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Message-Id: <C629E8CF-503B-4A32-A1CD-A2CD6ECA3602@palsenberg.com>
Date: Mon, 6 Jun 2011 12:47:38 +0200
From: Igmar Palsenberg <musl@...senberg.com>
To: musl@...ts.openwall.com
Subject: Re: Musl git 0d......455eee8 and recent compilers
> * Igmar Palsenberg <musl@...senberg.com> [2011-06-06 10:48:08 +0200]:
>> I was using Musle as a test for..
>
> musl
Sorry.... It's also the name of a cleaning substance here, so I usually het the name wrong :)
>
>> 1) The struct dirent in include/dirent.h uses a 1 byte array for d_name. In reality, it's larger : We allocate more space than the struct. Since muscle requires a C99 compiler anyway, what's keeping use from using d_name[0] or d_name[] ? If a C89 compiler includes dirent.h, we're screwed anyway :). That will probably silence GCC 4.5 and clang, and severely reduce the warnings it gives in similar cases.
>>
>
> what kind of warnings do you get?
Array out of bounds :
src/misc/nftw.c:77:11: warning: array index of '1' indexes past the end of an array (that contains 1 elements) [-Warray-bounds]
&& (!de->d_name[1]
The compiler is strictly speaking right in this case.
> char foo[1] gives warning but a flexible array member char foo[] does not?
Correct.
>> 2) The NULL pointer dereference in src/time/__asctime.c won't work with clang : It removes it. I suggest using either __builtin_trap() or an abort(). If you get to that point, you're in trouble anyway.
>>
>
> i guess __builtin_trap is compiler specific
> i don't think it's a big deal..
> there could be 0/0 as well i guess
> i wonder what
> main(){ return *(int*)0; }
> or even
> main(){ return ((int(*)())0)(); }
> does on clang..
Hmm.. Despite the warning :
int main(int argc, char **argv)
{
*(int*)0 = 0;
printf("XXX\n");
return 0;
}
segfaults. Clang is allowed to remove the dereference, we might to use abort() in this case. With O3, it gives an illegal instruction (probably an ud2). I either misread the warning, or clang doesn't do what it says :).
>
>> 3) Clang does't seem to grasp the weak_alias thingy. It need to check if those parts actually are correct
>>
>
> well it uses the alias __attribute__ extension of gcc
I need to check if the offending function / alias is there, or as clang says, isn't emitted.
>> 4) Is there a muscl testsuite somewhere ?
>>
>
> musl
>
> http://git.etalabs.net/cgi-bin/gitweb.cgi
I'll try that.
Regards,
Igmar
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