glibc/sysdeps/posix/sigintr.c

/* Copyright (C) 1992-2017 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <stddef.h>
#include <signal.h>
#include <errno.h>
#include <sigsetops.h>

/* If INTERRUPT is nonzero, make signal SIG interrupt system calls
   (causing them to fail with EINTR); if INTERRUPT is zero, make system
   calls be restarted after signal SIG.  */
int
siginterrupt (int sig, int interrupt)
{
#ifdef	SA_RESTART
  extern sigset_t _sigintr attribute_hidden;	/* Defined in signal.c.  */
  struct sigaction action;

  if (__sigaction (sig, (struct sigaction *) NULL, &action) < 0)
    return -1;

  if (interrupt)
    {
      __sigaddset (&_sigintr, sig);
      action.sa_flags &= ~SA_RESTART;
    }
  else
    {
      __sigdelset (&_sigintr, sig);
      action.sa_flags |= SA_RESTART;
    }

  if (__sigaction (sig, &action, (struct sigaction *) NULL) < 0)
    return -1;

  return 0;
#else
  __set_errno (ENOSYS);
  return -1;
#endif
}