[PATCH v2 3/3] samples/landlock: Clarify option parsing behaviour

[Mickaël Salaün]

On Thu, Oct 03, 2024 at 02:50:42AM +0200, Matthieu Buffet wrote:
> - Clarify which environment variables are optional, which ones are
>   mandatory
> - Clarify the difference between unset variables and empty ones

You can remove the "-" and just go with two sentences.

> 
> Signed-off-by: Matthieu Buffet <matthieu at buffet.re>
> ---
>  samples/landlock/sandboxer.c | 22 +++++++++++++---------
>  1 file changed, 13 insertions(+), 9 deletions(-)
> 
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index f16994d35d9e..a28e4a9c5f87 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -298,24 +298,27 @@ static bool check_ruleset_scope(const char *const env_var,
>  static void print_help(const char *argv0)
>  {
>  	fprintf(stderr,
> -		"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s "
> +		"usage: %s=\"...\" %s=\"...\" [other environment variables] %s "
>  		"<cmd> [args]...\n\n",
> -		ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
> -		ENV_TCP_CONNECT_NAME, ENV_SCOPED_NAME, argv0);
> +		ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv0);
>  	fprintf(stderr,
>  		"Execute a command in a restricted environment.\n\n");
>  	fprintf(stderr,
> -		"Environment variables containing paths and ports "
> -		"each separated by a colon:\n");
> +		"All environment variables can be multi-valued, with a "
> +		"colon delimiter.\n"
> +		"\n"
> +		"Mandatory settings:\n");
>  	fprintf(stderr,
>  		"* %s: list of paths allowed to be used in a read-only way.\n",
>  		ENV_FS_RO_NAME);
>  	fprintf(stderr,
> -		"* %s: list of paths allowed to be used in a read-write way.\n\n",
> +		"* %s: list of paths allowed to be used in a read-write way.\n",
>  		ENV_FS_RW_NAME);
>  	fprintf(stderr,
> -		"Environment variables containing ports are optional "
> -		"and could be skipped.\n");
> +		"\n"
> +		"Optional settings (when not set, their associated access "
> +		"check is always allowed, which is different from an empty "
> +		"string which means an empty list)\n");
>  	fprintf(stderr,
>  		"* %s: list of ports allowed to bind (server).\n",
>  		ENV_TCP_BIND_NAME);
> @@ -325,7 +328,8 @@ static void print_help(const char *argv0)
>  	fprintf(stderr, "* %s: list of scoped IPCs.\n",
>  		ENV_SCOPED_NAME);
>  	fprintf(stderr,
> -		"\nexample:\n"
> +		"\n"
> +		"Example:\n"
>  		"%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
>  		"%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
>  		"%s=\"9418\" "
> -- 
> 2.39.2
> 
>