[PATCH v2] git-commit: populate the edit buffer with 2 blank lines before s-o-b

[Brandon Casey <bcasey@nvidia.com>]

From: Brandon Casey <drafnel@gmail.com>

Before commit 33f2f9ab, 'commit -s' would populate the edit buffer with
a blank line before the Signed-off-by line.  This provided a nice
hint to the user that something should be filled in.  Let's restore that
behavior, but now let's ensure that the Signed-off-by line is preceded
by two blank lines to hint that something should be filled in, and that
a blank line should separate it from the Signed-off-by line.

Plus, add a test for this behavior.

Reported-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Brandon Casey <drafnel@gmail.com>
---

How about something like this?

-Brandon

 sequencer.c       | 27 +++++++++++++++++++++++++--
 t/t7502-commit.sh | 12 ++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/sequencer.c b/sequencer.c
index 53ee49a..a07d2d0 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1127,10 +1127,33 @@ void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
 		const char *append_newlines = NULL;
 		size_t len = msgbuf->len - ignore_footer;
 
-		if (len && msgbuf->buf[len - 1] != '\n')
+		if (!len) {
+			/*
+			 * The buffer is completely empty.  Leave foom for
+			 * the title and body to be filled in by the user.
+			 */
 			append_newlines = "\n\n";
-		else if (len > 1 && msgbuf->buf[len - 2] != '\n')
+		} else if (msgbuf->buf[len - 1] != '\n') {
+			/*
+			 * Incomplete line.  Complete the line and add a
+			 * blank one so that there is an empty line between
+			 * the message body and the sob.
+			 */
+			append_newlines = "\n\n";
+		} else if (len == 1) {
+			/*
+			 * Buffer contains a single newline.  Add another
+			 * so that we leave room for the title and body.
+			 */
+			append_newlines = "\n";
+		} else if (msgbuf->buf[len - 2] != '\n') {
+			/*
+			 * Buffer ends with a single newline.  Add another
+			 * so that there is an empty line between the message
+			 * body and the sob.
+			 */
 			append_newlines = "\n";
+		} /* else, the buffer already ends with two newlines. */
 
 		if (append_newlines)
 			strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0,
diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index deb187e..a53a1e0 100755
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -349,6 +349,18 @@ test_expect_success 'A single-liner subject with a token plus colon is not a foo
 
 '
 
+test_expect_success 'commit -s places sob on third line after two empty lines' '
+	git commit -s --allow-empty --allow-empty-message &&
+	cat <<-EOF >expect &&
+
+
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+
+	EOF
+	egrep -v '^#' .git/COMMIT_EDITMSG >actual &&
+	test_cmp expect actual
+'
+
 write_script .git/FAKE_EDITOR <<\EOF
 mv "$1" "$1.orig"
 (
-- 
1.8.1.3.566.gaa39828