[GSoC][PATCH v3 2/2] rebase-interactive: rewrite the edit-todo functionality in C

[Alban Gruin <alban.gruin@gmail.com>]

This rewrites the edit-todo functionality from shell to C.

To achieve that, a new command mode, `edit-todo`, is added, and the
`write-edit-todo` flag is removed, as the shell script does not need to
write the edit todo help message to the todo list anymore.

The shell version is then stripped in favour of a call to the helper.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
---
 builtin/rebase--helper.c   | 13 ++++++++-----
 git-rebase--interactive.sh | 11 +----------
 rebase-interactive.c       | 31 +++++++++++++++++++++++++++++++
 rebase-interactive.h       |  1 +
 4 files changed, 41 insertions(+), 15 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 05e73e71d..731a64971 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -13,12 +13,12 @@ static const char * const builtin_rebase_helper_usage[] = {
 int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 {
 	struct replay_opts opts = REPLAY_OPTS_INIT;
-	unsigned flags = 0, keep_empty = 0, rebase_merges = 0, write_edit_todo = 0;
+	unsigned flags = 0, keep_empty = 0, rebase_merges = 0;
 	int abbreviate_commands = 0, rebase_cousins = -1;
 	enum {
 		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
 		CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH,
-		ADD_EXEC, APPEND_TODO_HELP
+		ADD_EXEC, APPEND_TODO_HELP, EDIT_TODO
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -28,8 +28,6 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "rebase-merges", &rebase_merges, N_("rebase merge commits")),
 		OPT_BOOL(0, "rebase-cousins", &rebase_cousins,
 			 N_("keep original branch points of cousins")),
-		OPT_BOOL(0, "write-edit-todo", &write_edit_todo,
-			 N_("append the edit-todo message to the todo-list")),
 		OPT_CMDMODE(0, "continue", &command, N_("continue rebase"),
 				CONTINUE),
 		OPT_CMDMODE(0, "abort", &command, N_("abort rebase"),
@@ -50,6 +48,9 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			N_("insert exec commands in todo list"), ADD_EXEC),
 		OPT_CMDMODE(0, "append-todo-help", &command,
 			    N_("insert the help in the todo list"), APPEND_TODO_HELP),
+		OPT_CMDMODE(0, "edit-todo", &command,
+			    N_("edit the todo list during an interactive rebase"),
+			    EDIT_TODO),
 		OPT_END()
 	};
 
@@ -90,6 +91,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	if (command == ADD_EXEC && argc == 2)
 		return !!sequencer_add_exec_commands(argv[1]);
 	if (command == APPEND_TODO_HELP && argc == 1)
-		return !!append_todo_help(write_edit_todo, keep_empty);
+		return !!append_todo_help(0, keep_empty);
+	if (command == EDIT_TODO && argc == 1)
+		return !!edit_todo_list(flags);
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 94c23a7af..2defe607f 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -108,16 +108,7 @@ initiate_action () {
 		     --continue
 		;;
 	edit-todo)
-		git stripspace --strip-comments <"$todo" >"$todo".new
-		mv -f "$todo".new "$todo"
-		collapse_todo_ids
-		git rebase--helper --append-todo-help --write-edit-todo
-
-		git_sequence_editor "$todo" ||
-			die "$(gettext "Could not execute editor")"
-		expand_todo_ids
-
-		exit
+		exec git rebase--helper --edit-todo
 		;;
 	show-current-patch)
 		exec git show REBASE_HEAD --
diff --git a/rebase-interactive.c b/rebase-interactive.c
index c79c819b9..ace8e095b 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -66,3 +66,34 @@ int append_todo_help(unsigned edit_todo, unsigned keep_empty)
 
 	return ret;
 }
+
+int edit_todo_list(unsigned flags)
+{
+	struct strbuf buf = STRBUF_INIT;
+	const char *todo_file = rebase_path_todo();
+	FILE *todo;
+
+	if (strbuf_read_file(&buf, todo_file, 0) < 0)
+		return error_errno(_("could not read '%s'."), todo_file);
+
+	strbuf_stripspace(&buf, 1);
+	todo = fopen_or_warn(todo_file, "w");
+	if (!todo) {
+		strbuf_release(&buf);
+		return 1;
+	}
+
+	strbuf_write(&buf, todo);
+	fclose(todo);
+	strbuf_release(&buf);
+
+	transform_todos(flags | TODO_LIST_SHORTEN_IDS);
+	append_todo_help(1, 0);
+
+	if (launch_sequence_editor(todo_file, NULL, NULL))
+		return 1;
+
+	transform_todos(flags & ~(TODO_LIST_SHORTEN_IDS));
+
+	return 0;
+}
diff --git a/rebase-interactive.h b/rebase-interactive.h
index 47372624e..155219e74 100644
--- a/rebase-interactive.h
+++ b/rebase-interactive.h
@@ -2,5 +2,6 @@
 #define REBASE_INTERACTIVE_H
 
 int append_todo_help(unsigned edit_todo, unsigned keep_empty);
+int edit_todo_list(unsigned flags);
 
 #endif
-- 
2.18.0