glibc/sysdeps/unix/sysv/linux/i386/sigaction.c

/* POSIX.1 `sigaction' call for Linux/i386.
   Copyright (C) 1991, 95, 96, 97, 98, 99 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

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

/* We do not globally define the SA_RESTORER flag so do it here.  */
#define SA_RESTORER 0x04000000


extern int __syscall_rt_sigaction (int, const struct kernel_sigaction *,
				   struct kernel_sigaction *, size_t);

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

#ifdef __NR_rt_sigaction
static void restore_rt (void) asm ("__restore_rt");
#endif
static void restore (void) asm ("__restore");


/* 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
__sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
{
#if __ASSUME_REALTIME_SIGNALS == 0
  struct old_kernel_sigaction k_newact, k_oldact;
#endif
  int result;

#ifdef __NR_rt_sigaction

  /* First try the RT signals.  */
# if __ASSUME_REALTIME_SIGNALS == 0
  if (!__libc_missing_rt_sigs)
# endif
    {
      struct kernel_sigaction kact, koact;
# 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 | SA_RESTORER;

	  kact.sa_restorer = ((act->sa_flags & SA_SIGINFO)
			      ? &restore_rt : &restore);
	}

      /* 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 ? &kact : NULL,
			       oact ? &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;
	      oact->sa_restorer = koact.sa_restorer;
	    }
	  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_newact.k_sa_handler = act->sa_handler;
      k_newact.sa_mask = act->sa_mask.__val[0];
      k_newact.sa_flags = act->sa_flags | SA_RESTORER;

      k_newact.sa_restorer = &restore;
    }

  asm volatile ("pushl %%ebx\n"
		"movl %2, %%ebx\n"
		"int $0x80\n"
		"popl %%ebx"
		: "=a" (result)
		: "0" (SYS_ify (sigaction)), "r" (sig),
		  "c" (act ? &k_newact : 0), "d" (oact ? &k_oldact : 0));

  if (result < 0)
    {
      __set_errno (-result);
      return -1;
    }

  if (oact)
    {
      oact->sa_handler = k_oldact.k_sa_handler;
      oact->sa_mask.__val[0] = k_oldact.sa_mask;
      oact->sa_flags = k_oldact.sa_flags;
      oact->sa_restorer = k_oldact.sa_restorer;
    }

  return 0;
#endif
}

weak_alias (__sigaction, sigaction)

#define RESTORE(name, syscall) RESTORE2 (name, syscall)
#define RESTORE2(name, syscall) \
asm						\
  (						\
   ".align 16\n"				\
   "__" #name ":\n"					\
   "	movl $" #syscall ", %eax\n"		\
   "	int  $0x80"				\
   );

#ifdef __NR_rt_sigaction
/* The return code for realtime-signals.  */
RESTORE (restore_rt, __NR_rt_sigreturn)
#endif

/* For the boring old signals.  */
# undef RESTORE2
# define RESTORE2(name, syscall) \
asm						\
  (						\
   ".align 8\n"				\
   "__" #name ":\n"					\
   "	popl %eax\n"				\
   "	movl $" #syscall ", %eax\n"		\
   "	int  $0x80"				\
   );

RESTORE (restore, __NR_sigreturn)