Re: Using POSIX Named Semaphore After Fork
Re: Using POSIX Named Semaphore After Fork
- Subject: Re: Using POSIX Named Semaphore After Fork
- From: Abdulla Kamar <email@hidden>
- Date: Tue, 27 Oct 2009 18:32:29 +1100
Oh sorry, I should have said something. It turned out to be an issue in my code, it worked fine under Linux but there was a race in Mac OS X.
On Tue, Oct 27, 2009 at 6:23 PM, Steve Checkoway
<email@hidden> wrote:
On Oct 25, 2009, at 8:11 PM, Abdulla Kamar wrote:
Is it possible to use a named semaphore after a fork without reopening it in
the child process? This doesn't seem to be working for me, but may be an
issue with something I'm doing.
#include <stdio.h>
#include <semaphore.h>
#include <unistd.h>
#include <sys/wait.h>
int main()
{
sem_t *sem = sem_open( "foo", O_CREAT, 0666, 0 );
puts( "open" );
pid_t pid = fork();
int ret;
if( pid == -1 )
{
perror( "fork" );
return 1;
}
if( pid == 0)
{
puts( "child is posting" );
ret = sem_post( sem );
if( ret == -1 )
perror( "child sem_post" );
ret = sem_close( sem );
if( ret == -1 )
perror( "child sem_close" );
return 0;
}
puts( "parent is waiting" );
ret = sem_wait( sem );
if( ret == -1 )
perror( "parent sem_wait" );
else
puts( "parent finished waiting" );
pid = wait( &ret );
if( pid == -1 )
perror( "waitpid" );
ret = sem_unlink( "foo" );
if( ret == -1 )
perror( "sem_unlink" );
ret = sem_close( sem );
if( ret == -1 )
perror( "parent sem_close" );
return 0;
}
--
Steve Checkoway
"Anyone who says that the solution is to educate the users
hasn't ever met an actual user." -- Bruce Schneier
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--
Thank you
Abdulla
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