NetBSD/lib/libc/sys/sigtimedwait.2

155 lines
4.2 KiB
Groff

.\" $NetBSD: sigtimedwait.2,v 1.8 2012/04/02 22:06:47 agc Exp $
.\"
.\" Copyright (c) 2003 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Jaromir Dolecek.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd April 2, 2012
.Dt SIGTIMEDWAIT 2
.Os
.Sh NAME
.Nm sigtimedwait ,
.Nm sigwaitinfo ,
.Nm sigwait
.Nd wait for queued signals
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In signal.h
.Ft int
.Fn sigtimedwait "const sigset_t * restrict set" "siginfo_t * restrict info" "const struct timespec * restrict timeout"
.Ft int
.Fn sigwaitinfo "const sigset_t * restrict set" "siginfo_t * restrict info"
.Ft int
.Fn sigwait "const sigset_t * restrict set" "int * restrict sig"
.Sh DESCRIPTION
.Fn sigwaitinfo
and
.Fn sigwait
return the first pending signal from the set specified by
.Fa set .
Should multiple signals from
.Fa set
be pending, the lowest numbered one is returned.
The selection order between realtime and non-realtime signals is unspecified.
If there is no signal from
.Ar set
pending at the time of the call, the calling thread
is suspended until one of the specified signals is generated.
.Pp
.Fn sigtimedwait
is exactly equal to
.Fn sigwaitinfo ,
except
.Fa timeout
specifies the maximum time interval for which the calling thread will
be suspended.
If
.Fa timeout
is zero (tv_sec == tv_nsec == 0),
.Fn sigtimedwait
only checks the currently pending signals and returns immediately.
If
.Dv NULL
is used for
.Fa timeout ,
.Fn sigtimedwait
behaves exactly like
.Fn sigwaitinfo
in all regards.
.Pp
If several threads are waiting for a given signal, exactly one of them
returns from the signal wait when the signal is generated.
.Pp
Behaviour of these functions is unspecified if any of the signals in
.Fa set
are unblocked at the time these functions are called.
.Sh RETURN VALUES
Upon successful completion of
.Fn sigtimedwait
or
.Fn sigwaitinfo
.Fa info
is updated with signal information, and the function returns the signal number.
Otherwise, \-1 is returned and the global variable
.Va errno
indicates the error.
Upon successful completion of
.Fn sigwait
.Fa sig
is updated with the signal number, and the function returns 0.
Otherwise, a non-zero error code is returned.
.Sh ERRORS
.Fn sigwaitinfo
and
.Fn sigwait
always succeed.
.Pp
.Fn sigtimedwait
will fail and the
.Fa info
pointer will remain unchanged if:
.Bl -tag -width Er
.It Bq Er EAGAIN
No signal specified in
.Fa set
was generated in the specified
.Fa timeout .
.El
.Pp
.Fn sigtimedwait
may also fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
The specified
.Fa timeout
was invalid.
.El
.Pp
This error is only checked if no signal from
.Fa set
is pending and it would be necessary to wait.
.Sh SEE ALSO
.Xr sigaction 2 ,
.Xr sigprocmask 2 ,
.Xr signal 7
.Sh STANDARDS
The functions
.Fn sigtimedwait ,
.Fn sigwaitinfo ,
and
.Fn sigwait
conform to
.St -p1003.1-2001 .
.Sh HISTORY
The
.Fn sigtimedwait ,
.Fn sigwaitinfo ,
and
.Fn sigwait
functions appeared in
.Nx 2.0 .