Merge branch 'mh/fsck-reflog-entries' into maint

"git fsck" used to ignore missing or invalid objects recorded in reflog.

* mh/fsck-reflog-entries:
  fsck: report errors if reflog entries point at invalid objects
  fsck_handle_reflog_sha1(): new function

builtin/fsck.c

@@ -451,34 +451,40 @@ static void fsck_dir(int i, char *path)
 
 static int default_refs;
 
+static void fsck_handle_reflog_sha1(const char *refname, unsigned char *sha1)
+{
+	struct object *obj;
+
+	if (!is_null_sha1(sha1)) {
+		obj = lookup_object(sha1);
+		if (obj) {
+			obj->used = 1;
+			mark_object_reachable(obj);
+		} else {
+			error("%s: invalid reflog entry %s", refname, sha1_to_hex(sha1));
+			errors_found |= ERROR_REACHABLE;
+		}
+	}
+}
+
 static int fsck_handle_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 		const char *email, unsigned long timestamp, int tz,
 		const char *message, void *cb_data)
 {
-	struct object *obj;
+	const char *refname = cb_data;
 
 	if (verbose)
 		fprintf(stderr, "Checking reflog %s->%s\n",
 			sha1_to_hex(osha1), sha1_to_hex(nsha1));
 
-	if (!is_null_sha1(osha1)) {
-		obj = lookup_object(osha1);
-		if (obj) {
-			obj->used = 1;
-			mark_object_reachable(obj);
-		}
-	}
-	obj = lookup_object(nsha1);
-	if (obj) {
-		obj->used = 1;
-		mark_object_reachable(obj);
-	}
+	fsck_handle_reflog_sha1(refname, osha1);
+	fsck_handle_reflog_sha1(refname, nsha1);
 	return 0;
 }
 
 static int fsck_handle_reflog(const char *logname, const unsigned char *sha1, int flag, void *cb_data)
 {
-	for_each_reflog_ent(logname, fsck_handle_reflog_ent, NULL);
+	for_each_reflog_ent(logname, fsck_handle_reflog_ent, (void *)logname);
 	return 0;
 }