Re: [PATCH] Fix system() behaviour when parameter is NULL

[mouss <mouss%netoyen.net@localhost>]

Andy Shevchenko wrote:
> The ISO/IEC 9899:1999 describes in 7.20.4.6 behaviour of the system() when its
> parameter is NULL. So, we should check a presence of a command interpreter
> instead of returning 1.
> ---
>  lib/libc/stdlib/system.c |   11 +++++++++--
>  1 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/lib/libc/stdlib/system.c b/lib/libc/stdlib/system.c
> index 4cc3cbe..2b729b5 100644
> --- a/lib/libc/stdlib/system.c
> +++ b/lib/libc/stdlib/system.c
> @@ -64,8 +64,15 @@ system(command)
>         const char *argp[] = {"sh", "-c", NULL, NULL};
>         argp[2] = command;
>  
> -	if (command == NULL)		/* just checking... */
> -               return(1);
> +       /*
> +        * ISO/IEC 9899:1999 in 7.20.4.6 describes this special case.
> +        * We need to check availability of a command interpreter.
> +	 */ 
> +	if (command == NULL) {
> +               if (access(_PATH_BSHELL, R_OK | X_OK) == 0)
> +                       return 1;
> +               return 0;
> +       }
>  
>  	sa.sa_handler = SIG_IGN;
>         sigemptyset(&sa.sa_mask);


Is using access() a "clean" way? access(2) says:

"access() is a potential security hole and should never be used."

I understand "never" as never ;-p