1 files changed, 29 insertions, 2 deletions

diff --git a/builtin/am.c b/builtin/am.c
index 83b3d86e67..4f77e07b95 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1207,6 +1207,33 @@ static void NORETURN die_user_resolve(const struct am_state *state)
 	exit(128);
 }
 
+static void am_signoff(struct strbuf *sb)
+{
+	char *cp;
+	struct strbuf mine = STRBUF_INIT;
+
+	/* Does it end with our own sign-off? */
+	strbuf_addf(&mine, "\n%s%s\n",
+		    sign_off_header,
+		    fmt_name(getenv("GIT_COMMITTER_NAME"),
+			     getenv("GIT_COMMITTER_EMAIL")));
+	if (mine.len < sb->len &&
+	    !strcmp(mine.buf, sb->buf + sb->len - mine.len))
+		goto exit; /* no need to duplicate */
+
+	/* Does it have any Signed-off-by: in the text */
+	for (cp = sb->buf;
+	     cp && *cp && (cp = strstr(cp, sign_off_header)) != NULL;
+	     cp = strchr(cp, '\n')) {
+		if (sb->buf == cp || cp[-1] == '\n')
+			break;
+	}
+
+	strbuf_addstr(sb, mine.buf + !!cp);
+exit:
+	strbuf_release(&mine);
+}
+
 /**
  * Appends signoff to the "msg" field of the am_state.
  */
@@ -1215,7 +1242,7 @@ static void am_append_signoff(struct am_state *state)
 	struct strbuf sb = STRBUF_INIT;
 
 	strbuf_attach(&sb, state->msg, state->msg_len, state->msg_len);
-	append_signoff(&sb, 0, 0);
+	am_signoff(&sb);
 	state->msg = strbuf_detach(&sb, &state->msg_len);
 }
 
@@ -1319,7 +1346,7 @@ static int parse_mail(struct am_state *state, const char *mail)
 	stripspace(&msg, 0);
 
 	if (state->signoff)
-		append_signoff(&msg, 0, 0);
+		am_signoff(&msg);
 
 	assert(!state->author_name);
 	state->author_name = strbuf_detach(&author_name, NULL);