git/git-rebase--interactive.sh

# 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

# The rebase command lines that have already been processed.  A line
# is moved here when it is first handled, before any associated user
# actions.
done="$state_dir"/done

# The commit message that is planned to be used for any changes that
# need to be committed following a user interaction.
msg="$state_dir"/message

# The file into which is accumulated the suggested commit message for
# squash/fixup commands.  When the first of a series of squash/fixups
# is seen, the file is created and the commit message from the
# previous commit and from the first squash/fixup commit are written
# to it.  The commit message for each subsequent squash/fixup commit
# is appended to the file as it is processed.
#
# The first line of the file is of the form
#     # This is a combination of $count commits.
# where $count is the number of commits whose messages have been
# written to the file so far (including the initial "pick" commit).
# Each time that a commit message is processed, this line is read and
# updated.  It is deleted just before the combined commit is made.
squash_msg="$state_dir"/message-squash

# If the current series of squash/fixups has not yet included a squash
# command, then this file exists and holds the commit message of the
# original "pick" commit.  (If the series ends without a "squash"
# command, then this can be used as the commit message of the combined
# commit without opening the editor.)
fixup_msg="$state_dir"/message-fixup

# $rewritten is the name of a directory containing files for each
# commit that is reachable by at least one merge base of $head and
# $upstream. They are not necessarily rewritten, but their children
# might be.  This ensures that commits on merged, but otherwise
# unrelated side branches are left alone. (Think "X" in the man page's
# example.)
rewritten="$state_dir"/rewritten

dropped="$state_dir"/dropped

end="$state_dir"/end
msgnum="$state_dir"/msgnum

# A script to set the GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
# GIT_AUTHOR_DATE that will be used for the commit that is currently
# being rebased.
author_script="$state_dir"/author-script

# When an "edit" rebase command is being processed, the SHA1 of the
# commit to be edited is recorded in this file.  When "git rebase
# --continue" is executed, if there are any staged changes then they
# will be amended to the HEAD commit, but only provided the HEAD
# commit is still the commit to be edited.  When any other rebase
# command is processed, this file is deleted.
amend="$state_dir"/amend

# For the post-rewrite hook, we make a list of rewritten commits and
# their new sha1s.  The rewritten-pending list keeps the sha1s of
# commits that have been processed, but not committed yet,
# e.g. because they are waiting for a 'squash' command.
rewritten_list="$state_dir"/rewritten-list
rewritten_pending="$state_dir"/rewritten-pending

# Work around Git for Windows' Bash whose "read" does not strip CRLF
# and leaves CR at the end instead.
cr=$(printf "\015")

strategy_args=${strategy:+--strategy=$strategy}
test -n "$strategy_opts" &&
eval '
	for strategy_opt in '"$strategy_opts"'
	do
		strategy_args="$strategy_args -X$(git rev-parse --sq-quote "${strategy_opt#--}")"
	done
'

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

warn () {
	printf '%s\n' "$*" >&2
}

# Output the commit message for the specified commit.
commit_message () {
	git cat-file commit "$1" | sed "1,/^$/d"
}

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
}

last_count=
mark_action_done () {
	sed -e 1q < "$todo" >> "$done"
	sed -e 1d < "$todo" >> "$todo".new
	mv -f "$todo".new "$todo"
	new_count=$(( $(git stripspace --strip-comments <"$done" | wc -l) ))
	echo $new_count >"$msgnum"
	total=$(($new_count + $(git stripspace --strip-comments <"$todo" | wc -l)))
	echo $total >"$end"
	if test "$last_count" != "$new_count"
	then
		last_count=$new_count
		eval_gettext "Rebasing (\$new_count/\$total)"; printf "\r"
		test -z "$verbose" || echo
	fi
}

# Put the last action marked done at the beginning of the todo list
# again. If there has not been an action marked done yet, leave the list of
# items on the todo list unchanged.
reschedule_last_action () {
	tail -n 1 "$done" | cat - "$todo" >"$todo".new
	sed -e \$d <"$done" >"$done".new
	mv -f "$todo".new "$todo"
	mv -f "$done".new "$done"
}

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 <commit> = 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
}

make_patch () {
	sha1_and_parents="$(git rev-list --parents -1 "$1")"
	case "$sha1_and_parents" in
	?*' '?*' '?*)
		git diff --cc $sha1_and_parents
		;;
	?*' '?*)
		git diff-tree -p "$1^!"
		;;
	*)
		echo "Root commit"
		;;
	esac > "$state_dir"/patch
	test -f "$msg" ||
		commit_message "$1" > "$msg"
	test -f "$author_script" ||
		get_author_ident_from_commit "$1" > "$author_script"
}

die_with_patch () {
	echo "$1" > "$state_dir"/stopped-sha
	git update-ref REBASE_HEAD "$1"
	make_patch "$1"
	die "$2"
}

exit_with_patch () {
	echo "$1" > "$state_dir"/stopped-sha
	git update-ref REBASE_HEAD "$1"
	make_patch $1
	git rev-parse --verify HEAD > "$amend"
	gpg_sign_opt_quoted=${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")}
	warn "$(eval_gettext "\
You can amend the commit now, with

	git commit --amend \$gpg_sign_opt_quoted

Once you are satisfied with your changes, run

	git rebase --continue")"
	warn
	exit $2
}

die_abort () {
	apply_autostash
	rm -rf "$state_dir"
	die "$1"
}

has_action () {
	test -n "$(git stripspace --strip-comments <"$1")"
}

is_empty_commit() {
	tree=$(git rev-parse -q --verify "$1"^{tree} 2>/dev/null) || {
		sha1=$1
		die "$(eval_gettext "\$sha1: not a commit that can be picked")"
	}
	ptree=$(git rev-parse -q --verify "$1"^^{tree} 2>/dev/null) ||
		ptree=4b825dc642cb6eb9a060e54bf8d69288fbee4904
	test "$tree" = "$ptree"
}

is_merge_commit()
{
	git rev-parse --verify --quiet "$1"^2 >/dev/null 2>&1
}

# Run command with GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
# GIT_AUTHOR_DATE exported from the current environment.
do_with_author () {
	(
		export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE
		"$@"
	)
}

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 "$GIT_SEQUENCE_EDITOR" '"$@"'
}

pick_one () {
	ff=--ff

	case "$1" in -n) sha1=$2; ff= ;; *) sha1=$1 ;; esac
	case "$force_rebase" in '') ;; ?*) ff= ;; esac
	output git rev-parse --verify $sha1 || die "$(eval_gettext "Invalid commit name: \$sha1")"

	if is_empty_commit "$sha1"
	then
		empty_args="--allow-empty"
	fi

	test -d "$rewritten" &&
		pick_one_preserving_merges "$@" && return
	output eval git cherry-pick $allow_rerere_autoupdate $allow_empty_message \
			${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
			$signoff "$strategy_args" $empty_args $ff "$@"

	# If cherry-pick dies it leaves the to-be-picked commit unrecorded. Reschedule
	# previous task so this commit is not lost.
	ret=$?
	case "$ret" in [01]) ;; *) reschedule_last_action ;; esac
	return $ret
}

pick_one_preserving_merges () {
	fast_forward=t
	case "$1" in
	-n)
		fast_forward=f
		sha1=$2
		;;
	*)
		sha1=$1
		;;
	esac
	sha1=$(git rev-parse $sha1)

	if test -f "$state_dir"/current-commit && test "$fast_forward" = t
	then
		while read current_commit
		do
			git rev-parse HEAD > "$rewritten"/$current_commit
		done <"$state_dir"/current-commit
		rm "$state_dir"/current-commit ||
			die "$(gettext "Cannot write current commit's replacement sha1")"
	fi

	echo $sha1 >> "$state_dir"/current-commit

	# rewrite parents; if none were rewritten, we can fast-forward.
	new_parents=
	pend=" $(git rev-list --parents -1 $sha1 | cut -d' ' -s -f2-)"
	if test "$pend" = " "
	then
		pend=" root"
	fi
	while [ "$pend" != "" ]
	do
		p=$(expr "$pend" : ' \([^ ]*\)')
		pend="${pend# $p}"

		if test -f "$rewritten"/$p
		then
			new_p=$(cat "$rewritten"/$p)

			# If the todo reordered commits, and our parent is marked for
			# rewriting, but hasn't been gotten to yet, assume the user meant to
			# drop it on top of the current HEAD
			if test -z "$new_p"
			then
				new_p=$(git rev-parse HEAD)
			fi

			test $p != $new_p && fast_forward=f
			case "$new_parents" in
			*$new_p*)
				;; # do nothing; that parent is already there
			*)
				new_parents="$new_parents $new_p"
				;;
			esac
		else
			if test -f "$dropped"/$p
			then
				fast_forward=f
				replacement="$(cat "$dropped"/$p)"
				test -z "$replacement" && replacement=root
				pend=" $replacement$pend"
			else
				new_parents="$new_parents $p"
			fi
		fi
	done
	case $fast_forward in
	t)
		output warn "$(eval_gettext "Fast-forward to \$sha1")"
		output git reset --hard $sha1 ||
			die "$(eval_gettext "Cannot fast-forward to \$sha1")"
		;;
	f)
		first_parent=$(expr "$new_parents" : ' \([^ ]*\)')

		if [ "$1" != "-n" ]
		then
			# detach HEAD to current parent
			output git checkout $first_parent 2> /dev/null ||
				die "$(eval_gettext "Cannot move HEAD to \$first_parent")"
		fi

		case "$new_parents" in
		' '*' '*)
			test "a$1" = a-n && die "$(eval_gettext "Refusing to squash a merge: \$sha1")"

			# redo merge
			author_script_content=$(get_author_ident_from_commit $sha1)
			eval "$author_script_content"
			msg_content="$(commit_message $sha1)"
			# No point in merging the first parent, that's HEAD
			new_parents=${new_parents# $first_parent}
			merge_args="--no-log --no-ff"
			if ! do_with_author output eval \
				git merge ${gpg_sign_opt:+$(git rev-parse \
					--sq-quote "$gpg_sign_opt")} \
				$allow_rerere_autoupdate "$merge_args" \
				"$strategy_args" \
				-m "$(git rev-parse --sq-quote "$msg_content")" \
				"$new_parents"
			then
				printf "%s\n" "$msg_content" > "$GIT_DIR"/MERGE_MSG
				die_with_patch $sha1 "$(eval_gettext "Error redoing merge \$sha1")"
			fi
			echo "$sha1 $(git rev-parse HEAD^0)" >> "$rewritten_list"
			;;
		*)
			output eval git cherry-pick $allow_rerere_autoupdate \
				$allow_empty_message \
				${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
				"$strategy_args" "$@" ||
				die_with_patch $sha1 "$(eval_gettext "Could not pick \$sha1")"
			;;
		esac
		;;
	esac
}

this_nth_commit_message () {
	n=$1
	eval_gettext "This is the commit message #\${n}:"
}

skip_nth_commit_message () {
	n=$1
	eval_gettext "The commit message #\${n} will be skipped:"
}

update_squash_messages () {
	if test -f "$squash_msg"; then
		mv "$squash_msg" "$squash_msg".bak || exit
		count=$(($(sed -n \
			-e "1s/^$comment_char[^0-9]*\([0-9][0-9]*\).*/\1/p" \
			-e "q" < "$squash_msg".bak)+1))
		{
			printf '%s\n' "$comment_char $(eval_ngettext \
				"This is a combination of \$count commit." \
				"This is a combination of \$count commits." \
				$count)"
			sed -e 1d -e '2,/^./{
				/^$/d
			}' <"$squash_msg".bak
		} >"$squash_msg"
	else
		commit_message HEAD >"$fixup_msg" ||
		die "$(eval_gettext "Cannot write \$fixup_msg")"
		count=2
		{
			printf '%s\n' "$comment_char $(gettext "This is a combination of 2 commits.")"
			printf '%s\n' "$comment_char $(gettext "This is the 1st commit message:")"
			echo
			cat "$fixup_msg"
		} >"$squash_msg"
	fi
	case $1 in
	squash)
		rm -f "$fixup_msg"
		echo
		printf '%s\n' "$comment_char $(this_nth_commit_message $count)"
		echo
		commit_message $2
		;;
	fixup)
		echo
		printf '%s\n' "$comment_char $(skip_nth_commit_message $count)"
		echo
		# Change the space after the comment character to TAB:
		commit_message $2 | git stripspace --comment-lines | sed -e 's/ /	/'
		;;
	esac >>"$squash_msg"
}

peek_next_command () {
	git stripspace --strip-comments <"$todo" | sed -n -e 's/ .*//p' -e q
}

# A squash/fixup has failed.  Prepare the long version of the squash
# commit message, then die_with_patch.  This code path requires the
# user to edit the combined commit message for all commits that have
# been squashed/fixedup so far.  So also erase the old squash
# messages, effectively causing the combined commit to be used as the
# new basis for any further squash/fixups.  Args: sha1 rest
die_failed_squash() {
	sha1=$1
	rest=$2
	mv "$squash_msg" "$msg" || exit
	rm -f "$fixup_msg"
	cp "$msg" "$GIT_DIR"/MERGE_MSG || exit
	warn
	warn "$(eval_gettext "Could not apply \$sha1... \$rest")"
	die_with_patch $sha1 ""
}

flush_rewritten_pending() {
	test -s "$rewritten_pending" || return
	newsha1="$(git rev-parse HEAD^0)"
	sed "s/$/ $newsha1/" < "$rewritten_pending" >> "$rewritten_list"
	rm -f "$rewritten_pending"
}

record_in_rewritten() {
	oldsha1="$(git rev-parse $1)"
	echo "$oldsha1" >> "$rewritten_pending"

	case "$(peek_next_command)" in
	squash|s|fixup|f)
		;;
	*)
		flush_rewritten_pending
		;;
	esac
}

do_pick () {
	sha1=$1
	rest=$2
	if test "$(git rev-parse HEAD)" = "$squash_onto"
	then
		# Set the correct commit message and author info on the
		# sentinel root before cherry-picking the original changes
		# without committing (-n).  Finally, update the sentinel again
		# to include these changes.  If the cherry-pick results in a
		# conflict, this means our behaviour is similar to a standard
		# failed cherry-pick during rebase, with a dirty index to
		# resolve before manually running git commit --amend then git
		# rebase --continue.
		git commit --allow-empty --allow-empty-message --amend \
			   --no-post-rewrite -n -q -C $sha1 $signoff &&
			pick_one -n $sha1 &&
			git commit --allow-empty --allow-empty-message \
				   --amend --no-post-rewrite -n -q -C $sha1 $signoff \
				   ${gpg_sign_opt:+"$gpg_sign_opt"} ||
				   die_with_patch $sha1 "$(eval_gettext "Could not apply \$sha1... \$rest")"
	else
		pick_one $sha1 ||
			die_with_patch $sha1 "$(eval_gettext "Could not apply \$sha1... \$rest")"
	fi
}

do_next () {
	rm -f "$msg" "$author_script" "$amend" "$state_dir"/stopped-sha || exit
	read -r command sha1 rest < "$todo"
	case "$command" in
	"$comment_char"*|''|noop|drop|d)
		mark_action_done
		;;
	"$cr")
		# Work around CR left by "read" (e.g. with Git for Windows' Bash).
		mark_action_done
		;;
	pick|p)
		comment_for_reflog pick

		mark_action_done
		do_pick $sha1 "$rest"
		record_in_rewritten $sha1
		;;
	reword|r)
		comment_for_reflog reword

		mark_action_done
		do_pick $sha1 "$rest"
		git commit --amend --no-post-rewrite ${gpg_sign_opt:+"$gpg_sign_opt"} \
			$allow_empty_message || {
			warn "$(eval_gettext "\
Could not amend commit after successfully picking \$sha1... \$rest
This is most likely due to an empty commit message, or the pre-commit hook
failed. If the pre-commit hook failed, you may need to resolve the issue before
you are able to reword the commit.")"
			exit_with_patch $sha1 1
		}
		record_in_rewritten $sha1
		;;
	edit|e)
		comment_for_reflog edit

		mark_action_done
		do_pick $sha1 "$rest"
		sha1_abbrev=$(git rev-parse --short $sha1)
		warn "$(eval_gettext "Stopped at \$sha1_abbrev... \$rest")"
		exit_with_patch $sha1 0
		;;
	squash|s|fixup|f)
		case "$command" in
		squash|s)
			squash_style=squash
			;;
		fixup|f)
			squash_style=fixup
			;;
		esac
		comment_for_reflog $squash_style

		test -f "$done" && has_action "$done" ||
			die "$(eval_gettext "Cannot '\$squash_style' without a previous commit")"

		mark_action_done
		update_squash_messages $squash_style $sha1
		author_script_content=$(get_author_ident_from_commit HEAD)
		echo "$author_script_content" > "$author_script"
		eval "$author_script_content"
		if ! pick_one -n $sha1
		then
			git rev-parse --verify HEAD >"$amend"
			die_failed_squash $sha1 "$rest"
		fi
		case "$(peek_next_command)" in
		squash|s|fixup|f)
			# This is an intermediate commit; its message will only be
			# used in case of trouble.  So use the long version:
			do_with_author output git commit --amend --no-verify -F "$squash_msg" \
				${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
				die_failed_squash $sha1 "$rest"
			;;
		*)
			# This is the final command of this squash/fixup group
			if test -f "$fixup_msg"
			then
				do_with_author git commit --amend --no-verify -F "$fixup_msg" \
					${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
					die_failed_squash $sha1 "$rest"
			else
				cp "$squash_msg" "$GIT_DIR"/SQUASH_MSG || exit
				rm -f "$GIT_DIR"/MERGE_MSG
				do_with_author git commit --amend --no-verify -F "$GIT_DIR"/SQUASH_MSG -e \
					${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
					die_failed_squash $sha1 "$rest"
			fi
			rm -f "$squash_msg" "$fixup_msg"
			;;
		esac
		record_in_rewritten $sha1
		;;
	x|"exec")
		read -r command rest < "$todo"
		mark_action_done
		eval_gettextln "Executing: \$rest"
		"${SHELL:-@SHELL_PATH@}" -c "$rest" # Actual execution
		status=$?
		# Run in subshell because require_clean_work_tree can die.
		dirty=f
		(require_clean_work_tree "rebase" 2>/dev/null) || dirty=t
		if test "$status" -ne 0
		then
			warn "$(eval_gettext "Execution failed: \$rest")"
			test "$dirty" = f ||
				warn "$(gettext "and made changes to the index and/or the working tree")"

			warn "$(gettext "\
You can fix the problem, and then run

	git rebase --continue")"
			warn
			if test $status -eq 127		# command not found
			then
				status=1
			fi
			exit "$status"
		elif test "$dirty" = t
		then
			# TRANSLATORS: after these lines is a command to be issued by the user
			warn "$(eval_gettext "\
Execution succeeded: \$rest
but left changes to the index and/or the working tree
Commit or stash your changes, and then run

	git rebase --continue")"
			warn
			exit 1
		fi
		;;
	*)
		warn "$(eval_gettext "Unknown command: \$command \$sha1 \$rest")"
		fixtodo="$(gettext "Please fix this using 'git rebase --edit-todo'.")"
		if git rev-parse --verify -q "$sha1" >/dev/null
		then
			die_with_patch $sha1 "$fixtodo"
		else
			die "$fixtodo"
		fi
		;;
	esac
	test -s "$todo" && return

	comment_for_reflog finish &&
	newhead=$(git rev-parse HEAD) &&
	case $head_name in
	refs/*)
		message="$GIT_REFLOG_ACTION: $head_name onto $onto" &&
		git update-ref -m "$message" $head_name $newhead $orig_head &&
		git symbolic-ref \
		  -m "$GIT_REFLOG_ACTION: returning to $head_name" \
		  HEAD $head_name
		;;
	esac && {
		test ! -f "$state_dir"/verbose ||
			git diff-tree --stat $orig_head..HEAD
	} &&
	{
		test -s "$rewritten_list" &&
		git notes copy --for-rewrite=rebase < "$rewritten_list" ||
		true # we don't care if this copying failed
	} &&
	hook="$(git rev-parse --git-path hooks/post-rewrite)"
	if test -x "$hook" && test -s "$rewritten_list"; then
		"$hook" rebase < "$rewritten_list"
		true # we don't care if this hook failed
	fi &&
		warn "$(eval_gettext "Successfully rebased and updated \$head_name.")"

	return 1 # not failure; just to break the do_rest loop
}

# can only return 0, when the infinite loop breaks
do_rest () {
	while :
	do
		do_next || break
	done
}

expand_todo_ids() {
	git rebase--helper --expand-ids
}

collapse_todo_ids() {
	git rebase--helper --shorten-ids
}

# Switch to the branch in $into and notify it in the reflog
checkout_onto () {
	GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name"
	output git checkout $onto || die_abort "$(gettext "could not detach HEAD")"
	git update-ref ORIG_HEAD $orig_head
}

get_missing_commit_check_level () {
	check_level=$(git config --get rebase.missingCommitsCheck)
	check_level=${check_level:-ignore}
	# Don't be case sensitive
	printf '%s' "$check_level" | tr 'A-Z' 'a-z'
}

# Initiate an action. If the cannot be any
# further action it  may exec a command
# or exit and not return.
#
# TODO: Consider a cleaner return model so it
# never exits and always return 0 if process
# is complete.
#
# Parameter 1 is the action to initiate.
#
# Returns 0 if the action was able to complete
# and if 1 if further processing is required.
initiate_action () {
	case "$1" in
	continue)
		if test ! -d "$rewritten"
		then
			exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
				--continue
		fi
		# do we have anything to commit?
		if git diff-index --cached --quiet HEAD --
		then
			# Nothing to commit -- skip this commit

			test ! -f "$GIT_DIR"/CHERRY_PICK_HEAD ||
			rm "$GIT_DIR"/CHERRY_PICK_HEAD ||
			die "$(gettext "Could not remove CHERRY_PICK_HEAD")"
		else
			if ! test -f "$author_script"
			then
				gpg_sign_opt_quoted=${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")}
				die "$(eval_gettext "\
You have staged changes in your working tree.
If these changes are meant to be
squashed into the previous commit, run:

  git commit --amend \$gpg_sign_opt_quoted

If they are meant to go into a new commit, run:

  git commit \$gpg_sign_opt_quoted

In both cases, once you're done, continue with:

  git rebase --continue
")"
			fi
			. "$author_script" ||
				die "$(gettext "Error trying to find the author identity to amend commit")"
			if test -f "$amend"
			then
				current_head=$(git rev-parse --verify HEAD)
				test "$current_head" = $(cat "$amend") ||
				die "$(gettext "\
You have uncommitted changes in your working tree. Please commit them
first and then run 'git rebase --continue' again.")"
				do_with_author git commit --amend --no-verify -F "$msg" -e \
					${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
					die "$(gettext "Could not commit staged changes.")"
			else
				do_with_author git commit --no-verify -F "$msg" -e \
					${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
					die "$(gettext "Could not commit staged changes.")"
			fi
		fi

		if test -r "$state_dir"/stopped-sha
		then
			record_in_rewritten "$(cat "$state_dir"/stopped-sha)"
		fi

		require_clean_work_tree "rebase"
		do_rest
		return 0
		;;
	skip)
		git rerere clear

		if test ! -d "$rewritten"
		then
			exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
				--continue
		fi
		do_rest
		return 0
		;;
	edit-todo)
		git stripspace --strip-comments <"$todo" >"$todo".new
		mv -f "$todo".new "$todo"
		collapse_todo_ids
		append_todo_help
		gettext "
You are editing the todo file of an ongoing interactive rebase.
To continue rebase after editing, run:
    git rebase --continue

" | git stripspace --comment-lines >>"$todo"

		git_sequence_editor "$todo" ||
			die "$(gettext "Could not execute editor")"
		expand_todo_ids

		exit
		;;
	show-current-patch)
		exec git show REBASE_HEAD --
		;;
	*)
		return 1 # continue
		;;
	esac
}

setup_reflog_action () {
	comment_for_reflog start

	if test ! -z "$switch_to"
	then
		GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $switch_to"
		output git checkout "$switch_to" -- ||
			die "$(eval_gettext "Could not checkout \$switch_to")"

		comment_for_reflog start
	fi
}

init_basic_state () {
	orig_head=$(git rev-parse --verify HEAD) || die "$(gettext "No HEAD?")"
	mkdir -p "$state_dir" || die "$(eval_gettext "Could not create temporary \$state_dir")"
	rm -f "$(git rev-parse --git-path REBASE_HEAD)"

	: > "$state_dir"/interactive || die "$(gettext "Could not mark as interactive")"
	write_basic_state
}

init_revisions_and_shortrevisions () {
	shorthead=$(git rev-parse --short $orig_head)
	shortonto=$(git rev-parse --short $onto)
	if test -z "$rebase_root"
		# this is now equivalent to ! -z "$upstream"
	then
		shortupstream=$(git rev-parse --short $upstream)
		revisions=$upstream...$orig_head
		shortrevisions=$shortupstream..$shorthead
	else
		revisions=$onto...$orig_head
		shortrevisions=$shorthead
	fi
}

complete_action() {
	test -s "$todo" || echo noop >> "$todo"
	test -z "$autosquash" || git rebase--helper --rearrange-squash || exit
	test -n "$cmd" && git rebase--helper --add-exec-commands "$cmd"

	todocount=$(git stripspace --strip-comments <"$todo" | wc -l)
	todocount=${todocount##* }

cat >>"$todo" <<EOF

$comment_char $(eval_ngettext \
	"Rebase \$shortrevisions onto \$shortonto (\$todocount command)" \
	"Rebase \$shortrevisions onto \$shortonto (\$todocount commands)" \
	"$todocount")
EOF
	append_todo_help
	gettext "
	However, if you remove everything, the rebase will be aborted.

	" | git stripspace --comment-lines >>"$todo"

	if test -z "$keep_empty"
	then
		printf '%s\n' "$comment_char $(gettext "Note that empty commits are commented out")" >>"$todo"
	fi


	has_action "$todo" ||
		return 2

	cp "$todo" "$todo".backup
	collapse_todo_ids
	git_sequence_editor "$todo" ||
		die_abort "$(gettext "Could not execute editor")"

	has_action "$todo" ||
		return 2

	git rebase--helper --check-todo-list || {
		ret=$?
		checkout_onto
		exit $ret
	}

	expand_todo_ids

	test -d "$rewritten" || test -n "$force_rebase" ||
	onto="$(git rebase--helper --skip-unnecessary-picks)" ||
	die "Could not skip unnecessary pick commands"

	checkout_onto
	if test -z "$rebase_root" && test ! -d "$rewritten"
	then
		require_clean_work_tree "rebase"
		exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
			--continue
	fi
	do_rest
}

git_rebase__interactive () {
	initiate_action "$action"
	ret=$?
	if test $ret = 0; then
		return 0
	fi

	setup_reflog_action
	init_basic_state

	init_revisions_and_shortrevisions

	git rebase--helper --make-script ${keep_empty:+--keep-empty} \
		${rebase_merges:+--rebase-merges} \
		$revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
	die "$(gettext "Could not generate todo list")"

	complete_action
}

git_rebase__interactive__preserve_merges () {
	initiate_action "$action"
	ret=$?
	if test $ret = 0; then
		return 0
	fi

	setup_reflog_action
	init_basic_state

	if test -z "$rebase_root"
	then
		mkdir "$rewritten" &&
		for c in $(git merge-base --all $orig_head $upstream)
		do
			echo $onto > "$rewritten"/$c ||
				die "$(gettext "Could not init rewritten commits")"
		done
	else
		mkdir "$rewritten" &&
		echo $onto > "$rewritten"/root ||
			die "$(gettext "Could not init rewritten commits")"
	fi

	init_revisions_and_shortrevisions

	format=$(git config --get rebase.instructionFormat)
	# the 'rev-list .. | sed' requires %m to parse; the instruction requires %H to parse
	git rev-list --format="%m%H ${format:-%s}" \
		--reverse --left-right --topo-order \
		$revisions ${restrict_revision+^$restrict_revision} | \
		sed -n "s/^>//p" |
	while read -r sha1 rest
	do
		if test -z "$keep_empty" && is_empty_commit $sha1 && ! is_merge_commit $sha1
		then
			comment_out="$comment_char "
		else
			comment_out=
		fi

		if test -z "$rebase_root"
		then
			preserve=t
			for p in $(git rev-list --parents -1 $sha1 | cut -d' ' -s -f2-)
			do
				if test -f "$rewritten"/$p
				then
					preserve=f
				fi
			done
		else
			preserve=f
		fi
		if test f = "$preserve"
		then
			touch "$rewritten"/$sha1
			printf '%s\n' "${comment_out}pick $sha1 $rest" >>"$todo"
		fi
	done

	# Watch for commits that been dropped by --cherry-pick
	mkdir "$dropped"
	# Save all non-cherry-picked changes
	git rev-list $revisions --left-right --cherry-pick | \
		sed -n "s/^>//p" > "$state_dir"/not-cherry-picks
	# Now all commits and note which ones are missing in
	# not-cherry-picks and hence being dropped
	git rev-list $revisions |
	while read rev
	do
		if test -f "$rewritten"/$rev &&
		   ! sane_grep "$rev" "$state_dir"/not-cherry-picks >/dev/null
		then
			# Use -f2 because if rev-list is telling us this commit is
			# not worthwhile, we don't want to track its multiple heads,
			# just the history of its first-parent for others that will
			# be rebasing on top of it
			git rev-list --parents -1 $rev | cut -d' ' -s -f2 > "$dropped"/$rev
			sha1=$(git rev-list -1 $rev)
			sane_grep -v "^[a-z][a-z]* $sha1" <"$todo" > "${todo}2" ; mv "${todo}2" "$todo"
			rm "$rewritten"/$rev
		fi
	done

	complete_action
}