sigqueue(3C) Standard C Library Functions sigqueue(3C)NAMEsigqueue - queue a signal to a process
SYNOPSIS
#include <sys/types.h>
#include <signal.h>
int sigqueue(pid_t pid, int signo, const union sigval value);
DESCRIPTION
The sigqueue() function causes the signal specified by signo to be sent
with the value specified by value to the process specified by pid. If
signo is 0 (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) function.
The sigqueue() function returns immediately. If SA_SIGINFO is set for
signo and if the resources were available to queue the signal, the sig‐
nal is queued and sent to the receiving process. If SA_SIGINFO is not
set for signo, then signo is sent at least once to the receiving
process; it is unspecified whether value will be sent to the receiving
process as a result of this call.
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(2) function
for signo, either signo or at least the pending, unblocked signal will
be delivered to the calling thread before the sigqueue() function
returns. Should any of multiple pending signals in the range SIGRTMIN
to SIGRTMAX be selected for delivery, it will be the lowest numbered
one. The selection order between realtime and non-realtime signals, or
between multiple pending non-realtime signals, is unspecified.
RETURN VALUES
Upon successful completion, the specified signal will have been queued,
and the sigqueue() function returns 0. Otherwise, the function returns
−1 and sets errno to indicate the error.
ERRORS
The sigqueue() function will fail if:
EAGAIN No resources are available to queue the signal. The process
has already queued SIGQUEUE_MAX signals that are still pend‐
ing at the receiver(s), or a system wide resource limit has
been exceeded.
EINVAL The value of signo is an invalid or unsupported signal num‐
ber.
ENOSYS The sigqueue() function is not supported by the system.
EPERM The process does not have the appropriate privilege to send
the signal to the receiving process.
ESRCH The process pid does not exist.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ATTRIBUTE TYPE │ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │Async-Signal-Safe │
├─────────────────────────────┼─────────────────────────────┤
│Standard │See standards(5). │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOkill(2), siginfo.h(3HEAD), signal.h(3HEAD), sigwaitinfo(3C),
attributes(5), standards(5)SunOS 5.11 5 Feb 2008 sigqueue(3C)