[PATCH] bundle: don't segfault on "git bundle <subcmd>"

Since aef7d75e580 (builtin/bundle.c: let parse-options parse subcommands, 2022-08-19) we've been segfaulting if no argument was provided.

The fix is easy, as all of the "git bundle" subcommands require a non-option argument we can check that we have arguments left after calling parse-options().

This makes use of code added in 73c3253d75e (bundle: framework for options before bundle file, 2019-11-10), before this change that code has always been unreachable. In 73c3253d75e we'd never reach it as we already checked "argc < 2" in cmd_bundle() itself.

Then when aef7d75e580 (whose segfault we're fixing here) migrated this code to the subcommand API it removed that "argc < 2" check, but we were still checking the wrong "argc" in parse_options_cmd_bundle(), we need to check the "newargc". The "argc" will always be >= 1, as it will necessarily contain at least the subcommand name itself (e.g. "create").

As an aside, this could be safely squashed into this, but let's not do that for this minimal segfault fix, as it's an unrelated refactoring:

	--- a/builtin/bundle.c
	+++ b/builtin/bundle.c
	@@ -55,13 +55,12 @@ static int parse_options_cmd_bundle(int argc,
	 		const char * const usagestr[],
	 		const struct option options[],
	 		char **bundle_file) {
	-	int newargc;
	-	newargc = parse_options(argc, argv, NULL, options, usagestr,
	+	argc = parse_options(argc, argv, NULL, options, usagestr,
	 			     PARSE_OPT_STOP_AT_NON_OPTION);
	-	if (!newargc)
	+	if (!argc)
	 		usage_with_options(usagestr, options);
	 	*bundle_file = prefix_filename(prefix, argv[0]);
	-	return newargc;
	+	return argc;
	 }

	 static int cmd_bundle_create(int argc, const char **argv, const char *prefix) {

Reported-by: Hubert Jasudowicz <hubertj@stmcyber.pl>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

A proposed replacement for https://lore.kernel.org/git/20221220123142.812965-1-hubertj@stmcyber.pl/; let's move forward & add a test rather than reverting away from the subcommand APIe

 builtin/bundle.c       | 2 +-
 t/t6020-bundle-misc.sh | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)