[PATCH 4/5] sequencer.c: recognize "(cherry picked from ..." as part of s-o-b footer

[Brandon Casey <drafnel@gmail.com>]

Currently, if the s-o-b footer of a commit message contains a
"(cherry picked from ..." line that was added by a previous cherry-pick -x,
it is not recognized as a s-o-b footer and will cause a newline to be
inserted before an additional s-o-b is added.

So, rework ends_rfc2822_footer to recognize the "(cherry picked from ..."
string as part of the footer.  Plus mark the test in t3511 as fixed.

Signed-off-by: Brandon Casey <bcasey@nvidia.com>
---
 sequencer.c              | 44 +++++++++++++++++++++++++++++---------------
 t/t3511-cherry-pick-x.sh |  2 +-
 2 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 01edec2..27e684c 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -18,6 +18,7 @@
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
 const char sign_off_header[] = "Signed-off-by: ";
+const char cherry_picked_prefix[] = "(cherry picked from commit ";
 
 static void remove_sequencer_state(void)
 {
@@ -492,7 +493,7 @@ static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 		}
 
 		if (opts->record_origin) {
-			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
+			strbuf_addstr(&msgbuf, cherry_picked_prefix);
 			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 			strbuf_addstr(&msgbuf, ")\n");
 		}
@@ -1017,13 +1018,34 @@ int sequencer_pick_revisions(struct replay_opts *opts)
 	return pick_commits(todo_list, opts);
 }
 
+static int is_rfc2822_line(const char *buf, int len)
+{
+	int i;
+
+	for (i = 0; i < len; i++) {
+		int ch = buf[i];
+		if (ch == ':')
+			break;
+		if (isalnum(ch) || (ch == '-'))
+			continue;
+		return 0;
+	}
+
+	return 1;
+}
+
+static int is_cherry_pick_from_line(const char *buf, int len)
+{
+	return (strlen(cherry_picked_prefix) + 41) <= len &&
+		!prefixcmp(buf, cherry_picked_prefix);
+}
+
 static int ends_rfc2822_footer(struct strbuf *sb, int ignore_footer)
 {
-	int ch;
 	int hit = 0;
-	int i, j, k;
+	int i, k;
 	int len = sb->len - ignore_footer;
-	int first = 1;
+	int last_was_rfc2822 = 0;
 	const char *buf = sb->buf;
 
 	for (i = len - 1; i > 0; i--) {
@@ -1040,20 +1062,12 @@ static int ends_rfc2822_footer(struct strbuf *sb, int ignore_footer)
 			; /* do nothing */
 		k++;
 
-		if ((buf[i] == ' ' || buf[i] == '\t') && !first)
+		if (last_was_rfc2822 && (buf[i] == ' ' || buf[i] == '\t'))
 			continue;
 
-		first = 0;
-
-		for (j = 0; i + j < len; j++) {
-			ch = buf[i + j];
-			if (ch == ':')
-				break;
-			if (isalnum(ch) ||
-			    (ch == '-'))
-				continue;
+		if (!((last_was_rfc2822 = is_rfc2822_line(buf+i, k-i)) ||
+			is_cherry_pick_from_line(buf+i, k-i)))
 			return 0;
-		}
 	}
 	return 1;
 }
diff --git a/t/t3511-cherry-pick-x.sh b/t/t3511-cherry-pick-x.sh
index b2098e0..785486e 100755
--- a/t/t3511-cherry-pick-x.sh
+++ b/t/t3511-cherry-pick-x.sh
@@ -63,7 +63,7 @@ test_expect_success 'cherry-pick -s not confused by rfc2822 continuation line' '
 	test_cmp expect actual
 '
 
-test_expect_failure 'cherry-pick treats -s "(cherry picked from..." line as part of footer' '
+test_expect_success 'cherry-pick treats -s "(cherry picked from..." line as part of footer' '
 	pristine_detach initial &&
 	git cherry-pick -s rfc2822-cherry-base &&
 	cat <<-EOF >expect &&
-- 
1.8.0