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Subject: Re: [PATCH 1/3] posix: Remove dynamic memory allocation from
 execl{e,p}
To: Paul Eggert <eggert@cs.ucla.edu>, libc-alpha@sourceware.org
References: <1456495001-5298-1-git-send-email-adhemerval.zanella@linaro.org>
 <1456495001-5298-2-git-send-email-adhemerval.zanella@linaro.org>
 <56D09DD3.2050601@cs.ucla.edu>
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Message-ID: <56D0AA3A.9020207@linaro.org>
Date: Fri, 26 Feb 2016 19:44:00 -0000
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On 26-02-2016 15:47, Paul Eggert wrote:
> On 02/26/2016 05:56 AM, Adhemerval Zanella wrote:
>> +  for (i = 1; i < argc; i++)
>> +     argv[i] = va_arg (ap, char *);
>> +  argv[i] = NULL;
> 
> Change "i < argc" to "i <= argc" and remove the "argv[i] = NULL;", as that's a bit simpler and faster.

I added to make it explicit, I will change that.

> 
>> +  int i;
>> +  char *argv[argc + 1];
>> +  char **envp;
>> +  va_start (ap, arg);
>> +  argv[0] = (char *) arg;
>> +  for (i = 1; i <= argc; i++)
> 
> This sort of thing has undefined behavior on x86-64 if argc == INT_MAX. You can fix this by changing the type of argc and of i from int to ptrdiff_t.
> 

Indeed, but afaik this code won't execute if argc == INT_MAX (the argument
sanity check will make the function with E2BIG).

>> +      if (argc == INT_MAX)
>>       {
>> +      errno = E2BIG;
>> +      return -1;
>>       }
> 
> Doesn't that have undefined behavior? My impression from C11 is that since the function has called va_start it must call va_end before returning.
> 

Yes, I will remove it.

>> +      continue;
>>       }
> 
> That 'continue;' is redundant and should be removed.

I will remove it.