, &path2, &mode2); |
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if (!one.size) { |
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/* two has more entries */ |
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score += score_missing(mode2, path2); |
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update_tree_entry(&two); |
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continue; |
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} |
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if (!two.size) { |
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/* two lacks this entry */ |
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score += score_missing(mode1, path1); |
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update_tree_entry(&one); |
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continue; |
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} |
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cmp = base_name_compare(path1, strlen(path1), mode1, |
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path2, strlen(path2), mode2); |
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if (cmp < 0) { |
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/* path1 does not appear in two */ |
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score += score_missing(mode1, path1); |
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update_tree_entry(&one); |
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continue; |
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} |
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else if (cmp > 0) { |
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/* path2 does not appear in one */ |
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score += score_missing(mode2, path2); |
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update_tree_entry(&two); |
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continue; |
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} |
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else if (hashcmp(elem1, elem2)) |
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/* they are different */ |
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score += score_differs(mode1, mode2, path1); |
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else |
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/* same subtree or blob */ |
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score += score_matches(mode1, mode2, path1); |
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update_tree_entry(&one); |
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update_tree_entry(&two); |
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} |
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free(one_buf); |
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free(two_buf); |
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return score; |
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} |
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/* |
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* Match one itself and its subtrees with two and pick the best match. |
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*/ |
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static void match_trees(const unsigned char *hash1, |
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const unsigned char *hash2, |
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int *best_score, |
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char **best_match, |
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const char *base, |
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int recurse_limit) |
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{ |
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struct tree_desc one; |
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void *one_buf; |
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enum object_type type; |
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unsigned long size; |
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one_buf = read_sha1_file(hash1, &type, &size); |
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if (!one_buf) |
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die("unable to read tree (%s)", sha1_to_hex(hash1)); |
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if (type != OBJ_TREE) |
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die("%s is not a tree", sha1_to_hex(hash1)); |
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init_tree_desc(&one, one_buf, size); |
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while (one.size) { |
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const char *path; |
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const unsigned char *elem; |
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unsigned mode; |
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int score; |
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elem = tree_entry_extract(&one, &path, &mode); |
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if (!S_ISDIR(mode)) |
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goto next; |
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score = score_trees(elem, hash2); |
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if (*best_score < score) { |
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char *newpath; |
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newpath = xmalloc(strlen(base) + strlen(path) + 1); |
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sprintf(newpath, "%s%s", base, path); |
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free(*best_match); |
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*best_match = newpath; |
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*best_score = score; |
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} |
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if (recurse_limit) { |
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char *newbase; |
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newbase = xmalloc(strlen(base) + strlen(path) + 2); |
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sprintf(newbase, "%s%s/", base, path); |
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match_trees(elem, hash2, best_score, best_match, |
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newbase, recurse_limit - 1); |
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free(newbase); |
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} |
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next: |
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update_tree_entry(&one); |
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} |
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free(one_buf); |
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} |
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/* |
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* A tree "hash1" has a subdirectory at "prefix". Come up with a |
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* tree object by replacing it with another tree "hash2". |
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*/ |
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static int splice_tree(const unsigned char *hash1, |
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char *prefix, |
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const unsigned char *hash2, |
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unsigned char *result) |
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{ |
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char *subpath; |
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int toplen; |
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char *buf; |
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unsigned long sz; |
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struct tree_desc desc; |
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unsigned char *rewrite_here; |
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const unsigned char *rewrite_with; |
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unsigned char subtree[20]; |
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enum object_type type; |
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int status; |
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subpath = strchr(prefix, '/'); |
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if (!subpath) |
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toplen = strlen(prefix); |
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else { |
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toplen = subpath - prefix; |
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subpath++; |
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} |
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buf = read_sha1_file(hash1, &type, &sz); |
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if (!buf) |
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die("cannot read tree %s", sha1_to_hex(hash1)); |
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init_tree_desc(&desc, buf, sz); |
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rewrite_here = NULL; |
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while (desc.size) { |
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const char *name; |
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unsigned mode; |
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const unsigned char *sha1; |
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sha1 = tree_entry_extract(&desc, &name, &mode); |
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if (strlen(name) == toplen && |
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!memcmp(name, prefix, toplen)) { |
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if (!S_ISDIR(mode)) |
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die("entry %s in tree %s is not a tree", |
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name, sha1_to_hex(hash1)); |
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rewrite_here = (unsigned char *) sha1; |
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break; |
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} |
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update_tree_entry(&desc); |
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} |
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if (!rewrite_here) |
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die("entry %.*s not found in tree %s", |
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toplen, prefix, sha1_to_hex(hash1)); |
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if (subpath) { |
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status = splice_tree(rewrite_here, subpath, hash2, subtree); |
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if (status) |
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return status; |
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rewrite_with = subtree; |
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} |
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else |
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rewrite_with = hash2; |
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hashcpy(rewrite_here, rewrite_with); |
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status = write_sha1_file(buf, sz, tree_type, result); |
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free(buf); |
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return status; |
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} |
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/* |
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* We are trying to come up with a merge between one and two that |
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* results in a tree shape similar to one. The tree two might |
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* correspond to a subtree of one, in which case it needs to be |
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* shifted down by prefixing otherwise empty directories. On the |
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* other hand, it could cover tree one and we might need to pick a |
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* subtree of it. |
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*/ |
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void shift_tree(const unsigned char *hash1, |
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const unsigned char *hash2, |
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unsigned char *shifted, |
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int depth_limit) |
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{ |
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char *add_prefix; |
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char *del_prefix; |
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int add_score, del_score; |
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add_score = del_score = score_trees(hash1, hash2); |
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add_prefix = xcalloc(1, 1); |
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del_prefix = xcalloc(1, 1); |
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/* |
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* See if one's subtree resembles two; if so we need to prefix |
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* two with a few fake trees to match the prefix. |
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*/ |
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match_trees(hash1, hash2, &add_score, &add_prefix, "", depth_limit); |
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/* |
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* See if two's subtree resembles one; if so we need to |
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* pick only subtree of two. |
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*/ |
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match_trees(hash2, hash1, &del_score, &del_prefix, "", depth_limit); |
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/* Assume we do not have to do any shifting */ |
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hashcpy(shifted, hash2); |
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if (add_score < del_score) { |
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/* We need to pick a subtree of two */ |
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unsigned mode; |
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if (!*del_prefix) |
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return; |
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if (get_tree_entry(hash2, del_prefix, shifted, &mode)) |
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die("cannot find path %s in tree %s", |
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del_prefix, sha1_to_hex(hash2)); |
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return; |
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} |
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if (!*add_prefix) |
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return; |
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splice_tree(hash1, add_prefix, hash2, shifted); |
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}
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