sysdeps/unix/sysv/linux/sigaction.c

   1 /* Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <signal.h>
  21 #include <string.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25
  26 #include "kernel-features.h"
  27
  28 /* The difference here is that the sigaction structure used in the
  29    kernel is not the same as we use in the libc.  Therefore we must
  30    translate it here.  */
  31 #include <kernel_sigaction.h>
  32
  33 #if __ASSUME_REALTIME_SIGNALS == 0
  34 /* The variable is shared between all wrappers around signal handling
  35    functions which have RT equivalents.  This is the definition.  */
  36 int __libc_missing_rt_sigs;
  37
  38 extern int __syscall_sigaction (int, const struct old_kernel_sigaction *,
  39                                 struct old_kernel_sigaction *);
  40 #endif
  41 extern int __syscall_rt_sigaction (int, const struct kernel_sigaction *,
  42                                    struct kernel_sigaction *, size_t);
  43
  44
  45 /* If ACT is not NULL, change the action for SIG to *ACT.
  46    If OACT is not NULL, put the old action for SIG in *OACT.  */
  47 int
  48 __libc_sigaction (sig, act, oact)
  49      int sig;
  50      const struct sigaction *act;
  51      struct sigaction *oact;
  52 {
  53 #if __ASSUME_REALTIME_SIGNALS == 0
  54   struct old_kernel_sigaction k_sigact, k_osigact;
  55 #endif
  56   int result;
  57
  58 #if defined __NR_rt_sigaction || __ASSUME_REALTIME_SIGNALS > 0
  59   /* First try the RT signals.  */
  60 # if __ASSUME_REALTIME_SIGNALS == 0
  61   if (!__libc_missing_rt_sigs)
  62 # endif
  63     {
  64       struct kernel_sigaction kact, koact;
  65       /* Save the current error value for later.  We need not do this
  66          if we are guaranteed to have realtime signals.  */
  67 # if __ASSUME_REALTIME_SIGNALS == 0
  68       int saved_errno = errno;
  69 # endif
  70
  71       if (act)
  72         {
  73           kact.k_sa_handler = act->sa_handler;
  74           memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
  75           kact.sa_flags = act->sa_flags;
  76 # ifdef HAVE_SA_RESTORER
  77           kact.sa_restorer = act->sa_restorer;
  78 # endif
  79         }
  80
  81       /* XXX The size argument hopefully will have to be changed to the
  82          real size of the user-level sigset_t.  */
  83       result = INLINE_SYSCALL (rt_sigaction, 4, sig, act ? &kact : NULL,
  84                                oact ? &koact : NULL, _NSIG / 8);
  85
  86 # if __ASSUME_REALTIME_SIGNALS == 0
  87       if (result >= 0 || errno != ENOSYS)
  88 # endif
  89         {
  90           if (oact && result >= 0)
  91             {
  92               oact->sa_handler = koact.k_sa_handler;
  93               memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
  94               oact->sa_flags = koact.sa_flags;
  95 # ifdef HAVE_SA_RESTORER
  96               oact->sa_restorer = koact.sa_restorer;
  97 # endif
  98             }
  99           return result;
 100         }
 101
 102 # if __ASSUME_REALTIME_SIGNALS == 0
 103       __set_errno (saved_errno);
 104       __libc_missing_rt_sigs = 1;
 105 # endif
 106     }
 107 #endif
 108
 109 #if __ASSUME_REALTIME_SIGNALS == 0
 110   if (act)
 111     {
 112       k_sigact.k_sa_handler = act->sa_handler;
 113       k_sigact.sa_mask = act->sa_mask.__val[0];
 114       k_sigact.sa_flags = act->sa_flags;
 115 # ifdef HAVE_SA_RESTORER
 116       k_sigact.sa_restorer = act->sa_restorer;
 117 # endif
 118     }
 119   result = INLINE_SYSCALL (sigaction, 3, sig, act ? &k_sigact : NULL,
 120                            oact ? &k_osigact : NULL);
 121   if (oact && result >= 0)
 122     {
 123       oact->sa_handler = k_osigact.k_sa_handler;
 124       oact->sa_mask.__val[0] = k_osigact.sa_mask;
 125       oact->sa_flags = k_osigact.sa_flags;
 126 # ifdef HAVE_SA_RESTORER
 127       oact->sa_restorer = k_osigact.sa_restorer;
 128 # endif
 129     }
 130   return result;
 131 #endif
 132 }
 133
 134 string_alias (__libc_sigaction, __sigaction)
 135 weak_alias (__libc_sigaction, sigaction)