uclibc-ng/libc/sysdeps/linux/i386/sigaction.c

/* Copyright (C) 1997, 1998, 1999, 2000 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.  

   Totally hacked up for uClibc by Erik Andersen <andersen@codepoet.org>
   */

#include <errno.h>
#include <signal.h>
#include <string.h>
#include <sys/syscall.h>
#include <bits/kernel_sigaction.h>

#define SA_RESTORER	0x04000000

extern __typeof(sigaction) __libc_sigaction;

#if defined __NR_rt_sigaction
/* Experimentally off - libc_hidden_proto(memcpy) */

extern void restore_rt (void) __asm__ ("__restore_rt") attribute_hidden;
extern void restore (void) __asm__ ("__restore") attribute_hidden;

/* 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 (int sig, const struct sigaction *act, struct sigaction *oact)
{
    int result;
    struct kernel_sigaction kact, koact;

#ifdef SIGCANCEL
    if (sig == SIGCANCEL) {
	__set_errno (EINVAL);
	return -1;
    }
#endif

    if (act) {
	kact.k_sa_handler = act->sa_handler;
	memcpy (&kact.sa_mask, &act->sa_mask, sizeof (kact.sa_mask));
	kact.sa_flags = act->sa_flags;

	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 = __syscall_rt_sigaction(sig, act ? __ptrvalue (&kact) : NULL,
	    oact ? __ptrvalue (&koact) : NULL, _NSIG / 8);

    if (oact && result >= 0) {
	oact->sa_handler = koact.k_sa_handler;
	memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (oact->sa_mask));
	oact->sa_flags = koact.sa_flags;
	oact->sa_restorer = koact.sa_restorer;
    }
    return result;
}


#else
extern void restore (void) __asm__ ("__restore") attribute_hidden;

/* 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 (int sig, const struct sigaction *act, struct sigaction *oact)
{
    int result;
    struct old_kernel_sigaction kact, koact;

#ifdef SIGCANCEL
    if (sig == SIGCANCEL) {
	__set_errno (EINVAL);
	return -1;
    }
#endif

    if (act) {
	kact.k_sa_handler = act->sa_handler;
	kact.sa_mask = act->sa_mask.__val[0];
	kact.sa_flags = act->sa_flags | SA_RESTORER;
	kact.sa_restorer = &restore;
    }

    __asm__ __volatile__ ("pushl %%ebx\n"
	    "movl %2, %%ebx\n"
	    "int $0x80\n"
	    "popl %%ebx"
	    : "=a" (result)
	    : "0" (__NR_sigaction), "mr" (sig),
	    "c" (act ? __ptrvalue (&kact) : 0),
	    "d" (oact ? __ptrvalue (&koact) : 0));

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

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

#endif

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




/* NOTE: Please think twice before making any changes to the bits of
   code below.  GDB needs some intimate knowledge about it to
   recognize them as signal trampolines, and make backtraces through
   signal handlers work right.  Important are both the names
   (__restore and __restore_rt) and the exact instruction sequence.
   If you ever feel the need to make any changes, please notify the
   appropriate GDB maintainer.  */

#define RESTORE(name, syscall) RESTORE2 (name, syscall)
#define RESTORE2(name, syscall) \
__asm__						\
  (						\
   ".text\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

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

RESTORE (restore, __NR_sigreturn)
#endif