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 9.2 |