1  /* Convenience declarations when working with <signal.h>.
       2  
       3     Copyright (C) 2008-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file 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 Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser 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  /* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE, _GL_ATTRIBUTE_PURE.  */
      22  #if !_GL_CONFIG_H_INCLUDED
      23   #error "Please include config.h first."
      24  #endif
      25  
      26  #include <signal.h>
      27  
      28  _GL_INLINE_HEADER_BEGIN
      29  #ifndef SIG_HANDLER_INLINE
      30  # define SIG_HANDLER_INLINE _GL_INLINE
      31  #endif
      32  
      33  /* Convenience type when working with signal handlers.  */
      34  typedef void (*sa_handler_t) (int);
      35  
      36  /* Return the handler of a signal, as a sa_handler_t value regardless
      37     of its true type.  The resulting function can be compared to
      38     special values like SIG_IGN but it is not portable to call it.  */
      39  SIG_HANDLER_INLINE sa_handler_t _GL_ATTRIBUTE_PURE
      40  get_handler (struct sigaction const *a)
      41  {
      42    /* POSIX says that special values like SIG_IGN can only occur when
      43       action.sa_flags does not contain SA_SIGINFO.  But in Linux 2.4,
      44       for example, sa_sigaction and sa_handler are aliases and a signal
      45       is ignored if sa_sigaction (after casting) equals SIG_IGN.  In
      46       this case, this implementation relies on the fact that the two
      47       are aliases, and simply returns sa_handler.  */
      48    return a->sa_handler;
      49  }
      50  
      51  _GL_INLINE_HEADER_END
      52  
      53  #endif /* _GL_SIG_HANDLER_H */