+static int default_refs = 0;
+
+static int fsck_handle_ref(const char *refname, const unsigned char *sha1)
+{
+ struct object *obj;
+
+ obj = lookup_object(sha1);
+ if (!obj) {
+ if (!standalone && has_sha1_file(sha1)) {
+ default_refs++;
+ return 0; /* it is in a pack */
+ }
+ error("%s: invalid sha1 pointer %s", refname, sha1_to_hex(sha1));
+ /* We'll continue with the rest despite the error.. */
+ return 0;
+ }
+ default_refs++;
+ obj->used = 1;
+ mark_reachable(obj, REACHABLE);
+ return 0;
+}
+
+static void get_default_heads(void)
+{
+ for_each_ref(fsck_handle_ref);
+ if (!default_refs)
+ die("No default references");
+}
+
+static void fsck_object_dir(const char *path)
+{
+ int i;
+ for (i = 0; i < 256; i++) {
+ static char dir[4096];
+ sprintf(dir, "%s/%02x", path, i);
+ fsck_dir(i, dir);
+ }
+ fsck_sha1_list();
+}
+
+static int fsck_head_link(void)
+{
+ int fd, count;
+ char hex[40];
+ unsigned char sha1[20];
+ static char path[PATH_MAX], link[PATH_MAX];
+ const char *git_dir = gitenv(GIT_DIR_ENVIRONMENT) ? : DEFAULT_GIT_DIR_ENVIRONMENT;
+
+ snprintf(path, sizeof(path), "%s/HEAD", git_dir);
+ if (readlink(path, link, sizeof(link)) < 0)
+ return error("HEAD is not a symlink");
+ if (strncmp("refs/heads/", link, 11))
+ return error("HEAD points to something strange (%s)", link);
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ return error("HEAD: %s", strerror(errno));
+ count = read(fd, hex, sizeof(hex));
+ close(fd);
+ if (count < 0)
+ return error("HEAD: %s", strerror(errno));
+ if (count < 40 || get_sha1_hex(hex, sha1))
+ return error("HEAD: not a valid git pointer");
+ return 0;
+}
+