SIGQUEUE(2) Linux Programmer's Manual SIGQUEUE(2)
NAME
sigqueue - queue a signal and data to a process
SYNOPSIS
#include<signal.h>
intsigqueue(pid_t pid,int sig,constunionsigval value);
DESCRIPTION
sigqueue() sends the signal specified in sig to the process whose PID
is given in pid. The permissions required to send a signal are the
same as for kill(2). As with kill(2), the null signal (0) can be used
to check if a process with a given PID exists.
The value argument is used to specify an accompanying item of data
(either an integer or a pointer value) to be sent with the signal, and
has the following type:
union sigval {
int sival_int;
void *sival_ptr;
};
If the receiving process has installed a handler for this signal using
the SA_SIGINFO flag to sigaction(2), then it can obtain this data via
the si_value field of the siginfo_t structure passed as the second
argument to the handler. Furthermore, the si_code field of that struc-
ture will be set to SI_QUEUE.
RETURNVALUE
On success, sigqueue() returns 0, indicating that the signal was suc-
cessfully queued to the receiving proces. Otherwise -1 is returned and
errno is set to indicate the error.
ERRORS
EAGAIN The limit of signals which may be queued has been reached. (See
signal(7) for further information.)
EINVAL sig was invalid.
ESRCH No process has a PID matching pid.
EPERM The process does not have permission to send the signal to the
receiving process. (See kill(2) for further information.)
NOTES
If this function results in the sending of a signal to the process that
invoked it, and that signal was not blocked by the calling thread, and
no other threads were willing to handle this signal (either by having
it unblocked, or by waiting for it using sigwait(3)), then at least
some signal must be delivered to this thread before this function
returns.
CONFORMINGTO
POSIX 1003.1-2001
SEEALSO
kill(2), sigaction(2), signal(2), sigwait(3), signal(7)
Linux 2.4.18 2002-06-07 SIGQUEUE(2)
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