2 * GIT - The information manager from hell
4 * Copyright (C) Linus Torvalds, 2005
10 static int unpack_tree(unsigned char *sha1)
15 buffer = read_object_with_reference(sha1, "tree", &size, 0);
18 return read_tree(buffer, size, stage);
21 static char *lockfile_name;
23 static void remove_lock_file(void)
26 unlink(lockfile_name);
29 static int path_matches(struct cache_entry *a, struct cache_entry *b)
31 int len = ce_namelen(a);
32 return ce_namelen(b) == len &&
33 !memcmp(a->name, b->name, len);
36 static int same(struct cache_entry *a, struct cache_entry *b)
38 return a->ce_mode == b->ce_mode &&
39 !memcmp(a->sha1, b->sha1, 20);
44 * This removes all trivial merges that don't change the tree
45 * and collapses them to state 0.
47 * _Any_ other merge is left to user policy. That includes "both
48 * created the same file", and "both removed the same file" - which are
49 * trivial, but the user might still want to _note_ it.
51 static struct cache_entry *merge_entries(struct cache_entry *a,
52 struct cache_entry *b,
53 struct cache_entry *c)
55 int len = ce_namelen(a);
58 * Are they all the same filename? We won't do
61 if (ce_namelen(b) != len ||
62 ce_namelen(c) != len ||
63 memcmp(a->name, b->name, len) ||
64 memcmp(a->name, c->name, len))
68 * Ok, all three entries describe the same
69 * filename, but maybe the contents or file
72 * The trivial cases end up being the ones where two
73 * out of three files are the same:
74 * - both destinations the same, trivially take either
75 * - one of the destination versions hasn't changed,
78 * The "all entries exactly the same" case falls out as
79 * a special case of any of the "two same" cases.
81 * Here "a" is "original", and "b" and "c" are the two
82 * trees we are merging.
93 static void trivially_merge_cache(struct cache_entry **src, int nr)
95 static struct cache_entry null_entry;
96 struct cache_entry **dst = src;
97 struct cache_entry *old = &null_entry;
100 struct cache_entry *ce, *result;
104 /* We throw away original cache entries except for the stat information */
112 if (nr > 2 && (result = merge_entries(ce, src[1], src[2])) != NULL) {
114 * See if we can re-use the old CE directly?
115 * That way we get the uptodate stat info.
117 if (path_matches(result, old) && same(result, old))
120 ce->ce_flags &= ~htons(CE_STAGEMASK);
131 static void merge_stat_info(struct cache_entry **src, int nr)
133 static struct cache_entry null_entry;
134 struct cache_entry **dst = src;
135 struct cache_entry *old = &null_entry;
138 struct cache_entry *ce;
142 /* We throw away original cache entries except for the stat information */
150 if (path_matches(ce, old) && same(ce, old))
152 ce->ce_flags &= ~htons(CE_STAGEMASK);
159 static char *read_tree_usage = "read-tree (<sha> | -m <sha1> [<sha2> <sha3>])";
161 int main(int argc, char **argv)
164 unsigned char sha1[20];
165 static char lockfile[MAXPATHLEN+1];
166 const char *indexfile = get_index_file();
168 snprintf(lockfile, sizeof(lockfile), "%s.lock", indexfile);
170 newfd = open(lockfile, O_RDWR | O_CREAT | O_EXCL, 0600);
172 die("unable to create new cachefile");
173 atexit(remove_lock_file);
174 lockfile_name = lockfile;
177 for (i = 1; i < argc; i++) {
178 const char *arg = argv[i];
180 /* "-m" stands for "merge", meaning we start in stage 1 */
181 if (!strcmp(arg, "-m")) {
184 die("-m needs to come first");
186 for (i = 0; i < active_nr; i++) {
187 if (ce_stage(active_cache[i]))
188 die("you need to resolve your current index first");
194 if (get_sha1_hex(arg, sha1) < 0)
195 usage(read_tree_usage);
197 usage(read_tree_usage);
198 if (unpack_tree(sha1) < 0)
199 die("failed to unpack tree object %s", arg);
204 case 4: /* Three-way merge */
205 trivially_merge_cache(active_cache, active_nr);
207 case 2: /* Just read a tree, merge with old cache contents */
208 merge_stat_info(active_cache, active_nr);
211 die("just how do you expect me to merge %d trees?", stage-1);
214 if (write_cache(newfd, active_cache, active_nr) || rename(lockfile, indexfile))
215 die("unable to write new index file");
216 lockfile_name = NULL;