man3/sigwait.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 SIGWAIT 3 2021-03-22 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
   7 .SH NAME
   8 sigwait \- wait for a signal
   9 .SH LIBRARY
  10 Standard C library
  11 .RI ( libc ", " \-lc )
  12 .SH SYNOPSIS
  13 .nf
  14 .B #include <signal.h>
  15 .PP
  16 .BI "int sigwait(const sigset_t *restrict " set ", int *restrict " sig );
  17 .fi
  18 .PP
  19 .RS -4
  20 Feature Test Macro Requirements for glibc (see
  21 .BR feature_test_macros (7)):
  22 .RE
  23 .PP
  24 .BR sigwait ():
  25 .nf
  26     Since glibc 2.26:
  27         _POSIX_C_SOURCE >= 199506L
  28     Glibc 2.25 and earlier:
  29         _POSIX_C_SOURCE
  30 .fi
  31 .SH DESCRIPTION
  32 The
  33 .BR sigwait ()
  34 function suspends execution of the calling thread until
  35 one of the signals specified in the signal set
  36 .I set
  37 becomes pending.
  38 The function accepts the signal
  39 (removes it from the pending list of signals),
  40 and returns the signal number in
  41 .IR sig .
  42 .PP
  43 The operation of
  44 .BR sigwait ()
  45 is the same as
  46 .BR sigwaitinfo (2),
  47 except that:
  48 .IP * 2
  49 .BR sigwait ()
  50 returns only the signal number, rather than a
  51 .I siginfo_t
  52 structure describing the signal.
  53 .IP *
  54 The return values of the two functions are different.
  55 .SH RETURN VALUE
  56 On success,
  57 .BR sigwait ()
  58 returns 0.
  59 On error, it returns a positive error number (listed in ERRORS).
  60 .SH ERRORS
  61 .TP
  62 .B EINVAL
  63 .\" Does not occur for glibc.
  64 .I set
  65 contains an invalid signal number.
  66 .SH ATTRIBUTES
  67 For an explanation of the terms used in this section, see
  68 .BR attributes (7).
  69 .ad l
  70 .nh
  71 .TS
  72 allbox;
  73 lbx lb lb
  74 l l l.
  75 Interface       Attribute       Value
  76 T{
  77 .BR sigwait ()
  78 T}      Thread safety   MT-Safe
  79 .TE
  80 .hy
  81 .ad
  82 .sp 1
  83 .SH STANDARDS
  84 POSIX.1-2001, POSIX.1-2008.
  85 .SH NOTES
  86 .BR sigwait ()
  87 is implemented using
  88 .BR sigtimedwait (2).
  89 .PP
  90 The glibc implementation of
  91 .BR sigwait ()
  92 silently ignores attempts to wait for the two real-time signals that
  93 are used internally by the NPTL threading implementation.
  94 See
  95 .BR nptl (7)
  96 for details.
  97 .SH EXAMPLES
  98 See
  99 .BR pthread_sigmask (3).
 100 .SH SEE ALSO
 101 .BR sigaction (2),
 102 .BR signalfd (2),
 103 .BR sigpending (2),
 104 .BR sigsuspend (2),
 105 .BR sigwaitinfo (2),
 106 .BR sigsetops (3),
 107 .BR signal (7)