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 kernel_sigaction *,
  32                                    struct kernel_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 kernel_sigaction kact, koact;
  51       int saved_errno = errno;
  52
  53       if (act)
  54         {
  55           kact.k_sa_handler = act->sa_handler;
  56           memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
  57           kact.sa_flags = act->sa_flags;
  58
  59           kact.sa_restorer = ((act->sa_flags & SA_NOMASK)
  60                               ? &&restore_nomask : &&restore);
  61         }
  62
  63       /* XXX The size argument hopefully will have to be changed to the
  64          real size of the user-level sigset_t.  */
  65       result = __syscall_rt_sigaction (sig, act ? &kact : NULL,
  66                                        oact ? &koact : NULL, _NSIG / 8);
  67
  68       if (result >= 0 || errno != ENOSYS)
  69         {
  70           if (oact && result >= 0)
  71             {
  72               oact->sa_handler = koact.k_sa_handler;
  73               memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
  74               oact->sa_flags = koact.sa_flags;
  75               oact->sa_restorer = koact.sa_restorer;
  76             }
  77           return result;
  78         }
  79
  80       __set_errno (saved_errno);
  81       __libc_missing_rt_sigs = 1;
  82     }
  83
  84   if (act)
  85     {
  86       k_newact.k_sa_handler = act->sa_handler;
  87       k_newact.sa_mask = act->sa_mask.__val[0];
  88       k_newact.sa_flags = act->sa_flags;
  89
  90       k_newact.sa_restorer = ((act->sa_flags & SA_NOMASK)
  91                               ? &&restore_nomask : &&restore);
  92     }
  93
  94   asm volatile ("pushl %%ebx\n"
  95                 "movl %2, %%ebx\n"
  96                 "int $0x80\n"
  97                 "popl %%ebx"
  98                 : "=a" (result)
  99                 : "0" (SYS_ify (sigaction)), "r" (sig),
 100                   "c" (act ? &k_newact : 0), "d" (oact ? &k_oldact : 0));
 101
 102   if (result < 0)
 103     {
 104       __set_errno (-result);
 105       return -1;
 106     }
 107
 108   if (oact)
 109     {
 110       oact->sa_handler = k_oldact.k_sa_handler;
 111       oact->sa_mask.__val[0] = k_oldact.sa_mask;
 112       oact->sa_flags = k_oldact.sa_flags;
 113       oact->sa_restorer = k_oldact.sa_restorer;
 114     }
 115
 116   return 0;
 117
 118  restore:
 119   asm (
 120 #ifdef  PIC
 121        "        pushl %%ebx\n"
 122        "        call 0f\n"
 123        "0:      popl %%ebx\n"
 124        "        addl $_GLOBAL_OFFSET_TABLE_+[.-0b], %%ebx\n"
 125        "        addl $8, %%esp\n"
 126        "        call __sigsetmask@PLT\n"
 127        "        addl $8, %%esp\n"
 128        "        popl %%ebx\n"
 129 #else
 130        "        addl $4, %%esp\n"
 131        "        call __sigsetmask\n"
 132        "        addl $4, %%esp\n"
 133 #endif
 134        "        popl %%eax\n"
 135        "        popl %%ecx\n"
 136        "        popl %%edx\n"
 137        "        popf\n"
 138        "        ret"
 139        : : );
 140
 141  restore_nomask:
 142   asm ("        addl $4, %%esp\n"
 143        "        popl %%eax\n"
 144        "        popl %%ecx\n"
 145        "        popl %%edx\n"
 146        "        popf\n"
 147        "        ret"
 148        : : );
 149
 150   /* NOTREACHED */
 151   return -1;
 152 }
 153
 154 weak_alias (__sigaction, sigaction)