rebase-interactive: use todo_list_write_to_file() in edit_todo_list()

Just like complete_action(), edit_todo_list() used a
function (transform_todo_file()) that read the todo list from the disk
and wrote it back, resulting in useless disk accesses.

This changes edit_todo_list() to call directly todo_list_write_to_file()
instead.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rebase-interactive.c

@@ -79,39 +79,33 @@ void append_todo_help(unsigned edit_todo, unsigned keep_empty,
 
 int edit_todo_list(struct repository *r, unsigned flags)
 {
-	struct strbuf buf = STRBUF_INIT;
 	const char *todo_file = rebase_path_todo();
+	struct todo_list todo_list = TODO_LIST_INIT;
+	int res = 0;
 
-	if (strbuf_read_file(&buf, todo_file, 0) < 0)
+	if (strbuf_read_file(&todo_list.buf, todo_file, 0) < 0)
 		return error_errno(_("could not read '%s'."), todo_file);
 
-	strbuf_stripspace(&buf, 1);
-	if (write_message(buf.buf, buf.len, todo_file, 0)) {
-		strbuf_release(&buf);
+	strbuf_stripspace(&todo_list.buf, 1);
+	todo_list_parse_insn_buffer(r, todo_list.buf.buf, &todo_list);
+	if (todo_list_write_to_file(r, &todo_list, todo_file, NULL, NULL, -1,
+				    flags | TODO_LIST_SHORTEN_IDS | TODO_LIST_APPEND_TODO_HELP)) {
+		todo_list_release(&todo_list);
 		return -1;
 	}
 
-	strbuf_release(&buf);
-
-	transform_todo_file(r, flags | TODO_LIST_SHORTEN_IDS);
-
-	if (strbuf_read_file(&buf, todo_file, 0) < 0)
-		return error_errno(_("could not read '%s'."), todo_file);
-
-	append_todo_help(1, 0, &buf);
-	if (write_message(buf.buf, buf.len, todo_file, 0)) {
-		strbuf_release(&buf);
+	strbuf_reset(&todo_list.buf);
+	if (launch_sequence_editor(todo_file, &todo_list.buf, NULL)) {
+		todo_list_release(&todo_list);
 		return -1;
 	}
 
-	strbuf_release(&buf);
+	if (!todo_list_parse_insn_buffer(r, todo_list.buf.buf, &todo_list))
+		res = todo_list_write_to_file(r, &todo_list, todo_file, NULL, NULL, -1,
+					      flags & ~(TODO_LIST_SHORTEN_IDS));
 
-	if (launch_sequence_editor(todo_file, NULL, NULL))
-		return -1;
-
-	transform_todo_file(r, flags & ~(TODO_LIST_SHORTEN_IDS));
-
-	return 0;
+	todo_list_release(&todo_list);
+	return res;
 }
 
 define_commit_slab(commit_seen, unsigned char);

sequencer.c

@@ -383,8 +383,8 @@ static void print_advice(struct repository *r, int show_hint,
 	}
 }
 
-int write_message(const void *buf, size_t len, const char *filename,
-		  int append_eol)
+static int write_message(const void *buf, size_t len, const char *filename,
+			 int append_eol)
 {
 	struct lock_file msg_file = LOCK_INIT;
 

sequencer.h

@@ -64,9 +64,6 @@ struct replay_opts {
 };
 #define REPLAY_OPTS_INIT { .action = -1, .current_fixups = STRBUF_INIT }
 
-int write_message(const void *buf, size_t len, const char *filename,
-		  int append_eol);
-
 /*
  * Note that ordering matters in this enum. Not only must it match the mapping
  * of todo_command_info (in sequencer.c), it is also divided into several