Merge branch 'bc/append-signed-off-by'

Consolidate codepaths that inspect log-message-to-be and decide to
add a new Signed-off-by line in various commands.

* bc/append-signed-off-by:
  git-commit: populate the edit buffer with 2 blank lines before s-o-b
  Unify appending signoff in format-patch, commit and sequencer
  format-patch: update append_signoff prototype
  t4014: more tests about appending s-o-b lines
  sequencer.c: teach append_signoff to avoid adding a duplicate newline
  sequencer.c: teach append_signoff how to detect duplicate s-o-b
  sequencer.c: always separate "(cherry picked from" from commit body
  sequencer.c: require a conforming footer to be preceded by a blank line
  sequencer.c: recognize "(cherry picked from ..." as part of s-o-b footer
  t/t3511: add some tests of 'cherry-pick -s' functionality
  t/test-lib-functions.sh: allow to specify the tag name to test_commit
  commit, cherry-pick -s: remove broken support for multiline rfc2822 fields
  sequencer.c: rework search for start of footer to improve clarity

10 files changed, 650 insertions, 156 deletions

diff --git a/builtin/commit.c b/builtin/commit.c
index d21d07a1a8..46204375e7 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -702,7 +702,7 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 			previous = eol;
 		}
 
-		append_signoff(&sb, ignore_footer);
+		append_signoff(&sb, ignore_footer, 0);
 	}
 
 	if (fwrite(sb.buf, 1, sb.len, s->fp) < sb.len)
diff --git a/builtin/log.c b/builtin/log.c
index 8f0b2e84fe..59de484bc2 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1086,7 +1086,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct commit *origin = NULL, *head = NULL;
 	const char *in_reply_to = NULL;
 	struct patch_ids ids;
-	char *add_signoff = NULL;
 	struct strbuf buf = STRBUF_INIT;
 	int use_patch_format = 0;
 	int quiet = 0;
@@ -1193,16 +1192,6 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		rev.subject_prefix = strbuf_detach(&sprefix, NULL);
 	}
 
-	if (do_signoff) {
-		const char *committer;
-		const char *endpos;
-		committer = git_committer_info(IDENT_STRICT);
-		endpos = strchr(committer, '>');
-		if (!endpos)
-			die(_("bogus committer info %s"), committer);
-		add_signoff = xmemdupz(committer, endpos - committer + 1);
-	}
-
 	for (i = 0; i < extra_hdr.nr; i++) {
 		strbuf_addstr(&buf, extra_hdr.items[i].string);
 		strbuf_addch(&buf, '\n');
@@ -1393,7 +1382,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		total++;
 		start_number--;
 	}
-	rev.add_signoff = add_signoff;
+	rev.add_signoff = do_signoff;
 	while (0 <= --nr) {
 		int shown;
 		commit = list[nr];
diff --git a/log-tree.c b/log-tree.c
index 3d88823871..92bb2bf48e 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -9,6 +9,7 @@
 #include "string-list.h"
 #include "color.h"
 #include "gpg-interface.h"
+#include "sequencer.h"
 
 struct decoration name_decoration = { "object names" };
 
@@ -206,89 +207,6 @@ void show_decorations(struct rev_info *opt, struct commit *commit)
 	putchar(')');
 }
 
-/*
- * Search for "^[-A-Za-z]+: [^@]+@" pattern. It usually matches
- * Signed-off-by: and Acked-by: lines.
- */
-static int detect_any_signoff(char *letter, int size)
-{
-	char *cp;
-	int seen_colon = 0;
-	int seen_at = 0;
-	int seen_name = 0;
-	int seen_head = 0;
-
-	cp = letter + size;
-	while (letter <= --cp && *cp == '\n')
-		continue;
-
-	while (letter <= cp) {
-		char ch = *cp--;
-		if (ch == '\n')
-			break;
-
-		if (!seen_at) {
-			if (ch == '@')
-				seen_at = 1;
-			continue;
-		}
-		if (!seen_colon) {
-			if (ch == '@')
-				return 0;
-			else if (ch == ':')
-				seen_colon = 1;
-			else
-				seen_name = 1;
-			continue;
-		}
-		if (('A' <= ch && ch <= 'Z') ||
-		    ('a' <= ch && ch <= 'z') ||
-		    ch == '-') {
-			seen_head = 1;
-			continue;
-		}
-		/* no empty last line doesn't match */
-		return 0;
-	}
-	return seen_head && seen_name;
-}
-
-static void append_signoff(struct strbuf *sb, const char *signoff)
-{
-	static const char signed_off_by[] = "Signed-off-by: ";
-	size_t signoff_len = strlen(signoff);
-	int has_signoff = 0;
-	char *cp;
-
-	cp = sb->buf;
-
-	/* First see if we already have the sign-off by the signer */
-	while ((cp = strstr(cp, signed_off_by))) {
-
-		has_signoff = 1;
-
-		cp += strlen(signed_off_by);
-		if (cp + signoff_len >= sb->buf + sb->len)
-			break;
-		if (strncmp(cp, signoff, signoff_len))
-			continue;
-		if (!isspace(cp[signoff_len]))
-			continue;
-		/* we already have him */
-		return;
-	}
-
-	if (!has_signoff)
-		has_signoff = detect_any_signoff(sb->buf, sb->len);
-
-	if (!has_signoff)
-		strbuf_addch(sb, '\n');
-
-	strbuf_addstr(sb, signed_off_by);
-	strbuf_add(sb, signoff, signoff_len);
-	strbuf_addch(sb, '\n');
-}
-
 static unsigned int digits_in_number(unsigned int number)
 {
 	unsigned int i = 10, result = 1;
@@ -669,8 +587,10 @@ void show_log(struct rev_info *opt)
 	/*
 	 * And then the pretty-printed message itself
 	 */
-	if (ctx.need_8bit_cte >= 0)
-		ctx.need_8bit_cte = has_non_ascii(opt->add_signoff);
+	if (ctx.need_8bit_cte >= 0 && opt->add_signoff)
+		ctx.need_8bit_cte =
+			has_non_ascii(fmt_name(getenv("GIT_COMMITTER_NAME"),
+					       getenv("GIT_COMMITTER_EMAIL")));
 	ctx.date_mode = opt->date_mode;
 	ctx.date_mode_explicit = opt->date_mode_explicit;
 	ctx.abbrev = opt->diffopt.abbrev;
@@ -683,7 +603,7 @@ void show_log(struct rev_info *opt)
 	pretty_print_commit(&ctx, commit, &msgbuf);
 
 	if (opt->add_signoff)
-		append_signoff(&msgbuf, opt->add_signoff);
+		append_signoff(&msgbuf, 0, APPEND_SIGNOFF_DEDUP);
 
 	if ((ctx.fmt != CMIT_FMT_USERFORMAT) &&
 	    ctx.notes_message && *ctx.notes_message) {
diff --git a/revision.h b/revision.h
index 5da09ee3ef..01bd2b7c07 100644
--- a/revision.h
+++ b/revision.h
@@ -138,7 +138,7 @@ struct rev_info {
 	int		reroll_count;
 	char		*message_id;
 	struct string_list *ref_message_ids;
-	const char	*add_signoff;
+	int		add_signoff;
 	const char	*extra_headers;
 	const char	*log_reencode;
 	const char	*subject_prefix;
diff --git a/sequencer.c b/sequencer.c
index aef5e8a017..baa031052e 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -18,6 +18,89 @@
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
 const char sign_off_header[] = "Signed-off-by: ";
+static const char cherry_picked_prefix[] = "(cherry picked from commit ";
+
+static int is_rfc2822_line(const char *buf, int len)
+{
+	int i;
+
+	for (i = 0; i < len; i++) {
+		int ch = buf[i];
+		if (ch == ':')
+			return 1;
+		if (!isalnum(ch) && ch != '-')
+			break;
+	}
+
+	return 0;
+}
+
+static int is_cherry_picked_from_line(const char *buf, int len)
+{
+	/*
+	 * We only care that it looks roughly like (cherry picked from ...)
+	 */
+	return len > strlen(cherry_picked_prefix) + 1 &&
+		!prefixcmp(buf, cherry_picked_prefix) && buf[len - 1] == ')';
+}
+
+/*
+ * Returns 0 for non-conforming footer
+ * Returns 1 for conforming footer
+ * Returns 2 when sob exists within conforming footer
+ * Returns 3 when sob exists within conforming footer as last entry
+ */
+static int has_conforming_footer(struct strbuf *sb, struct strbuf *sob,
+	int ignore_footer)
+{
+	char prev;
+	int i, k;
+	int len = sb->len - ignore_footer;
+	const char *buf = sb->buf;
+	int found_sob = 0;
+
+	/* footer must end with newline */
+	if (!len || buf[len - 1] != '\n')
+		return 0;
+
+	prev = '\0';
+	for (i = len - 1; i > 0; i--) {
+		char ch = buf[i];
+		if (prev == '\n' && ch == '\n') /* paragraph break */
+			break;
+		prev = ch;
+	}
+
+	/* require at least one blank line */
+	if (prev != '\n' || buf[i] != '\n')
+		return 0;
+
+	/* advance to start of last paragraph */
+	while (i < len - 1 && buf[i] == '\n')
+		i++;
+
+	for (; i < len; i = k) {
+		int found_rfc2822;
+
+		for (k = i; k < len && buf[k] != '\n'; k++)
+			; /* do nothing */
+		k++;
+
+		found_rfc2822 = is_rfc2822_line(buf + i, k - i - 1);
+		if (found_rfc2822 && sob &&
+		    !strncmp(buf + i, sob->buf, sob->len))
+			found_sob = k;
+
+		if (!(found_rfc2822 ||
+		      is_cherry_picked_from_line(buf + i, k - i - 1)))
+			return 0;
+	}
+	if (found_sob == i)
+		return 3;
+	if (found_sob)
+		return 2;
+	return 1;
+}
 
 static void remove_sequencer_state(void)
 {
@@ -237,7 +320,7 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 	rollback_lock_file(&index_lock);
 
 	if (opts->signoff)
-		append_signoff(msgbuf, 0);
+		append_signoff(msgbuf, 0, 0);
 
 	if (!clean) {
 		int i;
@@ -496,7 +579,9 @@ static int do_pick_commit(struct commit *commit, struct replay_opts *opts)
 		}
 
 		if (opts->record_origin) {
-			strbuf_addstr(&msgbuf, "(cherry picked from commit ");
+			if (!has_conforming_footer(&msgbuf, NULL, 0))
+				strbuf_addch(&msgbuf, '\n');
+			strbuf_addstr(&msgbuf, cherry_picked_prefix);
 			strbuf_addstr(&msgbuf, sha1_to_hex(commit->object.sha1));
 			strbuf_addstr(&msgbuf, ")\n");
 		}
@@ -1021,62 +1106,67 @@ int sequencer_pick_revisions(struct replay_opts *opts)
 	return pick_commits(todo_list, opts);
 }
 
-static int ends_rfc2822_footer(struct strbuf *sb, int ignore_footer)
-{
-	int ch;
-	int hit = 0;
-	int i, j, k;
-	int len = sb->len - ignore_footer;
-	int first = 1;
-	const char *buf = sb->buf;
-
-	for (i = len - 1; i > 0; i--) {
-		if (hit && buf[i] == '\n')
-			break;
-		hit = (buf[i] == '\n');
-	}
-
-	while (i < len - 1 && buf[i] == '\n')
-		i++;
-
-	for (; i < len; i = k) {
-		for (k = i; k < len && buf[k] != '\n'; k++)
-			; /* do nothing */
-		k++;
-
-		if ((buf[k] == ' ' || buf[k] == '\t') && !first)
-			continue;
-
-		first = 0;
-
-		for (j = 0; i + j < len; j++) {
-			ch = buf[i + j];
-			if (ch == ':')
-				break;
-			if (isalnum(ch) ||
-			    (ch == '-'))
-				continue;
-			return 0;
-		}
-	}
-	return 1;
-}
-
-void append_signoff(struct strbuf *msgbuf, int ignore_footer)
+void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag)
 {
+	unsigned no_dup_sob = flag & APPEND_SIGNOFF_DEDUP;
 	struct strbuf sob = STRBUF_INIT;
-	int i;
+	int has_footer;
 
 	strbuf_addstr(&sob, sign_off_header);
 	strbuf_addstr(&sob, fmt_name(getenv("GIT_COMMITTER_NAME"),
 				getenv("GIT_COMMITTER_EMAIL")));
 	strbuf_addch(&sob, '\n');
-	for (i = msgbuf->len - 1 - ignore_footer; i > 0 && msgbuf->buf[i - 1] != '\n'; i--)
-		; /* do nothing */
-	if (prefixcmp(msgbuf->buf + i, sob.buf)) {
-		if (!i || !ends_rfc2822_footer(msgbuf, ignore_footer))
-			strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0, "\n", 1);
-		strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0, sob.buf, sob.len);
+
+	/*
+	 * If the whole message buffer is equal to the sob, pretend that we
+	 * found a conforming footer with a matching sob
+	 */
+	if (msgbuf->len - ignore_footer == sob.len &&
+	    !strncmp(msgbuf->buf, sob.buf, sob.len))
+		has_footer = 3;
+	else
+		has_footer = has_conforming_footer(msgbuf, &sob, ignore_footer);
+
+	if (!has_footer) {
+		const char *append_newlines = NULL;
+		size_t len = msgbuf->len - ignore_footer;
+
+		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 (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,
+				append_newlines, strlen(append_newlines));
 	}
+
+	if (has_footer != 3 && (!no_dup_sob || has_footer != 2))
+		strbuf_splice(msgbuf, msgbuf->len - ignore_footer, 0,
+				sob.buf, sob.len);
+
 	strbuf_release(&sob);
 }
diff --git a/sequencer.h b/sequencer.h
index 9d57d57524..1fc22dcabe 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -6,6 +6,8 @@
 #define SEQ_TODO_FILE	"sequencer/todo"
 #define SEQ_OPTS_FILE	"sequencer/opts"
 
+#define APPEND_SIGNOFF_DEDUP (1u << 0)
+
 enum replay_action {
 	REPLAY_REVERT,
 	REPLAY_PICK
@@ -48,6 +50,6 @@ int sequencer_pick_revisions(struct replay_opts *opts);
 
 extern const char sign_off_header[];
 
-void append_signoff(struct strbuf *msgbuf, int ignore_footer);
+void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag);
 
 #endif
diff --git a/t/t3511-cherry-pick-x.sh b/t/t3511-cherry-pick-x.sh
new file mode 100755
index 0000000000..f97727975b
--- /dev/null
+++ b/t/t3511-cherry-pick-x.sh
@@ -0,0 +1,219 @@
+#!/bin/sh
+
+test_description='Test cherry-pick -x and -s'
+
+. ./test-lib.sh
+
+pristine_detach () {
+	git cherry-pick --quit &&
+	git checkout -f "$1^0" &&
+	git read-tree -u --reset HEAD &&
+	git clean -d -f -f -q -x
+}
+
+mesg_one_line='base: commit message'
+
+mesg_no_footer="$mesg_one_line
+
+OneWordBodyThatsNotA-S-o-B"
+
+mesg_with_footer="$mesg_no_footer
+
+Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+Signed-off-by: A.U. Thor <author@example.com>
+Signed-off-by: B.U. Thor <buthor@example.com>"
+
+mesg_broken_footer="$mesg_no_footer
+
+The signed-off-by string should begin with the words Signed-off-by followed
+by a colon and space, and then the signers name and email address. e.g.
+Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>"
+
+mesg_with_footer_sob="$mesg_with_footer
+Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>"
+
+mesg_with_cherry_footer="$mesg_with_footer_sob
+(cherry picked from commit da39a3ee5e6b4b0d3255bfef95601890afd80709)
+Tested-by: C.U. Thor <cuthor@example.com>"
+
+
+test_expect_success setup '
+	git config advice.detachedhead false &&
+	echo unrelated >unrelated &&
+	git add unrelated &&
+	test_commit initial foo a &&
+	test_commit "$mesg_one_line" foo b mesg-one-line &&
+	git reset --hard initial &&
+	test_commit "$mesg_no_footer" foo b mesg-no-footer &&
+	git reset --hard initial &&
+	test_commit "$mesg_broken_footer" foo b mesg-broken-footer &&
+	git reset --hard initial &&
+	test_commit "$mesg_with_footer" foo b mesg-with-footer &&
+	git reset --hard initial &&
+	test_commit "$mesg_with_footer_sob" foo b mesg-with-footer-sob &&
+	git reset --hard initial &&
+	test_commit "$mesg_with_cherry_footer" foo b mesg-with-cherry-footer &&
+	pristine_detach initial &&
+	test_commit conflicting unrelated
+'
+
+test_expect_success 'cherry-pick -x inserts blank line after one line subject' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-one-line^0` &&
+	git cherry-pick -x mesg-one-line &&
+	cat <<-EOF >expect &&
+		$mesg_one_line
+
+		(cherry picked from commit $sha1)
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -s inserts blank line after one line subject' '
+	pristine_detach initial &&
+	git cherry-pick -s mesg-one-line &&
+	cat <<-EOF >expect &&
+		$mesg_one_line
+
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -s inserts blank line after non-conforming footer' '
+	pristine_detach initial &&
+	git cherry-pick -s mesg-broken-footer &&
+	cat <<-EOF >expect &&
+		$mesg_broken_footer
+
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -x inserts blank line when conforming footer not found' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-no-footer^0` &&
+	git cherry-pick -x mesg-no-footer &&
+	cat <<-EOF >expect &&
+		$mesg_no_footer
+
+		(cherry picked from commit $sha1)
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -s inserts blank line when conforming footer not found' '
+	pristine_detach initial &&
+	git cherry-pick -s mesg-no-footer &&
+	cat <<-EOF >expect &&
+		$mesg_no_footer
+
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -x -s inserts blank line when conforming footer not found' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-no-footer^0` &&
+	git cherry-pick -x -s mesg-no-footer &&
+	cat <<-EOF >expect &&
+		$mesg_no_footer
+
+		(cherry picked from commit $sha1)
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -s adds sob when last sob doesnt match committer' '
+	pristine_detach initial &&
+	git cherry-pick -s mesg-with-footer &&
+	cat <<-EOF >expect &&
+		$mesg_with_footer
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -x -s adds sob when last sob doesnt match committer' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-with-footer^0` &&
+	git cherry-pick -x -s mesg-with-footer &&
+	cat <<-EOF >expect &&
+		$mesg_with_footer
+		(cherry picked from commit $sha1)
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -s refrains from adding duplicate trailing sob' '
+	pristine_detach initial &&
+	git cherry-pick -s mesg-with-footer-sob &&
+	cat <<-EOF >expect &&
+		$mesg_with_footer_sob
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -x -s adds sob even when trailing sob exists for committer' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-with-footer-sob^0` &&
+	git cherry-pick -x -s mesg-with-footer-sob &&
+	cat <<-EOF >expect &&
+		$mesg_with_footer_sob
+		(cherry picked from commit $sha1)
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -x treats "(cherry picked from..." line as part of footer' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-with-cherry-footer^0` &&
+	git cherry-pick -x mesg-with-cherry-footer &&
+	cat <<-EOF >expect &&
+		$mesg_with_cherry_footer
+		(cherry picked from commit $sha1)
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -s treats "(cherry picked from..." line as part of footer' '
+	pristine_detach initial &&
+	git cherry-pick -s mesg-with-cherry-footer &&
+	cat <<-EOF >expect &&
+		$mesg_with_cherry_footer
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'cherry-pick -x -s treats "(cherry picked from..." line as part of footer' '
+	pristine_detach initial &&
+	sha1=`git rev-parse mesg-with-cherry-footer^0` &&
+	git cherry-pick -x -s mesg-with-cherry-footer &&
+	cat <<-EOF >expect &&
+		$mesg_with_cherry_footer
+		(cherry picked from commit $sha1)
+		Signed-off-by: $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL>
+	EOF
+	git log -1 --pretty=format:%B >actual &&
+	test_cmp expect actual
+'
+
+test_done
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index bb1fc47fe8..b993dae645 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -972,6 +972,268 @@ test_expect_success 'empty subject prefix does not have extra space' '
 	test_cmp expect actual
 '
 
+append_signoff()
+{
+	C=$(git commit-tree HEAD^^{tree} -p HEAD) &&
+	git format-patch --stdout --signoff $C^..$C >append_signoff.patch &&
+	sed -n -e "1,/^---$/p" append_signoff.patch |
+		egrep -n "^Subject|Sign|^$"
+}
+
+test_expect_success 'signoff: commit with no body' '
+	append_signoff </dev/null >actual &&
+	cat <<\EOF | sed "s/EOL$//" >expected &&
+4:Subject: [PATCH] EOL
+8:
+9:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: commit with only subject' '
+	echo subject | append_signoff >actual &&
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+9:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: commit with only subject that does not end with NL' '
+	printf subject | append_signoff >actual &&
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+9:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: no existing signoffs' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+11:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: no existing signoffs and no trailing NL' '
+	printf "subject\n\nbody" | append_signoff >actual &&
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+11:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: some random signoff' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+
+Signed-off-by: my@house
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+11:Signed-off-by: my@house
+12:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: misc conforming footer elements' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+
+Signed-off-by: my@house
+(cherry picked from commit da39a3ee5e6b4b0d3255bfef95601890afd80709)
+Tested-by: Some One <someone@example.com>
+Bug: 1234
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+11:Signed-off-by: my@house
+15:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: some random signoff-alike' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+Fooled-by-me: my@house
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+11:
+12:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: not really a signoff' '
+	append_signoff <<\EOF >actual &&
+subject
+
+I want to mention about Signed-off-by: here.
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+9:I want to mention about Signed-off-by: here.
+10:
+11:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: not really a signoff (2)' '
+	append_signoff <<\EOF >actual &&
+subject
+
+My unfortunate
+Signed-off-by: example happens to be wrapped here.
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:Signed-off-by: example happens to be wrapped here.
+11:
+12:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: valid S-o-b paragraph in the middle' '
+	append_signoff <<\EOF >actual &&
+subject
+
+Signed-off-by: my@house
+Signed-off-by: your@house
+
+A lot of houses.
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+9:Signed-off-by: my@house
+10:Signed-off-by: your@house
+11:
+13:
+14:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: the same signoff at the end' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+
+Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+11:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: the same signoff at the end, no trailing NL' '
+	printf "subject\n\nSigned-off-by: C O Mitter <committer@example.com>" |
+		append_signoff >actual &&
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+9:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: the same signoff NOT at the end' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+
+Signed-off-by: C O Mitter <committer@example.com>
+Signed-off-by: my@house
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+11:Signed-off-by: C O Mitter <committer@example.com>
+12:Signed-off-by: my@house
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: detect garbage in non-conforming footer' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+
+Tested-by: my@house
+Some Trash
+Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+13:Signed-off-by: C O Mitter <committer@example.com>
+14:
+15:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
+test_expect_success 'signoff: footer begins with non-signoff without @ sign' '
+	append_signoff <<\EOF >actual &&
+subject
+
+body
+
+Reviewed-id: Noone
+Tested-by: my@house
+Change-id: Ideadbeef
+Signed-off-by: C O Mitter <committer@example.com>
+Bug: 1234
+EOF
+	cat >expected <<\EOF &&
+4:Subject: [PATCH] subject
+8:
+10:
+14:Signed-off-by: C O Mitter <committer@example.com>
+EOF
+	test_cmp expected actual
+'
+
 test_expect_success 'format patch ignores color.ui' '
 	test_unconfig color.ui &&
 	git format-patch --stdout -1 >expect &&
diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index 256137f07a..a4938b1e45 100755
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -424,6 +424,18 @@ 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
+	sed -e "/^#/d" -e "s/^:.*//" .git/COMMIT_EDITMSG >actual &&
+	test_cmp expect actual
+'
+
 write_script .git/FAKE_EDITOR <<\EOF
 mv "$1" "$1.orig"
 (
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index fa62d010f6..61d0804435 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -135,12 +135,12 @@ test_pause () {
 	fi
 }
 
-# Call test_commit with the arguments "<message> [<file> [<contents>]]"
+# Call test_commit with the arguments "<message> [<file> [<contents> [<tag>]]]"
 #
 # This will commit a file with the given contents and the given commit
-# message.  It will also add a tag with <message> as name.
+# message, and tag the resulting commit with the given tag name.
 #
-# Both <file> and <contents> default to <message>.
+# <file>, <contents>, and <tag> all default to <message>.
 
 test_commit () {
 	notick= &&
@@ -168,7 +168,7 @@ test_commit () {
 		test_tick
 	fi &&
 	git commit $signoff -m "$1" &&
-	git tag "$1"
+	git tag "${4:-$1}"
 }
 
 # Call test_merge with the arguments "<message> <commit>", where <commit>