From 44b776c3e9bcbfcb7fbf78baafc67394cf56e812 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:28 +0200
Subject: [PATCH 01/20] sequencer: make three functions and an enum from
 sequencer.c public

This makes rebase_path_todo(), get_missing_commit_check_level(),
write_message() and the enum check_level accessible outside sequencer.c,
renames check_level to missing_commit_check_level, and prefixes its
value names by MISSING_COMMIT_ to avoid namespace pollution.

This function and this enum will eventually be moved to
rebase-interactive.c and become static again, so no special attention
was given to the naming.

This will be needed for the rewrite of append_todo_help() from shell to
C, as it will be in a new library source file, rebase-interactive.c.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 sequencer.c | 26 +++++++++++---------------
 sequencer.h | 11 +++++++++++
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 03c47405fb..33d73194d0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -52,7 +52,7 @@ static GIT_PATH_FUNC(rebase_path, "rebase-merge")
  * the lines are processed, they are removed from the front of this
  * file and written to the tail of 'done'.
  */
-static GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
+GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
 /*
  * The rebase command lines that have already been processed. A line
  * is moved here when it is first handled, before any associated user
@@ -373,8 +373,8 @@ static void print_advice(int show_hint, struct replay_opts *opts)
 	}
 }
 
-static int write_message(const void *buf, size_t len, const char *filename,
-			 int append_eol)
+int write_message(const void *buf, size_t len, const char *filename,
+		  int append_eol)
 {
 	struct lock_file msg_file = LOCK_INIT;
 
@@ -4245,24 +4245,20 @@ int transform_todos(unsigned flags)
 	return i;
 }
 
-enum check_level {
-	CHECK_IGNORE = 0, CHECK_WARN, CHECK_ERROR
-};
-
-static enum check_level get_missing_commit_check_level(void)
+enum missing_commit_check_level get_missing_commit_check_level(void)
 {
 	const char *value;
 
 	if (git_config_get_value("rebase.missingcommitscheck", &value) ||
 			!strcasecmp("ignore", value))
-		return CHECK_IGNORE;
+		return MISSING_COMMIT_CHECK_IGNORE;
 	if (!strcasecmp("warn", value))
-		return CHECK_WARN;
+		return MISSING_COMMIT_CHECK_WARN;
 	if (!strcasecmp("error", value))
-		return CHECK_ERROR;
+		return MISSING_COMMIT_CHECK_ERROR;
 	warning(_("unrecognized setting %s for option "
 		  "rebase.missingCommitsCheck. Ignoring."), value);
-	return CHECK_IGNORE;
+	return MISSING_COMMIT_CHECK_IGNORE;
 }
 
 define_commit_slab(commit_seen, unsigned char);
@@ -4274,7 +4270,7 @@ define_commit_slab(commit_seen, unsigned char);
  */
 int check_todo_list(void)
 {
-	enum check_level check_level = get_missing_commit_check_level();
+	enum missing_commit_check_level check_level = get_missing_commit_check_level();
 	struct strbuf todo_file = STRBUF_INIT;
 	struct todo_list todo_list = TODO_LIST_INIT;
 	struct strbuf missing = STRBUF_INIT;
@@ -4291,7 +4287,7 @@ int check_todo_list(void)
 	advise_to_edit_todo = res =
 		parse_insn_buffer(todo_list.buf.buf, &todo_list);
 
-	if (res || check_level == CHECK_IGNORE)
+	if (res || check_level == MISSING_COMMIT_CHECK_IGNORE)
 		goto leave_check;
 
 	/* Mark the commits in git-rebase-todo as seen */
@@ -4326,7 +4322,7 @@ int check_todo_list(void)
 	if (!missing.len)
 		goto leave_check;
 
-	if (check_level == CHECK_ERROR)
+	if (check_level == MISSING_COMMIT_CHECK_ERROR)
 		advise_to_edit_todo = res = 1;
 
 	fprintf(stderr,
diff --git a/sequencer.h b/sequencer.h
index c5787c6b56..792e448b67 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -3,6 +3,7 @@
 
 const char *git_path_commit_editmsg(void);
 const char *git_path_seq_dir(void);
+const char *rebase_path_todo(void);
 
 #define APPEND_SIGNOFF_DEDUP (1u << 0)
 
@@ -57,6 +58,15 @@ struct replay_opts {
 };
 #define REPLAY_OPTS_INIT { .action = -1, .current_fixups = STRBUF_INIT }
 
+enum missing_commit_check_level {
+	MISSING_COMMIT_CHECK_IGNORE = 0,
+	MISSING_COMMIT_CHECK_WARN,
+	MISSING_COMMIT_CHECK_ERROR
+};
+
+int write_message(const void *buf, size_t len, const char *filename,
+		  int append_eol);
+
 /* Call this to setup defaults before parsing command line options */
 void sequencer_init_config(struct replay_opts *opts);
 int sequencer_pick_revisions(struct replay_opts *opts);
@@ -79,6 +89,7 @@ int sequencer_make_script(FILE *out, int argc, const char **argv,
 
 int sequencer_add_exec_commands(const char *command);
 int transform_todos(unsigned flags);
+enum missing_commit_check_level get_missing_commit_check_level(void);
 int check_todo_list(void);
 int skip_unnecessary_picks(void);
 int rearrange_squash(void);

From 145e05ac44b4c574fc22e6d3af7c5a14ad9b7335 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:29 +0200
Subject: [PATCH 02/20] rebase -i: rewrite append_todo_help() in C

This rewrites append_todo_help() from shell to C. It also incorporates
some parts of initiate_action() and complete_action() that also write
help texts to the todo file.

This also introduces the source file rebase-interactive.c. This file
will contain functions necessary for interactive rebase that are too
specific for the sequencer, and is part of libgit.a.

Two flags are added to rebase--helper.c: one to call
append_todo_help() (`--append-todo-help`), and another one to tell
append_todo_help() to write the help text suited for the edit-todo
mode (`--write-edit-todo`).

Finally, append_todo_help() is removed from git-rebase--interactive.sh
to use `rebase--helper --append-todo-help` instead.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Makefile                   |  1 +
 builtin/rebase--helper.c   | 11 ++++--
 git-rebase--interactive.sh | 52 ++---------------------------
 rebase-interactive.c       | 68 ++++++++++++++++++++++++++++++++++++++
 rebase-interactive.h       |  6 ++++
 5 files changed, 86 insertions(+), 52 deletions(-)
 create mode 100644 rebase-interactive.c
 create mode 100644 rebase-interactive.h

diff --git a/Makefile b/Makefile
index 08e5c54549..909a687857 100644
--- a/Makefile
+++ b/Makefile
@@ -922,6 +922,7 @@ LIB_OBJS += protocol.o
 LIB_OBJS += quote.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
diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index f7c2a5fdc8..05e73e71d4 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -3,6 +3,7 @@
 #include "config.h"
 #include "parse-options.h"
 #include "sequencer.h"
+#include "rebase-interactive.h"
 
 static const char * const builtin_rebase_helper_usage[] = {
 	N_("git rebase--helper [<options>]"),
@@ -12,12 +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;
+	unsigned flags = 0, keep_empty = 0, rebase_merges = 0, write_edit_todo = 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
+		ADD_EXEC, APPEND_TODO_HELP
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -27,6 +28,8 @@ 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"),
@@ -45,6 +48,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			N_("rearrange fixup/squash lines"), REARRANGE_SQUASH),
 		OPT_CMDMODE(0, "add-exec-commands", &command,
 			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_END()
 	};
 
@@ -84,5 +89,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!rearrange_squash();
 	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);
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 299ded2137..94c23a7af2 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -39,38 +39,6 @@ comment_for_reflog () {
 	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"
@@ -143,13 +111,7 @@ initiate_action () {
 		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 rebase--helper --append-todo-help --write-edit-todo
 
 		git_sequence_editor "$todo" ||
 			die "$(gettext "Could not execute editor")"
@@ -220,17 +182,7 @@ $comment_char $(eval_ngettext \
 	"Rebase \$shortrevisions onto \$shortonto (\$todocount commands)" \
 	"$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
-
+	git rebase--helper --append-todo-help ${keep_empty:+--keep-empty}
 
 	has_action "$todo" ||
 		return 2
diff --git a/rebase-interactive.c b/rebase-interactive.c
new file mode 100644
index 0000000000..d7996bc8d9
--- /dev/null
+++ b/rebase-interactive.c
@@ -0,0 +1,68 @@
+#include "cache.h"
+#include "commit.h"
+#include "rebase-interactive.h"
+#include "sequencer.h"
+#include "strbuf.h"
+
+int append_todo_help(unsigned edit_todo, unsigned keep_empty)
+{
+	struct strbuf buf = STRBUF_INIT;
+	FILE *todo;
+	int ret;
+	const char *msg = _("\nCommands:\n"
+"p, pick <commit> = use commit\n"
+"r, reword <commit> = use commit, but edit the commit message\n"
+"e, edit <commit> = use commit, but stop for amending\n"
+"s, squash <commit> = use commit, but meld into previous commit\n"
+"f, fixup <commit> = like \"squash\", but discard this commit's log message\n"
+"x, exec <command> = run command (the rest of the line) using shell\n"
+"d, drop <commit> = remove commit\n"
+"l, label <label> = label current HEAD with a name\n"
+"t, reset <label> = reset HEAD to a label\n"
+"m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]\n"
+".       create a merge commit using the original merge commit's\n"
+".       message (or the oneline, if no original merge commit was\n"
+".       specified). Use -c <commit> to reword the commit message.\n"
+"\n"
+"These lines can be re-ordered; they are executed from top to bottom.\n");
+
+	todo = fopen_or_warn(rebase_path_todo(), "a");
+	if (!todo)
+		return 1;
+
+	strbuf_add_commented_lines(&buf, msg, strlen(msg));
+
+	if (get_missing_commit_check_level() == MISSING_COMMIT_CHECK_ERROR)
+		msg = _("\nDo not remove any line. Use 'drop' "
+			 "explicitly to remove a commit.\n");
+	else
+		msg = _("\nIf you remove a line here "
+			 "THAT COMMIT WILL BE LOST.\n");
+
+	strbuf_add_commented_lines(&buf, msg, strlen(msg));
+
+	if (edit_todo)
+		msg = _("\nYou are editing the todo file "
+			"of an ongoing interactive rebase.\n"
+			"To continue rebase after editing, run:\n"
+			"    git rebase --continue\n\n");
+	else
+		msg = _("\nHowever, if you remove everything, "
+			"the rebase will be aborted.\n\n");
+
+	strbuf_add_commented_lines(&buf, msg, strlen(msg));
+
+	if (!keep_empty) {
+		msg = _("Note that empty commits are commented out");
+		strbuf_add_commented_lines(&buf, msg, strlen(msg));
+	}
+
+	ret = fputs(buf.buf, todo);
+	if (ret < 0)
+		error_errno(_("could not append help text to '%s'"), rebase_path_todo());
+
+	fclose(todo);
+	strbuf_release(&buf);
+
+	return ret;
+}
diff --git a/rebase-interactive.h b/rebase-interactive.h
new file mode 100644
index 0000000000..47372624e0
--- /dev/null
+++ b/rebase-interactive.h
@@ -0,0 +1,6 @@
+#ifndef REBASE_INTERACTIVE_H
+#define REBASE_INTERACTIVE_H
+
+int append_todo_help(unsigned edit_todo, unsigned keep_empty);
+
+#endif

From 2aed01811daee2f412b795ea539a4eb5abb69510 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:30 +0200
Subject: [PATCH 03/20] editor: add a function to launch the sequence editor

As part of the rewrite of interactive rebase, the sequencer will need to
open the sequence editor to allow the user to edit the todo list.
Instead of duplicating the existing launch_editor() function, this
refactors it to a new function, launch_specified_editor(), which takes
the editor as a parameter, in addition to the path, the buffer and the
environment variables.  launch_sequence_editor() is then added to launch
the sequence editor.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 cache.h  |  1 +
 editor.c | 27 +++++++++++++++++++++++++--
 strbuf.h |  2 ++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/cache.h b/cache.h
index 8b447652a7..d70ae49ca2 100644
--- a/cache.h
+++ b/cache.h
@@ -1409,6 +1409,7 @@ 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/strbuf.h b/strbuf.h
index 60a35aef16..66da9822fd 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -575,6 +575,8 @@ extern void strbuf_add_unique_abbrev(struct strbuf *sb,
  * file's contents are not read into the buffer upon completion.
  */
 extern int launch_editor(const char *path, struct strbuf *buffer, const char *const *env);
+extern int launch_sequence_editor(const char *path, struct strbuf *buffer,
+				  const char *const *env);
 
 extern void strbuf_add_lines(struct strbuf *sb, const char *prefix, const char *buf, size_t size);
 

From 64a43cbd5da23718dee242d6ad4d5823128bf564 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:31 +0200
Subject: [PATCH 04/20] rebase -i: rewrite the edit-todo functionality in C

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   | 13 ++++++++-----
 git-rebase--interactive.sh | 11 +----------
 rebase-interactive.c       | 27 +++++++++++++++++++++++++++
 rebase-interactive.h       |  1 +
 4 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 05e73e71d4..731a64971d 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 94c23a7af2..2defe607f4 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 d7996bc8d9..3f9468fc69 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -66,3 +66,30 @@ 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();
+
+	if (strbuf_read_file(&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);
+		return -1;
+	}
+
+	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 47372624e0..155219e742 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

From 34bec2c458474bdc05ced34d6789ee6c9fb7f051 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:32 +0200
Subject: [PATCH 05/20] sequencer: add a new function to silence a command,
 except if it fails

This adds a new function, run_command_silent_on_success(), to
redirect the stdout and stderr of a command to a strbuf, and then to run
that command. This strbuf is printed only if the command fails. It is
functionnaly similar to output() from git-rebase.sh.

run_git_commit() is then refactored to use of
run_command_silent_on_success().

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 sequencer.c | 51 +++++++++++++++++++++++++--------------------------
 1 file changed, 25 insertions(+), 26 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 33d73194d0..960a935444 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -769,6 +769,23 @@ N_("you have staged changes in your working tree\n"
 #define VERIFY_MSG  (1<<4)
 #define CREATE_ROOT_COMMIT (1<<5)
 
+static int run_command_silent_on_success(struct child_process *cmd)
+{
+	struct strbuf buf = STRBUF_INIT;
+	int rc;
+
+	cmd->stdout_to_stderr = 1;
+	rc = pipe_command(cmd,
+			  NULL, 0,
+			  NULL, 0,
+			  &buf, 0);
+
+	if (rc)
+		fputs(buf.buf, stderr);
+	strbuf_release(&buf);
+	return rc;
+}
+
 /*
  * If we are cherry-pick, and if the merge did not result in
  * hand-editing, we will hit this commit and inherit the original
@@ -823,18 +840,11 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 
 	cmd.git_cmd = 1;
 
-	if (is_rebase_i(opts)) {
-		if (!(flags & EDIT_MSG)) {
-			cmd.stdout_to_stderr = 1;
-			cmd.err = -1;
-		}
+	if (is_rebase_i(opts) && read_env_script(&cmd.env_array)) {
+		const char *gpg_opt = gpg_sign_opt_quoted(opts);
 
-		if (read_env_script(&cmd.env_array)) {
-			const char *gpg_opt = gpg_sign_opt_quoted(opts);
-
-			return error(_(staged_changes_advice),
-				     gpg_opt, gpg_opt);
-		}
+		return error(_(staged_changes_advice),
+			     gpg_opt, gpg_opt);
 	}
 
 	argv_array_push(&cmd.args, "commit");
@@ -864,21 +874,10 @@ static int run_git_commit(const char *defmsg, struct replay_opts *opts,
 	if (opts->allow_empty_message)
 		argv_array_push(&cmd.args, "--allow-empty-message");
 
-	if (cmd.err == -1) {
-		/* hide stderr on success */
-		struct strbuf buf = STRBUF_INIT;
-		int rc = pipe_command(&cmd,
-				      NULL, 0,
-				      /* stdout is already redirected */
-				      NULL, 0,
-				      &buf, 0);
-		if (rc)
-			fputs(buf.buf, stderr);
-		strbuf_release(&buf);
-		return rc;
-	}
-
-	return run_command(&cmd);
+	if (is_rebase_i(opts) && !(flags & EDIT_MSG))
+		return run_command_silent_on_success(&cmd);
+	else
+		return run_command(&cmd);
 }
 
 static int rest_is_empty(const struct strbuf *sb, int start)

From 2c58483a5983d1313f674e2ba32b3bac24df6911 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:33 +0200
Subject: [PATCH 06/20] rebase -i: rewrite setup_reflog_action() in C
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This rewrites (the misnamed) setup_reflog_action() from shell to C. The
new version is called prepare_branch_to_be_rebased().

A new command is added to rebase--helper.c, “checkout-base”, as well as
a new flag, “verbose”, to avoid silencing the output of the checkout
operation called by checkout_base_commit().

The function `run_git_checkout()` will also be used in the next commit,
therefore its code is not part of `checkout_base_commit()`.

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

As $GIT_REFLOG_ACTION is no longer set at the first call of
checkout_onto(), a call to comment_for_reflog() is added at the
beginning of this function.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   |  7 ++++++-
 git-rebase--interactive.sh | 16 ++--------------
 sequencer.c                | 30 ++++++++++++++++++++++++++++++
 sequencer.h                |  2 ++
 4 files changed, 40 insertions(+), 15 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 731a64971d..0e76dadba6 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -18,7 +18,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	enum {
 		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
 		CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH,
-		ADD_EXEC, APPEND_TODO_HELP, EDIT_TODO
+		ADD_EXEC, APPEND_TODO_HELP, EDIT_TODO, PREPARE_BRANCH
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -28,6 +28,7 @@ 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__VERBOSE(&opts.verbose, N_("be verbose")),
 		OPT_CMDMODE(0, "continue", &command, N_("continue rebase"),
 				CONTINUE),
 		OPT_CMDMODE(0, "abort", &command, N_("abort rebase"),
@@ -51,6 +52,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		OPT_CMDMODE(0, "edit-todo", &command,
 			    N_("edit the todo list during an interactive rebase"),
 			    EDIT_TODO),
+		OPT_CMDMODE(0, "prepare-branch", &command,
+			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
 		OPT_END()
 	};
 
@@ -94,5 +97,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!append_todo_help(0, keep_empty);
 	if (command == EDIT_TODO && argc == 1)
 		return !!edit_todo_list(flags);
+	if (command == PREPARE_BRANCH && argc == 2)
+		return !!prepare_branch_to_be_rebased(&opts, argv[1]);
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 2defe607f4..77e972bb6c 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -72,6 +72,7 @@ collapse_todo_ids() {
 
 # Switch to the branch in $into and notify it in the reflog
 checkout_onto () {
+	comment_for_reflog start
 	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name"
 	output git checkout $onto || die_abort "$(gettext "could not detach HEAD")"
 	git update-ref ORIG_HEAD $orig_head
@@ -119,19 +120,6 @@ initiate_action () {
 	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")"
@@ -211,7 +199,7 @@ git_rebase__interactive () {
 		return 0
 	fi
 
-	setup_reflog_action
+	git rebase--helper --prepare-branch "$switch_to" ${verbose:+--verbose}
 	init_basic_state
 
 	init_revisions_and_shortrevisions
diff --git a/sequencer.c b/sequencer.c
index 960a935444..e48b37bc0e 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3139,6 +3139,36 @@ static const char *reflog_message(struct replay_opts *opts,
 	return buf.buf;
 }
 
+static int run_git_checkout(struct replay_opts *opts, const char *commit,
+			    const char *action)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	cmd.git_cmd = 1;
+
+	argv_array_push(&cmd.args, "checkout");
+	argv_array_push(&cmd.args, commit);
+	argv_array_pushf(&cmd.env_array, GIT_REFLOG_ACTION "=%s", action);
+
+	if (opts->verbose)
+		return run_command(&cmd);
+	else
+		return run_command_silent_on_success(&cmd);
+}
+
+int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit)
+{
+	const char *action;
+
+	if (commit && *commit) {
+		action = reflog_message(opts, "start", "checkout %s", commit);
+		if (run_git_checkout(opts, commit, action))
+			return error(_("could not checkout %s"), commit);
+	}
+
+	return 0;
+}
+
 static const char rescheduled_advice[] =
 N_("Could not execute the todo command\n"
 "\n"
diff --git a/sequencer.h b/sequencer.h
index 792e448b67..f619b02a13 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -109,6 +109,8 @@ int update_head_with_reflog(const struct commit *old_head,
 void commit_post_rewrite(const struct commit *current_head,
 			 const struct object_id *new_head);
 
+int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit);
+
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)
 void print_commit_summary(const char *prefix, const struct object_id *oid,

From 4df66c40b08931eb224964f12decbb0f660cf932 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:34 +0200
Subject: [PATCH 07/20] rebase -i: rewrite checkout_onto() in C
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This rewrites checkout_onto() from shell to C.

A new command (“checkout-onto”) is added to rebase--helper.c. The shell
version is then stripped.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   |  7 ++++++-
 git-rebase--interactive.sh | 25 ++++---------------------
 sequencer.c                | 19 +++++++++++++++++++
 sequencer.h                |  3 +++
 4 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 0e76dadba6..7d9426d23c 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -18,7 +18,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	enum {
 		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
 		CHECK_TODO_LIST, SKIP_UNNECESSARY_PICKS, REARRANGE_SQUASH,
-		ADD_EXEC, APPEND_TODO_HELP, EDIT_TODO, PREPARE_BRANCH
+		ADD_EXEC, APPEND_TODO_HELP, EDIT_TODO, PREPARE_BRANCH,
+		CHECKOUT_ONTO
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -54,6 +55,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			    EDIT_TODO),
 		OPT_CMDMODE(0, "prepare-branch", &command,
 			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
+		OPT_CMDMODE(0, "checkout-onto", &command,
+			    N_("checkout a commit"), CHECKOUT_ONTO),
 		OPT_END()
 	};
 
@@ -99,5 +102,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!edit_todo_list(flags);
 	if (command == PREPARE_BRANCH && argc == 2)
 		return !!prepare_branch_to_be_rebased(&opts, argv[1]);
+	if (command == CHECKOUT_ONTO && argc == 4)
+		return !!checkout_onto(&opts, argv[1], argv[2], argv[3]);
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 77e972bb6c..b68f108f28 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -28,17 +28,6 @@ case "$comment_char" in
 	;;
 esac
 
-orig_reflog_action="$GIT_REFLOG_ACTION"
-
-comment_for_reflog () {
-	case "$orig_reflog_action" in
-	''|rebase*)
-		GIT_REFLOG_ACTION="rebase -i ($1)"
-		export GIT_REFLOG_ACTION
-		;;
-	esac
-}
-
 die_abort () {
 	apply_autostash
 	rm -rf "$state_dir"
@@ -70,14 +59,6 @@ collapse_todo_ids() {
 	git rebase--helper --shorten-ids
 }
 
-# Switch to the branch in $into and notify it in the reflog
-checkout_onto () {
-	comment_for_reflog start
-	GIT_REFLOG_ACTION="$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}
@@ -176,7 +157,8 @@ EOF
 
 	git rebase--helper --check-todo-list || {
 		ret=$?
-		checkout_onto
+		git rebase--helper --checkout-onto "$onto_name" "$onto" \
+		    "$orig_head" ${verbose:+--verbose}
 		exit $ret
 	}
 
@@ -186,7 +168,8 @@ EOF
 	onto="$(git rebase--helper --skip-unnecessary-picks)" ||
 	die "Could not skip unnecessary pick commands"
 
-	checkout_onto
+	git rebase--helper --checkout-onto "$onto_name" "$onto" "$orig_head" \
+	    ${verbose:+--verbose}
 	require_clean_work_tree "rebase"
 	exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
 	     --continue
diff --git a/sequencer.c b/sequencer.c
index e48b37bc0e..df2c80d879 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3169,6 +3169,25 @@ int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit)
 	return 0;
 }
 
+int checkout_onto(struct replay_opts *opts,
+		  const char *onto_name, const char *onto,
+		  const char *orig_head)
+{
+	struct object_id oid;
+	const char *action = reflog_message(opts, "start", "checkout %s", onto_name);
+
+	if (get_oid(orig_head, &oid))
+		return error(_("%s: not a valid OID"), orig_head);
+
+	if (run_git_checkout(opts, onto, action)) {
+		apply_autostash(opts);
+		sequencer_remove_state(opts);
+		return error(_("could not detach HEAD"));
+	}
+
+	return update_ref(NULL, "ORIG_HEAD", &oid, NULL, 0, UPDATE_REFS_MSG_ON_ERR);
+}
+
 static const char rescheduled_advice[] =
 N_("Could not execute the todo command\n"
 "\n"
diff --git a/sequencer.h b/sequencer.h
index f619b02a13..d2b54adf45 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -110,6 +110,9 @@ void commit_post_rewrite(const struct commit *current_head,
 			 const struct object_id *new_head);
 
 int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit);
+int checkout_onto(struct replay_opts *opts,
+		  const char *onto_name, const char *onto,
+		  const char *orig_head);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)

From a9f5476fbca515171e42a4e06b584a9241341ae9 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:35 +0200
Subject: [PATCH 08/20] sequencer: refactor append_todo_help() to write its
 message to a buffer

This refactors append_todo_help() to write its message to a buffer
instead of the todo-list.  This is needed for the rewrite of
complete_action(), which will come after the next commit.

As rebase--helper still needs the file manipulation part of
append_todo_help(), it is extracted to a temporary function,
append_todo_help_to_file().  This function will go away after the
rewrite of complete_action().

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c |  2 +-
 rebase-interactive.c     | 43 ++++++++++++++++++++++++++++------------
 rebase-interactive.h     |  4 +++-
 3 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 7d9426d23c..313092c465 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -97,7 +97,7 @@ 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(0, keep_empty);
+		return !!append_todo_help_to_file(0, keep_empty);
 	if (command == EDIT_TODO && argc == 1)
 		return !!edit_todo_list(flags);
 	if (command == PREPARE_BRANCH && argc == 2)
diff --git a/rebase-interactive.c b/rebase-interactive.c
index 3f9468fc69..4a9a10eff4 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -4,11 +4,9 @@
 #include "sequencer.h"
 #include "strbuf.h"
 
-int append_todo_help(unsigned edit_todo, unsigned keep_empty)
+void append_todo_help(unsigned edit_todo, unsigned keep_empty,
+		      struct strbuf *buf)
 {
-	struct strbuf buf = STRBUF_INIT;
-	FILE *todo;
-	int ret;
 	const char *msg = _("\nCommands:\n"
 "p, pick <commit> = use commit\n"
 "r, reword <commit> = use commit, but edit the commit message\n"
@@ -26,11 +24,7 @@ int append_todo_help(unsigned edit_todo, unsigned keep_empty)
 "\n"
 "These lines can be re-ordered; they are executed from top to bottom.\n");
 
-	todo = fopen_or_warn(rebase_path_todo(), "a");
-	if (!todo)
-		return 1;
-
-	strbuf_add_commented_lines(&buf, msg, strlen(msg));
+	strbuf_add_commented_lines(buf, msg, strlen(msg));
 
 	if (get_missing_commit_check_level() == MISSING_COMMIT_CHECK_ERROR)
 		msg = _("\nDo not remove any line. Use 'drop' "
@@ -39,7 +33,7 @@ int append_todo_help(unsigned edit_todo, unsigned keep_empty)
 		msg = _("\nIf you remove a line here "
 			 "THAT COMMIT WILL BE LOST.\n");
 
-	strbuf_add_commented_lines(&buf, msg, strlen(msg));
+	strbuf_add_commented_lines(buf, msg, strlen(msg));
 
 	if (edit_todo)
 		msg = _("\nYou are editing the todo file "
@@ -50,12 +44,25 @@ int append_todo_help(unsigned edit_todo, unsigned keep_empty)
 		msg = _("\nHowever, if you remove everything, "
 			"the rebase will be aborted.\n\n");
 
-	strbuf_add_commented_lines(&buf, msg, strlen(msg));
+	strbuf_add_commented_lines(buf, msg, strlen(msg));
 
 	if (!keep_empty) {
 		msg = _("Note that empty commits are commented out");
-		strbuf_add_commented_lines(&buf, msg, strlen(msg));
+		strbuf_add_commented_lines(buf, msg, strlen(msg));
 	}
+}
+
+int append_todo_help_to_file(unsigned edit_todo, unsigned keep_empty)
+{
+	struct strbuf buf = STRBUF_INIT;
+	FILE *todo;
+	int ret;
+
+	todo = fopen_or_warn(rebase_path_todo(), "a");
+	if (!todo)
+		return -1;
+
+	append_todo_help(edit_todo, keep_empty, &buf);
 
 	ret = fputs(buf.buf, todo);
 	if (ret < 0)
@@ -84,7 +91,17 @@ int edit_todo_list(unsigned flags)
 	strbuf_release(&buf);
 
 	transform_todos(flags | TODO_LIST_SHORTEN_IDS);
-	append_todo_help(1, 0);
+
+	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);
+		return -1;
+	}
+
+	strbuf_release(&buf);
 
 	if (launch_sequence_editor(todo_file, NULL, NULL))
 		return -1;
diff --git a/rebase-interactive.h b/rebase-interactive.h
index 155219e742..d33f3176b7 100644
--- a/rebase-interactive.h
+++ b/rebase-interactive.h
@@ -1,7 +1,9 @@
 #ifndef REBASE_INTERACTIVE_H
 #define REBASE_INTERACTIVE_H
 
-int append_todo_help(unsigned edit_todo, unsigned keep_empty);
+void append_todo_help(unsigned edit_todo, unsigned keep_empty,
+		      struct strbuf *buf);
+int append_todo_help_to_file(unsigned edit_todo, unsigned keep_empty);
 int edit_todo_list(unsigned flags);
 
 #endif

From d4ed5d7713c779487a52d30e83185a056c4bf023 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:36 +0200
Subject: [PATCH 09/20] sequencer: change the way skip_unnecessary_picks()
 returns its result

Instead of skip_unnecessary_picks() printing its result to stdout, it
returns it into a struct object_id, as the rewrite of complete_action()
(to come in the next commit) will need it.

rebase--helper then is modified to fit this change.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c | 10 ++++++++--
 sequencer.c              | 13 ++++++-------
 sequencer.h              |  2 +-
 3 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 313092c465..bed3dd2b95 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -90,8 +90,14 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		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 == SKIP_UNNECESSARY_PICKS && argc == 1) {
+		struct object_id oid;
+		int ret = skip_unnecessary_picks(&oid);
+
+		if (!ret)
+			puts(oid_to_hex(&oid));
+		return !!ret;
+	}
 	if (command == REARRANGE_SQUASH && argc == 1)
 		return !!rearrange_squash();
 	if (command == ADD_EXEC && argc == 2)
diff --git a/sequencer.c b/sequencer.c
index df2c80d879..cd2374ee1a 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -4416,17 +4416,17 @@ static int rewrite_file(const char *path, const char *buf, size_t len)
 }
 
 /* skip picking commits whose parents are unchanged */
-int skip_unnecessary_picks(void)
+int skip_unnecessary_picks(struct object_id *output_oid)
 {
 	const char *todo_file = rebase_path_todo();
 	struct strbuf buf = STRBUF_INIT;
 	struct todo_list todo_list = TODO_LIST_INIT;
-	struct object_id onto_oid, *oid = &onto_oid, *parent_oid;
+	struct object_id *parent_oid;
 	int fd, i;
 
 	if (!read_oneliner(&buf, rebase_path_onto(), 0))
 		return error(_("could not read 'onto'"));
-	if (get_oid(buf.buf, &onto_oid)) {
+	if (get_oid(buf.buf, output_oid)) {
 		strbuf_release(&buf);
 		return error(_("need a HEAD to fixup"));
 	}
@@ -4456,9 +4456,9 @@ int skip_unnecessary_picks(void)
 		if (item->commit->parents->next)
 			break; /* merge commit */
 		parent_oid = &item->commit->parents->item->object.oid;
-		if (hashcmp(parent_oid->hash, oid->hash))
+		if (hashcmp(parent_oid->hash, output_oid->hash))
 			break;
-		oid = &item->commit->object.oid;
+		oidcpy(output_oid, &item->commit->object.oid);
 	}
 	if (i > 0) {
 		int offset = get_item_line_offset(&todo_list, i);
@@ -4487,11 +4487,10 @@ int skip_unnecessary_picks(void)
 
 		todo_list.current = i;
 		if (is_fixup(peek_command(&todo_list, 0)))
-			record_in_rewritten(oid, peek_command(&todo_list, 0));
+			record_in_rewritten(output_oid, peek_command(&todo_list, 0));
 	}
 
 	todo_list_release(&todo_list);
-	printf("%s\n", oid_to_hex(oid));
 
 	return 0;
 }
diff --git a/sequencer.h b/sequencer.h
index d2b54adf45..fcbcd246c2 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -91,7 +91,7 @@ int sequencer_add_exec_commands(const char *command);
 int transform_todos(unsigned flags);
 enum missing_commit_check_level get_missing_commit_check_level(void);
 int check_todo_list(void);
-int skip_unnecessary_picks(void);
+int skip_unnecessary_picks(struct object_id *output_oid);
 int rearrange_squash(void);
 
 extern const char sign_off_header[];

From d078c39106895b26512ca6b259d66fe64b274e1b Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Fri, 10 Aug 2018 18:51:37 +0200
Subject: [PATCH 10/20] t3404: todo list with commented-out commands only
 aborts

If the todo list generated by `--make-script` is empty,
complete_action() writes a noop, but if it has only commented-out
commands, it will abort with the message "Nothing to do", and does not
launch the editor.  This adds a new test to ensure that
complete_action() behaves this way.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 t/t3404-rebase-interactive.sh | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index d392160ba9..7755b68092 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -75,6 +75,16 @@ test_expect_success 'rebase --keep-empty' '
 	test_line_count = 6 actual
 '
 
+cat > expect <<EOF
+Nothing to do
+EOF
+
+test_expect_success 'rebase -i with empty HEAD' '
+	set_fake_editor &&
+	test_must_fail env FAKE_LINES="1 exec_true" git rebase -i HEAD^ >actual 2>&1 &&
+	test_i18ncmp expect actual
+'
+
 test_expect_success 'rebase -i with the exec command' '
 	git checkout master &&
 	(

From b97e187364990fb8410355ff8b4365d0e37bbbbe Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Tue, 28 Aug 2018 14:10:36 +0200
Subject: [PATCH 11/20] rebase -i: rewrite complete_action() in C
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This rewrites complete_action() from shell to C.

A new mode is added to rebase--helper (`--complete-action`), as well as
a new flag (`--autosquash`).

Finally, complete_action() is stripped from git-rebase--interactive.sh.

The original complete_action() would return the code 2 when the todo
list contained no actions.  This was a special case for rebase -i and
-p; git-rebase.sh would then apply the autostash, delete the state
directory, and die with the message "Nothing to do".  This cleanup is
rewritten in C instead of returning 2.  As rebase -i no longer returns
2, the comment describing this behaviour in git-rebase.sh is updated to
reflect this change.

The message "Nothing to do" is now printed with error(), and so becomes
"error: nothing to do".  Some tests in t3404 check this value, so they
are updated to fit this change.

The first check might seem useless as we write "noop" to the todo list
if it is empty.  Actually, the todo list might contain commented
commands (ie. empty commits).  In this case, complete_action() won’t
write "noop", and will abort without starting the editor.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c      |  12 +++-
 git-rebase--interactive.sh    |  53 ++---------------
 git-rebase.sh                 |   2 +-
 sequencer.c                   | 104 ++++++++++++++++++++++++++++++++++
 sequencer.h                   |   4 ++
 t/t3404-rebase-interactive.sh |   2 +-
 6 files changed, 124 insertions(+), 53 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index bed3dd2b95..01b3333958 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -13,13 +13,13 @@ 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;
+	unsigned flags = 0, keep_empty = 0, rebase_merges = 0, autosquash = 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, EDIT_TODO, PREPARE_BRANCH,
-		CHECKOUT_ONTO
+		CHECKOUT_ONTO, COMPLETE_ACTION
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -29,6 +29,8 @@ 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, "autosquash", &autosquash,
+			 N_("move commits that begin with squash!/fixup!")),
 		OPT__VERBOSE(&opts.verbose, N_("be verbose")),
 		OPT_CMDMODE(0, "continue", &command, N_("continue rebase"),
 				CONTINUE),
@@ -57,6 +59,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
 		OPT_CMDMODE(0, "checkout-onto", &command,
 			    N_("checkout a commit"), CHECKOUT_ONTO),
+		OPT_CMDMODE(0, "complete-action", &command,
+			    N_("complete the action"), COMPLETE_ACTION),
 		OPT_END()
 	};
 
@@ -110,5 +114,9 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!prepare_branch_to_be_rebased(&opts, argv[1]);
 	if (command == CHECKOUT_ONTO && argc == 4)
 		return !!checkout_onto(&opts, argv[1], argv[2], argv[3]);
+	if (command == COMPLETE_ACTION && argc == 6)
+		return !!complete_action(&opts, flags, argv[1], argv[2], argv[3],
+					 argv[4], argv[5], autosquash);
+
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index b68f108f28..59dc4888a6 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -127,54 +127,6 @@ init_revisions_and_shortrevisions () {
 	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
-	git rebase--helper --append-todo-help ${keep_empty:+--keep-empty}
-
-	has_action "$todo" ||
-		return 2
-
-	cp "$todo" "$todo".backup
-	collapse_todo_ids
-	git_sequence_editor "$todo" ||
-		die_abort "$(gettext "Could not execute editor")"
-
-	has_action "$todo" ||
-		return 2
-
-	git rebase--helper --check-todo-list || {
-		ret=$?
-		git rebase--helper --checkout-onto "$onto_name" "$onto" \
-		    "$orig_head" ${verbose:+--verbose}
-		exit $ret
-	}
-
-	expand_todo_ids
-
-	test -n "$force_rebase" ||
-	onto="$(git rebase--helper --skip-unnecessary-picks)" ||
-	die "Could not skip unnecessary pick commands"
-
-	git rebase--helper --checkout-onto "$onto_name" "$onto" "$orig_head" \
-	    ${verbose:+--verbose}
-	require_clean_work_tree "rebase"
-	exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
-	     --continue
-}
-
 git_rebase__interactive () {
 	initiate_action "$action"
 	ret=$?
@@ -193,5 +145,8 @@ git_rebase__interactive () {
 		$revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
 	die "$(gettext "Could not generate todo list")"
 
-	complete_action
+	exec git rebase--helper --complete-action "$shortrevisions" "$onto_name" \
+		"$shortonto" "$orig_head" "$cmd" $allow_empty_message \
+		${autosquash:+--autosquash} ${keep_empty:+--keep-empty} \
+		${verbose:+--verbose} ${force_rebase:+--no-ff}
 }
diff --git a/git-rebase.sh b/git-rebase.sh
index f3b10c7f62..86da3816be 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -219,7 +219,7 @@ run_specific_rebase () {
 	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/sequencer.c b/sequencer.c
index cd2374ee1a..98aacc8026 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -30,6 +30,7 @@
 #include "oidset.h"
 #include "commit-slab.h"
 #include "alias.h"
+#include "rebase-interactive.h"
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
@@ -53,6 +54,9 @@ static GIT_PATH_FUNC(rebase_path, "rebase-merge")
  * file and written to the tail of 'done'.
  */
 GIT_PATH_FUNC(rebase_path_todo, "rebase-merge/git-rebase-todo")
+static GIT_PATH_FUNC(rebase_path_todo_backup,
+		     "rebase-merge/git-rebase-todo.backup")
+
 /*
  * The rebase command lines that have already been processed. A line
  * is moved here when it is first handled, before any associated user
@@ -4495,6 +4499,106 @@ int skip_unnecessary_picks(struct object_id *output_oid)
 	return 0;
 }
 
+int complete_action(struct replay_opts *opts, unsigned flags,
+		    const char *shortrevisions, const char *onto_name,
+		    const char *onto, const char *orig_head, const char *cmd,
+		    unsigned autosquash)
+{
+	const char *shortonto, *todo_file = rebase_path_todo();
+	struct todo_list todo_list = TODO_LIST_INIT;
+	struct strbuf *buf = &(todo_list.buf);
+	struct object_id oid;
+	struct stat st;
+
+	get_oid(onto, &oid);
+	shortonto = find_unique_abbrev(&oid, DEFAULT_ABBREV);
+
+	if (!lstat(todo_file, &st) && st.st_size == 0 &&
+	    write_message("noop\n", 5, todo_file, 0))
+		return -1;
+
+	if (autosquash && rearrange_squash())
+		return -1;
+
+	if (cmd && *cmd)
+		sequencer_add_exec_commands(cmd);
+
+	if (strbuf_read_file(buf, todo_file, 0) < 0)
+		return error_errno(_("could not read '%s'."), todo_file);
+
+	if (parse_insn_buffer(buf->buf, &todo_list)) {
+		todo_list_release(&todo_list);
+		return error(_("unusable todo list: '%s'"), todo_file);
+	}
+
+	if (count_commands(&todo_list) == 0) {
+		apply_autostash(opts);
+		sequencer_remove_state(opts);
+		todo_list_release(&todo_list);
+
+		return error(_("nothing to do"));
+	}
+
+	strbuf_addch(buf, '\n');
+	strbuf_commented_addf(buf, Q_("Rebase %s onto %s (%d command)",
+				      "Rebase %s onto %s (%d commands)",
+				      count_commands(&todo_list)),
+			      shortrevisions, shortonto, count_commands(&todo_list));
+	append_todo_help(0, flags & TODO_LIST_KEEP_EMPTY, buf);
+
+	if (write_message(buf->buf, buf->len, todo_file, 0)) {
+		todo_list_release(&todo_list);
+		return -1;
+	}
+
+	if (copy_file(rebase_path_todo_backup(), todo_file, 0666))
+		return error(_("could not copy '%s' to '%s'."), todo_file,
+			     rebase_path_todo_backup());
+
+	if (transform_todos(flags | TODO_LIST_SHORTEN_IDS))
+		return error(_("could not transform the todo list"));
+
+	strbuf_reset(buf);
+
+	if (launch_sequence_editor(todo_file, buf, NULL)) {
+		apply_autostash(opts);
+		sequencer_remove_state(opts);
+		todo_list_release(&todo_list);
+
+		return -1;
+	}
+
+	strbuf_stripspace(buf, 1);
+	if (buf->len == 0) {
+		apply_autostash(opts);
+		sequencer_remove_state(opts);
+		todo_list_release(&todo_list);
+
+		return error(_("nothing to do"));
+	}
+
+	todo_list_release(&todo_list);
+
+	if (check_todo_list()) {
+		checkout_onto(opts, onto_name, onto, orig_head);
+		return -1;
+	}
+
+	if (transform_todos(flags & ~(TODO_LIST_SHORTEN_IDS)))
+		return error(_("could not transform the todo list"));
+
+	if (opts->allow_ff && skip_unnecessary_picks(&oid))
+		return error(_("could not skip unnecessary pick commands"));
+
+	if (checkout_onto(opts, onto_name, oid_to_hex(&oid), orig_head))
+		return -1;
+;
+	if (require_clean_work_tree("rebase", "", 1, 1))
+		return -1;
+
+	return sequencer_continue(opts);
+}
+
 struct subject2item_entry {
 	struct hashmap_entry entry;
 	int i;
diff --git a/sequencer.h b/sequencer.h
index fcbcd246c2..d58766c6d7 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -92,6 +92,10 @@ int transform_todos(unsigned flags);
 enum missing_commit_check_level get_missing_commit_check_level(void);
 int check_todo_list(void);
 int skip_unnecessary_picks(struct object_id *output_oid);
+int complete_action(struct replay_opts *opts, unsigned flags,
+		    const char *shortrevisions, const char *onto_name,
+		    const char *onto, const char *orig_head, const char *cmd,
+		    unsigned autosquash);
 int rearrange_squash(void);
 
 extern const char sign_off_header[];
diff --git a/t/t3404-rebase-interactive.sh b/t/t3404-rebase-interactive.sh
index 7755b68092..90c3ca70e6 100755
--- a/t/t3404-rebase-interactive.sh
+++ b/t/t3404-rebase-interactive.sh
@@ -76,7 +76,7 @@ test_expect_success 'rebase --keep-empty' '
 '
 
 cat > expect <<EOF
-Nothing to do
+error: nothing to do
 EOF
 
 test_expect_success 'rebase -i with empty HEAD' '

From 91f0d95dcb4dd9c388881b64a7d79a3809927126 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Tue, 28 Aug 2018 14:10:37 +0200
Subject: [PATCH 12/20] rebase -i: remove unused modes and functions

This removes the modes `--skip-unnecessary-picks`, `--append-todo-help`,
and `--checkout-onto` from rebase--helper.c, the functions of
git-rebase--interactive.sh that were rendered useless by the rewrite of
complete_action(), and append_todo_help_to_file() from
rebase-interactive.c.

skip_unnecessary_picks() and checkout_onto() becomes static, as they are
only used inside of the sequencer.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   | 23 ++----------------
 git-rebase--interactive.sh | 50 --------------------------------------
 rebase-interactive.c       | 22 -----------------
 rebase-interactive.h       |  1 -
 sequencer.c                |  8 +++---
 sequencer.h                |  4 ---
 6 files changed, 6 insertions(+), 102 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 01b3333958..e1460136f5 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -17,9 +17,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	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, EDIT_TODO, PREPARE_BRANCH,
-		CHECKOUT_ONTO, COMPLETE_ACTION
+		CHECK_TODO_LIST, REARRANGE_SQUASH, ADD_EXEC, EDIT_TODO, PREPARE_BRANCH,
+		COMPLETE_ACTION
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -44,21 +43,15 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			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_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_CMDMODE(0, "prepare-branch", &command,
 			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
-		OPT_CMDMODE(0, "checkout-onto", &command,
-			    N_("checkout a commit"), CHECKOUT_ONTO),
 		OPT_CMDMODE(0, "complete-action", &command,
 			    N_("complete the action"), COMPLETE_ACTION),
 		OPT_END()
@@ -94,26 +87,14 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!transform_todos(flags);
 	if (command == CHECK_TODO_LIST && argc == 1)
 		return !!check_todo_list();
-	if (command == SKIP_UNNECESSARY_PICKS && argc == 1) {
-		struct object_id oid;
-		int ret = skip_unnecessary_picks(&oid);
-
-		if (!ret)
-			puts(oid_to_hex(&oid));
-		return !!ret;
-	}
 	if (command == REARRANGE_SQUASH && argc == 1)
 		return !!rearrange_squash();
 	if (command == ADD_EXEC && argc == 2)
 		return !!sequencer_add_exec_commands(argv[1]);
-	if (command == APPEND_TODO_HELP && argc == 1)
-		return !!append_todo_help_to_file(0, keep_empty);
 	if (command == EDIT_TODO && argc == 1)
 		return !!edit_todo_list(flags);
 	if (command == PREPARE_BRANCH && argc == 2)
 		return !!prepare_branch_to_be_rebased(&opts, argv[1]);
-	if (command == CHECKOUT_ONTO && argc == 4)
-		return !!checkout_onto(&opts, argv[1], argv[2], argv[3]);
 	if (command == COMPLETE_ACTION && argc == 6)
 		return !!complete_action(&opts, flags, argv[1], argv[2], argv[3],
 					 argv[4], argv[5], autosquash);
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 59dc4888a6..0d66c0f8b8 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -16,56 +16,6 @@ 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
-
-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" '"$@"'
-}
-
-expand_todo_ids() {
-	git rebase--helper --expand-ids
-}
-
-collapse_todo_ids() {
-	git rebase--helper --shorten-ids
-}
-
-get_missing_commit_check_level () {
-	check_level=$(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.
diff --git a/rebase-interactive.c b/rebase-interactive.c
index 4a9a10eff4..0f4119cbae 100644
--- a/rebase-interactive.c
+++ b/rebase-interactive.c
@@ -52,28 +52,6 @@ void append_todo_help(unsigned edit_todo, unsigned keep_empty,
 	}
 }
 
-int append_todo_help_to_file(unsigned edit_todo, unsigned keep_empty)
-{
-	struct strbuf buf = STRBUF_INIT;
-	FILE *todo;
-	int ret;
-
-	todo = fopen_or_warn(rebase_path_todo(), "a");
-	if (!todo)
-		return -1;
-
-	append_todo_help(edit_todo, keep_empty, &buf);
-
-	ret = fputs(buf.buf, todo);
-	if (ret < 0)
-		error_errno(_("could not append help text to '%s'"), rebase_path_todo());
-
-	fclose(todo);
-	strbuf_release(&buf);
-
-	return ret;
-}
-
 int edit_todo_list(unsigned flags)
 {
 	struct strbuf buf = STRBUF_INIT;
diff --git a/rebase-interactive.h b/rebase-interactive.h
index d33f3176b7..971da03776 100644
--- a/rebase-interactive.h
+++ b/rebase-interactive.h
@@ -3,7 +3,6 @@
 
 void append_todo_help(unsigned edit_todo, unsigned keep_empty,
 		      struct strbuf *buf);
-int append_todo_help_to_file(unsigned edit_todo, unsigned keep_empty);
 int edit_todo_list(unsigned flags);
 
 #endif
diff --git a/sequencer.c b/sequencer.c
index 98aacc8026..de2b5f8208 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -3173,9 +3173,9 @@ int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit)
 	return 0;
 }
 
-int checkout_onto(struct replay_opts *opts,
-		  const char *onto_name, const char *onto,
-		  const char *orig_head)
+static int checkout_onto(struct replay_opts *opts,
+			 const char *onto_name, const char *onto,
+			 const char *orig_head)
 {
 	struct object_id oid;
 	const char *action = reflog_message(opts, "start", "checkout %s", onto_name);
@@ -4420,7 +4420,7 @@ static int rewrite_file(const char *path, const char *buf, size_t len)
 }
 
 /* skip picking commits whose parents are unchanged */
-int skip_unnecessary_picks(struct object_id *output_oid)
+static int skip_unnecessary_picks(struct object_id *output_oid)
 {
 	const char *todo_file = rebase_path_todo();
 	struct strbuf buf = STRBUF_INIT;
diff --git a/sequencer.h b/sequencer.h
index d58766c6d7..02e3d7940e 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -91,7 +91,6 @@ int sequencer_add_exec_commands(const char *command);
 int transform_todos(unsigned flags);
 enum missing_commit_check_level get_missing_commit_check_level(void);
 int check_todo_list(void);
-int skip_unnecessary_picks(struct object_id *output_oid);
 int complete_action(struct replay_opts *opts, unsigned flags,
 		    const char *shortrevisions, const char *onto_name,
 		    const char *onto, const char *orig_head, const char *cmd,
@@ -114,9 +113,6 @@ void commit_post_rewrite(const struct commit *current_head,
 			 const struct object_id *new_head);
 
 int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit);
-int checkout_onto(struct replay_opts *opts,
-		  const char *onto_name, const char *onto,
-		  const char *orig_head);
 
 #define SUMMARY_INITIAL_COMMIT   (1 << 0)
 #define SUMMARY_SHOW_AUTHOR_DATE (1 << 1)

From 6ab54d17be3f51153444d8efebb0ae363eb9b7c9 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Tue, 28 Aug 2018 14:10:38 +0200
Subject: [PATCH 13/20] rebase -i: implement the logic to initialize $revisions
 in C
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This rewrites the part of init_revisions_and_shortrevisions() needed by
`--make-script` from shell to C.  The new version is called
get_revision_ranges(), and is a static function inside of
rebase--helper.c.  As this does not initialize $shortrevision, the
original shell version is not yet stripped.

Unlike init_revisions_and_shortrevisions(), get_revision_ranges()
doesn’t write $squash_onto to the state directory, it’s done by the
handler of `--make-script` instead.

Finally, this drops the $revision argument passed to `--make-script` in
git-rebase--interactive.sh, and rebase--helper is changed accordingly.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   | 56 ++++++++++++++++++++++++++++++++++++--
 git-rebase--interactive.sh |  4 ++-
 2 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index e1460136f5..acc71a6f99 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -4,6 +4,25 @@
 #include "parse-options.h"
 #include "sequencer.h"
 #include "rebase-interactive.h"
+#include "argv-array.h"
+
+static GIT_PATH_FUNC(path_squash_onto, "rebase-merge/squash-onto")
+
+static int get_revision_ranges(const char *upstream, const char *onto,
+			       const char **head_hash,
+			       char **revisions)
+{
+	const char *base_rev = upstream ? upstream : onto;
+	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);
+
+	return 0;
+}
 
 static const char * const builtin_rebase_helper_usage[] = {
 	N_("git rebase--helper [<options>]"),
@@ -14,7 +33,9 @@ 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, autosquash = 0;
-	int abbreviate_commands = 0, rebase_cousins = -1;
+	int abbreviate_commands = 0, rebase_cousins = -1, ret;
+	const char *head_hash = NULL, *onto = NULL, *restrict_revision = NULL,
+		*squash_onto = NULL, *upstream = NULL;
 	enum {
 		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
 		CHECK_TODO_LIST, REARRANGE_SQUASH, ADD_EXEC, EDIT_TODO, PREPARE_BRANCH,
@@ -54,6 +75,13 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
 		OPT_CMDMODE(0, "complete-action", &command,
 			    N_("complete the action"), COMPLETE_ACTION),
+		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_END()
 	};
 
@@ -81,8 +109,30 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		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 == MAKE_SCRIPT && argc == 1) {
+		char *revisions = NULL;
+		struct argv_array make_script_args = ARGV_ARRAY_INIT;
+
+		if (!upstream && squash_onto)
+			write_file(path_squash_onto(), "%s\n", squash_onto);
+
+		ret = get_revision_ranges(upstream, onto, &head_hash, &revisions);
+		if (ret)
+			return ret;
+
+		argv_array_pushl(&make_script_args, "", revisions, NULL);
+		if (restrict_revision)
+			argv_array_push(&make_script_args, restrict_revision);
+
+		ret = sequencer_make_script(stdout,
+					    make_script_args.argc, make_script_args.argv,
+					    flags);
+
+		free(revisions);
+		argv_array_clear(&make_script_args);
+
+		return !!ret;
+	}
 	if ((command == SHORTEN_OIDS || command == EXPAND_OIDS) && argc == 1)
 		return !!transform_todos(flags);
 	if (command == CHECK_TODO_LIST && argc == 1)
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 0d66c0f8b8..4ca47aed1e 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -92,7 +92,9 @@ git_rebase__interactive () {
 	git rebase--helper --make-script ${keep_empty:+--keep-empty} \
 		${rebase_merges:+--rebase-merges} \
 		${rebase_cousins:+--rebase-cousins} \
-		$revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
+		${upstream:+--upstream "$upstream"} ${onto:+--onto "$onto"} \
+		${squash_onto:+--squash-onto "$squash_onto"} \
+		${restrict_revision:+--restrict-revision ^"$restrict_revision"} >"$todo" ||
 	die "$(gettext "Could not generate todo list")"
 
 	exec git rebase--helper --complete-action "$shortrevisions" "$onto_name" \

From f22e4e1a3c2faaac59099aaca15641c18f478f77 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Tue, 28 Aug 2018 14:10:39 +0200
Subject: [PATCH 14/20] rebase -i: rewrite the rest of
 init_revisions_and_shortrevisions() in C

This rewrites the part of init_revisions_and_shortrevisions() needed by
`--complete-action` (which initialize $shortrevisions) from shell to C.

When `upstream` is empty, it means that the user launched a `rebase
--root`, and `onto` contains the ID of an empty commit.  As a range
between an empty commit and `head` is not really meaningful, `onto` is
not used to initialize `shortrevisions` in this case.

The corresponding arguments passed to `--complete-action` are then
dropped, and init_revisions_and_shortrevisions() is stripped from
git-rebase--interactive.sh

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   | 40 ++++++++++++++++++++++++++++++++------
 git-rebase--interactive.sh | 27 ++++---------------------
 2 files changed, 38 insertions(+), 29 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index acc71a6f99..0716bbfd78 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -10,7 +10,7 @@ static GIT_PATH_FUNC(path_squash_onto, "rebase-merge/squash-onto")
 
 static int get_revision_ranges(const char *upstream, const char *onto,
 			       const char **head_hash,
-			       char **revisions)
+			       char **revisions, char **shortrevisions)
 {
 	const char *base_rev = upstream ? upstream : onto;
 	struct object_id orig_head;
@@ -19,7 +19,25 @@ static int get_revision_ranges(const char *upstream, const char *onto,
 		return error(_("no HEAD?"));
 
 	*head_hash = find_unique_abbrev(&orig_head, GIT_MAX_HEXSZ);
-	*revisions = xstrfmt("%s...%s", base_rev, *head_hash);
+
+	if (revisions)
+		*revisions = xstrfmt("%s...%s", base_rev, *head_hash);
+	if (shortrevisions) {
+		const char *shorthead;
+
+		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;
 }
@@ -116,7 +134,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		if (!upstream && squash_onto)
 			write_file(path_squash_onto(), "%s\n", squash_onto);
 
-		ret = get_revision_ranges(upstream, onto, &head_hash, &revisions);
+		ret = get_revision_ranges(upstream, onto, &head_hash, &revisions, NULL);
 		if (ret)
 			return ret;
 
@@ -145,9 +163,19 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		return !!edit_todo_list(flags);
 	if (command == PREPARE_BRANCH && argc == 2)
 		return !!prepare_branch_to_be_rebased(&opts, argv[1]);
-	if (command == COMPLETE_ACTION && argc == 6)
-		return !!complete_action(&opts, flags, argv[1], argv[2], argv[3],
-					 argv[4], argv[5], autosquash);
+	if (command == COMPLETE_ACTION && argc == 3) {
+		char *shortrevisions = NULL;
+
+		ret = get_revision_ranges(upstream, onto, &head_hash, NULL, &shortrevisions);
+		if (ret)
+			return ret;
+
+		ret = complete_action(&opts, flags, shortrevisions, argv[1], onto,
+				      head_hash, argv[2], autosquash);
+
+		free(shortrevisions);
+		return !!ret;
+	}
 
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 4ca47aed1e..08e9a21c2f 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -60,23 +60,6 @@ init_basic_state () {
 	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" >"$state_dir"/squash-onto
-	fi
-}
-
 git_rebase__interactive () {
 	initiate_action "$action"
 	ret=$?
@@ -87,8 +70,6 @@ git_rebase__interactive () {
 	git rebase--helper --prepare-branch "$switch_to" ${verbose:+--verbose}
 	init_basic_state
 
-	init_revisions_and_shortrevisions
-
 	git rebase--helper --make-script ${keep_empty:+--keep-empty} \
 		${rebase_merges:+--rebase-merges} \
 		${rebase_cousins:+--rebase-cousins} \
@@ -97,8 +78,8 @@ git_rebase__interactive () {
 		${restrict_revision:+--restrict-revision ^"$restrict_revision"} >"$todo" ||
 	die "$(gettext "Could not generate todo list")"
 
-	exec git rebase--helper --complete-action "$shortrevisions" "$onto_name" \
-		"$shortonto" "$orig_head" "$cmd" $allow_empty_message \
-		${autosquash:+--autosquash} ${keep_empty:+--keep-empty} \
-		${verbose:+--verbose} ${force_rebase:+--no-ff}
+	exec git rebase--helper --complete-action "$onto_name" "$cmd" \
+		$allow_empty_message ${autosquash:+--autosquash} ${verbose:+--verbose} \
+		${keep_empty:+--keep-empty} ${force_rebase:+--no-ff} \
+		${upstream:+--upstream "$upstream"} ${onto:+--onto "$onto"}
 }

From 65850686cf072d6de88880247adb7113db8a52f2 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Tue, 28 Aug 2018 14:10:40 +0200
Subject: [PATCH 15/20] rebase -i: rewrite write_basic_state() in C

This rewrites write_basic_state() from git-rebase.sh in C.  This is the
first step in the conversion of init_basic_state(), hence the mode in
rebase--helper.c is called INIT_BASIC_STATE.  init_basic_state() will be
converted in the next commit.

The part of read_strategy_opts() that parses the stategy options is
moved to a new function to allow its use in rebase--helper.c.

Finally, the call to write_basic_state() is removed from
git-rebase--interactive.sh, replaced by a call to `--init-basic-state`.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   | 28 +++++++++++++-
 git-rebase--interactive.sh |  7 +++-
 sequencer.c                | 77 ++++++++++++++++++++++++++++++++------
 sequencer.h                |  4 ++
 4 files changed, 102 insertions(+), 14 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 0716bbfd78..63c5086e42 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -5,6 +5,8 @@
 #include "sequencer.h"
 #include "rebase-interactive.h"
 #include "argv-array.h"
+#include "rerere.h"
+#include "alias.h"
 
 static GIT_PATH_FUNC(path_squash_onto, "rebase-merge/squash-onto")
 
@@ -53,11 +55,12 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 	unsigned flags = 0, keep_empty = 0, rebase_merges = 0, autosquash = 0;
 	int abbreviate_commands = 0, rebase_cousins = -1, ret;
 	const char *head_hash = NULL, *onto = NULL, *restrict_revision = NULL,
-		*squash_onto = NULL, *upstream = NULL;
+		*squash_onto = NULL, *upstream = NULL, *head_name = NULL;
+	char *raw_strategies = NULL;
 	enum {
 		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
 		CHECK_TODO_LIST, REARRANGE_SQUASH, ADD_EXEC, EDIT_TODO, PREPARE_BRANCH,
-		COMPLETE_ACTION
+		COMPLETE_ACTION, INIT_BASIC_STATE
 	} command = 0;
 	struct option options[] = {
 		OPT_BOOL(0, "ff", &opts.allow_ff, N_("allow fast-forward")),
@@ -69,6 +72,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			 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),
@@ -93,6 +97,8 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
 		OPT_CMDMODE(0, "complete-action", &command,
 			    N_("complete the action"), COMPLETE_ACTION),
+		OPT_CMDMODE(0, "init-basic-state", &command,
+			    N_("initialise the rebase state"), INIT_BASIC_STATE),
 		OPT_STRING(0, "onto", &onto, N_("onto"), N_("onto")),
 		OPT_STRING(0, "restrict-revision", &restrict_revision,
 			   N_("restrict-revision"), N_("restrict revision")),
@@ -100,6 +106,14 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 			   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")),
+		OPT_STRING('S', "gpg-sign", &opts.gpg_sign, N_("gpg-sign"),
+			   N_("GPG-sign commits")),
+		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_RERERE_AUTOUPDATE(&opts.allow_rerere_auto),
 		OPT_END()
 	};
 
@@ -176,6 +190,16 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		free(shortrevisions);
 		return !!ret;
 	}
+	if (command == INIT_BASIC_STATE) {
+		if (raw_strategies)
+			parse_strategy_opts(&opts, raw_strategies);
+
+		ret = get_revision_ranges(upstream, onto, &head_hash, NULL, NULL);
+		if (ret)
+			return ret;
+
+		return !!write_basic_state(&opts, head_name, onto, head_hash);
+	}
 
 	usage_with_options(builtin_rebase_helper_usage, options);
 }
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 08e9a21c2f..6367da66e2 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -57,7 +57,6 @@ init_basic_state () {
 	rm -f "$(git rev-parse --git-path REBASE_HEAD)"
 
 	: > "$state_dir"/interactive || die "$(gettext "Could not mark as interactive")"
-	write_basic_state
 }
 
 git_rebase__interactive () {
@@ -70,6 +69,12 @@ git_rebase__interactive () {
 	git rebase--helper --prepare-branch "$switch_to" ${verbose:+--verbose}
 	init_basic_state
 
+	git rebase--helper --init-basic-state ${upstream:+--upstream "$upstream"} \
+		${onto:+--onto "$onto"} ${head_name:+--head-name "$head_name"} \
+		${verbose:+--verbose} ${strategy:+--strategy "$strategy"} \
+		${strategy_opts:+--strategy-opts="$strategy_opts"} \
+		"$allow_rerere_autoupdate" "$gpg_sign_opt" "$signoff" || exit
+
 	git rebase--helper --make-script ${keep_empty:+--keep-empty} \
 		${rebase_merges:+--rebase-merges} \
 		${rebase_cousins:+--rebase-cousins} \
diff --git a/sequencer.c b/sequencer.c
index de2b5f8208..8dd6db5a01 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -144,7 +144,7 @@ static GIT_PATH_FUNC(rebase_path_refs_to_delete, "rebase-merge/refs-to-delete")
 
 /*
  * The following files are written by git-rebase just after parsing the
- * command-line (and are only consumed, not modified, by the sequencer).
+ * command-line.
  */
 static GIT_PATH_FUNC(rebase_path_gpg_sign_opt, "rebase-merge/gpg_sign_opt")
 static GIT_PATH_FUNC(rebase_path_orig_head, "rebase-merge/orig-head")
@@ -156,6 +156,7 @@ static GIT_PATH_FUNC(rebase_path_autostash, "rebase-merge/autostash")
 static GIT_PATH_FUNC(rebase_path_strategy, "rebase-merge/strategy")
 static GIT_PATH_FUNC(rebase_path_strategy_opts, "rebase-merge/strategy_opts")
 static GIT_PATH_FUNC(rebase_path_allow_rerere_autoupdate, "rebase-merge/allow_rerere_autoupdate")
+static GIT_PATH_FUNC(rebase_path_quiet, "rebase-merge/quiet")
 
 static int git_sequencer_config(const char *k, const char *v, void *cb)
 {
@@ -2207,21 +2208,14 @@ static int populate_opts_cb(const char *key, const char *value, void *data)
 	return 0;
 }
 
-static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
+void parse_strategy_opts(struct replay_opts *opts, char *raw_opts)
 {
 	int i;
-	char *strategy_opts_string;
+	char *strategy_opts_string = raw_opts;
 
-	strbuf_reset(buf);
-	if (!read_oneliner(buf, rebase_path_strategy(), 0))
-		return;
-	opts->strategy = strbuf_detach(buf, NULL);
-	if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
-		return;
-
-	strategy_opts_string = buf->buf;
 	if (*strategy_opts_string == ' ')
 		strategy_opts_string++;
+
 	opts->xopts_nr = split_cmdline(strategy_opts_string,
 				       (const char ***)&opts->xopts);
 	for (i = 0; i < opts->xopts_nr; i++) {
@@ -2232,6 +2226,18 @@ static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
 	}
 }
 
+static void read_strategy_opts(struct replay_opts *opts, struct strbuf *buf)
+{
+	strbuf_reset(buf);
+	if (!read_oneliner(buf, rebase_path_strategy(), 0))
+		return;
+	opts->strategy = strbuf_detach(buf, NULL);
+	if (!read_oneliner(buf, rebase_path_strategy_opts(), 0))
+		return;
+
+	parse_strategy_opts(opts, buf->buf);
+}
+
 static int read_populate_opts(struct replay_opts *opts)
 {
 	if (is_rebase_i(opts)) {
@@ -2299,6 +2305,55 @@ static int read_populate_opts(struct replay_opts *opts)
 	return 0;
 }
 
+static void write_strategy_opts(struct replay_opts *opts)
+{
+	int i;
+	struct strbuf buf = STRBUF_INIT;
+
+	for (i = 0; i < opts->xopts_nr; ++i)
+		strbuf_addf(&buf, " --%s", opts->xopts[i]);
+
+	write_file(rebase_path_strategy_opts(), "%s\n", buf.buf);
+	strbuf_release(&buf);
+}
+
+int write_basic_state(struct replay_opts *opts, const char *head_name,
+		      const char *onto, const char *orig_head)
+{
+	const char *quiet = getenv("GIT_QUIET");
+
+	if (head_name)
+		write_file(rebase_path_head_name(), "%s\n", head_name);
+	if (onto)
+		write_file(rebase_path_onto(), "%s\n", onto);
+	if (orig_head)
+		write_file(rebase_path_orig_head(), "%s\n", orig_head);
+
+	if (quiet)
+		write_file(rebase_path_quiet(), "%s\n", quiet);
+	else
+		write_file(rebase_path_quiet(), "\n");
+
+	if (opts->verbose)
+		write_file(rebase_path_verbose(), "");
+	if (opts->strategy)
+		write_file(rebase_path_strategy(), "%s\n", opts->strategy);
+	if (opts->xopts_nr > 0)
+		write_strategy_opts(opts);
+
+	if (opts->allow_rerere_auto == RERERE_AUTOUPDATE)
+		write_file(rebase_path_allow_rerere_autoupdate(), "--rerere-autoupdate\n");
+	else if (opts->allow_rerere_auto == RERERE_NOAUTOUPDATE)
+		write_file(rebase_path_allow_rerere_autoupdate(), "--no-rerere-autoupdate\n");
+
+	if (opts->gpg_sign)
+		write_file(rebase_path_gpg_sign_opt(), "-S%s\n", opts->gpg_sign);
+	if (opts->signoff)
+		write_file(rebase_path_signoff(), "--signoff\n");
+
+	return 0;
+}
+
 static int walk_revs_populate_todo(struct todo_list *todo_list,
 				struct replay_opts *opts)
 {
diff --git a/sequencer.h b/sequencer.h
index 02e3d7940e..aab280f276 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -119,3 +119,7 @@ int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit);
 void print_commit_summary(const char *prefix, const struct object_id *oid,
 			  unsigned int flags);
 #endif
+
+void parse_strategy_opts(struct replay_opts *opts, char *raw_opts);
+int write_basic_state(struct replay_opts *opts, const char *head_name,
+		      const char *onto, const char *orig_head);

From d59cd14de8e05111f45ad55a507493225cd849bc Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Tue, 28 Aug 2018 14:10:41 +0200
Subject: [PATCH 16/20] rebase -i: rewrite init_basic_state() in C

This rewrites init_basic_state() from shell to C.  The call to
write_basic_state() in cmd_rebase__helper() is replaced by a call to the
new function.

The shell version is then stripped from git-rebase--interactive.sh.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--helper.c   | 23 ++++++++++++++++++++++-
 git-rebase--interactive.sh |  9 ---------
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/builtin/rebase--helper.c b/builtin/rebase--helper.c
index 63c5086e42..f8128037d3 100644
--- a/builtin/rebase--helper.c
+++ b/builtin/rebase--helper.c
@@ -5,10 +5,13 @@
 #include "sequencer.h"
 #include "rebase-interactive.h"
 #include "argv-array.h"
+#include "refs.h"
 #include "rerere.h"
 #include "alias.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,
@@ -44,6 +47,24 @@ static int get_revision_ranges(const char *upstream, const char *onto,
 	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 const char * const builtin_rebase_helper_usage[] = {
 	N_("git rebase--helper [<options>]"),
 	NULL
@@ -198,7 +219,7 @@ int cmd_rebase__helper(int argc, const char **argv, const char *prefix)
 		if (ret)
 			return ret;
 
-		return !!write_basic_state(&opts, head_name, onto, head_hash);
+		return !!init_basic_state(&opts, head_name, onto, head_hash);
 	}
 
 	usage_with_options(builtin_rebase_helper_usage, options);
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 6367da66e2..761be95ed1 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -51,14 +51,6 @@ initiate_action () {
 	esac
 }
 
-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 "$(gettext "Could not mark as interactive")"
-}
-
 git_rebase__interactive () {
 	initiate_action "$action"
 	ret=$?
@@ -67,7 +59,6 @@ git_rebase__interactive () {
 	fi
 
 	git rebase--helper --prepare-branch "$switch_to" ${verbose:+--verbose}
-	init_basic_state
 
 	git rebase--helper --init-basic-state ${upstream:+--upstream "$upstream"} \
 		${onto:+--onto "$onto"} ${head_name:+--head-name "$head_name"} \

From 53bbcfbde7c29611f16722c3fbcdb2b78718f633 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Thu, 27 Sep 2018 23:56:07 +0200
Subject: [PATCH 17/20] rebase -i: implement the main part of interactive
 rebase as a builtin

This rewrites the part of interactive rebase which initializes the
basic state, make the script and complete the action, as a buitin, named
git-rebase--interactive2 for now.  Others modes (`--continue`,
`--edit-todo`, etc.) will be rewritten in the next commit.

git-rebase--interactive.sh is modified to call git-rebase--interactive2
instead of git-rebase--helper.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 .gitignore                     |   1 +
 Makefile                       |   1 +
 builtin.h                      |   1 +
 builtin/rebase--interactive2.c | 207 +++++++++++++++++++++++++++++++++
 git-rebase--interactive.sh     |  41 ++++---
 git.c                          |   1 +
 6 files changed, 233 insertions(+), 19 deletions(-)
 create mode 100644 builtin/rebase--interactive2.c

diff --git a/.gitignore b/.gitignore
index 3284a1e9b1..404c9a8472 100644
--- a/.gitignore
+++ b/.gitignore
@@ -118,6 +118,7 @@
 /git-rebase--am
 /git-rebase--helper
 /git-rebase--interactive
+/git-rebase--interactive2
 /git-rebase--merge
 /git-rebase--preserve-merges
 /git-receive-pack
diff --git a/Makefile b/Makefile
index 909a687857..71f8f45fe5 100644
--- a/Makefile
+++ b/Makefile
@@ -1060,6 +1060,7 @@ BUILTIN_OBJS += builtin/prune.o
 BUILTIN_OBJS += builtin/pull.o
 BUILTIN_OBJS += builtin/push.o
 BUILTIN_OBJS += builtin/read-tree.o
+BUILTIN_OBJS += builtin/rebase--interactive2.o
 BUILTIN_OBJS += builtin/rebase--helper.o
 BUILTIN_OBJS += builtin/receive-pack.o
 BUILTIN_OBJS += builtin/reflog.o
diff --git a/builtin.h b/builtin.h
index 0362f1ce25..ed89b4f495 100644
--- a/builtin.h
+++ b/builtin.h
@@ -202,6 +202,7 @@ extern int cmd_prune_packed(int argc, const char **argv, const char *prefix);
 extern int cmd_pull(int argc, const char **argv, const char *prefix);
 extern int cmd_push(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__interactive(int argc, const char **argv, const char *prefix);
 extern int cmd_rebase__helper(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);
diff --git a/builtin/rebase--interactive2.c b/builtin/rebase--interactive2.c
new file mode 100644
index 0000000000..45336073a8
--- /dev/null
+++ b/builtin/rebase--interactive2.c
@@ -0,0 +1,207 @@
+#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;
+	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;
+	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_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;
+
+	if (rebase_cousins >= 0 && !rebase_merges)
+		warning(_("--[no-]rebase-cousins has no effect without "
+			  "--rebase-merges"));
+
+	if (!onto && !upstream)
+		die(_("a base commit must be provided with --upstream or --onto"));
+
+	return !!do_interactive_rebase(&opts, flags, switch_to, upstream, onto,
+				       onto_name, squash_onto, head_name, restrict_revision,
+				       raw_strategies, cmd, autosquash);
+}
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 761be95ed1..e87d708a4d 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -58,24 +58,27 @@ git_rebase__interactive () {
 		return 0
 	fi
 
-	git rebase--helper --prepare-branch "$switch_to" ${verbose:+--verbose}
+	test -n "$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_revisions" && restrict_revisions="--restrict-revisions=^$restrict_revisions"
+	test -n "$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"
 
-	git rebase--helper --init-basic-state ${upstream:+--upstream "$upstream"} \
-		${onto:+--onto "$onto"} ${head_name:+--head-name "$head_name"} \
-		${verbose:+--verbose} ${strategy:+--strategy "$strategy"} \
-		${strategy_opts:+--strategy-opts="$strategy_opts"} \
-		"$allow_rerere_autoupdate" "$gpg_sign_opt" "$signoff" || exit
-
-	git rebase--helper --make-script ${keep_empty:+--keep-empty} \
-		${rebase_merges:+--rebase-merges} \
-		${rebase_cousins:+--rebase-cousins} \
-		${upstream:+--upstream "$upstream"} ${onto:+--onto "$onto"} \
-		${squash_onto:+--squash-onto "$squash_onto"} \
-		${restrict_revision:+--restrict-revision ^"$restrict_revision"} >"$todo" ||
-	die "$(gettext "Could not generate todo list")"
-
-	exec git rebase--helper --complete-action "$onto_name" "$cmd" \
-		$allow_empty_message ${autosquash:+--autosquash} ${verbose:+--verbose} \
-		${keep_empty:+--keep-empty} ${force_rebase:+--no-ff} \
-		${upstream:+--upstream "$upstream"} ${onto:+--onto "$onto"}
+	exec git rebase--interactive2 "$keep_empty" "$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"
 }
diff --git a/git.c b/git.c
index 3fded74519..8309fb24a6 100644
--- a/git.c
+++ b/git.c
@@ -518,6 +518,7 @@ static struct cmd_struct commands[] = {
 	{ "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 	{ "push", cmd_push, RUN_SETUP },
 	{ "read-tree", cmd_read_tree, RUN_SETUP | SUPPORT_SUPER_PREFIX},
+	{ "rebase--interactive2", cmd_rebase__interactive, RUN_SETUP | NEED_WORK_TREE },
 	{ "rebase--helper", cmd_rebase__helper, RUN_SETUP | NEED_WORK_TREE },
 	{ "receive-pack", cmd_receive_pack },
 	{ "reflog", cmd_reflog, RUN_SETUP },

From 0af129b2ed4a5c73484c4d3e816df104d5438947 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Thu, 27 Sep 2018 23:56:08 +0200
Subject: [PATCH 18/20] rebase--interactive2: rewrite the submodes of
 interactive rebase in C

This rewrites the submodes of interactive rebase (`--continue`,
`--skip`, `--edit-todo`, and `--show-current-patch`) in C.

git-rebase.sh is then modified to call directly git-rebase--interactive2
instead of git-rebase--interactive.sh.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/rebase--interactive2.c | 51 ++++++++++++++++++++++++++++++----
 git-rebase.sh                  | 45 +++++++++++++++++++++++++++---
 2 files changed, 86 insertions(+), 10 deletions(-)

diff --git a/builtin/rebase--interactive2.c b/builtin/rebase--interactive2.c
index 45336073a8..aaf13c9621 100644
--- a/builtin/rebase--interactive2.c
+++ b/builtin/rebase--interactive2.c
@@ -134,11 +134,14 @@ 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;
+	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
+	} 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")),
@@ -151,6 +154,13 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
 			 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_STRING(0, "onto", &onto, N_("onto"), N_("onto")),
 		OPT_STRING(0, "restrict-revision", &restrict_revision,
 			   N_("restrict-revision"), N_("restrict revision")),
@@ -198,10 +208,39 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
 		warning(_("--[no-]rebase-cousins has no effect without "
 			  "--rebase-merges"));
 
-	if (!onto && !upstream)
-		die(_("a base commit must be provided with --upstream or --onto"));
+	switch (command) {
+	case NONE:
+		if (!onto && !upstream)
+			die(_("a base commit must be provided with --upstream or --onto"));
 
-	return !!do_interactive_rebase(&opts, flags, switch_to, upstream, onto,
-				       onto_name, squash_onto, head_name, restrict_revision,
-				       raw_strategies, cmd, autosquash);
+		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;
+	}
+	default:
+		BUG("invalid command '%d'", command);
+	}
+
+	return !!ret;
 }
diff --git a/git-rebase.sh b/git-rebase.sh
index 86da3816be..0d78475cc0 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -200,19 +200,56 @@ 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="--$action"
+
+	exec git rebase--interactive2 "$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=$?

From cf808208ec09727d993d670619c517bdcb00ca2b Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Thu, 27 Sep 2018 23:56:09 +0200
Subject: [PATCH 19/20] rebase -i: remove git-rebase--interactive.sh

This removes git-rebase--interactive.sh, as its functionnality has been
replaced by git-rebase--interactive2.

git-rebase--interactive2.c is then renamed to git-rebase--interactive.c.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 .gitignore                                    |  1 -
 Makefile                                      |  4 +-
 ...--interactive2.c => rebase--interactive.c} |  0
 git-rebase--interactive.sh                    | 84 -------------------
 git-rebase.sh                                 |  2 +-
 git.c                                         |  2 +-
 6 files changed, 3 insertions(+), 90 deletions(-)
 rename builtin/{rebase--interactive2.c => rebase--interactive.c} (100%)
 delete mode 100644 git-rebase--interactive.sh

diff --git a/.gitignore b/.gitignore
index 404c9a8472..3284a1e9b1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -118,7 +118,6 @@
 /git-rebase--am
 /git-rebase--helper
 /git-rebase--interactive
-/git-rebase--interactive2
 /git-rebase--merge
 /git-rebase--preserve-merges
 /git-receive-pack
diff --git a/Makefile b/Makefile
index 71f8f45fe5..584834726d 100644
--- a/Makefile
+++ b/Makefile
@@ -619,7 +619,6 @@ SCRIPT_SH += git-web--browse.sh
 SCRIPT_LIB += git-mergetool--lib
 SCRIPT_LIB += git-parse-remote
 SCRIPT_LIB += git-rebase--am
-SCRIPT_LIB += git-rebase--interactive
 SCRIPT_LIB += git-rebase--preserve-merges
 SCRIPT_LIB += git-rebase--merge
 SCRIPT_LIB += git-sh-setup
@@ -1060,8 +1059,8 @@ BUILTIN_OBJS += builtin/prune.o
 BUILTIN_OBJS += builtin/pull.o
 BUILTIN_OBJS += builtin/push.o
 BUILTIN_OBJS += builtin/read-tree.o
-BUILTIN_OBJS += builtin/rebase--interactive2.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
@@ -2400,7 +2399,6 @@ 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/rebase--interactive2.c b/builtin/rebase--interactive.c
similarity index 100%
rename from builtin/rebase--interactive2.c
rename to builtin/rebase--interactive.c
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
deleted file mode 100644
index e87d708a4d..0000000000
--- a/git-rebase--interactive.sh
+++ /dev/null
@@ -1,84 +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
-
-# 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} $allow_empty_message \
-		     --continue
-		;;
-	edit-todo)
-		exec git rebase--helper --edit-todo
-		;;
-	show-current-patch)
-		exec git show REBASE_HEAD --
-		;;
-	*)
-		return 1 # continue
-		;;
-	esac
-}
-
-git_rebase__interactive () {
-	initiate_action "$action"
-	ret=$?
-	if test $ret = 0; then
-		return 0
-	fi
-
-	test -n "$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_revisions" && restrict_revisions="--restrict-revisions=^$restrict_revisions"
-	test -n "$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=$cmd"
-
-	exec git rebase--interactive2 "$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" "$signoff"
-}
diff --git a/git-rebase.sh b/git-rebase.sh
index 0d78475cc0..48bc84456a 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -223,7 +223,7 @@ run_interactive () {
 	test -n "$cmd" && cmd="--cmd=$cmd"
 	test -n "$action" && action="--$action"
 
-	exec git rebase--interactive2 "$action" "$keep_empty" "$rebase_merges" "$rebase_cousins" \
+	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" \
diff --git a/git.c b/git.c
index 8309fb24a6..19d0b6e3b8 100644
--- a/git.c
+++ b/git.c
@@ -518,7 +518,7 @@ static struct cmd_struct commands[] = {
 	{ "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
 	{ "push", cmd_push, RUN_SETUP },
 	{ "read-tree", cmd_read_tree, RUN_SETUP | SUPPORT_SUPER_PREFIX},
-	{ "rebase--interactive2", cmd_rebase__interactive, RUN_SETUP | NEED_WORK_TREE },
+	{ "rebase--interactive", cmd_rebase__interactive, RUN_SETUP | NEED_WORK_TREE },
 	{ "rebase--helper", cmd_rebase__helper, RUN_SETUP | NEED_WORK_TREE },
 	{ "receive-pack", cmd_receive_pack },
 	{ "reflog", cmd_reflog, RUN_SETUP },

From 34b47315d9721a576b9536492cca0c11588113a2 Mon Sep 17 00:00:00 2001
From: Alban Gruin <alban.gruin@gmail.com>
Date: Thu, 27 Sep 2018 23:56:10 +0200
Subject: [PATCH 20/20] rebase -i: move rebase--helper modes to
 rebase--interactive

This moves the rebase--helper modes still used by
git-rebase--preserve-merges.sh (`--shorten-ids`, `--expand-ids`,
`--check-todo-list`, `--rearrange-squash` and `--add-exec-commands`) to
rebase--interactive.c.

git-rebase--preserve-merges.sh is modified accordingly, and
rebase--helper.c is removed as it is useless now.

Signed-off-by: Alban Gruin <alban.gruin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 .gitignore                     |   1 -
 Makefile                       |   1 -
 builtin.h                      |   1 -
 builtin/rebase--helper.c       | 226 ---------------------------------
 builtin/rebase--interactive.c  |  27 +++-
 git-rebase--preserve-merges.sh |  10 +-
 git.c                          |   1 -
 7 files changed, 31 insertions(+), 236 deletions(-)
 delete mode 100644 builtin/rebase--helper.c

diff --git a/.gitignore b/.gitignore
index 3284a1e9b1..406f26d050 100644
--- a/.gitignore
+++ b/.gitignore
@@ -116,7 +116,6 @@
 /git-read-tree
 /git-rebase
 /git-rebase--am
-/git-rebase--helper
 /git-rebase--interactive
 /git-rebase--merge
 /git-rebase--preserve-merges
diff --git a/Makefile b/Makefile
index 584834726d..ca3a0888dd 100644
--- a/Makefile
+++ b/Makefile
@@ -1059,7 +1059,6 @@ BUILTIN_OBJS += builtin/prune.o
 BUILTIN_OBJS += builtin/pull.o
 BUILTIN_OBJS += builtin/push.o
 BUILTIN_OBJS += builtin/read-tree.o
-BUILTIN_OBJS += builtin/rebase--helper.o
 BUILTIN_OBJS += builtin/rebase--interactive.o
 BUILTIN_OBJS += builtin/receive-pack.o
 BUILTIN_OBJS += builtin/reflog.o
diff --git a/builtin.h b/builtin.h
index ed89b4f495..7feb689d87 100644
--- a/builtin.h
+++ b/builtin.h
@@ -203,7 +203,6 @@ extern int cmd_pull(int argc, const char **argv, const char *prefix);
 extern int cmd_push(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__interactive(int argc, const char **argv, const char *prefix);
-extern int cmd_rebase__helper(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 f8128037d3..0000000000
--- a/builtin/rebase--helper.c
+++ /dev/null
@@ -1,226 +0,0 @@
-#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 "alias.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;
-	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);
-
-	if (revisions)
-		*revisions = xstrfmt("%s...%s", base_rev, *head_hash);
-	if (shortrevisions) {
-		const char *shorthead;
-
-		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 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, autosquash = 0;
-	int abbreviate_commands = 0, rebase_cousins = -1, ret;
-	const char *head_hash = NULL, *onto = NULL, *restrict_revision = NULL,
-		*squash_onto = NULL, *upstream = NULL, *head_name = NULL;
-	char *raw_strategies = NULL;
-	enum {
-		CONTINUE = 1, ABORT, MAKE_SCRIPT, SHORTEN_OIDS, EXPAND_OIDS,
-		CHECK_TODO_LIST, REARRANGE_SQUASH, ADD_EXEC, EDIT_TODO, PREPARE_BRANCH,
-		COMPLETE_ACTION, INIT_BASIC_STATE
-	} 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, "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, "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_CMDMODE(0, "edit-todo", &command,
-			    N_("edit the todo list during an interactive rebase"),
-			    EDIT_TODO),
-		OPT_CMDMODE(0, "prepare-branch", &command,
-			    N_("prepare the branch to be rebased"), PREPARE_BRANCH),
-		OPT_CMDMODE(0, "complete-action", &command,
-			    N_("complete the action"), COMPLETE_ACTION),
-		OPT_CMDMODE(0, "init-basic-state", &command,
-			    N_("initialise the rebase state"), INIT_BASIC_STATE),
-		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")),
-		OPT_STRING('S', "gpg-sign", &opts.gpg_sign, N_("gpg-sign"),
-			   N_("GPG-sign commits")),
-		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_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;
-
-	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) {
-		char *revisions = NULL;
-		struct argv_array make_script_args = ARGV_ARRAY_INIT;
-
-		if (!upstream && squash_onto)
-			write_file(path_squash_onto(), "%s\n", squash_onto);
-
-		ret = get_revision_ranges(upstream, onto, &head_hash, &revisions, NULL);
-		if (ret)
-			return ret;
-
-		argv_array_pushl(&make_script_args, "", revisions, NULL);
-		if (restrict_revision)
-			argv_array_push(&make_script_args, restrict_revision);
-
-		ret = sequencer_make_script(stdout,
-					    make_script_args.argc, make_script_args.argv,
-					    flags);
-
-		free(revisions);
-		argv_array_clear(&make_script_args);
-
-		return !!ret;
-	}
-	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 == REARRANGE_SQUASH && argc == 1)
-		return !!rearrange_squash();
-	if (command == ADD_EXEC && argc == 2)
-		return !!sequencer_add_exec_commands(argv[1]);
-	if (command == EDIT_TODO && argc == 1)
-		return !!edit_todo_list(flags);
-	if (command == PREPARE_BRANCH && argc == 2)
-		return !!prepare_branch_to_be_rebased(&opts, argv[1]);
-	if (command == COMPLETE_ACTION && argc == 3) {
-		char *shortrevisions = NULL;
-
-		ret = get_revision_ranges(upstream, onto, &head_hash, NULL, &shortrevisions);
-		if (ret)
-			return ret;
-
-		ret = complete_action(&opts, flags, shortrevisions, argv[1], onto,
-				      head_hash, argv[2], autosquash);
-
-		free(shortrevisions);
-		return !!ret;
-	}
-	if (command == INIT_BASIC_STATE) {
-		if (raw_strategies)
-			parse_strategy_opts(&opts, raw_strategies);
-
-		ret = get_revision_ranges(upstream, onto, &head_hash, NULL, NULL);
-		if (ret)
-			return ret;
-
-		return !!init_basic_state(&opts, head_name, onto, head_hash);
-	}
-
-	usage_with_options(builtin_rebase_helper_usage, options);
-}
diff --git a/builtin/rebase--interactive.c b/builtin/rebase--interactive.c
index aaf13c9621..a2ab68ed06 100644
--- a/builtin/rebase--interactive.c
+++ b/builtin/rebase--interactive.c
@@ -140,7 +140,8 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
 		*switch_to = NULL, *cmd = NULL;
 	char *raw_strategies = NULL;
 	enum {
-		NONE = 0, CONTINUE, SKIP, EDIT_TODO, SHOW_CURRENT_PATCH
+		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")),
@@ -161,6 +162,16 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
 			    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")),
@@ -203,6 +214,7 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
 	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 "
@@ -238,6 +250,19 @@ int cmd_rebase__interactive(int argc, const char **argv, const char *prefix)
 
 		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);
 	}
diff --git a/git-rebase--preserve-merges.sh b/git-rebase--preserve-merges.sh
index c51c7828e7..d43b4b582e 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=${todocount##* }
@@ -912,7 +912,7 @@ EOF
 	has_action "$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 19d0b6e3b8..81aabd1423 100644
--- a/git.c
+++ b/git.c
@@ -519,7 +519,6 @@ static struct cmd_struct commands[] = {
 	{ "push", cmd_push, RUN_SETUP },
 	{ "read-tree", cmd_read_tree, RUN_SETUP | SUPPORT_SUPER_PREFIX},
 	{ "rebase--interactive", cmd_rebase__interactive, RUN_SETUP | NEED_WORK_TREE },
-	{ "rebase--helper", cmd_rebase__helper, RUN_SETUP | NEED_WORK_TREE },
 	{ "receive-pack", cmd_receive_pack },
 	{ "reflog", cmd_reflog, RUN_SETUP },
 	{ "remote", cmd_remote, RUN_SETUP },