glibc/sysdeps/unix/sysv/linux/sigaction.c

/* Copyright (C) 1997,1998,1999,2000,2002,2003 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <signal.h>
#include <string.h>

#include <sysdep.h>
#include <sys/syscall.h>

#include "kernel-features.h"

/* The difference here is that the sigaction structure used in the
   kernel is not the same as we use in the libc.  Therefore we must
   translate it here.  */
#include <kernel_sigaction.h>

#if __ASSUME_REALTIME_SIGNALS == 0
/* The variable is shared between all wrappers around signal handling
   functions which have RT equivalents.  This is the definition.  */
int __libc_missing_rt_sigs;
#endif


/* If ACT is not NULL, change the action for SIG to *ACT.
   If OACT is not NULL, put the old action for SIG in *OACT.  */
int
__libc_sigaction (sig, act, oact)
     int sig;
     const struct sigaction *act;
     struct sigaction *oact;
{
#if __ASSUME_REALTIME_SIGNALS == 0
  struct old_kernel_sigaction k_sigact, k_osigact;
#endif
  int result;

#if defined __NR_rt_sigaction || __ASSUME_REALTIME_SIGNALS > 0
  /* First try the RT signals.  */
# if __ASSUME_REALTIME_SIGNALS == 0
  if (!__libc_missing_rt_sigs)
# endif
    {
      struct kernel_sigaction kact, koact;
      /* Save the current error value for later.  We need not do this
	 if we are guaranteed to have realtime signals.  */
# if __ASSUME_REALTIME_SIGNALS == 0
      int saved_errno = errno;
# endif

      if (act)
	{
	  kact.k_sa_handler = act->sa_handler;
	  memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
	  kact.sa_flags = act->sa_flags;
# ifdef HAVE_SA_RESTORER
	  kact.sa_restorer = act->sa_restorer;
# endif
	}

      /* XXX The size argument hopefully will have to be changed to the
	 real size of the user-level sigset_t.  */
      result = INLINE_SYSCALL (rt_sigaction, 4, sig,
			       act ? __ptrvalue (&kact) : NULL,
			       oact ? __ptrvalue (&koact) : NULL, _NSIG / 8);

# if __ASSUME_REALTIME_SIGNALS == 0
      if (result >= 0 || errno != ENOSYS)
# endif
	{
	  if (oact && result >= 0)
	    {
	      oact->sa_handler = koact.k_sa_handler;
	      memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
	      oact->sa_flags = koact.sa_flags;
# ifdef HAVE_SA_RESTORER
	      oact->sa_restorer = koact.sa_restorer;
# endif
	    }
	  return result;
	}

# if __ASSUME_REALTIME_SIGNALS == 0
      __set_errno (saved_errno);
      __libc_missing_rt_sigs = 1;
# endif
    }
#endif

#if __ASSUME_REALTIME_SIGNALS == 0
  if (act)
    {
      k_sigact.k_sa_handler = act->sa_handler;
      k_sigact.sa_mask = act->sa_mask.__val[0];
      k_sigact.sa_flags = act->sa_flags;
# ifdef HAVE_SA_RESTORER
      k_sigact.sa_restorer = act->sa_restorer;
# endif
    }
  result = INLINE_SYSCALL (sigaction, 3, sig,
			   act ? __ptrvalue (&k_sigact) : NULL,
			   oact ? __ptrvalue (&k_osigact) : NULL);
  if (oact && result >= 0)
    {
      oact->sa_handler = k_osigact.k_sa_handler;
      oact->sa_mask.__val[0] = k_osigact.sa_mask;
      oact->sa_flags = k_osigact.sa_flags;
# ifdef HAVE_SA_RESTORER
      oact->sa_restorer = k_osigact.sa_restorer;
# endif
    }
  return result;
#endif
}
libc_hidden_def (__libc_sigaction)

#ifndef LIBC_SIGACTION
weak_alias (__libc_sigaction, __sigaction)
libc_hidden_weak (__sigaction)
weak_alias (__libc_sigaction, sigaction)
#endif