freebsd-src/lib/libsys/sigprocmask.2

.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
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.\"    may be used to endorse or promote products derived from this software
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" 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)
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.Dd May 7, 2010
.Dt SIGPROCMASK 2
.Os
.Sh NAME
.Nm sigprocmask
.Nd manipulate current signal mask
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In signal.h
.Ft int
.Fo sigprocmask
.Fa "int how"
.Fa "const sigset_t * restrict set"
.Fa "sigset_t * restrict oset"
.Fc
.Sh DESCRIPTION
The
.Fn sigprocmask
system call examines and/or changes the current signal mask (those signals
that are blocked from delivery).
Signals are blocked if they are members of the current signal mask set.
.Pp
If
.Fa set
is not null, the action of
.Fn sigprocmask
depends on the value of the
.Fa how
argument.
The signal mask is changed as a function of the specified
.Fa set
and the current mask.
The function is specified by
.Fa how
using one of the following values from
.In signal.h :
.Bl -tag -width SIG_UNBLOCK
.It Dv SIG_BLOCK
The new mask is the union of the current mask and the specified
.Fa set .
.It Dv SIG_UNBLOCK
The new mask is the intersection of the current mask
and the complement of the specified
.Fa set .
.It Dv SIG_SETMASK
The current mask is replaced by the specified
.Fa set .
.El
.Pp
If
.Fa oset
is not null, it is set to
the previous value of the signal mask.
When
.Fa set
is null,
the value of
.Fa how
is insignificant and the mask remains unset
providing a way to examine the signal mask without modification.
.Pp
The system
quietly disallows
.Dv SIGKILL
or
.Dv SIGSTOP
to be blocked.
.Pp
In threaded applications,
.Xr pthread_sigmask 3
must be used instead of
.Fn sigprocmask .
.Sh RETURN VALUES
.Rv -std sigprocmask
.Sh ERRORS
The
.Fn sigprocmask
system call will fail and the signal mask will be unchanged if one
of the following occurs:
.Bl -tag -width Er
.It Bq Er EINVAL
The
.Fa how
argument
has a value other than those listed here.
.El
.Sh SEE ALSO
.Xr kill 2 ,
.Xr sigaction 2 ,
.Xr sigpending 2 ,
.Xr sigsuspend 2 ,
.Xr fpsetmask 3 ,
.Xr pthread_sigmask 3 ,
.Xr sigsetops 3
.Sh STANDARDS
The
.Fn sigprocmask
system call is expected to
conform to
.St -p1003.1-90 .
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" Copyright (c) 1983, 1991, 1993`
			`.\" The Regents of the University of California. 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, 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.`
Renumber copyright clause 4 Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96 2017-02-28 23:42:47 +00:00			`.\" 3. Neither the name of the University nor the names of its contributors`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.\" may be used to endorse or promote products derived from this software`
			`.\" without specific prior written permission.`
			`.\"`
			.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.`
			`.\"`
sigprocmask(2): pthread_sigmask(3) must be used in threaded processes. Although libthr's pthread_sigmask() just calls sigprocmask() and this is unlikely to change, mention this POSIX requirement on applications. MFC after: 1 week 2010-05-07 20:46:22 +00:00			`.Dd May 7, 2010`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Dt SIGPROCMASK 2`
			`.Os`
			`.Sh NAME`
			`.Nm sigprocmask`
			`.Nd manipulate current signal mask`
Introduce ".Lb" macro to libc manpages. More libraries manpages updates following. 2000-04-21 09:42:15 +00:00			`.Sh LIBRARY`
			`.Lb libc`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SYNOPSIS`
mdoc(7) police: Use the new .In macro for #include statements. 2001-10-01 16:09:29 +00:00			`.In signal.h`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Ft int`
mdoc(7) police: formatting nits. Approved by: re 2002-11-29 15:57:50 +00:00			`.Fo sigprocmask`
			`.Fa "int how"`
			`.Fa "const sigset_t * restrict set"`
			`.Fa "sigset_t * restrict oset"`
			`.Fc`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh DESCRIPTION`
			`The`
			`.Fn sigprocmask`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call examines and/or changes the current signal mask (those signals`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`that are blocked from delivery).`
			`Signals are blocked if they are members of the current signal mask set.`
			`.Pp`
			`If`
			`.Fa set`
			`is not null, the action of`
			`.Fn sigprocmask`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`depends on the value of the`
			`.Fa how`
			`argument.`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`The signal mask is changed as a function of the specified`
			`.Fa set`
			`and the current mask.`
			`The function is specified by`
			`.Fa how`
			`using one of the following values from`
mdoc(7): Use the new feature of the .In macro. 2003-09-08 19:57:22 +00:00			`.In signal.h :`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Bl -tag -width SIG_UNBLOCK`
			`.It Dv SIG_BLOCK`
			`The new mask is the union of the current mask and the specified`
			`.Fa set .`
			`.It Dv SIG_UNBLOCK`
			`The new mask is the intersection of the current mask`
			`and the complement of the specified`
			`.Fa set .`
			`.It Dv SIG_SETMASK`
			`The current mask is replaced by the specified`
			`.Fa set .`
			`.El`
			`.Pp`
			`If`
			`.Fa oset`
			`is not null, it is set to`
			`the previous value of the signal mask.`
			`When`
			`.Fa set`
			`is null,`
			`the value of`
mdoc(7) police: Fixed abuses of the .Ar and .Em macros. 2002-12-18 13:33:04 +00:00			`.Fa how`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`is insignificant and the mask remains unset`
			`providing a way to examine the signal mask without modification.`
			`.Pp`
			`The system`
			`quietly disallows`
			`.Dv SIGKILL`
			`or`
			`.Dv SIGSTOP`
			`to be blocked.`
sigprocmask(2): pthread_sigmask(3) must be used in threaded processes. Although libthr's pthread_sigmask() just calls sigprocmask() and this is unlikely to change, mention this POSIX requirement on applications. MFC after: 1 week 2010-05-07 20:46:22 +00:00			`.Pp`
			`In threaded applications,`
			`.Xr pthread_sigmask 3`
			`must be used instead of`
			`.Fn sigprocmask .`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh RETURN VALUES`
Use the ``.Rv -std'' mdoc(7) macro in appropriate cases. Reviewed by: ru 2001-08-09 13:32:13 +00:00			`.Rv -std sigprocmask`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh ERRORS`
			`The`
			`.Fn sigprocmask`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call will fail and the signal mask will be unchanged if one`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`of the following occurs:`
Use `Er' variable to define first column width in ERRORS section. It was initially suggested by mdoc(7) style, but was broken over the years 2000-05-04 13:09:25 +00:00			`.Bl -tag -width Er`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.It Bq Er EINVAL`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`The`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Fa how`
mdoc(7) police: "The .Fa argument.". 2002-12-19 09:40:28 +00:00			`argument`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`has a value other than those listed here.`
Prepare for mdoc(7)NG. 2000-12-29 14:08:20 +00:00			`.El`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh SEE ALSO`
			`.Xr kill 2 ,`
			`.Xr sigaction 2 ,`
Unify cross-references between sigpending(2), sigprocmask(2), and sigsuspend(2), all three of which operate or depend on the process signal mask. Add a missing xref to sigsetops(3), without which the above three syscalls would be useless. 2003-06-24 15:41:19 +00:00			`.Xr sigpending 2 ,`
Sort cross references. 1997-01-20 23:23:22 +00:00			`.Xr sigsuspend 2 ,`
Document the fpgetprec/fpsetprec functions in their man page. Add cross-references to the elusive fpsetmask() function to various other man pages. Reviewed by: bde 1998-02-04 22:30:20 +00:00			`.Xr fpsetmask 3 ,`
sigprocmask(2): pthread_sigmask(3) must be used in threaded processes. Although libthr's pthread_sigmask() just calls sigprocmask() and this is unlikely to change, mention this POSIX requirement on applications. MFC after: 1 week 2010-05-07 20:46:22 +00:00			`.Xr pthread_sigmask 3 ,`
Sort cross references. 1997-01-20 23:23:22 +00:00			`.Xr sigsetops 3`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`.Sh STANDARDS`
			`The`
Correctly use .Fn instead of .Nm to reference function names in a bunch of man pages. Use the correct .Bx (BSD UNIX) or .At (AT&T UNIX) macros instead of explicitly specifying the version in the text in a bunch of man pages. 1996-08-22 23:31:07 +00:00			`.Fn sigprocmask`
mdoc(7) police: Tidy up the syscall language. Stop calling system calls "function calls". Use "The .Fn system call" a-la "The .Nm utility". When referring to a non-BSD implementation in the HISTORY section, call syscall a function, to be safe. 2002-12-18 09:22:32 +00:00			`system call is expected to`
BSD 4.4 Lite Lib Sources 1994-05-27 05:00:24 +00:00			`conform to`
upgrade STANDARDS from POSIX 1003.1-88 to 1003.1-90 using .St macro use ``is expected to conform to'' phrase, not ``conforms to'' Pointed out by: Bruce->NIST-PCTS 1996-12-02 20:03:58 +00:00			`.St -p1003.1-90 .`