Re: That '[' file in /usr/bin

[Pádraig Brady]

On 03/04/2013 12:01 AM, H. Peter Anvin wrote:
> Mike Frysinger <address@hidden> wrote:
>> On Sunday 03 March 2013 14:03:24 H. Peter Anvin wrote:
>>> On 03/03/2013 02:53 AM, Pádraig Brady wrote:
>>>>> personally, i find it a bit ironic that a lot of GNU apps
>> (including
>>>>> coreutils) simply abort() themselves when argv[0]==NULL
>> considering the
>>>>> project's hard line position about not relying on argv[0] for
>> behavior.
>>>>
>>>> This issue was mentioned here:
>>>>
>> http://lists.gnu.org/archive/html/bug-coreutils/2009-11/msg00215.html
>>>>
>>>> The problem with avoiding the aborts is that NULL is only
>>>> one of many invalid values for argv[0]
>>>
>>> Come again?
>>>
>>> You can't seriously say that checking for a null pointer or an
>> invalid
>>> string (for whatever definition of "valid" you happen to have) is
>> hard.
>>
>> he's saying that, why special case NULL if we think this scenario is
>> invalid.  
>> a pointer of argv[0] = 1 will crash just as hard.
>> -mike
> 
> The kernel will never pass that; that will fail at the exec side.

Oh right, exec will return EFAULT.
I guess NULL is allowed for backwards compat reasons.

Looking at the actual code in gnulib, it aborts() on purpose
when argv[0] == NULL:

http://git.sv.gnu.org/gitweb/?p=gnulib.git;a=commit;h=3941f59c

Maybe we should output the diagnostic but continue?
However we've not received any reports that this is an issue.

thanks,
Pádraig.