filebuf: remove lockfile upon rename errors

When we have an error renaming the lockfile, we need to make sure
that we remove it upon cleanup. For this, we need to keep track of
whether we opened the file and whether the rename succeeded.

If we did create the lockfile but the rename did not succeed, we
remove the lockfile. This won't protect against all errors, but
the most common ones (target file is open) does get handled.

src/filebuf.c

@@ -101,7 +101,7 @@ void git_filebuf_cleanup(git_filebuf *file)
 	if (file->fd_is_open && file->fd >= 0)
 		p_close(file->fd);
 
-	if (file->fd_is_open && file->path_lock && git_path_exists(file->path_lock))
+	if (file->created_lock && !file->did_rename && file->path_lock && git_path_exists(file->path_lock))
 		p_unlink(file->path_lock);
 
 	if (file->compute_digest) {
@@ -258,6 +258,7 @@ int git_filebuf_open(git_filebuf *file, const char *path, int flags, mode_t mode
 			goto cleanup;
 		}
 		file->fd_is_open = true;
+		file->created_lock = true;
 
 		/* No original path */
 		file->path_original = NULL;
@@ -281,6 +282,8 @@ int git_filebuf_open(git_filebuf *file, const char *path, int flags, mode_t mode
 		/* open the file for locking */
 		if ((error = lock_file(file, flags, mode)) < 0)
 			goto cleanup;
+
+		file->created_lock = true;
 	}
 
 	return 0;
@@ -340,6 +343,8 @@ int git_filebuf_commit(git_filebuf *file)
 		goto on_error;
 	}
 
+	file->did_rename = true;
+
 	git_filebuf_cleanup(file);
 	return 0;
 

src/filebuf.h

@@ -44,6 +44,8 @@ struct git_filebuf {
 	size_t buf_size, buf_pos;
 	git_file fd;
 	bool fd_is_open;
+	bool created_lock;
+	bool did_rename;
 	bool do_not_buffer;
 	int last_error;
 };

tests/core/filebuf.c

@@ -148,6 +148,6 @@ void test_core_filebuf__rename_error(void)
 	p_close(fd);
 
 	git_filebuf_cleanup(&file);
-	cl_assert_equal_i(false, git_path_exists(test_lock));
 
+	cl_assert_equal_i(false, git_path_exists(test_lock));
 }