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

   1 /* POSIX.1 `sigaction' call for Linux/i386.
   2    Copyright (C) 1991, 1995, 1996, 1997, 1998 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <sysdep.h>
  21 #include <errno.h>
  22 #include <stddef.h>
  23 #include <signal.h>
  24
  25 /* The difference here is that the sigaction structure used in the
  26    kernel is not the same as we use in the libc.  Therefore we must
  27    translate it here.  */
  28 #include <kernel_sigaction.h>
  29
  30
  31 extern int __syscall_rt_sigaction (int, const struct sigaction *,
  32                                    struct sigaction *, size_t);
  33
  34 /* The variable is shared between all wrappers around signal handling
  35    functions which have RT equivalents.  */
  36 int __libc_missing_rt_sigs;
  37
  38
  39 /* If ACT is not NULL, change the action for SIG to *ACT.
  40    If OACT is not NULL, put the old action for SIG in *OACT.  */
  41 int
  42 __sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
  43 {
  44   struct old_kernel_sigaction k_newact, k_oldact;
  45   int result;
  46
  47   /* First try the RT signals.  */
  48   if (!__libc_missing_rt_sigs)
  49     {
  50       struct sigaction nact, *nactp;
  51
  52       if (act)
  53         {
  54           nact.sa_handler = act->sa_handler;
  55           memcpy (&nact.sa_mask, &act->sa_mask, sizeof (sigset_t));
  56           nact.sa_flags = act->sa_flags;
  57
  58           nact.sa_restorer = ((act->sa_flags & SA_NOMASK)
  59                               ? &&restore_nomask : &&restore);
  60           nactp = &nact;
  61         }
  62       else
  63         nactp = NULL;
  64
  65       /* XXX The size argument hopefully will have to be changed to the
  66          real size of the user-level sigset_t.  */
  67       result = __syscall_rt_sigaction (sig, nactp, oact, _NSIG / 8);
  68
  69       if (result >= 0 || errno != ENOSYS)
  70         return result;
  71
  72       __libc_missing_rt_sigs = 1;
  73     }
  74
  75   if (act)
  76     {
  77       k_newact.k_sa_handler = act->sa_handler;
  78       k_newact.sa_mask = act->sa_mask.__val[0];
  79       k_newact.sa_flags = act->sa_flags;
  80
  81       k_newact.sa_restorer = ((act->sa_flags & SA_NOMASK)
  82                               ? &&restore_nomask : &&restore);
  83     }
  84
  85   asm volatile ("pushl %%ebx\n"
  86                 "movl %2, %%ebx\n"
  87                 "int $0x80\n"
  88                 "popl %%ebx"
  89                 : "=a" (result)
  90                 : "0" (SYS_ify (sigaction)), "r" (sig),
  91                   "c" (act ? &k_newact : 0), "d" (oact ? &k_oldact : 0));
  92
  93   if (result < 0)
  94     {
  95       __set_errno (-result);
  96       return -1;
  97     }
  98
  99   if (oact)
 100     {
 101       oact->sa_handler = k_oldact.k_sa_handler;
 102       oact->sa_mask.__val[0] = k_oldact.sa_mask;
 103       oact->sa_flags = k_oldact.sa_flags;
 104       oact->sa_restorer = k_oldact.sa_restorer;
 105     }
 106
 107   return 0;
 108
 109  restore:
 110   asm (
 111 #ifdef  PIC
 112        "        pushl %%ebx\n"
 113        "        call 0f\n"
 114        "0:      popl %%ebx\n"
 115        "        addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %%ebx\n"
 116        "        addl $8, %%esp\n"
 117        "        call __sigsetmask@PLT\n"
 118        "        addl $8, %%esp\n"
 119        "        popl %%ebx\n"
 120 #else
 121        "        addl $4, %%esp\n"
 122        "        call __sigsetmask\n"
 123        "        addl $4, %%esp\n"
 124 #endif
 125        "        popl %%eax\n"
 126        "        popl %%ecx\n"
 127        "        popl %%edx\n"
 128        "        popf\n"
 129        "        ret"
 130        : : );
 131
 132  restore_nomask:
 133   asm ("        addl $4, %%esp\n"
 134        "        popl %%eax\n"
 135        "        popl %%ecx\n"
 136        "        popl %%edx\n"
 137        "        popf\n"
 138        "        ret"
 139        : : );
 140
 141   /* NOTREACHED */
 142   return -1;
 143 }
 144
 145 weak_alias (__sigaction, sigaction)