Re: [PATCH v3] submodule: port subcommand 'set-branch' from shell to C

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: May 22, 2020, 22:21 UTC
Message-ID: <nycvar.QRO.7.76.6.2005230012090.56@tvgsbejvaqbjf.bet>
In-Reply-To: <20200521163819.12544-1-shouryashukla.oo@gmail.com>

Hi Shourya,

On Thu, 21 May 2020, Shourya Shukla wrote:

Show 47 quoted lines

> diff --git a/builtin/submodule--helper.c b/builtin/submodule--helper.c
> index f50745a03f..d14b9856a3 100644
> --- a/builtin/submodule--helper.c
> +++ b/builtin/submodule--helper.c
> @@ -2284,6 +2284,50 @@ static int module_set_url(int argc, const char **argv, const char *prefix)
>  	return 0;
>  }
>
> +static int module_set_branch(int argc, const char **argv, const char *prefix)
> +{
> +	/*
> +	 * The `quiet` option is present for backward compatibility
> +	 * but is currently not used.
> +	 */
> +	int quiet = 0, opt_default = 0;
> +	const char *opt_branch = NULL;
> +	const char *path;
> +	char *config_name;
> +
> +	struct option options[] = {
> +		OPT__QUIET(&quiet,
> +			N_("suppress output for setting default tracking branch")),
> +		OPT_BOOL(0, "default", &opt_default,
> +			N_("set the default tracking branch to master")),
> +		OPT_STRING(0, "branch", &opt_branch, N_("branch"),
> +			N_("set the default tracking branch")),
> +		OPT_END()
> +	};
> +	const char *const usage[] = {
> +		N_("git submodule--helper set-branch [--quiet] (-d|--default) <path>"),
> +		N_("git submodule--helper set-branch [--quiet] (-b|--branch) <branch> <path>"),
> +		NULL
> +	};
> +
> +	argc = parse_options(argc, argv, prefix, options, usage, 0);
> +
> +	if (!opt_branch && !opt_default)
> +		die(_("--branch or --default required"));
> +
> +	if (opt_branch && opt_default)
> +		die(_("--branch and --default are mutually exclusive"));
> +
> +	if (argc != 1 || !(path = argv[0]))
> +		usage_with_options(usage, options);
> +
> +	config_name = xstrfmt("submodule.%s.branch", path);
> +	config_set_in_gitmodules_file_gently(config_name, opt_branch);

What happens if this fails? E.g. when the permission is denied or disk is full? This C code would then still `return 0`, pretending that it succeeded. But the original shell script calls `git submodule--helper config [...]` which calls `module_config()`, which in turn passes through the return value of the `config_set_in_gitmodules_file_gently()` call.

In other words, you need something like this:

	int ret;

	[...]

	ret = config_set_in_gitmodules_file_gently(config_name, opt_branch);

	free(config_name);
	return ret;

Show 13 quoted lines

> +
> +	free(config_name);
> +	return 0;
> +}
> +
>  #define SUPPORT_SUPER_PREFIX (1<<0)
>
>  struct cmd_struct {
> @@ -2315,6 +2359,7 @@ static struct cmd_struct commands[] = {
>  	{"check-name", check_name, 0},
>  	{"config", module_config, 0},
>  	{"set-url", module_set_url, 0},
> +	{"set-branch", module_set_branch, 0},

BTW I just noticed that the return value of these helpers is returned by the `cmd_submodule__helper()` function. That is not correct, as the convention is for Git's functions to return negative values in case of errors _except_ for `cmd_*()` functions, which need to return an exit code (valid values are between 0 and 127).

So I think we'll also need this (it's unrelated to your patch, at least unrelated enough that it merits its own, separate patch):

-                       return commands[i].fn(argc - 1, argv + 1, prefix);
+                       return !!commands[i].fn(argc - 1, argv + 1, prefix);

Ciao, Dscho

Show 64 quoted lines

>  };
>
>  int cmd_submodule__helper(int argc, const char **argv, const char *prefix)
> diff --git a/git-submodule.sh b/git-submodule.sh
> index 39ebdf25b5..8c56191f77 100755
> --- a/git-submodule.sh
> +++ b/git-submodule.sh
> @@ -719,7 +719,7 @@ cmd_update()
>  # $@ = requested path
>  #
>  cmd_set_branch() {
> -	unset_branch=false
> +	default=
>  	branch=
>
>  	while test $# -ne 0
> @@ -729,7 +729,7 @@ cmd_set_branch() {
>  			# we don't do anything with this but we need to accept it
>  			;;
>  		-d|--default)
> -			unset_branch=true
> +			default=1
>  			;;
>  		-b|--branch)
>  			case "$2" in '') usage ;; esac
> @@ -750,33 +750,7 @@ cmd_set_branch() {
>  		shift
>  	done
>
> -	if test $# -ne 1
> -	then
> -		usage
> -	fi
> -
> -	# we can't use `git submodule--helper name` here because internally, it
> -	# hashes the path so a trailing slash could lead to an unintentional no match
> -	name="$(git submodule--helper list "$1" | cut -f2)"
> -	if test -z "$name"
> -	then
> -		exit 1
> -	fi
> -
> -	test -n "$branch"; has_branch=$?
> -	test "$unset_branch" = true; has_unset_branch=$?
> -
> -	if test $((!$has_branch != !$has_unset_branch)) -eq 0
> -	then
> -		usage
> -	fi
> -
> -	if test $has_branch -eq 0
> -	then
> -		git submodule--helper config submodule."$name".branch "$branch"
> -	else
> -		git submodule--helper config --unset submodule."$name".branch
> -	fi
> +	git ${wt_prefix:+-C "$wt_prefix"} ${prefix:+--super-prefix "$prefix"} submodule--helper set-branch ${GIT_QUIET:+--quiet} ${branch:+--branch $branch} ${default:+--default} -- "$@"
>  }
>
>  #
> --
> 2.26.2
>
>