b88c83ff14
Although libthr's pthread_sigmask() just calls sigprocmask() and this is unlikely to change, mention this POSIX requirement on applications. MFC after: 1 week
132 lines
3.6 KiB
Groff
132 lines
3.6 KiB
Groff
.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. 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, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)sigprocmask.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd May 7, 2010
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.Dt SIGPROCMASK 2
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.Os
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.Sh NAME
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.Nm sigprocmask
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.Nd manipulate current signal mask
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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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.Fo sigprocmask
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.Fa "int how"
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.Fa "const sigset_t * restrict set"
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.Fa "sigset_t * restrict oset"
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.Fc
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.Sh DESCRIPTION
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The
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.Fn sigprocmask
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system call examines and/or changes the current signal mask (those signals
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that are blocked from delivery).
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Signals are blocked if they are members of the current signal mask set.
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.Pp
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If
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.Fa set
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is not null, the action of
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.Fn sigprocmask
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depends on the value of the
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.Fa how
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argument.
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The signal mask is changed as a function of the specified
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.Fa set
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and the current mask.
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The function is specified by
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.Fa how
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using one of the following values from
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.In signal.h :
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.Bl -tag -width SIG_UNBLOCK
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.It Dv SIG_BLOCK
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The new mask is the union of the current mask and the specified
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.Fa set .
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.It Dv SIG_UNBLOCK
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The new mask is the intersection of the current mask
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and the complement of the specified
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.Fa set .
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.It Dv SIG_SETMASK
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The current mask is replaced by the specified
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.Fa set .
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.El
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.Pp
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If
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.Fa oset
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is not null, it is set to
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the previous value of the signal mask.
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When
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.Fa set
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is null,
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the value of
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.Fa how
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is insignificant and the mask remains unset
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providing a way to examine the signal mask without modification.
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.Pp
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The system
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quietly disallows
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.Dv SIGKILL
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or
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.Dv SIGSTOP
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to be blocked.
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.Pp
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In threaded applications,
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.Xr pthread_sigmask 3
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must be used instead of
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.Fn sigprocmask .
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.Sh RETURN VALUES
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.Rv -std sigprocmask
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.Sh ERRORS
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The
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.Fn sigprocmask
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system call will fail and the signal mask will be unchanged if one
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of the following occurs:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The
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.Fa how
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argument
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has a value other than those listed here.
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.El
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.Sh SEE ALSO
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.Xr kill 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 fpsetmask 3 ,
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.Xr pthread_sigmask 3 ,
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.Xr sigsetops 3
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.Sh STANDARDS
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The
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.Fn sigprocmask
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system call is expected to
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conform to
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.St -p1003.1-90 .
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