4 static const char git_update_ref_usage[] = "git-update-ref <refname> <value> [<oldval>]";
8 const char *resolve_ref(const char *path, unsigned char *sha1)
10 int depth = MAXDEPTH, len;
20 /* Special case: non-existing file */
21 if (lstat(path, &st) < 0) {
28 /* Follow "normalized" - ie "refs/.." symlinks by hand */
29 if (S_ISLNK(st.st_mode)) {
30 len = readlink(path, buffer, sizeof(buffer)-1);
31 if (len >= 5 && !memcmp("refs/", buffer, 5)) {
32 path = git_path("%.*s", len, buffer);
38 * Anything else, just open it and try to use it as
41 fd = open(path, O_RDONLY);
44 len = read(fd, buffer, sizeof(buffer)-1);
48 if (len < 40 || get_sha1_hex(buffer, sha1))
53 int main(int argc, char **argv)
56 const char *refname, *value, *oldval, *path, *lockpath;
57 unsigned char sha1[20], oldsha1[20], currsha1[20];
60 setup_git_directory();
61 if (argc < 3 || argc > 4)
62 usage(git_update_ref_usage);
67 if (get_sha1(value, sha1) < 0)
68 die("%s: not a valid SHA1", value);
69 memset(oldsha1, 0, 20);
70 if (oldval && get_sha1(oldval, oldsha1) < 0)
71 die("%s: not a valid old SHA1", oldval);
73 path = resolve_ref(git_path("%s", refname), currsha1);
75 die("No such ref: %s", refname);
78 if (memcmp(currsha1, oldsha1, 20))
79 die("Ref %s changed to %s", refname, sha1_to_hex(currsha1));
81 if (!memcmp(oldsha1, sha1, 20))
85 lockpath = mkpath("%s.lock", path);
87 fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
89 die("Unable to create %s", lockpath);
90 hex = sha1_to_hex(sha1);
92 written = write(fd, hex, 41);
96 die("Unable to write to %s", lockpath);
102 * We should re-read the old ref here, and re-verify that it
103 * matches "oldsha1". Otherwise there's a small race.
106 if (rename(lockpath, path) < 0) {
108 die("Unable to create %s", path);