[stgt] [PATCH] improved conversion and checking of numerical cmd lineargs

[Alexander Nezhinsky]

Redoing the patch discussed below. 
Using the direction that Tomo had suggested with some variations.

On 06/20/2010 05:01 AM, FUJITA Tomonori wrote:

> On Thu, 17 Jun 2010 16:19:43 +0300 (IDT)
> Alexander Nezhinsky <alexandern at voltaire.com> wrote:
> 
>> When a numerical command line param value is out of range or contains garbage
>> (both tgtd and tgtadm), this remains unchecked in many cases.
>> In some of them 0 value will be used, which may lead to unpredicted or
>> "silently" faulty behavior.
>>
>> This fix defines a new function str_to_uit64() which uses strtoull() and
>> detects its errors properly, by checking 1) errno (range errors) and
>> 2) comparing endptr to the original argument (nun-numerical garbage);
>> must check both.
>>
>> str_to_uit64() is declared static twice, in tgtd.c and tgtadm.c, as
>> tgtadm does not uses util.c, where the natural place of this function
>> would be otherwise.
>>
>> It returns the converted integer value directly, while error is returned
>> through a pointer argument. Although the opposite arrangement may seem
>> intuitive, this one allows free casting of the returned value to various
>> types. Return type uint64 is choosen to cover all possible cases.
>> min and max arguments support range checking. To use the natural integer
>> ranges, use ULLONG_MAX, ULONG_MAX, USHRT_MAX etc.
>>
>> Signed-off-by: Alexander Nezhinsky <alexandern at voltaire.com>
> 
> I'm for the strict checking however two comments.
> 
> - casting a returned value looks ugly.
> 
> - duplicating the same function isn't nice.
> 
> 
> How about something like this?
> 
> diff --git a/usr/tgtadm.c b/usr/tgtadm.c
> index 28ed754..2282c86 100644
> --- a/usr/tgtadm.c
> +++ b/usr/tgtadm.c
> @@ -471,8 +471,8 @@ int main(int argc, char **argv)
>  			mode = str_to_mode(optarg);
>  			break;
>  		case 't':
> -			tid = strtol(optarg, NULL, 10);
> -			if (errno == EINVAL) {
> +			tid = str_to_val(optarg, int, 0, INT_MAX, &rc);
> +			if (rc == EINVAL) {
>  				eprintf("invalid tid '%s'\n", optarg);
>  				exit(EINVAL);
>  			}
> diff --git a/usr/util.h b/usr/util.h
> index 6e1fd6f..fc406b1 100644
> --- a/usr/util.h
> +++ b/usr/util.h
> @@ -156,4 +156,17 @@ struct signalfd_siginfo {
>  };
>  #endif
>  
> +#define str_to_val(str, type, min, max, err_ptr)	\
> +({							\
> +	char *ptr;					\
> +	int ret = 0;					\
> +	typeof(type) v = strtoull(str, &ptr, 0);	\
> +	if (errno || ptr == str)			\
> +		ret = EINVAL;				\
> +	if (v < min|| v > max)				\
> +		ret = ERANGE;				\
> +	*err_ptr = ret;					\
> +	v;						\
> +})							\
> +
>  #endif


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