Merge branch 'jn/revert-quit'

* jn/revert-quit:
  revert: remove --reset compatibility option
  revert: introduce --abort to cancel a failed cherry-pick
  revert: write REVERT_HEAD pseudoref during conflicted revert
  revert: improve error message for cherry-pick during cherry-pick
  revert: rearrange pick_revisions() for clarity
  revert: rename --reset option to --quit

10 files changed, 314 insertions, 54 deletions

diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 2660a842fc..fed5097e00 100644
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -9,8 +9,9 @@ SYNOPSIS
 --------
 [verse]
 'git cherry-pick' [--edit] [-n] [-m parent-number] [-s] [-x] [--ff] <commit>...
-'git cherry-pick' --reset
 'git cherry-pick' --continue
+'git cherry-pick' --quit
+'git cherry-pick' --abort
 
 DESCRIPTION
 -----------
diff --git a/Documentation/git-revert.txt b/Documentation/git-revert.txt
index f3519413e7..b699a3458e 100644
--- a/Documentation/git-revert.txt
+++ b/Documentation/git-revert.txt
@@ -9,8 +9,9 @@ SYNOPSIS
 --------
 [verse]
 'git revert' [--edit | --no-edit] [-n] [-m parent-number] [-s] <commit>...
-'git revert' --reset
 'git revert' --continue
+'git revert' --quit
+'git revert' --abort
 
 DESCRIPTION
 -----------
diff --git a/Documentation/sequencer.txt b/Documentation/sequencer.txt
index 3e6df338be..5747f442f2 100644
--- a/Documentation/sequencer.txt
+++ b/Documentation/sequencer.txt
@@ -1,9 +1,12 @@
---reset::
-	Forget about the current operation in progress.  Can be used
-	to clear the sequencer state after a failed cherry-pick or
-	revert.
-
 --continue::
 	Continue the operation in progress using the information in
 	'.git/sequencer'.  Can be used to continue after resolving
 	conflicts in a failed cherry-pick or revert.
+
+--quit::
+	Forget about the current operation in progress.  Can be used
+	to clear the sequencer state after a failed cherry-pick or
+	revert.
+
+--abort::
+	Cancel the operation and return to the pre-sequence state.
diff --git a/branch.c b/branch.c
index d8098762f6..025a97be02 100644
--- a/branch.c
+++ b/branch.c
@@ -241,6 +241,7 @@ void create_branch(const char *head,
 void remove_branch_state(void)
 {
 	unlink(git_path("CHERRY_PICK_HEAD"));
+	unlink(git_path("REVERT_HEAD"));
 	unlink(git_path("MERGE_HEAD"));
 	unlink(git_path("MERGE_RR"));
 	unlink(git_path("MERGE_MSG"));
diff --git a/builtin/commit.c b/builtin/commit.c
index c46f2d18e1..8f2bebecf3 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1514,6 +1514,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 	}
 
 	unlink(git_path("CHERRY_PICK_HEAD"));
+	unlink(git_path("REVERT_HEAD"));
 	unlink(git_path("MERGE_HEAD"));
 	unlink(git_path("MERGE_MSG"));
 	unlink(git_path("MERGE_MODE"));
diff --git a/builtin/revert.c b/builtin/revert.c
index 544e8c3057..0c61668b85 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -40,7 +40,12 @@ static const char * const cherry_pick_usage[] = {
 };
 
 enum replay_action { REVERT, CHERRY_PICK };
-enum replay_subcommand { REPLAY_NONE, REPLAY_RESET, REPLAY_CONTINUE };
+enum replay_subcommand {
+	REPLAY_NONE,
+	REPLAY_REMOVE_STATE,
+	REPLAY_CONTINUE,
+	REPLAY_ROLLBACK
+};
 
 struct replay_opts {
 	enum replay_action action;
@@ -133,11 +138,13 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 {
 	const char * const * usage_str = revert_or_cherry_pick_usage(opts);
 	const char *me = action_name(opts);
-	int reset = 0;
+	int remove_state = 0;
 	int contin = 0;
+	int rollback = 0;
 	struct option options[] = {
-		OPT_BOOLEAN(0, "reset", &reset, "forget the current operation"),
-		OPT_BOOLEAN(0, "continue", &contin, "continue the current operation"),
+		OPT_BOOLEAN(0, "quit", &remove_state, "end revert or cherry-pick sequence"),
+		OPT_BOOLEAN(0, "continue", &contin, "resume revert or cherry-pick sequence"),
+		OPT_BOOLEAN(0, "abort", &rollback, "cancel revert or cherry-pick sequence"),
 		OPT_BOOLEAN('n', "no-commit", &opts->no_commit, "don't automatically commit"),
 		OPT_BOOLEAN('e', "edit", &opts->edit, "edit the commit message"),
 		OPT_NOOP_NOARG('r', NULL),
@@ -168,25 +175,32 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 
 	/* Check for incompatible subcommands */
 	verify_opt_mutually_compatible(me,
-				"--reset", reset,
+				"--quit", remove_state,
 				"--continue", contin,
+				"--abort", rollback,
 				NULL);
 
 	/* Set the subcommand */
-	if (reset)
-		opts->subcommand = REPLAY_RESET;
+	if (remove_state)
+		opts->subcommand = REPLAY_REMOVE_STATE;
 	else if (contin)
 		opts->subcommand = REPLAY_CONTINUE;
+	else if (rollback)
+		opts->subcommand = REPLAY_ROLLBACK;
 	else
 		opts->subcommand = REPLAY_NONE;
 
 	/* Check for incompatible command line arguments */
 	if (opts->subcommand != REPLAY_NONE) {
 		char *this_operation;
-		if (opts->subcommand == REPLAY_RESET)
-			this_operation = "--reset";
-		else
+		if (opts->subcommand == REPLAY_REMOVE_STATE)
+			this_operation = "--quit";
+		else if (opts->subcommand == REPLAY_CONTINUE)
 			this_operation = "--continue";
+		else {
+			assert(opts->subcommand == REPLAY_ROLLBACK);
+			this_operation = "--abort";
+		}
 
 		verify_opt_compatible(me, this_operation,
 				"--no-commit", opts->no_commit,
@@ -286,7 +300,7 @@ static char *get_encoding(const char *message)
 	return NULL;
 }
 
-static void write_cherry_pick_head(struct commit *commit)
+static void write_cherry_pick_head(struct commit *commit, const char *pseudoref)
 {
 	const char *filename;
 	int fd;
@@ -294,7 +308,7 @@ static void write_cherry_pick_head(struct commit *commit)
 
 	strbuf_addf(&buf, "%s\n", sha1_to_hex(commit->object.sha1));
 
-	filename = git_path("CHERRY_PICK_HEAD");
+	filename = git_path(pseudoref);
 	fd = open(filename, O_WRONLY | O_CREAT, 0666);
 	if (fd < 0)
 		die_errno(_("Could not open '%s' for writing"), filename);
@@ -594,7 +608,9 @@ static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 	 * write it at all.
 	 */
 	if (opts->action == CHERRY_PICK && !opts->no_commit && (res == 0 || res == 1))
-		write_cherry_pick_head(commit);
+		write_cherry_pick_head(commit, "CHERRY_PICK_HEAD");
+	if (opts->action == REVERT && ((opts->no_commit && res == 0) || res == 1))
+		write_cherry_pick_head(commit, "REVERT_HEAD");
 
 	if (res) {
 		error(opts->action == REVERT
@@ -843,8 +859,11 @@ static int create_seq_dir(void)
 {
 	const char *seq_dir = git_path(SEQ_DIR);
 
-	if (file_exists(seq_dir))
-		return error(_("%s already exists."), seq_dir);
+	if (file_exists(seq_dir)) {
+		error(_("a cherry-pick or revert is already in progress"));
+		advise(_("try \"git cherry-pick (--continue | --quit | --abort)\""));
+		return -1;
+	}
 	else if (mkdir(seq_dir, 0777) < 0)
 		die_errno(_("Could not create sequencer directory %s"), seq_dir);
 	return 0;
@@ -865,6 +884,71 @@ static void save_head(const char *head)
 		die(_("Error wrapping up %s."), head_file);
 }
 
+static int reset_for_rollback(const unsigned char *sha1)
+{
+	const char *argv[4];	/* reset --merge <arg> + NULL */
+	argv[0] = "reset";
+	argv[1] = "--merge";
+	argv[2] = sha1_to_hex(sha1);
+	argv[3] = NULL;
+	return run_command_v_opt(argv, RUN_GIT_CMD);
+}
+
+static int rollback_single_pick(void)
+{
+	unsigned char head_sha1[20];
+
+	if (!file_exists(git_path("CHERRY_PICK_HEAD")) &&
+	    !file_exists(git_path("REVERT_HEAD")))
+		return error(_("no cherry-pick or revert in progress"));
+	if (!resolve_ref("HEAD", head_sha1, 0, NULL))
+		return error(_("cannot resolve HEAD"));
+	if (is_null_sha1(head_sha1))
+		return error(_("cannot abort from a branch yet to be born"));
+	return reset_for_rollback(head_sha1);
+}
+
+static int sequencer_rollback(struct replay_opts *opts)
+{
+	const char *filename;
+	FILE *f;
+	unsigned char sha1[20];
+	struct strbuf buf = STRBUF_INIT;
+
+	filename = git_path(SEQ_HEAD_FILE);
+	f = fopen(filename, "r");
+	if (!f && errno == ENOENT) {
+		/*
+		 * There is no multiple-cherry-pick in progress.
+		 * If CHERRY_PICK_HEAD or REVERT_HEAD indicates
+		 * a single-cherry-pick in progress, abort that.
+		 */
+		return rollback_single_pick();
+	}
+	if (!f)
+		return error(_("cannot open %s: %s"), filename,
+						strerror(errno));
+	if (strbuf_getline(&buf, f, '\n')) {
+		error(_("cannot read %s: %s"), filename, ferror(f) ?
+			strerror(errno) : _("unexpected end of file"));
+		goto fail;
+	}
+	if (get_sha1_hex(buf.buf, sha1) || buf.buf[40] != '\0') {
+		error(_("stored pre-cherry-pick HEAD file '%s' is corrupt"),
+			filename);
+		goto fail;
+	}
+	if (reset_for_rollback(sha1))
+		goto fail;
+	strbuf_release(&buf);
+	fclose(f);
+	return 0;
+fail:
+	strbuf_release(&buf);
+	fclose(f);
+	return -1;
+}
+
 static void save_todo(struct commit_list *todo_list, struct replay_opts *opts)
 {
 	const char *todo_file = git_path(SEQ_TODO_FILE);
@@ -965,43 +1049,41 @@ static int pick_revisions(struct replay_opts *opts)
 	 * cherry-pick should be handled differently from an existing
 	 * one that is being continued
 	 */
-	if (opts->subcommand == REPLAY_RESET) {
+	if (opts->subcommand == REPLAY_REMOVE_STATE) {
 		remove_sequencer_state(1);
 		return 0;
-	} else if (opts->subcommand == REPLAY_CONTINUE) {
+	}
+	if (opts->subcommand == REPLAY_ROLLBACK)
+		return sequencer_rollback(opts);
+	if (opts->subcommand == REPLAY_CONTINUE) {
 		if (!file_exists(git_path(SEQ_TODO_FILE)))
-			goto error;
+			return error(_("No %s in progress"), action_name(opts));
 		read_populate_opts(&opts);
 		read_populate_todo(&todo_list, opts);
 
 		/* Verify that the conflict has been resolved */
 		if (!index_differs_from("HEAD", 0))
 			todo_list = todo_list->next;
-	} else {
-		/*
-		 * Start a new cherry-pick/ revert sequence; but
-		 * first, make sure that an existing one isn't in
-		 * progress
-		 */
+		return pick_commits(todo_list, opts);
+	}
 
-		walk_revs_populate_todo(&todo_list, opts);
-		if (create_seq_dir() < 0) {
-			error(_("A cherry-pick or revert is in progress."));
-			advise(_("Use --continue to continue the operation"));
-			advise(_("or --reset to forget about it"));
-			return -1;
-		}
-		if (get_sha1("HEAD", sha1)) {
-			if (opts->action == REVERT)
-				return error(_("Can't revert as initial commit"));
-			return error(_("Can't cherry-pick into empty head"));
-		}
-		save_head(sha1_to_hex(sha1));
-		save_opts(opts);
+	/*
+	 * Start a new cherry-pick/ revert sequence; but
+	 * first, make sure that an existing one isn't in
+	 * progress
+	 */
+
+	walk_revs_populate_todo(&todo_list, opts);
+	if (create_seq_dir() < 0)
+		return -1;
+	if (get_sha1("HEAD", sha1)) {
+		if (opts->action == REVERT)
+			return error(_("Can't revert as initial commit"));
+		return error(_("Can't cherry-pick into empty head"));
 	}
+	save_head(sha1_to_hex(sha1));
+	save_opts(opts);
 	return pick_commits(todo_list, opts);
-error:
-	return error(_("No %s in progress"), action_name(opts));
 }
 
 int cmd_revert(int argc, const char **argv, const char *prefix)
diff --git a/sequencer.h b/sequencer.h
index 905d295012..f435fdb4b1 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -13,7 +13,7 @@
  *
  * With the aggressive flag, it additionally removes SEQ_OLD_DIR,
  * ignoring any errors.  Inteded to be used by the sequencer's
- * '--reset' subcommand.
+ * '--quit' subcommand.
  */
 void remove_sequencer_state(int aggressive);
 
diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index cb45574a7b..ee1659c178 100755
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -253,6 +253,60 @@ test_expect_success 'revert also handles conflicts sanely' '
 	test_cmp expected actual
 '
 
+test_expect_success 'failed revert sets REVERT_HEAD' '
+	pristine_detach initial &&
+	test_must_fail git revert picked &&
+	test_cmp_rev picked REVERT_HEAD
+'
+
+test_expect_success 'successful revert does not set REVERT_HEAD' '
+	pristine_detach base &&
+	git revert base &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD &&
+	test_must_fail git rev-parse --verify REVERT_HEAD
+'
+
+test_expect_success 'revert --no-commit sets REVERT_HEAD' '
+	pristine_detach base &&
+	git revert --no-commit base &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD &&
+	test_cmp_rev base REVERT_HEAD
+'
+
+test_expect_success 'revert w/dirty tree does not set REVERT_HEAD' '
+	pristine_detach base &&
+	echo foo > foo &&
+	test_must_fail git revert base &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD &&
+	test_must_fail git rev-parse --verify REVERT_HEAD
+'
+
+test_expect_success 'GIT_CHERRY_PICK_HELP does not suppress REVERT_HEAD' '
+	pristine_detach initial &&
+	(
+		GIT_CHERRY_PICK_HELP="and then do something else" &&
+		GIT_REVERT_HELP="and then do something else, again" &&
+		export GIT_CHERRY_PICK_HELP GIT_REVERT_HELP &&
+		test_must_fail git revert picked
+	) &&
+	test_must_fail git rev-parse --verify CHERRY_PICK_HEAD &&
+	test_cmp_rev picked REVERT_HEAD
+'
+
+test_expect_success 'git reset clears REVERT_HEAD' '
+	pristine_detach initial &&
+	test_must_fail git revert picked &&
+	git reset &&
+	test_must_fail git rev-parse --verify REVERT_HEAD
+'
+
+test_expect_success 'failed commit does not clear REVERT_HEAD' '
+	pristine_detach initial &&
+	test_must_fail git revert picked &&
+	test_must_fail git commit &&
+	test_cmp_rev picked REVERT_HEAD
+'
+
 test_expect_success 'revert conflict, diff3 -m style' '
 	pristine_detach initial &&
 	git config merge.conflictstyle diff3 &&
diff --git a/t/t3510-cherry-pick-sequence.sh b/t/t3510-cherry-pick-sequence.sh
index 3bca2b3dd5..2c4c1c851d 100755
--- a/t/t3510-cherry-pick-sequence.sh
+++ b/t/t3510-cherry-pick-sequence.sh
@@ -2,6 +2,7 @@
 
 test_description='Test cherry-pick continuation features
 
+  + yetanotherpick: rewrites foo to e
   + anotherpick: rewrites foo to d
   + picked: rewrites foo to c
   + unrelatedpick: rewrites unrelated to reallyunrelated
@@ -13,12 +14,18 @@ test_description='Test cherry-pick continuation features
 . ./test-lib.sh
 
 pristine_detach () {
-	git cherry-pick --reset &&
+	git cherry-pick --quit &&
 	git checkout -f "$1^0" &&
 	git read-tree -u --reset HEAD &&
 	git clean -d -f -f -q -x
 }
 
+test_cmp_rev () {
+	git rev-parse --verify "$1" >expect.rev &&
+	git rev-parse --verify "$2" >actual.rev &&
+	test_cmp expect.rev actual.rev
+}
+
 test_expect_success setup '
 	echo unrelated >unrelated &&
 	git add unrelated &&
@@ -27,6 +34,7 @@ test_expect_success setup '
 	test_commit unrelatedpick unrelated reallyunrelated &&
 	test_commit picked foo c &&
 	test_commit anotherpick foo d &&
+	test_commit yetanotherpick foo e &&
 	git config advice.detachedhead false
 
 '
@@ -70,18 +78,117 @@ test_expect_success 'cherry-pick cleans up sequencer state upon success' '
 	test_path_is_missing .git/sequencer
 '
 
-test_expect_success '--reset does not complain when no cherry-pick is in progress' '
+test_expect_success '--quit does not complain when no cherry-pick is in progress' '
 	pristine_detach initial &&
-	git cherry-pick --reset
+	git cherry-pick --quit
 '
 
-test_expect_success '--reset cleans up sequencer state' '
+test_expect_success '--abort requires cherry-pick in progress' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick --abort
+'
+
+test_expect_success '--quit cleans up sequencer state' '
 	pristine_detach initial &&
 	test_must_fail git cherry-pick base..picked &&
-	git cherry-pick --reset &&
+	git cherry-pick --quit &&
 	test_path_is_missing .git/sequencer
 '
 
+test_expect_success '--quit keeps HEAD and conflicted index intact' '
+	pristine_detach initial &&
+	cat >expect <<-\EOF &&
+	OBJID
+	:100644 100644 OBJID OBJID M	unrelated
+	OBJID
+	:000000 100644 OBJID OBJID A	foo
+	:000000 100644 OBJID OBJID A	unrelated
+	EOF
+	test_must_fail git cherry-pick base..picked &&
+	git cherry-pick --quit &&
+	test_path_is_missing .git/sequencer &&
+	test_must_fail git update-index --refresh &&
+	{
+		git rev-list HEAD |
+		git diff-tree --root --stdin |
+		sed "s/$_x40/OBJID/g"
+	} >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--abort to cancel multiple cherry-pick' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick base..anotherpick &&
+	git cherry-pick --abort &&
+	test_path_is_missing .git/sequencer &&
+	test_cmp_rev initial HEAD &&
+	git update-index --refresh &&
+	git diff-index --exit-code HEAD
+'
+
+test_expect_success '--abort to cancel single cherry-pick' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick picked &&
+	git cherry-pick --abort &&
+	test_path_is_missing .git/sequencer &&
+	test_cmp_rev initial HEAD &&
+	git update-index --refresh &&
+	git diff-index --exit-code HEAD
+'
+
+test_expect_success 'cherry-pick --abort to cancel multiple revert' '
+	pristine_detach anotherpick &&
+	test_must_fail git revert base..picked &&
+	git cherry-pick --abort &&
+	test_path_is_missing .git/sequencer &&
+	test_cmp_rev anotherpick HEAD &&
+	git update-index --refresh &&
+	git diff-index --exit-code HEAD
+'
+
+test_expect_success 'revert --abort works, too' '
+	pristine_detach anotherpick &&
+	test_must_fail git revert base..picked &&
+	git revert --abort &&
+	test_path_is_missing .git/sequencer &&
+	test_cmp_rev anotherpick HEAD
+'
+
+test_expect_success '--abort to cancel single revert' '
+	pristine_detach anotherpick &&
+	test_must_fail git revert picked &&
+	git revert --abort &&
+	test_path_is_missing .git/sequencer &&
+	test_cmp_rev anotherpick HEAD &&
+	git update-index --refresh &&
+	git diff-index --exit-code HEAD
+'
+
+test_expect_success '--abort keeps unrelated change, easy case' '
+	pristine_detach unrelatedpick &&
+	echo changed >expect &&
+	test_must_fail git cherry-pick picked..yetanotherpick &&
+	echo changed >unrelated &&
+	git cherry-pick --abort &&
+	test_cmp expect unrelated
+'
+
+test_expect_success '--abort refuses to clobber unrelated change, harder case' '
+	pristine_detach initial &&
+	echo changed >expect &&
+	test_must_fail git cherry-pick base..anotherpick &&
+	echo changed >unrelated &&
+	test_must_fail git cherry-pick --abort &&
+	test_cmp expect unrelated &&
+	git rev-list HEAD >log &&
+	test_line_count = 2 log &&
+	test_must_fail git update-index --refresh &&
+
+	git checkout unrelated &&
+	git cherry-pick --abort &&
+	test_cmp_rev initial HEAD
+'
+
 test_expect_success 'cherry-pick cleans up sequencer state when one commit is left' '
 	pristine_detach initial &&
 	test_must_fail git cherry-pick base..picked &&
@@ -106,6 +213,16 @@ test_expect_success 'cherry-pick cleans up sequencer state when one commit is le
 	test_cmp expect actual
 '
 
+test_expect_failure '--abort after last commit in sequence' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick base..picked &&
+	git cherry-pick --abort &&
+	test_path_is_missing .git/sequencer &&
+	test_cmp_rev initial HEAD &&
+	git update-index --refresh &&
+	git diff-index --exit-code HEAD
+'
+
 test_expect_success 'cherry-pick does not implicitly stomp an existing operation' '
 	pristine_detach initial &&
 	test_must_fail git cherry-pick base..anotherpick &&
diff --git a/t/t7106-reset-sequence.sh b/t/t7106-reset-sequence.sh
index 4956caaf82..3f86e8c5e8 100755
--- a/t/t7106-reset-sequence.sh
+++ b/t/t7106-reset-sequence.sh
@@ -12,7 +12,7 @@ test_description='Test interaction of reset --hard with sequencer
 . ./test-lib.sh
 
 pristine_detach () {
-	git cherry-pick --reset &&
+	git cherry-pick --quit &&
 	git checkout -f "$1^0" &&
 	git read-tree -u --reset HEAD &&
 	git clean -d -f -f -q -x