timer_create(2)                   SDK R4.11                  timer_create(2)


NAME
       timer_create - create a per-process timer

SYNOPSIS
       #include <signal.h>
       #include <time.h>

       int timercreate (clockid, *expirationsignal, *timerid)
            clockt        clockid;
            struct sigevent*expirationsignal;
            timert        *timerid;

DESCRIPTION
       Use timercreate(2) to create a process timer:

        clockid    is CLOCK_REALTIME.

        expirationsignal
                    is a pointer to a structure containing the signal number
                    to be sent to the calling process on expiration. If
                    expirationsignal is NULL, signal SIGALRM is sent to the
                    calling process upon the timer's expiration.

        timerid    If successful, timercreate returns a timer ID in this
                    location.  The timer ID is unique within the calling
                    process, until the timer is deleted. This timer ID is
                    used to identify the timer in other timer requests.

       At present, the only capability provided by sigevent supported by
       DG/UX is to define the signal number to be sent to the calling
       process on expiration.  The sigevnotify member of sigevent must be
       set to SIGEV_SIGNAL.  The sigevsigno member of sigevent is the
       signal number to send.  All other fields of sigevent are ignored.

       Sending application-supplied data to a signal handler depends on the
       POSIX realtime signal extensions, which DG/UX does not currently
       support. To compensate for this lack, DG/UX defines four user-defined
       signals that you can specify in sigevsigno and easily check for in a
       signal handler: SIGDGTIMER1, SIGDGTIMER2, SIGDGTIMER3, SIGDGTIMER4.

       Child processes of the caller created with fork(2) do not inherit the
       timer. An exec(2) call disables and deletes the timer.

       The maximum number of per-process timers is stored in the system
       variable _POSIX_TIMER_MAX. You can obtain this value by calling
       sysconf(2) with parameter _SC_TIMER_MAX. The current maximum for
       DG/UX is 32.

   Note
        * This routine is based on POSIX realtime extension document P1003.4
          draft 14. It is therefore subject to change.

        * Compilation of a source file using this routine requires that
          feature macro _POSIX4_DRAFT_SOURCE be defined.  This feature macro
          is not enabled by any other feature macro, nor does it enable any
          other feature macro.

        * The compiled routine must be linked to library librte.a.

RETURN VALUE
       If successful, timercreate returns a zero, and updates the location
       referenced by timerid to a timert which can be passed to the other
       timer calls.  If unsuccessful, the routine returns -1 and sets ERRNO
       to one of the following:

        EAGAIN The system lacks the resources to honor the request.

        EAGAIN The calling process already has the maximum number of timers
               open.

        EFAULT The address of expirationsignal is bad.

        EINVAL The value of clockid is not CLOCK_REALTIME.

        EINVAL The signal pointed to by expirationsignal is not valid.

        EINVAL The notification pointed to by expirationsignal is not
               SIGEV_SIGNAL.

SEE ALSO
       clockgetres(2), sysconf(2), timerdelete(2), timersettime(2),
       timergettime(2), timergetoverrun(2).


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