lib/sig-handler.h

   1 /* Convenience declarations when working with <signal.h>.
   2
   3    Copyright (C) 2008-2018 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _GL_SIG_HANDLER_H
  19 #define _GL_SIG_HANDLER_H
  20
  21 #include <signal.h>
  22
  23 #ifndef _GL_INLINE_HEADER_BEGIN
  24  #error "Please include config.h first."
  25 #endif
  26 _GL_INLINE_HEADER_BEGIN
  27 #ifndef SIG_HANDLER_INLINE
  28 # define SIG_HANDLER_INLINE _GL_INLINE
  29 #endif
  30
  31 /* Convenience type when working with signal handlers.  */
  32 typedef void (*sa_handler_t) (int);
  33
  34 /* Return the handler of a signal, as a sa_handler_t value regardless
  35    of its true type.  The resulting function can be compared to
  36    special values like SIG_IGN but it is not portable to call it.  */
  37 SIG_HANDLER_INLINE sa_handler_t _GL_ATTRIBUTE_PURE
  38 get_handler (struct sigaction const *a)
  39 {
  40   /* POSIX says that special values like SIG_IGN can only occur when
  41      action.sa_flags does not contain SA_SIGINFO.  But in Linux 2.4,
  42      for example, sa_sigaction and sa_handler are aliases and a signal
  43      is ignored if sa_sigaction (after casting) equals SIG_IGN.  In
  44      this case, this implementation relies on the fact that the two
  45      are aliases, and simply returns sa_handler.  */
  46   return a->sa_handler;
  47 }
  48
  49 _GL_INLINE_HEADER_END
  50
  51 #endif /* _GL_SIG_HANDLER_H */