sequencer: future-proof read_populate_todo()

Over the next commits, we will work on improving the sequencer to the
point where it can process the edit script of an interactive rebase. To
that end, we will need to teach the sequencer to read interactive
rebase's todo file. In preparation, we consolidate all places where
that todo file is needed to call a function that we will later extend.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

sequencer.c

@@ -32,6 +32,11 @@ static const char *get_dir(const struct replay_opts *opts)
 	return git_path_seq_dir();
 }
 
+static const char *get_todo_path(const struct replay_opts *opts)
+{
+	return git_path_todo_file();
+}
+
 static int is_rfc2822_line(const char *buf, int len)
 {
 	int i;
@@ -747,25 +752,25 @@ static int parse_insn_buffer(char *buf, struct commit_list **todo_list,
 static int read_populate_todo(struct commit_list **todo_list,
 			struct replay_opts *opts)
 {
+	const char *todo_file = get_todo_path(opts);
 	struct strbuf buf = STRBUF_INIT;
 	int fd, res;
 
-	fd = open(git_path_todo_file(), O_RDONLY);
+	fd = open(todo_file, O_RDONLY);
 	if (fd < 0)
 		return error(_("Could not open %s (%s)"),
-			git_path_todo_file(), strerror(errno));
+			todo_file, strerror(errno));
 	if (strbuf_read(&buf, fd, 0) < 0) {
 		close(fd);
 		strbuf_release(&buf);
-		return error(_("Could not read %s."), git_path_todo_file());
+		return error(_("Could not read %s."), todo_file);
 	}
 	close(fd);
 
 	res = parse_insn_buffer(buf.buf, todo_list, opts);
 	strbuf_release(&buf);
 	if (res)
-		return error(_("Unusable instruction sheet: %s"),
-			git_path_todo_file());
+		return error(_("Unusable instruction sheet: %s"), todo_file);
 	return 0;
 }
 
@@ -1021,7 +1026,7 @@ static int sequencer_continue(struct replay_opts *opts)
 {
 	struct commit_list *todo_list = NULL;
 
-	if (!file_exists(git_path_todo_file()))
+	if (!file_exists(get_todo_path(opts)))
 		return continue_single_pick();
 	if (read_populate_opts(opts) ||
 			read_populate_todo(&todo_list, opts))