Merge branch 'ag/rebase-i-in-c'

Rewrite of the remaining "rebase -i" machinery in C.

* ag/rebase-i-in-c:
  rebase -i: move rebase--helper modes to rebase--interactive
  rebase -i: remove git-rebase--interactive.sh
  rebase--interactive2: rewrite the submodes of interactive rebase in C
  rebase -i: implement the main part of interactive rebase as a builtin
  rebase -i: rewrite init_basic_state() in C
  rebase -i: rewrite write_basic_state() in C
  rebase -i: rewrite the rest of init_revisions_and_shortrevisions() in C
  rebase -i: implement the logic to initialize $revisions in C
  rebase -i: remove unused modes and functions
  rebase -i: rewrite complete_action() in C
  t3404: todo list with commented-out commands only aborts
  sequencer: change the way skip_unnecessary_picks() returns its result
  sequencer: refactor append_todo_help() to write its message to a buffer
  rebase -i: rewrite checkout_onto() in C
  rebase -i: rewrite setup_reflog_action() in C
  sequencer: add a new function to silence a command, except if it fails
  rebase -i: rewrite the edit-todo functionality in C
  editor: add a function to launch the sequence editor
  rebase -i: rewrite append_todo_help() in C
  sequencer: make three functions and an enum from sequencer.c public

17 files changed, 742 insertions, 451 deletions

diff --git a/.gitignore b/.gitignore
index 4d5de166e8..0d77ea5894 100644
--- a/.gitignore
+++ b/.gitignore
@@ -123,7 +123,6 @@
 /git-rebase
 /git-rebase--am
 /git-rebase--common
-/git-rebase--helper
 /git-rebase--interactive
 /git-rebase--merge
 /git-rebase--preserve-merges
diff --git a/Makefile b/Makefile
index 95b93c709d..bbfbb4292d 100644
--- a/Makefile
+++ b/Makefile
@@ -627,7 +627,6 @@ SCRIPT_LIB += git-mergetool--lib
 SCRIPT_LIB += git-parse-remote
 SCRIPT_LIB += git-rebase--am
 SCRIPT_LIB += git-rebase--common
-SCRIPT_LIB += git-rebase--interactive
 SCRIPT_LIB += git-rebase--preserve-merges
 SCRIPT_LIB += git-rebase--merge
 SCRIPT_LIB += git-sh-setup
@@ -955,6 +954,7 @@ LIB_OBJS += quote.o
 LIB_OBJS += range-diff.o
 LIB_OBJS += reachable.o
 LIB_OBJS += read-cache.o
+LIB_OBJS += rebase-interactive.o
 LIB_OBJS += reflog-walk.o
 LIB_OBJS += refs.o
 LIB_OBJS += refs/files-backend.o
@@ -1095,7 +1095,7 @@ BUILTIN_OBJS += builtin/push.o
 BUILTIN_OBJS += builtin/range-diff.o
 BUILTIN_OBJS += builtin/read-tree.o
 BUILTIN_OBJS += builtin/rebase.o
-BUILTIN_OBJS += builtin/rebase--helper.o
+BUILTIN_OBJS += builtin/rebase--interactive.o
 BUILTIN_OBJS += builtin/receive-pack.o
 BUILTIN_OBJS += builtin/reflog.o
 BUILTIN_OBJS += builtin/remote.o
@@ -2436,7 +2436,6 @@ XGETTEXT_FLAGS_PERL = $(XGETTEXT_FLAGS) --language=Perl \
 LOCALIZED_C = $(C_OBJ:o=c) $(LIB_H) $(GENERATED_H)
 LOCALIZED_SH = $(SCRIPT_SH)
 LOCALIZED_SH += git-parse-remote.sh
-LOCALIZED_SH += git-rebase--interactive.sh
 LOCALIZED_SH += git-rebase--preserve-merges.sh
 LOCALIZED_SH += git-sh-setup.sh
 LOCALIZED_PERL = $(SCRIPT_PERL)
diff --git a/builtin.h b/builtin.h
index 6fb66f5ba4..6538932e99 100644
--- a/builtin.h
+++ b/builtin.h
@@ -205,7 +205,7 @@ extern int cmd_push(int argc, const char **argv, const char *prefix);
 extern int cmd_range_diff(int argc, const char **argv, const char *prefix);
 extern int cmd_read_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_rebase(int argc, const char **argv, const char *prefix);
-extern int cmd_rebase__helper(int argc, const char **argv, const char *prefix);
+extern int cmd_rebase__interactive(int argc, const char **argv, const char *prefix);
 extern int cmd_receive_pack(int argc, const char **argv, const char *prefix);
 extern int cmd_reflog(int argc, const char **argv, const char *prefix);
 extern int cmd_remote(int argc, const char **argv, const char *prefix);
diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
deleted file mode 100644
index f7c2a5fdc8..0000000000
--- a/builtin/rebase--helper.c
+++ /dev/null
@@ -1,88 +0,0 @@
-#include "builtin.h"
-#include "cache.h"
-#include "config.h"
-#include "parse-options.h"
-#include "sequencer.h"
-
-static const char * const builtin_rebase_helper_usage[] = {
-	N_("git rebase--helper [<options>]"),
-	NULL
-};
-
-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;
-	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
-	} command = 0;
-	struct option options[] = {
-		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
-		OPT_BOOL(0, "keep-empty", &keep_empty, N_("keep empty commits")),
-		OPT_BOOL(0, "allow-empty-message", &opts.allow_empty_message,
-			N_("allow commits with empty messages")),
-		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_CMDMODE(0, "continue", &command, N_("continue rebase"),
-				CONTINUE),
-		OPT_CMDMODE(0, "abort", &command, N_("abort rebase"),
-				ABORT),
-		OPT_CMDMODE(0, "make-script", &command,
-			N_("make rebase script"), MAKE_SCRIPT),
-		OPT_CMDMODE(0, "shorten-ids", &command,
-			N_("shorten commit ids in the todo list"), SHORTEN_OIDS),
-		OPT_CMDMODE(0, "expand-ids", &command,
-			N_("expand commit ids in the todo list"), EXPAND_OIDS),
-		OPT_CMDMODE(0, "check-todo-list", &command,
-			N_("check the todo list"), CHECK_TODO_LIST),
-		OPT_CMDMODE(0, "skip-unnecessary-picks", &command,
-			N_("skip unnecessary picks"), SKIP_UNNECESSARY_PICKS),
-		OPT_CMDMODE(0, "rearrange-squash", &command,
-			N_("rearrange fixup/squash lines"), REARRANGE_SQUASH),
-		OPT_CMDMODE(0, "add-exec-commands", &command,
-			N_("insert exec commands in todo list"), ADD_EXEC),
-		OPT_END()
-	};
-
-	sequencer_init_config(&opts);
-	git_config_get_bool("rebase.abbreviatecommands", &abbreviate_commands);
-
-	opts.action = REPLAY_INTERACTIVE_REBASE;
-	opts.allow_ff = 1;
-	opts.allow_empty = 1;
-
-	argc = parse_options(argc, argv, NULL, options,
-			builtin_rebase_helper_usage, PARSE_OPT_KEEP_ARGV0);
-
-	flags |= keep_empty ? TODO_LIST_KEEP_EMPTY : 0;
-	flags |= abbreviate_commands ? TODO_LIST_ABBREVIATE_CMDS : 0;
-	flags |= rebase_merges ? TODO_LIST_REBASE_MERGES : 0;
-	flags |= rebase_cousins > 0 ? TODO_LIST_REBASE_COUSINS : 0;
-	flags |= command == SHORTEN_OIDS ? TODO_LIST_SHORTEN_IDS : 0;
-
-	if (rebase_cousins >= 0 && !rebase_merges)
-		warning(_("--[no-]rebase-cousins has no effect without "
-			  "--rebase-merges"));
-
-	if (command == CONTINUE && argc == 1)
-		return !!sequencer_continue(&opts);
-	if (command == ABORT && argc == 1)
-		return !!sequencer_remove_state(&opts);
-	if (command == MAKE_SCRIPT && argc > 1)
-		return !!sequencer_make_script(stdout, argc, argv, flags);
-	if ((command == SHORTEN_OIDS || command == EXPAND_OIDS) && argc == 1)
-		return !!transform_todos(flags);
-	if (command == CHECK_TODO_LIST && argc == 1)
-		return !!check_todo_list();
-	if (command == SKIP_UNNECESSARY_PICKS && argc == 1)
-		return !!skip_unnecessary_picks();
-	if (command == REARRANGE_SQUASH && argc == 1)
-		return !!rearrange_squash();
-	if (command == ADD_EXEC && argc == 2)
-		return !!sequencer_add_exec_commands(argv[1]);
-	usage_with_options(builtin_rebase_helper_usage, options);
-}
diff --git a/builtin/rebase--interactive.c b/builtin/rebase--interactive.c
new file mode 100644
index 0000000000..a2ab68ed06
--- /dev/null
+++ b/builtin/rebase--interactive.c
@@ -0,0 +1,271 @@
+#include "builtin.h"
+#include "cache.h"
+#include "config.h"
+#include "parse-options.h"
+#include "sequencer.h"
+#include "rebase-interactive.h"
+#include "argv-array.h"
+#include "refs.h"
+#include "rerere.h"
+#include "run-command.h"
+
+static GIT_PATH_FUNC(path_state_dir, "rebase-merge/")
+static GIT_PATH_FUNC(path_squash_onto, "rebase-merge/squash-onto")
+static GIT_PATH_FUNC(path_interactive, "rebase-merge/interactive")
+
+static int get_revision_ranges(const char *upstream, const char *onto,
+			       const char **head_hash,
+			       char **revisions, char **shortrevisions)
+{
+	const char *base_rev = upstream ? upstream : onto, *shorthead;
+	struct object_id orig_head;
+
+	if (get_oid("HEAD", &orig_head))
+		return error(_("no HEAD?"));
+
+	*head_hash = find_unique_abbrev(&orig_head, GIT_MAX_HEXSZ);
+	*revisions = xstrfmt("%s...%s", base_rev, *head_hash);
+
+	shorthead = find_unique_abbrev(&orig_head, DEFAULT_ABBREV);
+
+	if (upstream) {
+		const char *shortrev;
+		struct object_id rev_oid;
+
+		get_oid(base_rev, &rev_oid);
+		shortrev = find_unique_abbrev(&rev_oid, DEFAULT_ABBREV);
+
+		*shortrevisions = xstrfmt("%s..%s", shortrev, shorthead);
+	} else
+		*shortrevisions = xstrdup(shorthead);
+
+	return 0;
+}
+
+static int init_basic_state(struct replay_opts *opts, const char *head_name,
+			    const char *onto, const char *orig_head)
+{
+	FILE *interactive;
+
+	if (!is_directory(path_state_dir()) && mkdir_in_gitdir(path_state_dir()))
+		return error_errno(_("could not create temporary %s"), path_state_dir());
+
+	delete_reflog("REBASE_HEAD");
+
+	interactive = fopen(path_interactive(), "w");
+	if (!interactive)
+		return error_errno(_("could not mark as interactive"));
+	fclose(interactive);
+
+	return write_basic_state(opts, head_name, onto, orig_head);
+}
+
+static int do_interactive_rebase(struct replay_opts *opts, unsigned flags,
+				 const char *switch_to, const char *upstream,
+				 const char *onto, const char *onto_name,
+				 const char *squash_onto, const char *head_name,
+				 const char *restrict_revision, char *raw_strategies,
+				 const char *cmd, unsigned autosquash)
+{
+	int ret;
+	const char *head_hash = NULL;
+	char *revisions = NULL, *shortrevisions = NULL;
+	struct argv_array make_script_args = ARGV_ARRAY_INIT;
+	FILE *todo_list;
+
+	if (prepare_branch_to_be_rebased(opts, switch_to))
+		return -1;
+
+	if (get_revision_ranges(upstream, onto, &head_hash,
+				&revisions, &shortrevisions))
+		return -1;
+
+	if (raw_strategies)
+		parse_strategy_opts(opts, raw_strategies);
+
+	if (init_basic_state(opts, head_name, onto, head_hash)) {
+		free(revisions);
+		free(shortrevisions);
+
+		return -1;
+	}
+
+	if (!upstream && squash_onto)
+		write_file(path_squash_onto(), "%s\n", squash_onto);
+
+	todo_list = fopen(rebase_path_todo(), "w");
+	if (!todo_list) {
+		free(revisions);
+		free(shortrevisions);
+
+		return error_errno(_("could not open %s"), rebase_path_todo());
+	}
+
+	argv_array_pushl(&make_script_args, "", revisions, NULL);
+	if (restrict_revision)
+		argv_array_push(&make_script_args, restrict_revision);
+
+	ret = sequencer_make_script(todo_list,
+				    make_script_args.argc, make_script_args.argv,
+				    flags);
+	fclose(todo_list);
+
+	if (ret)
+		error(_("could not generate todo list"));
+	else {
+		discard_cache();
+		ret = complete_action(opts, flags, shortrevisions, onto_name, onto,
+				      head_hash, cmd, autosquash);
+	}
+
+	free(revisions);
+	free(shortrevisions);
+	argv_array_clear(&make_script_args);
+
+	return ret;
+}
+
+static const char * const builtin_rebase_interactive_usage[] = {
+	N_("git rebase--interactive [<options>]"),
+	NULL
+};
+
+int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
+{
+	struct replay_opts opts = REPLAY_OPTS_INIT;
+	unsigned flags = 0, keep_empty = 0, rebase_merges = 0, autosquash = 0;
+	int abbreviate_commands = 0, rebase_cousins = -1, ret = 0;
+	const char *onto = NULL, *onto_name = NULL, *restrict_revision = NULL,
+		*squash_onto = NULL, *upstream = NULL, *head_name = NULL,
+		*switch_to = NULL, *cmd = NULL;
+	char *raw_strategies = NULL;
+	enum {
+		NONE = 0, CONTINUE, SKIP, EDIT_TODO, SHOW_CURRENT_PATCH,
+		SHORTEN_OIDS, EXPAND_OIDS, CHECK_TODO_LIST, REARRANGE_SQUASH, ADD_EXEC
+	} command = 0;
+	struct option options[] = {
+		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
+		OPT_BOOL(0, "keep-empty", &keep_empty, N_("keep empty commits")),
+		OPT_BOOL(0, "allow-empty-message", &opts.allow_empty_message,
+			 N_("allow commits with empty messages")),
+		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, "autosquash", &autosquash,
+			 N_("move commits that begin with squash!/fixup!")),
+		OPT_BOOL(0, "signoff", &opts.signoff, N_("sign commits")),
+		OPT__VERBOSE(&opts.verbose, N_("be verbose")),
+		OPT_CMDMODE(0, "continue", &command, N_("continue rebase"),
+			    CONTINUE),
+		OPT_CMDMODE(0, "skip", &command, N_("skip commit"), SKIP),
+		OPT_CMDMODE(0, "edit-todo", &command, N_("edit the todo list"),
+			    EDIT_TODO),
+		OPT_CMDMODE(0, "show-current-patch", &command, N_("show the current patch"),
+			    SHOW_CURRENT_PATCH),
+		OPT_CMDMODE(0, "shorten-ids", &command,
+			N_("shorten commit ids in the todo list"), SHORTEN_OIDS),
+		OPT_CMDMODE(0, "expand-ids", &command,
+			N_("expand commit ids in the todo list"), EXPAND_OIDS),
+		OPT_CMDMODE(0, "check-todo-list", &command,
+			N_("check the todo list"), CHECK_TODO_LIST),
+		OPT_CMDMODE(0, "rearrange-squash", &command,
+			N_("rearrange fixup/squash lines"), REARRANGE_SQUASH),
+		OPT_CMDMODE(0, "add-exec-commands", &command,
+			N_("insert exec commands in todo list"), ADD_EXEC),
+		OPT_STRING(0, "onto", &onto, N_("onto"), N_("onto")),
+		OPT_STRING(0, "restrict-revision", &restrict_revision,
+			   N_("restrict-revision"), N_("restrict revision")),
+		OPT_STRING(0, "squash-onto", &squash_onto, N_("squash-onto"),
+			   N_("squash onto")),
+		OPT_STRING(0, "upstream", &upstream, N_("upstream"),
+			   N_("the upstream commit")),
+		OPT_STRING(0, "head-name", &head_name, N_("head-name"), N_("head name")),
+		{ OPTION_STRING, 'S', "gpg-sign", &opts.gpg_sign, N_("key-id"),
+			N_("GPG-sign commits"),
+			PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
+		OPT_STRING(0, "strategy", &opts.strategy, N_("strategy"),
+			   N_("rebase strategy")),
+		OPT_STRING(0, "strategy-opts", &raw_strategies, N_("strategy-opts"),
+			   N_("strategy options")),
+		OPT_STRING(0, "switch-to", &switch_to, N_("switch-to"),
+			   N_("the branch or commit to checkout")),
+		OPT_STRING(0, "onto-name", &onto_name, N_("onto-name"), N_("onto name")),
+		OPT_STRING(0, "cmd", &cmd, N_("cmd"), N_("the command to run")),
+		OPT_RERERE_AUTOUPDATE(&opts.allow_rerere_auto),
+		OPT_END()
+	};
+
+	sequencer_init_config(&opts);
+	git_config_get_bool("rebase.abbreviatecommands", &abbreviate_commands);
+
+	opts.action = REPLAY_INTERACTIVE_REBASE;
+	opts.allow_ff = 1;
+	opts.allow_empty = 1;
+
+	if (argc == 1)
+		usage_with_options(builtin_rebase_interactive_usage, options);
+
+	argc = parse_options(argc, argv, NULL, options,
+			builtin_rebase_interactive_usage, PARSE_OPT_KEEP_ARGV0);
+
+	opts.gpg_sign = xstrdup_or_null(opts.gpg_sign);
+
+	flags |= keep_empty ? TODO_LIST_KEEP_EMPTY : 0;
+	flags |= abbreviate_commands ? TODO_LIST_ABBREVIATE_CMDS : 0;
+	flags |= rebase_merges ? TODO_LIST_REBASE_MERGES : 0;
+	flags |= rebase_cousins > 0 ? TODO_LIST_REBASE_COUSINS : 0;
+	flags |= command == SHORTEN_OIDS ? TODO_LIST_SHORTEN_IDS : 0;
+
+	if (rebase_cousins >= 0 && !rebase_merges)
+		warning(_("--[no-]rebase-cousins has no effect without "
+			  "--rebase-merges"));
+
+	switch (command) {
+	case NONE:
+		if (!onto && !upstream)
+			die(_("a base commit must be provided with --upstream or --onto"));
+
+		ret = do_interactive_rebase(&opts, flags, switch_to, upstream, onto,
+					    onto_name, squash_onto, head_name, restrict_revision,
+					    raw_strategies, cmd, autosquash);
+		break;
+	case SKIP: {
+		struct string_list merge_rr = STRING_LIST_INIT_DUP;
+
+		rerere_clear(&merge_rr);
+		/* fallthrough */
+	case CONTINUE:
+		ret = sequencer_continue(&opts);
+		break;
+	}
+	case EDIT_TODO:
+		ret = edit_todo_list(flags);
+		break;
+	case SHOW_CURRENT_PATCH: {
+		struct child_process cmd = CHILD_PROCESS_INIT;
+
+		cmd.git_cmd = 1;
+		argv_array_pushl(&cmd.args, "show", "REBASE_HEAD", "--", NULL);
+		ret = run_command(&cmd);
+
+		break;
+	}
+	case SHORTEN_OIDS:
+	case EXPAND_OIDS:
+		ret = transform_todos(flags);
+		break;
+	case CHECK_TODO_LIST:
+		ret = check_todo_list();
+		break;
+	case REARRANGE_SQUASH:
+		ret = rearrange_squash();
+		break;
+	case ADD_EXEC:
+		ret = sequencer_add_exec_commands(cmd);
+		break;
+	default:
+		BUG("invalid command '%d'", command);
+	}
+
+	return !!ret;
+}
diff --git a/cache.h b/cache.h
index f7fabdde8f..8b1ee42ae9 100644
--- a/cache.h
+++ b/cache.h
@@ -1487,6 +1487,7 @@ extern const char *fmt_name(const char *name, const char *email);
 extern const char *ident_default_name(void);
 extern const char *ident_default_email(void);
 extern const char *git_editor(void);
+extern const char *git_sequence_editor(void);
 extern const char *git_pager(int stdout_is_tty);
 extern int is_terminal_dumb(void);
 extern int git_ident_config(const char *, const char *, void *);
diff --git a/editor.c b/editor.c
index 9a9b4e12d1..c985eee1f9 100644
--- a/editor.c
+++ b/editor.c
@@ -1,4 +1,5 @@
 #include "cache.h"
+#include "config.h"
 #include "strbuf.h"
 #include "run-command.h"
 #include "sigchain.h"
@@ -34,10 +35,21 @@ const char *git_editor(void)
 	return editor;
 }
 
-int launch_editor(const char *path, struct strbuf *buffer, const char *const *env)
+const char *git_sequence_editor(void)
 {
-	const char *editor = git_editor();
+	const char *editor = getenv("GIT_SEQUENCE_EDITOR");
+
+	if (!editor)
+		git_config_get_string_const("sequence.editor", &editor);
+	if (!editor)
+		editor = git_editor();
 
+	return editor;
+}
+
+static int launch_specified_editor(const char *editor, const char *path,
+				   struct strbuf *buffer, const char *const *env)
+{
 	if (!editor)
 		return error("Terminal is dumb, but EDITOR unset");
 
@@ -95,3 +107,14 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
 		return error_errno("could not read file '%s'", path);
 	return 0;
 }
+
+int launch_editor(const char *path, struct strbuf *buffer, const char *const *env)
+{
+	return launch_specified_editor(git_editor(), path, buffer, env);
+}
+
+int launch_sequence_editor(const char *path, struct strbuf *buffer,
+			   const char *const *env)
+{
+	return launch_specified_editor(git_sequence_editor(), path, buffer, env);
+}
diff --git a/git-legacy-rebase.sh b/git-legacy-rebase.sh
index 5d92648014..75a08b2683 100755
--- a/git-legacy-rebase.sh
+++ b/git-legacy-rebase.sh
@@ -135,26 +135,63 @@ finish_rebase () {
 	rm -rf "$state_dir"
 }
 
+run_interactive () {
+	GIT_CHERRY_PICK_HELP="$resolvemsg"
+	export GIT_CHERRY_PICK_HELP
+
+	test -n "$keep_empty" && keep_empty="--keep-empty"
+	test -n "$rebase_merges" && rebase_merges="--rebase-merges"
+	test -n "$rebase_cousins" && rebase_cousins="--rebase-cousins"
+	test -n "$autosquash" && autosquash="--autosquash"
+	test -n "$verbose" && verbose="--verbose"
+	test -n "$force_rebase" && force_rebase="--no-ff"
+	test -n "$restrict_revision" && \
+		restrict_revision="--restrict-revision=^$restrict_revision"
+	test -n "$upstream" && upstream="--upstream=$upstream"
+	test -n "$onto" && onto="--onto=$onto"
+	test -n "$squash_onto" && squash_onto="--squash-onto=$squash_onto"
+	test -n "$onto_name" && onto_name="--onto-name=$onto_name"
+	test -n "$head_name" && head_name="--head-name=$head_name"
+	test -n "$strategy" && strategy="--strategy=$strategy"
+	test -n "$strategy_opts" && strategy_opts="--strategy-opts=$strategy_opts"
+	test -n "$switch_to" && switch_to="--switch-to=$switch_to"
+	test -n "$cmd" && cmd="--cmd=$cmd"
+	test -n "$action" && action="--$action"
+
+	exec git rebase--interactive "$action" "$keep_empty" "$rebase_merges" "$rebase_cousins" \
+		"$upstream" "$onto" "$squash_onto" "$restrict_revision" \
+		"$allow_empty_message" "$autosquash" "$verbose" \
+		"$force_rebase" "$onto_name" "$head_name" "$strategy" \
+		"$strategy_opts" "$cmd" "$switch_to" \
+		"$allow_rerere_autoupdate" "$gpg_sign_opt" "$signoff"
+}
+
 run_specific_rebase () {
 	if [ "$interactive_rebase" = implied ]; then
 		GIT_EDITOR=:
 		export GIT_EDITOR
 		autosquash=
 	fi
-	. git-rebase--$type
 
-	if test -z "$preserve_merges"
+	if test -n "$interactive_rebase" -a -z "$preserve_merges"
 	then
-		git_rebase__$type
+		run_interactive
 	else
-		git_rebase__preserve_merges
+		. git-rebase--$type
+
+		if test -z "$preserve_merges"
+		then
+			git_rebase__$type
+		else
+			git_rebase__preserve_merges
+		fi
 	fi
 
 	ret=$?
 	if test $ret -eq 0
 	then
 		finish_rebase
-	elif test $ret -eq 2 # special exit status for rebase -i
+	elif test $ret -eq 2 # special exit status for rebase -p
 	then
 		apply_autostash &&
 		rm -rf "$state_dir" &&
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
deleted file mode 100644
index 299ded2137..0000000000
--- a/git-rebase--interactive.sh
+++ /dev/null
@@ -1,283 +0,0 @@
-# This shell script fragment is sourced by git-rebase to implement
-# its interactive mode.  "git rebase --interactive" makes it easy
-# to fix up commits in the middle of a series and rearrange commits.
-#
-# Copyright (c) 2006 Johannes E. Schindelin
-#
-# The original idea comes from Eric W. Biederman, in
-# https://public-inbox.org/git/m1odwkyuf5.fsf_-_@ebiederm.dsl.xmission.com/
-#
-# The file containing rebase commands, comments, and empty lines.
-# This file is created by "git rebase -i" then edited by the user.  As
-# the lines are processed, they are removed from the front of this
-# file and written to the tail of $done.
-todo="$state_dir"/git-rebase-todo
-
-GIT_CHERRY_PICK_HELP="$resolvemsg"
-export GIT_CHERRY_PICK_HELP
-
-comment_char=$(git config --get core.commentchar 2>/dev/null)
-case "$comment_char" in
-'' | auto)
-	comment_char="#"
-	;;
-?)
-	;;
-*)
-	comment_char=$(echo "$comment_char" | cut -c1)
-	;;
-esac
-
-orig_reflog_action="$GIT_REFLOG_ACTION"
-
-comment_for_reflog () {
-	case "$orig_reflog_action" in
-	''|rebase*)
-		GIT_REFLOG_ACTION="rebase -i ($1)"
-		export GIT_REFLOG_ACTION
-		;;
-	esac
-}
-
-append_todo_help () {
-	gettext "
-Commands:
-p, pick <commit> = use commit
-r, reword <commit> = use commit, but edit the commit message
-e, edit <commit> = use commit, but stop for amending
-s, squash <commit> = use commit, but meld into previous commit
-f, fixup <commit> = like \"squash\", but discard this commit's log message
-x, exec <command> = run command (the rest of the line) using shell
-d, drop <commit> = remove commit
-l, label <label> = label current HEAD with a name
-t, reset <label> = reset HEAD to a label
-m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]
-.       create a merge commit using the original merge commit's
-.       message (or the oneline, if no original merge commit was
-.       specified). Use -c <commit> to reword the commit message.
-
-These lines can be re-ordered; they are executed from top to bottom.
-" | git stripspace --comment-lines >>"$todo"
-
-	if test $(get_missing_commit_check_level) = error
-	then
-		gettext "
-Do not remove any line. Use 'drop' explicitly to remove a commit.
-" | git stripspace --comment-lines >>"$todo"
-	else
-		gettext "
-If you remove a line here THAT COMMIT WILL BE LOST.
-" | git stripspace --comment-lines >>"$todo"
-	fi
-}
-
-die_abort () {
-	apply_autostash
-	rm -rf "$state_dir"
-	die "$1"
-}
-
-has_action () {
-	test -n "$(git stripspace --strip-comments <"$1")"
-}
-
-git_sequence_editor () {
-	if test -z "$GIT_SEQUENCE_EDITOR"
-	then
-		GIT_SEQUENCE_EDITOR="$(git config sequence.editor)"
-		if [ -z "$GIT_SEQUENCE_EDITOR" ]
-		then
-			GIT_SEQUENCE_EDITOR="$(git var GIT_EDITOR)" || return $?
-		fi
-	fi
-
-	eval "$GIT_SEQUENCE_EDITOR" '"$@"'
-}
-
-expand_todo_ids() {
-	git rebase--helper --expand-ids
-}
-
-collapse_todo_ids() {
-	git rebase--helper --shorten-ids
-}
-
-# Switch to the branch in $into and notify it in the reflog
-checkout_onto () {
-	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name"
-	output git checkout $onto || die_abort "$(gettext "could not detach HEAD")"
-	git update-ref ORIG_HEAD $orig_head
-}
-
-get_missing_commit_check_level () {
-	check_level=$(git config --get rebase.missingCommitsCheck)
-	check_level=${check_level:-ignore}
-	# Don't be case sensitive
-	printf '%s' "$check_level" | tr 'A-Z' 'a-z'
-}
-
-# Initiate an action. If the cannot be any
-# further action it  may exec a command
-# or exit and not return.
-#
-# TODO: Consider a cleaner return model so it
-# never exits and always return 0 if process
-# is complete.
-#
-# Parameter 1 is the action to initiate.
-#
-# Returns 0 if the action was able to complete
-# and if 1 if further processing is required.
-initiate_action () {
-	case "$1" in
-	continue)
-		exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
-		     --continue
-		;;
-	skip)
-		git rerere clear
-		exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
-		     --continue
-		;;
-	edit-todo)
-		git stripspace --strip-comments <"$todo" >"$todo".new
-		mv -f "$todo".new "$todo"
-		collapse_todo_ids
-		append_todo_help
-		gettext "
-You are editing the todo file of an ongoing interactive rebase.
-To continue rebase after editing, run:
-    git rebase --continue
-
-" | git stripspace --comment-lines >>"$todo"
-
-		git_sequence_editor "$todo" ||
-			die "$(gettext "Could not execute editor")"
-		expand_todo_ids
-
-		exit
-		;;
-	show-current-patch)
-		exec git show REBASE_HEAD --
-		;;
-	*)
-		return 1 # continue
-		;;
-	esac
-}
-
-setup_reflog_action () {
-	comment_for_reflog start
-
-	if test ! -z "$switch_to"
-	then
-		GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $switch_to"
-		output git checkout "$switch_to" -- ||
-			die "$(eval_gettext "Could not checkout \$switch_to")"
-
-		comment_for_reflog start
-	fi
-}
-
-init_basic_state () {
-	orig_head=$(git rev-parse --verify HEAD) || die "$(gettext "No HEAD?")"
-	mkdir -p "$state_dir" || die "$(eval_gettext "Could not create temporary \$state_dir")"
-	rm -f "$(git rev-parse --git-path REBASE_HEAD)"
-
-	: > "$state_dir"/interactive || die "$(gettext "Could not mark as interactive")"
-	write_basic_state
-}
-
-init_revisions_and_shortrevisions () {
-	shorthead=$(git rev-parse --short $orig_head)
-	shortonto=$(git rev-parse --short $onto)
-	if test -z "$rebase_root"
-		# this is now equivalent to ! -z "$upstream"
-	then
-		shortupstream=$(git rev-parse --short $upstream)
-		revisions=$upstream...$orig_head
-		shortrevisions=$shortupstream..$shorthead
-	else
-		revisions=$onto...$orig_head
-		shortrevisions=$shorthead
-		test -z "$squash_onto" ||
-		echo "$squash_onto" >"$state_dir"/squash-onto
-	fi
-}
-
-complete_action() {
-	test -s "$todo" || echo noop >> "$todo"
-	test -z "$autosquash" || git rebase--helper --rearrange-squash || exit
-	test -n "$cmd" && git rebase--helper --add-exec-commands "$cmd"
-
-	todocount=$(git stripspace --strip-comments <"$todo" | wc -l)
-	todocount=${todocount##* }
-
-cat >>"$todo" <<EOF
-
-$comment_char $(eval_ngettext \
-	"Rebase \$shortrevisions onto \$shortonto (\$todocount command)" \
-	"Rebase \$shortrevisions onto \$shortonto (\$todocount commands)" \
-	"$todocount")
-EOF
-	append_todo_help
-	gettext "
-	However, if you remove everything, the rebase will be aborted.
-
-	" | git stripspace --comment-lines >>"$todo"
-
-	if test -z "$keep_empty"
-	then
-		printf '%s\n' "$comment_char $(gettext "Note that empty commits are commented out")" >>"$todo"
-	fi
-
-
-	has_action "$todo" ||
-		return 2
-
-	cp "$todo" "$todo".backup
-	collapse_todo_ids
-	git_sequence_editor "$todo" ||
-		die_abort "$(gettext "Could not execute editor")"
-
-	has_action "$todo" ||
-		return 2
-
-	git rebase--helper --check-todo-list || {
-		ret=$?
-		checkout_onto
-		exit $ret
-	}
-
-	expand_todo_ids
-
-	test -n "$force_rebase" ||
-	onto="$(git rebase--helper --skip-unnecessary-picks)" ||
-	die "Could not skip unnecessary pick commands"
-
-	checkout_onto
-	require_clean_work_tree "rebase"
-	exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
-	     --continue
-}
-
-git_rebase__interactive () {
-	initiate_action "$action"
-	ret=$?
-	if test $ret = 0; then
-		return 0
-	fi
-
-	setup_reflog_action
-	init_basic_state
-
-	init_revisions_and_shortrevisions
-
-	git rebase--helper --make-script ${keep_empty:+--keep-empty} \
-		${rebase_merges:+--rebase-merges} \
-		${rebase_cousins:+--rebase-cousins} \
-		$revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
-	die "$(gettext "Could not generate todo list")"
-
-	complete_action
-}
diff --git a/git-rebase--preserve-merges.sh b/git-rebase--preserve-merges.sh
index c214c5e4d6..afbb65765d 100644
--- a/git-rebase--preserve-merges.sh
+++ b/git-rebase--preserve-merges.sh
@@ -711,11 +711,11 @@ do_rest () {
 }
 
 expand_todo_ids() {
-	git rebase--helper --expand-ids
+	git rebase--interactive --expand-ids
 }
 
 collapse_todo_ids() {
-	git rebase--helper --shorten-ids
+	git rebase--interactive --shorten-ids
 }
 
 # Switch to the branch in $into and notify it in the reflog
@@ -876,8 +876,8 @@ init_revisions_and_shortrevisions () {
 
 complete_action() {
 	test -s "$todo" || echo noop >> "$todo"
-	test -z "$autosquash" || git rebase--helper --rearrange-squash || exit
-	test -n "$cmd" && git rebase--helper --add-exec-commands "$cmd"
+	test -z "$autosquash" || git rebase--interactive --rearrange-squash || exit
+	test -n "$cmd" && git rebase--interactive --add-exec-commands --cmd "$cmd"
 
 	todocount=$(git stripspace --strip-comments <"$todo" | wc -l)
 	todocount=${todocount##* }
@@ -912,7 +912,7 @@ However, if you remove everything, the rebase will be aborted.
 	has_action "$todo" ||
 		return 2
 
-	git rebase--helper --check-todo-list || {
+	git rebase--interactive --check-todo-list || {
 		ret=$?
 		checkout_onto
 		exit $ret
diff --git a/git.c b/git.c
index 8e52276831..2f604a41ea 100644
--- a/git.c
+++ b/git.c
@@ -532,7 +532,7 @@ static struct cmd_struct commands[] = {
 	 * RUN_SETUP | NEED_WORK_TREE
 	 */
 	{ "rebase", cmd_rebase },
-	{ "rebase--helper", cmd_rebase__helper, RUN_SETUP | NEED_WORK_TREE },
+	{ "rebase--interactive", cmd_rebase__interactive, RUN_SETUP | NEED_WORK_TREE },
 	{ "receive-pack", cmd_receive_pack },
 	{ "reflog", cmd_reflog, RUN_SETUP },
 	{ "remote", cmd_remote, RUN_SETUP },
diff --git a/rebase-interactive.c b/rebase-interactive.c
new file mode 100644
index 0000000000..0f4119cbae
--- /dev/null
+++ b/rebase-i