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Re: SIGSEGV when called sem_init() with gdb.


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@pop.ma.ultranet.com>
To: <oreste.bernardi@st.com>; <cygwin@cygwin.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.bernardi@st.com
Date: Tue, 10 Dec 2002 16:01:16 +0100
To: cygwin@cygwin.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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