io: path: add function to query the path used to open a file

io/sys/darwin/file.c

@@ -274,6 +274,11 @@ static enum b_status stream_seek(
 	return b_file_cursor(file, &stream->s_cursor);
 }
 
+const struct b_path *b_file_path(const struct b_file *file)
+{
+	return file->path;
+}
+
 enum b_status b_file_open_stream(struct b_file *file, struct b_stream **out)
 {
 	struct b_stream *stream = malloc(sizeof *stream);