commit/reset: try to clean up sequencer state

When cherry-picking or reverting a sequence of commits and if the final
pick/revert has conflicts and the user uses `git commit` to commit the
conflict resolution and does not run `git cherry-pick --continue` then
the sequencer state is left behind. This can cause problems later. In my
case I cherry-picked a sequence of commits the last one of which I
committed with `git commit` after resolving some conflicts, then a while
later, on a different branch I aborted a revert which rewound my HEAD to
the end of the cherry-pick sequence on the previous branch. Avoid this
potential problem by removing the sequencer state if we're committing or
resetting the final pick in a sequence.

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

1 files changed, 51 insertions, 0 deletions

diff --git a/sequencer.c b/sequencer.c
index 0db410d..7c7b8a0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -2220,6 +2220,57 @@ static ssize_t strbuf_read_file_or_whine(struct strbuf *sb, const char *path)
 	return len;
 }
 
+static int have_finished_the_last_pick(void)
+{
+	struct strbuf buf = STRBUF_INIT;
+	const char *eol;
+	const char *todo_path = git_path_todo_file();
+	int ret = 0;
+
+	if (strbuf_read_file(&buf, todo_path, 0) < 0) {
+		if (errno == ENOENT) {
+			return 0;
+		} else {
+			error_errno("unable to open '%s'", todo_path);
+			return 0;
+		}
+	}
+	/* If there is only one line then we are done */
+	eol = strchr(buf.buf, '\n');
+	if (!eol || !eol[1])
+		ret = 1;
+
+	strbuf_release(&buf);
+
+	return ret;
+}
+
+void sequencer_post_commit_cleanup(struct repository *r)
+{
+	struct replay_opts opts = REPLAY_OPTS_INIT;
+	int need_cleanup = 0;
+
+	if (file_exists(git_path_cherry_pick_head(r))) {
+		unlink(git_path_cherry_pick_head(r));
+		opts.action = REPLAY_PICK;
+		need_cleanup = 1;
+	}
+
+	if (file_exists(git_path_revert_head(r))) {
+		unlink(git_path_revert_head(r));
+		opts.action = REPLAY_REVERT;
+		need_cleanup = 1;
+	}
+
+	if (!need_cleanup)
+		return;
+
+	if (!have_finished_the_last_pick())
+		return;
+
+	sequencer_remove_state(&opts);
+}
+
 static int read_populate_todo(struct repository *r,
 			      struct todo_list *todo_list,
 			      struct replay_opts *opts)