| SIGQUEUE(2) | System Calls Manual | SIGQUEUE(2) | 
sigqueue, sigqueueinfo —
#include <signal.h>
int
  
  sigqueue(pid_t
    pid, int signo,
    const union sigval
    value);
int
  
  sigqueueinfo(pid_t
    pid, const siginfo_t
    *info);
sigqueue() system call causes the signal specified
  by signo to be sent with the value specified by
  value to the process specified by
  pid. If signo is zero (the null
  signal), error checking is performed but no signal is actually sent. The null
  signal can be used to check the validity of PID.
The conditions required for a process to have permission to queue
    a signal to another process are the same as for the
    kill(2) system call. The
    sigqueue() system call queues a signal to a single
    process specified by the pid argument.
The sigqueue() system call is implemented
    using sigqueueinfo() and passing the appropriate
    information in the info argument.
The sigqueue() system call returns
    immediately. If the resources were available to queue the signal, the signal
    will be queued and sent to the receiving process.
If the value of pid causes
    signo to be generated for the sending process, and if
    signo is not blocked for the calling thread and if no
    other thread has signo unblocked or is waiting in a
    sigwait() system call for
    signo, either signo or at least
    the pending, unblocked signal will be delivered to the calling thread before
    sigqueue() returns. Should any multiple pending
    signals in the range SIGRTMIN to
    SIGRTMAX be selected for delivery, it is the lowest
    numbered one. The selection order between realtime and non-realtime signals,
    or between multiple pending non-realtime signals, is unspecified.
sigqueue() system call will fail if:
EAGAIN]SIGQUEUE_MAX} signals that are still
      pending at the receiver(s), or a system-wide resource limit has been
      exceeded.EINVAL]EPERM]ESRCH]sigqueue() system call conforms to
  IEEE Std 1003.1-2004 (“POSIX.1”).
| January 9, 2011 | NetBSD 9.4 |