b30cd8df7c
Passing an invalid pointer results in undefined behaviour. The wrappers in libthr access some of the data pointed to by the arguments in userland, so that an invalid pointer will cause a signal and not an [EFAULT] error return. Furthermore, if the [EFAULT] error occurs when the kernel is writing, it is not a proper error in the sense that the call still commits (changing the signal disposition or accepting the signal). MFC after: 1 week
125 lines
3.6 KiB
Groff
125 lines
3.6 KiB
Groff
.\" Copyright (C) 2000 Jason Evans <jasone@FreeBSD.org>.
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" 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(s), this list of conditions and the following disclaimer as
|
|
.\" the first lines of this file unmodified other than the possible
|
|
.\" addition of one or more copyright notices.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice(s), 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 COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd September 27, 2012
|
|
.Dt SIGWAIT 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm sigwait
|
|
.Nd select a set of signals
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In signal.h
|
|
.Ft int
|
|
.Fn sigwait "const sigset_t * restrict set" "int * restrict sig"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn sigwait
|
|
system call selects a set of signals, specified by
|
|
.Fa set .
|
|
If none of the selected signals are pending,
|
|
.Fn sigwait
|
|
waits until one or more of the selected signals has been generated.
|
|
Then
|
|
.Fn sigwait
|
|
atomically clears one of the selected signals from the set of pending signals
|
|
for the process and sets the location pointed to by
|
|
.Fa sig
|
|
to the signal number that was cleared.
|
|
.Pp
|
|
The signals specified by
|
|
.Fa set
|
|
should be blocked at the time of the call to
|
|
.Fn sigwait .
|
|
.Pp
|
|
If more than one thread is using
|
|
.Fn sigwait
|
|
to wait for the same signal, no more than one of these threads will return from
|
|
.Fn sigwait
|
|
with the signal number.
|
|
If more than a single thread is blocked in
|
|
.Fn sigwait
|
|
for a signal when that signal is generated for the process, it is unspecified
|
|
which of the waiting threads returns from
|
|
.Fn sigwait .
|
|
If the signal is generated for a specific thread, as by
|
|
.Fn pthread_kill ,
|
|
only that thread will return.
|
|
.Pp
|
|
Should any of the multiple pending signals in the range
|
|
.Dv SIGRTMIN
|
|
to
|
|
.Dv SIGRTMAX
|
|
be
|
|
selected, 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.
|
|
.Sh IMPLEMENTATION NOTES
|
|
The
|
|
.Fn sigwait
|
|
function is implemented as a wrapper around the
|
|
.Fn __sys_sigwait
|
|
system call, which retries the call on
|
|
.Er EINTR
|
|
error.
|
|
.Sh RETURN VALUES
|
|
If successful,
|
|
.Fn sigwait
|
|
returns 0 and sets the location pointed to by
|
|
.Fa sig
|
|
to the cleared signal number.
|
|
Otherwise, an error number is returned.
|
|
.Sh ERRORS
|
|
The
|
|
.Fn sigwait
|
|
system call will fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa set
|
|
argument
|
|
specifies one or more invalid signal numbers.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr sigaction 2 ,
|
|
.Xr sigpending 2 ,
|
|
.Xr sigqueue 2 ,
|
|
.Xr sigsuspend 2 ,
|
|
.Xr sigtimedwait 2 ,
|
|
.Xr sigwaitinfo 2 ,
|
|
.Xr pause 3 ,
|
|
.Xr pthread_sigmask 3
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn sigwait
|
|
function conforms to
|
|
.St -p1003.1-96 .
|