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Message-ID: <3DF6FBD8.6090702@gmx.net>
Date: Wed, 11 Dec 2002 09:48:24 +0100
From: Thomas Pfaff <tpfaff AT gmx DOT net>
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To: oreste DOT bernardi AT st DOT com
CC: cygwin AT cygwin DOT com
Subject: Re: SIGSEGV when called sem_init() with gdb.
References: <63340-220021221016341397 AT M2W082 DOT mail2web DOT com> <003e01c2a077$3b065ba0$940782a4 AT agr DOT st DOT com> <3DF6F700 DOT 2030305 AT gmx DOT net>
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Sorry, I forgot to mention:

Your work around is not portable. The type of sem_t is not necessary a 
pointer.

Portable would be something like:
memset(&sem, 0, sizeof(sem));

Thomas

Thomas Pfaff wrote:
> Just add a breakpoint after the sem_init call.
> To avoid multiple initializations sem_init checks if the semaphore is 
> already initialized and will return EBUSY in that case.
> The check is done via IsBadWritePtr which will trigger a SEGV if the 
> pointer is invalid and not NULL.
> The SEGV is handled internally and will not cause the program to stop.
> 
> Thomas
> 
> Oreste Bernardi wrote:
> 
>> I installed
>> gdb                 20020718-1.
>>
>> I tried again and I see same behavior.
>>
>> By the way, is gdb 20020718-1 experimental version or stable version ?
>>
>> Oreste
>>
>>
>> ----- Original Message ----- From: <lhall AT pop DOT ma DOT ultranet DOT com>
>> To: <oreste DOT bernardi AT st DOT com>; <cygwin AT cygwin DOT com>
>> Sent: Tuesday, December 10, 2002 5:03 PM
>> Subject: RE: SIGSEGV when called sem_init() with gdb.
>>
>>
>> Rerun setup and update your gdb.  If that doesn't help, let the list 
>> know.
>>
>> Larry
>>
>> Original Message:
>> -----------------
>> From: Oreste Bernardi oreste DOT bernardi AT st DOT com
>> Date: Tue, 10 Dec 2002 16:01:16 +0100
>> To: cygwin AT cygwin DOT com
>> Subject: SIGSEGV when called sem_init() with gdb.
>>
>>
>> Dear, all
>>
>> #include <semaphore.h>
>> int main () {
>> int p;
>> sem_t sem;
>> int i=0,d;
>> //sem=(sem_t)NULL; //With this There isn't any problem
>> sem_init (&sem,0,1);
>> sem_post (&sem);
>> sem_wait(&sem);
>> return i;
>> }
>>
>> cygwin 1.3.17-1
>> gcc  3.2-3
>> gdb  20010428-3
>>
>> When executing this source code with gdb I get an SIGSEGV signal  when
>> sem_init() function is called.
>> If I continue on, program works fine.
>> If program is not executed from gdb, it works without any error.
>> If I initialize it with NULL, I don't get any error.
>>
>> I think that is the same behavior as described by following mail:
>> http://sources.redhat.com/ml/cygwin/2002-10/msg00956.html
>> Is this true ?
>>
>> To avoid annoying gdb error message, is my solution ("sem=(sem_t)NULL")
>> reliable and portable ?
>>
>> Best Regards
>> Oreste Bernardi
>>
>>
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> 
> 
> 



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