rebase: extend --signoff support

Allow --signoff to be used with --interactive and --merge. In
interactive mode only commits marked to be picked, edited or reworded
will be signed off.

The main motivation for this patch was to allow one to run 'git rebase
--exec "make check" --signoff' which is useful when preparing a patch
series for publication and is more convenient than doing the signoff
with another --exec command.

This change also allows --root without --onto to work with --signoff
as well (--root with --onto was already supported).

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 72 insertions, 9 deletions

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 8a861c1e0d..86a887a9c5 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -354,9 +354,10 @@ default is `--no-fork-point`, otherwise the default is `--fork-point`.
 	Incompatible with the --interactive option.
 
 --signoff::
-	This flag is passed to 'git am' to sign off all the rebased
-	commits (see linkgit:git-am[1]). Incompatible with the
-	--interactive option.
+	Add a Signed-off-by: trailer to all the rebased commits. Note
+	that if `--interactive` is given then only commits marked to be
+	picked, edited or reworded will have the trailer added. Incompatible
+	with the `--preserve-merges` option.
 
 -i::
 --interactive::
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index d47bd29593..2bcdb67982 100644
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -283,7 +283,7 @@ pick_one () {
 		pick_one_preserving_merges "$@" && return
 	output eval git cherry-pick $allow_rerere_autoupdate \
 			${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
-			"$strategy_args" $empty_args $ff "$@"
+			$signoff "$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.
@@ -524,10 +524,10 @@ do_pick () {
 		# 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 &&
+			   --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 \
+				   --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
diff --git a/git-rebase--merge.sh b/git-rebase--merge.sh
index 06a4723d4d..9a60cef052 100644
--- a/git-rebase--merge.sh
+++ b/git-rebase--merge.sh
@@ -27,7 +27,7 @@ continue_merge () {
 	cmt=$(cat "$state_dir/current")
 	if ! git diff-index --quiet --ignore-submodules HEAD --
 	then
-		if ! git commit ${gpg_sign_opt:+"$gpg_sign_opt"} --no-verify -C "$cmt"
+		if ! git commit ${gpg_sign_opt:+"$gpg_sign_opt"} $signoff --no-verify -C "$cmt"
 		then
 			echo "Commit failed, please do not call \"git commit\""
 			echo "directly, but instead do one of the following: "
diff --git a/git-rebase.sh b/git-rebase.sh
index 37b8f13971..5a5a65f3d2 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -90,6 +90,7 @@ action=
 preserve_merges=
 autosquash=
 keep_empty=
+signoff=
 test "$(git config --bool rebase.autosquash)" = "true" && autosquash=t
 case "$(git config --bool commit.gpgsign)" in
 true)	gpg_sign_opt=-S ;;
@@ -119,6 +120,10 @@ read_basic_state () {
 		allow_rerere_autoupdate="$(cat "$state_dir"/allow_rerere_autoupdate)"
 	test -f "$state_dir"/gpg_sign_opt &&
 		gpg_sign_opt="$(cat "$state_dir"/gpg_sign_opt)"
+	test -f "$state_dir"/signoff && {
+		signoff="$(cat "$state_dir"/signoff)"
+		force_rebase=t
+	}
 }
 
 write_basic_state () {
@@ -133,6 +138,7 @@ write_basic_state () {
 	test -n "$allow_rerere_autoupdate" && echo "$allow_rerere_autoupdate" > \
 		"$state_dir"/allow_rerere_autoupdate
 	test -n "$gpg_sign_opt" && echo "$gpg_sign_opt" > "$state_dir"/gpg_sign_opt
+	test -n "$signoff" && echo "$signoff" >"$state_dir"/signoff
 }
 
 output () {
@@ -328,7 +334,13 @@ do
 	--ignore-whitespace)
 		git_am_opt="$git_am_opt $1"
 		;;
-	--committer-date-is-author-date|--ignore-date|--signoff|--no-signoff)
+	--signoff)
+		signoff=--signoff
+		;;
+	--no-signoff)
+		signoff=
+		;;
+	--committer-date-is-author-date|--ignore-date)
 		git_am_opt="$git_am_opt $1"
 		force_rebase=t
 		;;
@@ -458,6 +470,12 @@ then
 	git_format_patch_opt="$git_format_patch_opt --progress"
 fi
 
+if test -n "$signoff"
+then
+	git_am_opt="$git_am_opt $signoff"
+	force_rebase=t
+fi
+
 if test -z "$rebase_root"
 then
 	case "$#" in
diff --git a/sequencer.c b/sequencer.c
index 45aa7e3072..4aeaef20e7 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -127,6 +127,7 @@ static GIT_PATH_FUNC(rebase_path_rewritten_pending,
 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")
 static GIT_PATH_FUNC(rebase_path_verbose, "rebase-merge/verbose")
+static GIT_PATH_FUNC(rebase_path_signoff, "rebase-merge/signoff")
 static GIT_PATH_FUNC(rebase_path_head_name, "rebase-merge/head-name")
 static GIT_PATH_FUNC(rebase_path_onto, "rebase-merge/onto")
 static GIT_PATH_FUNC(rebase_path_autostash, "rebase-merge/autostash")
@@ -1605,7 +1606,7 @@ static int do_pick_commit(enum todo_command command, struct commit *commit,
 		}
 	}
 
-	if (opts->signoff)
+	if (opts->signoff && !is_fixup(command))
 		append_signoff(&msgbuf, 0, 0);
 
 	if (is_rebase_i(opts) && write_author_script(msg.message) < 0)
@@ -2035,6 +2036,11 @@ static int read_populate_opts(struct replay_opts *opts)
 		if (file_exists(rebase_path_verbose()))
 			opts->verbose = 1;
 
+		if (file_exists(rebase_path_signoff())) {
+			opts->allow_ff = 0;
+			opts->signoff = 1;
+		}
+
 		read_strategy_opts(opts, &buf);
 		strbuf_release(&buf);
 
diff --git a/t/t3428-rebase-signoff.sh b/t/t3428-rebase-signoff.sh
index 2afb564701..f6993b7e14 100755
--- a/t/t3428-rebase-signoff.sh
+++ b/t/t3428-rebase-signoff.sh
@@ -12,6 +12,13 @@ cat >file <<EOF
 a
 EOF
 
+# Expected commit message for initial commit after rebase --signoff
+cat >expected-initial-signed <<EOF
+Initial empty commit
+
+Signed-off-by: $(git var GIT_COMMITTER_IDENT | sed -e "s/>.*/>/")
+EOF
+
 # Expected commit message after rebase --signoff
 cat >expected-signed <<EOF
 first
@@ -43,4 +50,35 @@ test_expect_success 'rebase --no-signoff does not add a sign-off line' '
 	test_cmp expected-unsigned actual
 '
 
+test_expect_success 'rebase --exec --signoff adds a sign-off line' '
+	test_when_finished "rm exec" &&
+	git commit --amend -m "first" &&
+	git rebase --exec "touch exec" --signoff HEAD^ &&
+	test_path_is_file exec &&
+	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	test_cmp expected-signed actual
+'
+
+test_expect_success 'rebase --root --signoff adds a sign-off line' '
+	git commit --amend -m "first" &&
+	git rebase --root --keep-empty --signoff &&
+	git cat-file commit HEAD^ | sed -e "1,/^\$/d" >actual &&
+	test_cmp expected-initial-signed actual &&
+	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	test_cmp expected-signed actual
+'
+
+test_expect_success 'rebase -i --signoff fails' '
+	git commit --amend -m "first" &&
+	git rebase -i --signoff HEAD^ &&
+	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	test_cmp expected-signed actual
+'
+
+test_expect_success 'rebase -m --signoff fails' '
+	git commit --amend -m "first" &&
+	git rebase -m --signoff HEAD^ &&
+	git cat-file commit HEAD | sed -e "1,/^\$/d" >actual &&
+	test_cmp expected-signed actual
+'
 test_done