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Re: mbrtoc32 in MinGW-w64 buggy?

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Am 29.03.2014 14:08, schrieb Eric Sosman:
> On 3/29/2014 8:16 AM, Werner Wenzel wrote:
>> Running the following MinGW-w64-built code on Windows 7 64 bit crashes
>> with me:
>>
>> #include <stdio.h>
>> #include <uchar.h>
>>
>> int main(void)
>> {
>>      mbstate_t mbstate;
>>
>>      puts("So far okay ...");
>>      mbrtoc32(NULL, "", 1, &mbstate);
>>      puts("Not reached due to crash!");
>>      return 0;
>> }
>>
>> It should not crash as the problematic line derives from ISO C11 (N1570)
>> 7.28.1.3p2.
>>
>> As far as I can see this issue is caused by
>> \mingw-builds\sources\mingw-w64-v3.1.0\mingw-w64-crt\misc\uchar_mbrtoc32.c,
>>
>> line 32, which--in this special case--dereferences NULL.
>>
>> Is this thought correct or am I missing something?
>
>      I am no expert on wide-character utilities and I have not looked
> at the source code, but it looks to me like the `mbstate' variable
> has never been initialized, and so may "contain garbage."  What
> happens if you use `mbstate_t mbstate = { 0 };' instead?
>

Actually, it still crashes with "mbstate_t mbstate = { 0 };".

The cited MinGW-w64 code reads as follows:

size_t mbrtoc32 (char32_t *__restrict__ pc32,
		 const char *__restrict__ s,
		 size_t n,
		 mbstate_t *__restrict__ __UNUSED_PARAM(ps))
{
     if (*s == 0)
     {
	*pc32 = 0;
	return 0;
     }
...

In this special case the empty string (2nd argument) triggers an 
assignment of 0 to where pc32 points to and pc32 points nowhere.

In my opinion the arguable code should read:

if (pc32) *pc32 = 0;

Werner

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mbrtoc32 in MinGW-w64 buggy? Werner Wenzel <werner.wenzel@netcologne.de> - 2014-03-29 13:16 +0100
  Re: mbrtoc32 in MinGW-w64 buggy? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-03-29 09:08 -0400
    Re: mbrtoc32 in MinGW-w64 buggy? Werner Wenzel <werner.wenzel@netcologne.de> - 2014-03-29 15:09 +0100
      Re: mbrtoc32 in MinGW-w64 buggy? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-03-29 10:27 -0400
    Re: mbrtoc32 in MinGW-w64 buggy? Keith Thompson <kst-u@mib.org> - 2014-03-29 14:38 -0700
      Re: mbrtoc32 in MinGW-w64 buggy? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-03-29 17:44 -0400
        Re: mbrtoc32 in MinGW-w64 buggy? Keith Thompson <kst-u@mib.org> - 2014-03-29 16:50 -0700
          Re: mbrtoc32 in MinGW-w64 buggy? James Kuyper <jameskuyper@verizon.net> - 2014-03-31 10:54 -0400
  Re: mbrtoc32 in MinGW-w64 buggy? James Kuyper <jameskuyper@verizon.net> - 2014-03-29 09:17 -0400

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