reftable/stack: refactor stack reloading to have common exit path

The `reftable_stack_reload_maybe_reuse()` function is responsible for
reloading the reftable list from disk. The function is quite hard to
follow though because it has a bunch of different exit paths, many of
which have to free the same set of resources.

Refactor the function to have a common exit path. While at it, touch up
the style of this function a bit to match our usual coding style better.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

reftable/stack.c

@@ -304,69 +304,67 @@ static int tv_cmp(struct timeval *a, struct timeval *b)
 static int reftable_stack_reload_maybe_reuse(struct reftable_stack *st,
 					     int reuse_open)
 {
-	struct timeval deadline = { 0 };
-	int err = gettimeofday(&deadline, NULL);
+	char **names = NULL, **names_after = NULL;
+	struct timeval deadline;
 	int64_t delay = 0;
-	int tries = 0;
-	if (err < 0)
-		return err;
+	int tries = 0, err;
 
+	err = gettimeofday(&deadline, NULL);
+	if (err < 0)
+		goto out;
 	deadline.tv_sec += 3;
+
 	while (1) {
-		char **names = NULL;
-		char **names_after = NULL;
-		struct timeval now = { 0 };
-		int err = gettimeofday(&now, NULL);
-		int err2 = 0;
-		if (err < 0) {
-			return err;
-		}
+		struct timeval now;
 
-		/* Only look at deadlines after the first few times. This
-		   simplifies debugging in GDB */
+		err = gettimeofday(&now, NULL);
+		if (err < 0)
+			goto out;
+
+		/*
+		 * Only look at deadlines after the first few times. This
+		 * simplifies debugging in GDB.
+		 */
 		tries++;
-		if (tries > 3 && tv_cmp(&now, &deadline) >= 0) {
-			break;
-		}
+		if (tries > 3 && tv_cmp(&now, &deadline) >= 0)
+			goto out;
 
 		err = read_lines(st->list_file, &names);
-		if (err < 0) {
-			free_names(names);
-			return err;
-		}
+		if (err < 0)
+			goto out;
+
 		err = reftable_stack_reload_once(st, names, reuse_open);
-		if (err == 0) {
-			free_names(names);
+		if (!err)
 			break;
-		}
-		if (err != REFTABLE_NOT_EXIST_ERROR) {
-			free_names(names);
-			return err;
-		}
-
-		/* err == REFTABLE_NOT_EXIST_ERROR can be caused by a concurrent
-		   writer. Check if there was one by checking if the name list
-		   changed.
-		*/
-		err2 = read_lines(st->list_file, &names_after);
-		if (err2 < 0) {
-			free_names(names);
-			return err2;
-		}
-
+		if (err != REFTABLE_NOT_EXIST_ERROR)
+			goto out;
+
+		/*
+		 * REFTABLE_NOT_EXIST_ERROR can be caused by a concurrent
+		 * writer. Check if there was one by checking if the name list
+		 * changed.
+		 */
+		err = read_lines(st->list_file, &names_after);
+		if (err < 0)
+			goto out;
 		if (names_equal(names_after, names)) {
-			free_names(names);
-			free_names(names_after);
-			return err;
+			err = REFTABLE_NOT_EXIST_ERROR;
+			goto out;
 		}
+
 		free_names(names);
+		names = NULL;
 		free_names(names_after);
+		names_after = NULL;
 
 		delay = delay + (delay * rand()) / RAND_MAX + 1;
 		sleep_millisec(delay);
 	}
 
-	return 0;
+out:
+	free_names(names);
+	free_names(names_after);
+	return err;
 }
 
 /* -1 = error