Re: Some tests fail in VC++2005

[Steve Croall <s.croall@btinternet.com>]

If I have time I will download VC++2005 from MSDN and see what the 
problem is.  If there is one :)

After using Microsoft's COM+ event system it wouldn't surprise me if 
there are problems :)

Steve.

Ross Johnson wrote:
> On Thu, 2005-04-21 at 16:07 +0200, Uenal Mutlu wrote:
> 
>>I've tried the latest 2 pthreads releases with MS compilers.
>>VC++6 passes all tests, but VC++2005 fails with about 26 of the
>>test programs (tested only in beta 1, beta 2 is out since last monday
>>or so but I don't have it yet).
>>The first one of the failing test programs is semaphore1.c, line 89:
>>
>>nmake clean VC
>>...
>>... Running VC test: mutex1r.exe
>>...... Passed
>>cl /D__CLEANUP_C /O2 /Ob0 /W3 /WX /MD /nologo /Yd /Zi -I. semaphore1.c /Fesemaphore1.exe /link /INCREMENTAL:NO pthreadVC2.lib
>>ws2_32.lib
>>cl : Command line warning D9035 : option 'Yd' has been deprecated and will be removed in a future release
>>semaphore1.c
>>... Running VC test: semaphore1.exe
>>thread: sem_trywait 1: expected error: No error
>>Assertion failed: (errno == EAGAIN), file semaphore1.c, line 89
>>NMAKE : fatal error U1077: '.\semaphore1.exe' : return code '0x1'
>>Stop.
>>NMAKE : fatal error U1077: 'nmake' : return code '0x2'
>>Stop.
>>
> 
> 
> Strange. It was previously reported that all tests passed with VC++ 2005
> beta:
> http://sources.redhat.com/ml/pthreads-win32/2005/msg00035.html
> 
> Also reported as passing using VC++ 8.0 and VS .NET 2003.
> 
> 
>>Below is the function from semaphore1.c where the error occurs.
>>It is the line
>>     assert(errno == EAGAIN);
>>I wonder where errno gets set to this value.
>>Is it done in sem_trywait() or maybe in perror()?
>>And frankly I don't understand how the below code works at all
>>because that branch is entered only if result is -1. The funny
>>thing here (for me) is that then the program should stop in the
>>previous assert(), but this isn't happening! Then I wonder how
>>and why the if condition becomes true...
>>
> 
> 
> [See my comments later re perror.]
> 
> The test is expecting EAGAIN to be set by sem_trywait(). Since the
> semaphore was initialised to 0, sem_trywait should return EAGAIN to
> indicate that it would have had to wait.
> 
> But the output is saying that after sem_trywait returns -1, errno is 0
> ('no error'). So it seems as if errno may not be correctly defined in
> pthread.h and is conflicting with how it's supposed to work with VC+
> +2005 - and is not thread-safe as a result.
> 
> Usually errno is defined as:
> 
> #define errno *errno()
> 
> where errno() is a function that returns a pointer to a thread-specific
> errno location.
> 
> I don't have access to VC++2005 so won't be able to fix this and test
> that it works afterwards. If you (or anyone else can) it would sure
> help. I have a similar problem with the Borland and Watcom compilers,
> and I just can't figure out what I need to do to fix it.
> 
> 
>>void *
>>thr(void * arg)
>>{
>>  sem_t s;
>>  int result;
>>
>>  assert(sem_init(&s, PTHREAD_PROCESS_PRIVATE, 0) == 0);
>>
>>  assert((result = sem_trywait(&s)) == -1);
>>
>>  if ( result == -1 )
>>  {
>>    perror("thread: sem_trywait 1: expected error"); // No error
>>    assert(errno == EAGAIN);
>>  }
>>...
>>
>>I have posted this issue also in
>>news://news.microsoft.com/microsoft.public.dotnet.languages.vc
>>under the subject "VC++ 2005 beta1 fails with pthreads benchmark tests"
>>but the MS guys say the code is broken. Maybe someone could clarify this.
>>
> 
> 
> Hmmm, my Googling just now hit on this discussion between UM (you?) and
> someone else. Is this the same discussion as the news link you gave:
> http://www.codecomments.com/forum292/message465116-2.html
> 
> Apart from the unhelpful and highly defensive/diversionary comments from
> the other guy about assert abuse etc., I agree that errno should
> probably not be read again after the perror call. The standard doesn't
> say that perror should preserve errno - only that perror doesn't return
> a value and that no errors are defined for it. I'll change the tests.
> 
> By the way, here's some code from the MSDN perror web page:
> http://msdn.microsoft.com/library/default.asp?url=/library/en-
> us/vclib/html/_crt_perror.2c_._wperror.asp
> 
> Note that it expects errno to be preserved through the perror() call
> too.
> 
> // crt_perror.c
> /* This program attempts to open a file named
>  * NOSUCHF.ILE. Because this file probably doesn't exist,
>  * an error message is displayed. The same message is
>  * created using perror, strerror, and _strerror.
>  */
> 
> #include <fcntl.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <io.h>
> #include <stdlib.h>
> #include <stdio.h>
> #include <string.h>
> 
> int main( void )
> {
>    int  fh;
> 
>    if( (fh = _open( "NOSUCHF.ILE", _O_RDONLY )) == -1 )
>    {
>       /* Three ways to create error message: */
>       perror( "perror says open failed" );
>       printf( "strerror says open failed: %s\n", strerror( errno ) );
>       printf( _strerror( "_strerror says open failed" ) );
>    }
>    else
>    {
>       printf( "open succeeded on input file\n" );
>       _close( fh );
>    }
> }
> 
> Ross
> 
> 
> 
> 

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