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

   1 /* POSIX.1 `sigaction' call for Linux/i386.
   2    Copyright (C) 1991,95,96,97,98,99,2000,02 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <sysdep.h>
  21 #include <errno.h>
  22 #include <stddef.h>
  23 #include <signal.h>
  24 #include <string.h>
  25
  26 #include <sysdep.h>
  27 #include <sys/syscall.h>
  28
  29 #include <kernel-features.h>
  30
  31 /* The difference here is that the sigaction structure used in the
  32    kernel is not the same as we use in the libc.  Therefore we must
  33    translate it here.  */
  34 #include <kernel_sigaction.h>
  35
  36 /* We do not globally define the SA_RESTORER flag so do it here.  */
  37 #define SA_RESTORER 0x04000000
  38
  39
  40 extern int __syscall_rt_sigaction (int, const struct kernel_sigaction *__unbounded,
  41                                    struct kernel_sigaction *__unbounded, size_t);
  42
  43 #if __ASSUME_REALTIME_SIGNALS == 0
  44 /* The variable is shared between all wrappers around signal handling
  45    functions which have RT equivalents.  */
  46 int __libc_missing_rt_sigs;
  47 #endif
  48
  49 /* Using the hidden attribute here does not change the code but it
  50    helps to avoid warnings.  */
  51 #if defined HAVE_HIDDEN && defined HAVE_VISIBILITY_ATTRIBUTE \
  52     && !defined HAVE_BROKEN_VISIBILITY_ATTRIBUTE
  53 # ifdef __NR_rt_sigaction
  54 extern void restore_rt (void) asm ("__restore_rt") attribute_hidden;
  55 # endif
  56 extern void restore (void) asm ("__restore") attribute_hidden;
  57 #else
  58 # ifdef __NR_rt_sigaction
  59 static void restore_rt (void) asm ("__restore_rt");
  60 # endif
  61 static void restore (void) asm ("__restore");
  62 #endif
  63
  64
  65 /* If ACT is not NULL, change the action for SIG to *ACT.
  66    If OACT is not NULL, put the old action for SIG in *OACT.  */
  67 int
  68 __libc_sigaction (int sig, const struct sigaction *act, struct sigaction *oact)
  69 {
  70 #if __ASSUME_REALTIME_SIGNALS == 0
  71   struct old_kernel_sigaction k_newact, k_oldact;
  72 #endif
  73   int result;
  74
  75 #ifdef __NR_rt_sigaction
  76
  77   /* First try the RT signals.  */
  78 # if __ASSUME_REALTIME_SIGNALS == 0
  79   if (!__libc_missing_rt_sigs)
  80 # endif
  81     {
  82       struct kernel_sigaction kact, koact;
  83 # if __ASSUME_REALTIME_SIGNALS == 0
  84       int saved_errno = errno;
  85 # endif
  86
  87       if (act)
  88         {
  89           kact.k_sa_handler = act->sa_handler;
  90           memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
  91           kact.sa_flags = act->sa_flags | SA_RESTORER;
  92
  93           kact.sa_restorer = ((act->sa_flags & SA_SIGINFO)
  94                               ? &restore_rt : &restore);
  95         }
  96
  97       /* XXX The size argument hopefully will have to be changed to the
  98          real size of the user-level sigset_t.  */
  99       result = INLINE_SYSCALL (rt_sigaction, 4,
 100                                sig, act ? __ptrvalue (&kact) : NULL,
 101                                oact ? __ptrvalue (&koact) : NULL, _NSIG / 8);
 102
 103 # if __ASSUME_REALTIME_SIGNALS == 0
 104       if (result >= 0 || errno != ENOSYS)
 105 # endif
 106         {
 107           if (oact && result >= 0)
 108             {
 109               oact->sa_handler = koact.k_sa_handler;
 110               memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
 111               oact->sa_flags = koact.sa_flags;
 112               oact->sa_restorer = koact.sa_restorer;
 113             }
 114           return result;
 115         }
 116
 117 # if __ASSUME_REALTIME_SIGNALS == 0
 118       __set_errno (saved_errno);
 119       __libc_missing_rt_sigs = 1;
 120 # endif
 121     }
 122 #endif
 123
 124 #if __ASSUME_REALTIME_SIGNALS == 0
 125   if (act)
 126     {
 127       k_newact.k_sa_handler = act->sa_handler;
 128       k_newact.sa_mask = act->sa_mask.__val[0];
 129       k_newact.sa_flags = act->sa_flags | SA_RESTORER;
 130
 131       k_newact.sa_restorer = &restore;
 132     }
 133
 134   result = INTERNAL_SYCALL (sigaction, 3, sig,
 135                             act ? __ptrvalue (&k_newact) : 0,
 136                             oact ? __ptrvalue (&k_oldact) : 0);
 137
 138   if (result < 0)
 139     {
 140       __set_errno (-result);
 141       return -1;
 142     }
 143
 144   if (oact)
 145     {
 146       oact->sa_handler = k_oldact.k_sa_handler;
 147       oact->sa_mask.__val[0] = k_oldact.sa_mask;
 148       oact->sa_flags = k_oldact.sa_flags;
 149       oact->sa_restorer = k_oldact.sa_restorer;
 150     }
 151
 152   return 0;
 153 #endif
 154 }
 155 libc_hidden_def (__libc_sigaction)
 156
 157 #ifndef SIGCANCEL
 158 weak_alias (__libc_sigaction, __sigaction)
 159 libc_hidden_weak (__sigaction)
 160 weak_alias (__libc_sigaction, sigaction)
 161 #else
 162 int
 163 __sigaction (sig, act, oact)
 164      int sig;
 165      const struct sigaction *act;
 166      struct sigaction *oact;
 167 {
 168   if (sig == SIGCANCEL)
 169     {
 170       __set_errno (EINVAL);
 171       return -1;
 172     }
 173
 174   return __libc_sigaction (sig, act, oact);
 175 }
 176 libc_hidden_weak (__sigaction)
 177 weak_alias (__sigaction, sigaction)
 178 #endif
 179
 180 /* NOTE: Please think twice before making any changes to the bits of
 181    code below.  GDB needs some intimate knowledge about it to
 182    recognize them as signal trampolines, and make backtraces through
 183    signal handlers work right.  Important are both the names
 184    (__restore and __restore_rt) and the exact instruction sequence.
 185    If you ever feel the need to make any changes, please notify the
 186    appropriate GDB maintainer.  */
 187
 188 #define RESTORE(name, syscall) RESTORE2 (name, syscall)
 189 #define RESTORE2(name, syscall) \
 190 asm                                             \
 191   (                                             \
 192    ".text\n"                                    \
 193    "    .align 16\n"                            \
 194    "__" #name ":\n"                             \
 195    "    movl $" #syscall ", %eax\n"             \
 196    "    int  $0x80"                             \
 197    );
 198
 199 #ifdef __NR_rt_sigaction
 200 /* The return code for realtime-signals.  */
 201 RESTORE (restore_rt, __NR_rt_sigreturn)
 202 #endif
 203
 204 /* For the boring old signals.  */
 205 # undef RESTORE2
 206 # define RESTORE2(name, syscall) \
 207 asm                                             \
 208   (                                             \
 209    ".text\n"                                    \
 210    "    .align 8\n"                             \
 211    "__" #name ":\n"                             \
 212    "    popl %eax\n"                            \
 213    "    movl $" #syscall ", %eax\n"             \
 214    "    int  $0x80"                             \
 215    );
 216
 217 RESTORE (restore, __NR_sigreturn)