sysdeps/unix/sysv/linux/sigaction.c

   1 /* Copyright (C) 1997-2000,2002,2003,2005,2006 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    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 #endif
  38
  39
  40 /* If ACT is not NULL, change the action for SIG to *ACT.
  41    If OACT is not NULL, put the old action for SIG in *OACT.  */
  42 int
  43 __libc_sigaction (sig, act, oact)
  44      int sig;
  45      const struct sigaction *act;
  46      struct sigaction *oact;
  47 {
  48 #if __ASSUME_REALTIME_SIGNALS == 0
  49   struct old_kernel_sigaction k_sigact, k_osigact;
  50 #endif
  51   int result;
  52
  53 #if defined __NR_rt_sigaction || __ASSUME_REALTIME_SIGNALS > 0
  54   /* First try the RT signals.  */
  55 # if __ASSUME_REALTIME_SIGNALS == 0
  56   if (!__libc_missing_rt_sigs)
  57 # endif
  58     {
  59       struct kernel_sigaction kact, koact;
  60       /* Save the current error value for later.  We need not do this
  61          if we are guaranteed to have realtime signals.  */
  62 # if __ASSUME_REALTIME_SIGNALS == 0
  63       int saved_errno = errno;
  64 # endif
  65
  66       if (act)
  67         {
  68           kact.k_sa_handler = act->sa_handler;
  69           memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
  70           kact.sa_flags = act->sa_flags;
  71 # ifdef HAVE_SA_RESTORER
  72           kact.sa_restorer = act->sa_restorer;
  73 # endif
  74         }
  75
  76       /* XXX The size argument hopefully will have to be changed to the
  77          real size of the user-level sigset_t.  */
  78       result = INLINE_SYSCALL (rt_sigaction, 4, sig,
  79                                act ? __ptrvalue (&kact) : NULL,
  80                                oact ? __ptrvalue (&koact) : NULL, _NSIG / 8);
  81
  82 # if __ASSUME_REALTIME_SIGNALS == 0
  83       if (result >= 0 || errno != ENOSYS)
  84 # endif
  85         {
  86           if (oact && result >= 0)
  87             {
  88               oact->sa_handler = koact.k_sa_handler;
  89               memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
  90               oact->sa_flags = koact.sa_flags;
  91 # ifdef HAVE_SA_RESTORER
  92               oact->sa_restorer = koact.sa_restorer;
  93 # endif
  94             }
  95           return result;
  96         }
  97
  98 # if __ASSUME_REALTIME_SIGNALS == 0
  99       __set_errno (saved_errno);
 100       __libc_missing_rt_sigs = 1;
 101 # endif
 102     }
 103 #endif
 104
 105 #if __ASSUME_REALTIME_SIGNALS == 0
 106   if (act)
 107     {
 108       k_sigact.k_sa_handler = act->sa_handler;
 109       k_sigact.sa_mask = act->sa_mask.__val[0];
 110       k_sigact.sa_flags = act->sa_flags;
 111 # ifdef HAVE_SA_RESTORER
 112       k_sigact.sa_restorer = act->sa_restorer;
 113 # endif
 114     }
 115   result = INLINE_SYSCALL (sigaction, 3, sig,
 116                            act ? __ptrvalue (&k_sigact) : NULL,
 117                            oact ? __ptrvalue (&k_osigact) : NULL);
 118   if (oact && result >= 0)
 119     {
 120       oact->sa_handler = k_osigact.k_sa_handler;
 121       oact->sa_mask.__val[0] = k_osigact.sa_mask;
 122       oact->sa_flags = k_osigact.sa_flags;
 123 # ifdef HAVE_SA_RESTORER
 124       oact->sa_restorer = k_osigact.sa_restorer;
 125 # endif
 126     }
 127   return result;
 128 #endif
 129 }
 130 libc_hidden_def (__libc_sigaction)
 131
 132 #ifdef WRAPPER_INCLUDE
 133 # include WRAPPER_INCLUDE
 134 #endif
 135
 136 #ifndef LIBC_SIGACTION
 137 weak_alias (__libc_sigaction, __sigaction)
 138 libc_hidden_weak (__sigaction)
 139 weak_alias (__libc_sigaction, sigaction)
 140 #endif