man3/pthread_attr_setsigmask_np.3

   1 .\" Copyright (c) 2008 Linux Foundation, written by Michael Kerrisk
   2 .\"     <mtk.manpages@gmail.com>
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .TH PTHREAD_ATTR_SETSIGMASK_NP 3 2021-03-22 "Linux" "Linux Programmer's Manual"
   7 .SH NAME
   8 pthread_attr_setsigmask_np, pthread_attr_getsigmask_np \- set/get
   9 signal mask attribute in thread attributes object
  10 .SH LIBRARY
  11 POSIX threads library
  12 .RI ( libpthread ", " \-lpthread )
  13 .SH SYNOPSIS
  14 .nf
  15 .BR "#define _GNU_SOURCE" "             /* See feature_test_macros(7) */"
  16 .B #include <pthread.h>
  17 .PP
  18 .BI "int pthread_attr_setsigmask_np(pthread_attr_t *" attr ,
  19 .BI "                               const sigset_t *" sigmask );
  20 .BI "int pthread_attr_getsigmask_np(const pthread_attr_t *" attr ,
  21 .BI "                               sigset_t *" sigmask );
  22 .fi
  23 .SH DESCRIPTION
  24 The
  25 .BR pthread_attr_setsigmask_np ()
  26 function sets the signal mask attribute of the
  27 thread attributes object referred to by
  28 .I attr
  29 to the value specified in
  30 .IR *sigmask .
  31 If
  32 .I sigmask
  33 is specified as NULL, then any existing signal mask attribute in
  34 .I attr
  35 is unset.
  36 .PP
  37 The
  38 .BR pthread_attr_getsigmask_np ()
  39 function returns the signal mask attribute of the thread attributes object
  40 referred to by
  41 .I attr
  42 in the buffer pointed to by
  43 .IR sigmask .
  44 If the signal mask attribute is currently unset,
  45 then this function returns the special value
  46 .B PTHREAD_ATTR_NO_SIGMASK_NP
  47 as its result.
  48 .SH RETURN VALUE
  49 The
  50 .BR pthread_attr_setsigmask_np ()
  51 function returns 0 on success, or a nonzero error number on failure.
  52 .PP
  53 the
  54 .BR pthread_attr_getsigmask_np ()
  55 function returns either 0 or
  56 .BR PTHREAD_ATTR_NO_SIGMASK_NP .
  57 When 0 is returned, the signal mask attribute is returned via
  58 .IR sigmask .
  59 A return value of
  60 .B PTHREAD_ATTR_NO_SIGMASK_NP
  61 indicates that the signal mask attribute is not set in
  62 .IR attr .
  63 .PP
  64 On error, these functions return a positive error number.
  65 .SH ERRORS
  66 .TP
  67 .B ENOMEM
  68 .RB ( pthread_attr_setsigmask_np ())
  69 Could not allocate memory.
  70 .SH VERSIONS
  71 These functions are provided by glibc since version 2.32.
  72 .SH ATTRIBUTES
  73 For an explanation of the terms used in this section, see
  74 .BR attributes (7).
  75 .ad l
  76 .nh
  77 .TS
  78 allbox;
  79 lbx lb lb
  80 l l l.
  81 Interface       Attribute       Value
  82 T{
  83 .BR pthread_attr_setsigmask_np (),
  84 .BR pthread_attr_getsigmask_np ()
  85 T}      Thread safety   MT-Safe
  86 .TE
  87 .hy
  88 .ad
  89 .sp 1
  90 .SH CONFORMING TO
  91 These functions are nonstandard GNU extensions;
  92 hence the suffix "_np" (nonportable) in the names.
  93 .SH NOTES
  94 The signal mask attribute determines the signal mask that will be assigned to
  95 a thread created using the thread attributes object
  96 .IR attr .
  97 If this attribute is not set, then a thread created using
  98 .I attr
  99 will inherit a copy of the creating thread's signal mask.
 100 .PP
 101 For more details on signal masks, see
 102 .BR sigprocmask (2).
 103 For a description of a set of macros
 104 that can be used to manipulate and inspect signal sets, see
 105 .BR sigsetops (3).
 106 .PP
 107 In the absence of
 108 .BR pthread_attr_setsigmask_np ()
 109 it is possible to create a thread with a desired signal mask as follows:
 110 .IP \(bu 2
 111 The creating thread uses
 112 .BR pthread_sigmask (3)
 113 to save its current signal mask and set its mask to block all signals.
 114 .IP \(bu
 115 The new thread is then created using
 116 .BR pthread_create ();
 117 the new thread will inherit the creating thread's signal mask.
 118 .IP \(bu
 119 The new thread sets its signal mask to the desired value using
 120 .BR pthread_sigmask (3).
 121 .IP \(bu
 122 The creating thread restores its signal mask to the original value.
 123 .PP
 124 Following the above steps,
 125 there is no possibility for the new thread to receive a signal
 126 before it has adjusted its signal mask to the desired value.
 127 .SH SEE ALSO
 128 .BR sigprocmask (2),
 129 .BR pthread_attr_init (3),
 130 .BR pthread_sigmask (3),
 131 .BR pthreads (7),
 132 .BR signal (7)