130 lines
4.0 KiB
Groff
130 lines
4.0 KiB
Groff
.\" Copyright (c) 2005 David Xu <davidxu@freebsd.org>
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice(s), this list of conditions and the following disclaimer as
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.\" the first lines of this file unmodified other than the possible
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.\" addition of one or more copyright notices.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice(s), this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
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.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
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.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
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.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
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.\" EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd Nov 11, 2005
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.Dt SIGQUEUE 2
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.Os
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.Sh NAME
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.Nm sigqueue
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.Nd queue a signal to a process (REALTIME)
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In signal.h
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.Ft int
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.Fn sigqueue "pid_t pid" "int signo" "const union sigval value"
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.Sh DESCRIPTION
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The
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.Fn sigqueue
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function causes the signal specified by
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.Fa signo
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to be sent with the value specified by
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.Fa value
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to the process specified by
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.Fa pid .
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If
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.Fa signo
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is zero (the null signal), error checking is performed but
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no signal is actually sent. The null signal can be used to check the
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validity of pid.
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.Pp
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The conditions required for a process to have permission to queue a
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signal to another process are the same as for the
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.Fn kill
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function.
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The
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.Fn sigqueue
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function queues a signal to a single process specified by the pid argument.
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.Pp
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The sigqueue() function returns immediately. If the resources were
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available to queue the signal, the signal will be queued and sent to
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the receiving process.
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.Pp
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If the value of
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.Fa pid
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causes
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.Fa signo
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to be generated for the sending process, and if
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.Fa signo
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is not blocked for the calling thread and if no other thread has
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.Fa signo
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unblocked or is waiting in a
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.Fn sigwait
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function for
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.Fa signo ,
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either
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.Fa signo
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or at least the pending, unblocked signal will be delivered to the
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calling thread before the
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.Fn sigqueue
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function returns. Should any multiple pending signals in the range
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SIGRTMIN to SIGRTMAX be selected for delivery, it is the lowest numbered
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one. The selection order between realtime and non-realtime signals, or
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between multiple pending non-realtime signals, is unspecified.
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.Sh RETURN VALUES
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Upon successful completion, the specified signal has been queued, and
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the
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.Fn sigqueue
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function returns a value of zero. Otherwise, the function returns a value
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of -1 and set errno to indicate the error.
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.Sh ERRORS
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The
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.Fn sigqueue
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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No resources are available to queue the signal. The process has already
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queued {SIGQUEUE_MAX} signals that are still pending at the receiver(s),
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or a system-wide resource limit has been exceeded.
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.It Bq Er EINVAL
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The value of the
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.Fa signo
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argument is an invalid or unsupported signal number.
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.It Bq Er EEPERM
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The process does not have the appropriate privilege to send the signal
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to the receiving process.
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.It Bq Er ESRCH
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The process pid does not exist.
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.El
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.Sh SEE ALSO
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.Xr sigwait 2 ,
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.Xr sigtimedwait 2 ,
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.Xr sigwaitinfo 2 ,
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.Xr sigqueue 2 ,
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.Xr sigaction 2 ,
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.Xr sigpending 2 ,
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.Xr sigsuspend 2 ,
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.Xr pause 3 ,
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.Xr pthread_sigmask 3
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.Sh STANDARDS
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The
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.Fn sigqueue
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function conforms to
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.St -p1003.1-96 .
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