builtin-commit: resurrect behavior for multiple -m options

When more than one -m option is given, the message does not replace
the previous, but is appended as a new paragraph.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-commit.c

@@ -30,13 +30,27 @@ static char *use_message_buffer;
 static const char commit_editmsg[] = "COMMIT_EDITMSG";
 static struct lock_file lock_file;
 
-static char *logfile, *force_author, *message, *template_file;
+static char *logfile, *force_author, *template_file;
 static char *edit_message, *use_message;
 static int all, edit_flag, also, interactive, only, amend, signoff;
 static int quiet, verbose, untracked_files, no_verify;
 
 static int no_edit, initial_commit, in_merge;
 const char *only_include_assumed;
+struct strbuf message;
+
+static int opt_parse_m(const struct option *opt, const char *arg, int unset)
+{
+	struct strbuf *buf = opt->value;
+	if (unset)
+		strbuf_setlen(buf, 0);
+	else {
+		strbuf_addstr(buf, arg);
+		strbuf_addch(buf, '\n');
+		strbuf_addch(buf, '\n');
+	}
+	return 0;
+}
 
 static struct option builtin_commit_options[] = {
 	OPT__QUIET(&quiet),
@@ -45,7 +59,7 @@ static struct option builtin_commit_options[] = {
 
 	OPT_STRING('F', "file", &logfile, "FILE", "read log from file"),
 	OPT_STRING(0, "author", &force_author, "AUTHOR", "override author for commit"),
-	OPT_STRING('m', "message", &message, "MESSAGE", "specify commit message"),
+	OPT_CALLBACK('m', "message", &message, "MESSAGE", "specify commit message", opt_parse_m),
 	OPT_STRING('c', "reedit-message", &edit_message, "COMMIT", "reuse and edit message from specified commit "),
 	OPT_STRING('C', "reuse-message", &use_message, "COMMIT", "reuse message from specified commit"),
 	OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by: header"),
@@ -150,8 +164,8 @@ static int prepare_log_message(const char *index_file, const char *prefix)
 	FILE *fp;
 
 	strbuf_init(&sb, 0);
-	if (message) {
-		strbuf_add(&sb, message, strlen(message));
+	if (message.len) {
+		strbuf_addbuf(&sb, &message);
 	} else if (logfile && !strcmp(logfile, "-")) {
 		if (isatty(0))
 			fprintf(stderr, "(reading log message from standard input)\n");
@@ -322,7 +336,7 @@ static int parse_and_validate_options(int argc, const char *argv[])
 	argc = parse_options(argc, argv, builtin_commit_options,
 			     builtin_commit_usage, 0);
 
-	if (logfile || message || use_message)
+	if (logfile || message.len || use_message)
 		no_edit = 1;
 	if (edit_flag)
 		no_edit = 0;
@@ -347,7 +361,7 @@ static int parse_and_validate_options(int argc, const char *argv[])
 		f++;
 	if (f > 1)
 		die("Only one of -c/-C/-F can be used.");
-	if (message && f > 0)
+	if (message.len && f > 0)
 		die("Option -m cannot be combined with -c/-C/-F.");
 	if (edit_message)
 		use_message = edit_message;