multi-pack-index: fix potential segfault without sub-command

ttaylorr · gitster · commit 88617d11f9d2 · 2021-07-19T15:24:01.000-07:00
Since cd57bc4 (builtin/multi-pack-index.c: display usage on unrecognized command, 2021-03-30) we have used a "usage" label to avoid having two separate callers of usage_with_options (one when no arguments are given, and another for unrecognized sub-commands). But the first caller has been broken since cd57bc4, since it will happily jump to usage without arguments, and then pass argv[0] to the "unrecognized subcommand" error. Many compilers will save us from a segfault here, but the end result is ugly, since it mentions an unrecognized subcommand when we didn't even pass one, and (on GCC) includes "(null)" in its output. Move the "usage" label down past the error about unrecognized subcommands so that it is only triggered when it should be. While we're at it, bulk up our test coverage in this area, too. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/builtin/multi-pack-index.c b/builtin/multi-pack-index.c
@@ -176,8 +176,8 @@ int cmd_multi_pack_index(int argc, const char **argv,
 	else if (!strcmp(argv[0], "expire"))
 		return cmd_multi_pack_index_expire(argc, argv);
 	else {
-usage:
 		error(_("unrecognized subcommand: %s"), argv[0]);
+usage:
 		usage_with_options(builtin_multi_pack_index_usage,
 				   builtin_multi_pack_index_options);
 	}
diff --git a/t/t5319-multi-pack-index.sh b/t/t5319-multi-pack-index.sh
@@ -824,4 +824,9 @@ test_expect_success 'load reverse index when missing .idx, .pack' '
 	)
 '
 
+test_expect_success 'usage shown without sub-command' '
+	test_expect_code 129 git multi-pack-index 2>err &&
+	! test_i18ngrep "unrecognized subcommand" err
+'
+
 test_done

Original file line number	Diff line number	Diff line change
`@@ -824,4 +824,9 @@ test_expect_success 'load reverse index when missing .idx, .pack' '`
`824`	`824`	`)`
`825`	`825`	`'`
`826`	`826`
	`827`	`+test_expect_success 'usage shown without sub-command' '`
	`828`	`+ test_expect_code 129 git multi-pack-index 2>err &&`
	`829`	`+ ! test_i18ngrep "unrecognized subcommand" err`
	`830`	`+'`
	`831`	`+`
`827`	`832`	`test_done`