man3/sigsetops.3

   1 .\" Copyright (c) 1994 Mike Battersby
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  25 .\" Modified by aeb, 960721
  26 .\" 2005-11-21, mtk, added descriptions of sigisemptyset(), sigandset(),
  27 .\"                  and sigorset()
  28 .\" 2007-10-26 mdw   added wording that a sigset_t must be initialized
  29 .\"                  prior to use
  30 .\"
  31 .TH SIGSETOPS 3 2015-08-08 "Linux" "Linux Programmer's Manual"
  32 .SH NAME
  33 sigemptyset, sigfillset, sigaddset, sigdelset, sigismember \- POSIX
  34 signal set operations
  35 .SH SYNOPSIS
  36 .B #include <signal.h>
  37 .sp
  38 .BI "int sigemptyset(sigset_t *" set );
  39 .sp
  40 .BI "int sigfillset(sigset_t *" set );
  41 .sp
  42 .BI "int sigaddset(sigset_t *" set ", int " signum );
  43 .sp
  44 .BI "int sigdelset(sigset_t *" set ", int " signum );
  45 .sp
  46 .BI "int sigismember(const sigset_t *" set ", int " signum );
  47 .sp
  48 .in -4n
  49 Feature Test Macro Requirements for glibc (see
  50 .BR feature_test_macros (7)):
  51 .in
  52 .sp
  53 .ad l
  54 .BR sigemptyset (),
  55 .BR sigfillset (),
  56 .BR sigaddset (),
  57 .BR sigdelset (),
  58 .BR sigismember ():
  59 .RS 4
  60 _POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE
  61 .RE
  62 .ad b
  63 .SH DESCRIPTION
  64 These functions allow the manipulation of POSIX signal sets.
  65 .PP
  66 .BR sigemptyset ()
  67 initializes the signal set given by
  68 .I set
  69 to empty, with all signals excluded from the set.
  70 .PP
  71 .BR sigfillset ()
  72 initializes
  73 .I set
  74 to full, including all signals.
  75 .PP
  76 .BR sigaddset ()
  77 and
  78 .BR sigdelset ()
  79 add and delete respectively signal
  80 .I signum
  81 from
  82 .IR set .
  83 .PP
  84 .BR sigismember ()
  85 tests whether
  86 .I signum
  87 is a member of
  88 .IR set .
  89 .PP
  90 Objects of type
  91 .I sigset_t
  92 must be initialized by a call to either
  93 .BR sigemptyset ()
  94 or
  95 .BR sigfillset ()
  96 before being passed to the functions
  97 .BR sigaddset (),
  98 .BR sigdelset ()
  99 and
 100 .BR sigismember ()
 101 or the additional glibc functions described below
 102 .RB ( sigisemptyset (),
 103 .BR sigandset (),
 104 and
 105 .BR sigorset ()).
 106 The results are undefined if this is not done.
 107 .SH RETURN VALUE
 108 .BR sigemptyset (),
 109 .BR sigfillset (),
 110 .BR sigaddset (),
 111 and
 112 .BR sigdelset ()
 113 return 0 on success and \-1 on error.
 114 .PP
 115 .BR sigismember ()
 116 returns 1 if
 117 .I signum
 118 is a member of
 119 .IR set ,
 120 0 if
 121 .I signum
 122 is not a member, and \-1 on error.
 123
 124 On error, these functions set
 125 .I errno
 126 to indicate the cause of the error.
 127 .SH ERRORS
 128 .TP
 129 .B EINVAL
 130 .I sig
 131 is not a valid signal.
 132 .SH ATTRIBUTES
 133 For an explanation of the terms used in this section, see
 134 .BR attributes (7).
 135 .TS
 136 allbox;
 137 lbw31 lb lb
 138 l l l.
 139 Interface       Attribute       Value
 140 T{
 141 .BR sigemptyset (),
 142 .BR sigfillset (),
 143 .br
 144 .BR sigaddset (),
 145 .BR sigdelset (),
 146 .br
 147 .BR sigismember (),
 148 .BR sigisemptyset (),
 149 .br
 150 .BR sigorset (),
 151 .BR sigandset ()
 152 T}      Thread safety   MT-Safe
 153 .TE
 154 .SH CONFORMING TO
 155 POSIX.1-2001, POSIX.1-2008.
 156 .SH NOTES
 157 When creating a filled signal set, the glibc
 158 .BR sigfillset ()
 159 function does not include the two real-time signals used internally
 160 by the NPTL threading implementation.
 161 See
 162 .BR nptl (7)
 163 for details.
 164 .\"
 165 .SS Glibc extensions
 166 If the
 167 .B _GNU_SOURCE
 168 feature test macro is defined, then \fI<signal.h>\fP
 169 exposes three other functions for manipulating signal
 170 sets:
 171
 172 .nf
 173 .BI "int sigisemptyset(const sigset_t *" set );
 174 .BI "int sigorset(sigset_t *" dest ", const sigset_t *" left ,
 175 .BI "              const sigset_t *" right );
 176 .BI "int sigandset(sigset_t *" dest ", const sigset_t *" left ,
 177 .BI "              const sigset_t *" right );
 178 .fi
 179
 180 .BR sigisemptyset ()
 181 returns 1 if
 182 .I set
 183 contains no signals, and 0 otherwise.
 184
 185 .BR sigorset ()
 186 places the union of the sets
 187 .I left
 188 and
 189 .I right
 190 in
 191 .IR dest .
 192 .BR sigandset ()
 193 places the intersection of the sets
 194 .I left
 195 and
 196 .I right
 197 in
 198 .IR dest .
 199 Both functions return 0 on success, and \-1 on failure.
 200 .PP
 201 These functions are nonstandard (a few other systems provide similar
 202 functions) and their use should be avoided in portable applications.
 203 .SH SEE ALSO
 204 .BR sigaction (2),
 205 .BR sigpending (2),
 206 .BR sigprocmask (2),
 207 .BR sigsuspend (2)