- int depth = MAXDEPTH, len;
- char buffer[256];
-
- for (;;) {
- struct stat st;
- int fd;
-
- if (--depth < 0)
- return NULL;
-
- /* Special case: non-existing file */
- if (lstat(path, &st) < 0) {
- if (errno != ENOENT)
- return NULL;
- memset(sha1, 0, 20);
- return path;
- }
-
- /* Follow "normalized" - ie "refs/.." symlinks by hand */
- if (S_ISLNK(st.st_mode)) {
- len = readlink(path, buffer, sizeof(buffer)-1);
- if (len >= 5 && !memcmp("refs/", buffer, 5)) {
- path = git_path("%.*s", len, buffer);
- continue;
- }
- }
-
- /*
- * Anything else, just open it and try to use it as
- * a ref
- */
- fd = open(path, O_RDONLY);
- if (fd < 0)
- return NULL;
- len = read(fd, buffer, sizeof(buffer)-1);
- close(fd);
- break;
- }
- if (len < 40 || get_sha1_hex(buffer, sha1))
- return NULL;
- return path;
+ char buf[40];
+ int fd = open(path, O_RDONLY), nr;
+ if (fd < 0)
+ return -1;
+ nr = read(fd, buf, 40);
+ close(fd);
+ if (nr != 40 || get_sha1_hex(buf, currsha1) < 0)
+ return -1;
+ return memcmp(oldsha1, currsha1, 20) ? -1 : 0;