trailer: parse trailers from file or stdin

Read trailers from a file or from stdin, parse the trailers and then
put the result into a doubly linked list.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

trailer.c

@@ -69,6 +69,14 @@ static int same_trailer(struct trailer_item *a, struct trailer_item *b)
 	return same_token(a, b) && same_value(a, b);
 }
 
+static inline int contains_only_spaces(const char *str)
+{
+	const char *s = str;
+	while (*s && isspace(*s))
+		s++;
+	return !*s;
+}
+
 static void free_trailer_item(struct trailer_item *item)
 {
 	free(item->conf.name);
@@ -574,3 +582,118 @@ static struct trailer_item *process_command_line_args(struct string_list *traile
 
 	return arg_tok_first;
 }
+
+static struct strbuf **read_input_file(const char *file)
+{
+	struct strbuf **lines;
+	struct strbuf sb = STRBUF_INIT;
+
+	if (file) {
+		if (strbuf_read_file(&sb, file, 0) < 0)
+			die_errno(_("could not read input file '%s'"), file);
+	} else {
+		if (strbuf_read(&sb, fileno(stdin), 0) < 0)
+			die_errno(_("could not read from stdin"));
+	}
+
+	lines = strbuf_split(&sb, '\n');
+
+	strbuf_release(&sb);
+
+	return lines;
+}
+
+/*
+ * Return the (0 based) index of the start of the patch or the line
+ * count if there is no patch in the message.
+ */
+static int find_patch_start(struct strbuf **lines, int count)
+{
+	int i;
+
+	/* Get the start of the patch part if any */
+	for (i = 0; i < count; i++) {
+		if (starts_with(lines[i]->buf, "---"))
+			return i;
+	}
+
+	return count;
+}
+
+/*
+ * Return the (0 based) index of the first trailer line or count if
+ * there are no trailers. Trailers are searched only in the lines from
+ * index (count - 1) down to index 0.
+ */
+static int find_trailer_start(struct strbuf **lines, int count)
+{
+	int start, only_spaces = 1;
+
+	/*
+	 * Get the start of the trailers by looking starting from the end
+	 * for a line with only spaces before lines with one separator.
+	 */
+	for (start = count - 1; start >= 0; start--) {
+		if (lines[start]->buf[0] == comment_line_char)
+			continue;
+		if (contains_only_spaces(lines[start]->buf)) {
+			if (only_spaces)
+				continue;
+			return start + 1;
+		}
+		if (strcspn(lines[start]->buf, separators) < lines[start]->len) {
+			if (only_spaces)
+				only_spaces = 0;
+			continue;
+		}
+		return count;
+	}
+
+	return only_spaces ? count : 0;
+}
+
+static int has_blank_line_before(struct strbuf **lines, int start)
+{
+	for (;start >= 0; start--) {
+		if (lines[start]->buf[0] == comment_line_char)
+			continue;
+		return contains_only_spaces(lines[start]->buf);
+	}
+	return 0;
+}
+
+static void print_lines(struct strbuf **lines, int start, int end)
+{
+	int i;
+	for (i = start; lines[i] && i < end; i++)
+		printf("%s", lines[i]->buf);
+}
+
+static int process_input_file(struct strbuf **lines,
+			      struct trailer_item **in_tok_first,
+			      struct trailer_item **in_tok_last)
+{
+	int count = 0;
+	int patch_start, trailer_start, i;
+
+	/* Get the line count */
+	while (lines[count])
+		count++;
+
+	patch_start = find_patch_start(lines, count);
+	trailer_start = find_trailer_start(lines, patch_start);
+
+	/* Print lines before the trailers as is */
+	print_lines(lines, 0, trailer_start);
+
+	if (!has_blank_line_before(lines, trailer_start - 1))
+		printf("\n");
+
+	/* Parse trailer lines */
+	for (i = trailer_start; i < patch_start; i++) {
+		struct trailer_item *new = create_trailer_item(lines[i]->buf);
+		add_trailer_item(in_tok_first, in_tok_last, new);
+	}
+
+	return patch_start;
+}