'\" t
.\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
.\"     <mtk.manpages@gmail.com>
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH pthread_attr_setsigmask_np 3 2023-10-31 "Linux man-pages 6.7"
.SH NAME
pthread_attr_setsigmask_np, pthread_attr_getsigmask_np \- set/get
signal mask attribute in thread attributes object
.SH LIBRARY
POSIX threads library
.RI ( libpthread ", " \-lpthread )
.SH SYNOPSIS
.nf
.BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
.B #include <pthread.h>
.P
.BI "int pthread_attr_setsigmask_np(pthread_attr_t *" attr ,
.BI "                               const sigset_t *" sigmask );
.BI "int pthread_attr_getsigmask_np(const pthread_attr_t *" attr ,
.BI "                               sigset_t *" sigmask );
.fi
.SH DESCRIPTION
The
.BR pthread_attr_setsigmask_np ()
function sets the signal mask attribute of the
thread attributes object referred to by
.I attr
to the value specified in
.IR *sigmask .
If
.I sigmask
is specified as NULL, then any existing signal mask attribute in
.I attr
is unset.
.P
The
.BR pthread_attr_getsigmask_np ()
function returns the signal mask attribute of the thread attributes object
referred to by
.I attr
in the buffer pointed to by
.IR sigmask .
If the signal mask attribute is currently unset,
then this function returns the special value
.B PTHREAD_ATTR_NO_SIGMASK_NP
as its result.
.SH RETURN VALUE
The
.BR pthread_attr_setsigmask_np ()
function returns 0 on success, or a nonzero error number on failure.
.P
the
.BR pthread_attr_getsigmask_np ()
function returns either 0 or
.BR PTHREAD_ATTR_NO_SIGMASK_NP .
When 0 is returned, the signal mask attribute is returned via
.IR sigmask .
A return value of
.B PTHREAD_ATTR_NO_SIGMASK_NP
indicates that the signal mask attribute is not set in
.IR attr .
.P
On error, these functions return a positive error number.
.SH ERRORS
.TP
.B ENOMEM
.RB ( pthread_attr_setsigmask_np ())
Could not allocate memory.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR pthread_attr_setsigmask_np (),
.BR pthread_attr_getsigmask_np ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
GNU;
hence the suffix "_np" (nonportable) in the names.
.SH HISTORY
glibc 2.32.
.SH NOTES
The signal mask attribute determines the signal mask that will be assigned to
a thread created using the thread attributes object
.IR attr .
If this attribute is not set, then a thread created using
.I attr
will inherit a copy of the creating thread's signal mask.
.P
For more details on signal masks, see
.BR sigprocmask (2).
For a description of a set of macros
that can be used to manipulate and inspect signal sets, see
.BR sigsetops (3).
.P
In the absence of
.BR pthread_attr_setsigmask_np ()
it is possible to create a thread with a desired signal mask as follows:
.IP \[bu] 3
The creating thread uses
.BR pthread_sigmask (3)
to save its current signal mask and set its mask to block all signals.
.IP \[bu]
The new thread is then created using
.BR pthread_create ();
the new thread will inherit the creating thread's signal mask.
.IP \[bu]
The new thread sets its signal mask to the desired value using
.BR pthread_sigmask (3).
.IP \[bu]
The creating thread restores its signal mask to the original value.
.P
Following the above steps,
there is no possibility for the new thread to receive a signal
before it has adjusted its signal mask to the desired value.
.SH SEE ALSO
.BR sigprocmask (2),
.BR pthread_attr_init (3),
.BR pthread_sigmask (3),
.BR pthreads (7),
.BR signal (7)