get_exporter: use argv_array

This simplifies the code and avoids a fixed array size that
we might accidentally overflow. It also prevents a leak
after finish_command is run, by using the argv_array that
run-command manages for us.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport-helper.c

@@ -418,30 +418,24 @@ static int get_exporter(struct transport *transport,
 {
 	struct helper_data *data = transport->data;
 	struct child_process *helper = get_helper(transport);
-	int argc = 0, i;
-	struct strbuf tmp = STRBUF_INIT;
+	int i;
 
 	memset(fastexport, 0, sizeof(*fastexport));
 
 	/* we need to duplicate helper->in because we want to use it after
 	 * fastexport is done with it. */
 	fastexport->out = dup(helper->in);
-	fastexport->argv = xcalloc(6 + revlist_args->nr, sizeof(*fastexport->argv));
-	fastexport->argv[argc++] = "fast-export";
-	fastexport->argv[argc++] = "--use-done-feature";
-	fastexport->argv[argc++] = data->signed_tags ?
-		"--signed-tags=verbatim" : "--signed-tags=warn-strip";
-	if (data->export_marks) {
-		strbuf_addf(&tmp, "--export-marks=%s.tmp", data->export_marks);
-		fastexport->argv[argc++] = strbuf_detach(&tmp, NULL);
-	}
-	if (data->import_marks) {
-		strbuf_addf(&tmp, "--import-marks=%s", data->import_marks);
-		fastexport->argv[argc++] = strbuf_detach(&tmp, NULL);
-	}
+	argv_array_push(&fastexport->args, "fast-export");
+	argv_array_push(&fastexport->args, "--use-done-feature");
+	argv_array_push(&fastexport->args, data->signed_tags ?
+		"--signed-tags=verbatim" : "--signed-tags=warn-strip");
+	if (data->export_marks)
+		argv_array_pushf(&fastexport->args, "--export-marks=%s.tmp", data->export_marks);
+	if (data->import_marks)
+		argv_array_pushf(&fastexport->args, "--import-marks=%s", data->import_marks);
 
 	for (i = 0; i < revlist_args->nr; i++)
-		fastexport->argv[argc++] = revlist_args->items[i].string;
+		argv_array_push(&fastexport->args, revlist_args->items[i].string);
 
 	fastexport->git_cmd = 1;
 	return start_command(fastexport);