man3/gsignal.3

   1 .\" Copyright (C) 2002 Andries Brouwer <aeb@cwi.nl>
   2 .\"
   3 .\" %%%LICENSE_START(VERBATIM)
   4 .\" Permission is granted to make and distribute verbatim copies of this
   5 .\" manual provided the copyright notice and this permission notice are
   6 .\" preserved on all copies.
   7 .\"
   8 .\" Permission is granted to copy and distribute modified versions of this
   9 .\" manual under the conditions for verbatim copying, provided that the
  10 .\" entire resulting derived work is distributed under the terms of a
  11 .\" permission notice identical to this one.
  12 .\"
  13 .\" Since the Linux kernel and libraries are constantly changing, this
  14 .\" manual page may be incorrect or out-of-date.  The author(s) assume no
  15 .\" responsibility for errors or omissions, or for damages resulting from
  16 .\" the use of the information contained herein.  The author(s) may not
  17 .\" have taken the same level of care in the production of this manual,
  18 .\" which is licensed free of charge, as they might when working
  19 .\" professionally.
  20 .\"
  21 .\" Formatted or processed versions of this manual, if unaccompanied by
  22 .\" the source, must acknowledge the copyright and authors of this work.
  23 .\" %%%LICENSE_END
  24 .\"
  25 .\" This replaces an earlier man page written by Walter Harms
  26 .\" <walter.harms@informatik.uni-oldenburg.de>.
  27 .TH GSIGNAL 3  2017-09-15 "" "Linux Programmer's Manual"
  28 .SH NAME
  29 gsignal, ssignal \- software signal facility
  30 .SH SYNOPSIS
  31 .nf
  32 .B #include <signal.h>
  33 .PP
  34 .B typedef void (*sighandler_t)(int);
  35 .PP
  36 .BI "int gsignal(int " signum );
  37 .PP
  38 .BI "sighandler_t ssignal(int " signum ", sighandler_t " action );
  39 .fi
  40 .PP
  41 .in -4n
  42 Feature Test Macro Requirements for glibc (see
  43 .BR feature_test_macros (7)):
  44 .in
  45 .PP
  46 .BR gsignal (),
  47 .BR ssignal ():
  48     Since glibc 2.19:
  49         _DEFAULT_SOURCE
  50     Glibc 2.19 and earlier:
  51         _SVID_SOURCE
  52 .SH DESCRIPTION
  53 Don't use these functions under Linux.
  54 Due to a historical mistake, under Linux these functions are
  55 aliases for
  56 .BR raise (3)
  57 and
  58 .BR signal (2),
  59 respectively.
  60 .PP
  61 Elsewhere, on System V-like systems, these functions implement
  62 software signaling, entirely independent of the classical
  63 .BR signal (2)
  64 and
  65 .BR kill (2)
  66 functions.
  67 The function
  68 .BR ssignal ()
  69 defines the action to take when the software signal with
  70 number
  71 .I signum
  72 is raised using the function
  73 .BR gsignal (),
  74 and returns the previous such action or
  75 .BR SIG_DFL .
  76 The function
  77 .BR gsignal ()
  78 does the following: if no action (or the action
  79 .BR SIG_DFL )
  80 was
  81 specified for
  82 .IR signum ,
  83 then it does nothing and returns 0.
  84 If the action
  85 .B SIG_IGN
  86 was specified for
  87 .IR signum ,
  88 then it does nothing and returns 1.
  89 Otherwise, it resets the action to
  90 .B SIG_DFL
  91 and calls
  92 the action function with argument
  93 .IR signum ,
  94 and returns the value returned by that function.
  95 The range of possible values
  96 .I signum
  97 varies (often 1\(en15 or 1\(en17).
  98 .SH ATTRIBUTES
  99 For an explanation of the terms used in this section, see
 100 .BR attributes (7).
 101 .TS
 102 allbox;
 103 lb lb lb
 104 l l l.
 105 Interface       Attribute       Value
 106 T{
 107 .BR gsignal ()
 108 T}      Thread safety   MT-Safe
 109 T{
 110 .BR ssignal ()
 111 T}      Thread safety   MT-Safe sigintr
 112 .TE
 113 .sp 1
 114 .SH CONFORMING TO
 115 These functions are available under AIX, DG/UX, HP-UX, SCO, Solaris, Tru64.
 116 They are called obsolete under most of these systems, and are
 117 broken under Linux libc and glibc.
 118 Some systems also have
 119 .BR gsignal_r ()
 120 and
 121 .BR ssignal_r ().
 122 .SH SEE ALSO
 123 .BR kill (2),
 124 .BR signal (2),
 125 .BR raise (3)