1  /* Convenience declarations when working with <signal.h>.
       2  
       3     Copyright (C) 2008-2021 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 */