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

1 files changed, 141 insertions, 51 deletions

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);
 }