sigaction.c

它通过提供glibc兼容使得应用程序移植到较小的c 库时相当得容易. 它能够应用到带虚拟存储的Linux和uClinux上.在大多数带MMU部件的平台上为使它更加紧凑,它也能够编译成共享库.uClib

/* 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 <[e-mail]>
   */

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

#define SA_RESTORER	0x04000000
extern void __default_sa_restorer(void);
extern void __default_rt_sa_restorer(void);

#if defined __NR_rt_sigaction

/* 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;

    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;
# ifdef HAVE_SA_RESTORER
	if (kact.sa_flags & (SA_RESTORER | SA_ONSTACK)) {
	    kact.sa_restorer = act->sa_restorer;
	} else {
	    if (kact.sa_flags & SA_SIGINFO) {
		kact.sa_restorer = __default_rt_sa_restorer;
	    } else {
		kact.sa_restorer = __default_sa_restorer;
		kact.sa_flags |= SA_RESTORER;
	    }
	}
# endif
    }

    /* 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;
# ifdef HAVE_SA_RESTORER
	oact->sa_restorer = koact.sa_restorer;
# endif
    }
    return result;
}


#else

/* 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;

    if (act) {
	kact.k_sa_handler = act->sa_handler;
	kact.sa_mask = act->sa_mask.__val[0];
	kact.sa_flags = act->sa_flags;
# ifdef HAVE_SA_RESTORER
	/* See the comments above for why we test SA_ONSTACK.  */
	if (kact.sa_flags & (SA_RESTORER | SA_ONSTACK)) {
	    kact.sa_restorer = act->sa_restorer;
	} else {
	    kact.sa_restorer = __default_sa_restorer;
	    kact.sa_flags |= SA_RESTORER;
	}
# endif
    }
    result = __syscall_sigaction(sig, act ? __ptrvalue (&kact) : NULL,
	    oact ? __ptrvalue (&koact) : NULL);

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

#endif

weak_alias(__libc_sigaction, sigaction)