lockfile: report when rollback fails

We do not report to the caller when rolling back a lockfile fails, which
will be needed by the reftable compaction logic in a subsequent commit.
It also cannot really report on all errors because the function calls
`delete_tempfile()`, which doesn't return an error either.

Refactor the code so that both `delete_tempfile()` and
`rollback_lock_file()` return an error code.

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

Author: pks-t

lockfile.h

@@ -321,11 +321,11 @@ static inline int commit_lock_file_to(struct lock_file *lk, const char *path)
  * Roll back `lk`: close the file descriptor and/or file pointer and
  * remove the lockfile. It is a NOOP to call `rollback_lock_file()`
  * for a `lock_file` object that has already been committed or rolled
- * back.
+ * back. No error will be returned in this case.
  */
-static inline void rollback_lock_file(struct lock_file *lk)
+static inline int rollback_lock_file(struct lock_file *lk)
 {
-	delete_tempfile(&lk->tempfile);
+	return delete_tempfile(&lk->tempfile);
 }
 
 #endif /* LOCKFILE_H */

tempfile.c

@@ -50,15 +50,17 @@
 
 static VOLATILE_LIST_HEAD(tempfile_list);
 
-static void remove_template_directory(struct tempfile *tempfile,
+static int remove_template_directory(struct tempfile *tempfile,
 				      int in_signal_handler)
 {
 	if (tempfile->directory) {
 		if (in_signal_handler)
-			rmdir(tempfile->directory);
+			return rmdir(tempfile->directory);
 		else
-			rmdir_or_warn(tempfile->directory);
+			return rmdir_or_warn(tempfile->directory);
 	}
+
+	return 0;
 }
 
 static void remove_tempfiles(int in_signal_handler)
@@ -353,16 +355,19 @@ int rename_tempfile(struct tempfile **tempfile_p, const char *path)
 	return 0;
 }
 
-void delete_tempfile(struct tempfile **tempfile_p)
+int delete_tempfile(struct tempfile **tempfile_p)
 {
 	struct tempfile *tempfile = *tempfile_p;
+	int err = 0;
 
 	if (!is_tempfile_active(tempfile))
-		return;
+		return 0;
 
-	close_tempfile_gently(tempfile);
-	unlink_or_warn(tempfile->filename.buf);
-	remove_template_directory(tempfile, 0);
+	err |= close_tempfile_gently(tempfile);
+	err |= unlink_or_warn(tempfile->filename.buf);
+	err |= remove_template_directory(tempfile, 0);
 	deactivate_tempfile(tempfile);
 	*tempfile_p = NULL;
+
+	return err ? -1 : 0;
 }

tempfile.h

@@ -269,7 +269,7 @@ int reopen_tempfile(struct tempfile *tempfile);
  * `delete_tempfile()` for a `tempfile` object that has already been
  * deleted or renamed.
  */
-void delete_tempfile(struct tempfile **tempfile_p);
+int delete_tempfile(struct tempfile **tempfile_p);
 
 /*
  * Close the file descriptor and/or file pointer if they are still