Date: Tue, 21 Nov 2000 17:06:05 +0300 (MSK) From: Dmitry Dicky <diwil@dataart.com> To: Vladimir Terziev <vladimirt@rila.bg> Cc: hackers@FreeBSD.ORG Subject: RE: Semaphore blocking and signal handling Message-ID: <XFMail.001121170605.diwil@dataart.com> In-Reply-To: <200011211357.PAA63147@star.rila.bg>
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Hi,
easy:
-------------------------------
extern int errno;
int sem_lock(int semnumb)
{
struct sembuf sb[2];
sb[0].sem_num = semnumb;
sb[0].sem_op = -1;
sb[0].sem_flg = 0;
again:
if( semop(sh->sem, sb,1) )
{
errmsg("Semaphore %d erorr: %s\n",sh->sem, strerror(errno));
// here you'll see the reason why semaphore returned an error
if(errno = EINTR) goto again;
return -1;
}
return 0;
}
----------------------------------
At least it works in my case.
Regards,
D.
On 21-Nov-00 Vladimir Terziev wrote:
> Hi.
>
> Am I right for the following:
>
> When a process is blocked on semop (trying to get resource) and receives
> a signal (for which the process has a handler), the process gets
> unblocked
> from the semop wait (to handle the signal), and after handling the
> signal
> continues with the instruction after semop, as if it was unblocked by
> successful semop.
>
> Is this behaviour normal, and is there a way for the process to
> distinguish
> between signal handling unblock and successful semop operation (may be
> by
> setting a global variable in the signal-handling function) ?
>
> Thank you in advance.
>
> Vladimir Terziev
>
>
>
>
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