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

   1 /* Copyright (C) 1997,1998,1999,2000,2002,2003 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 #include <kernel-features.h>
  26
  27 /* The difference here is that the sigaction structure used in the
  28    kernel is not the same as we use in the libc.  Therefore we must
  29    translate it here.  */
  30 #include <kernel_sigaction.h>
  31
  32 /* The variable is shared between all wrappers around signal handling
  33    functions which have RT equivalents.  */
  34 int __libc_missing_rt_sigs;
  35
  36 #define SA_RESTORER     0x04000000
  37
  38 extern void __default_sa_restorer(void);
  39 extern void __default_rt_sa_restorer(void);
  40
  41 /* When RT signals are in use we need to use a different return stub.  */
  42 #ifdef __NR_rt_sigreturn
  43 #define choose_restorer(flags)                                  \
  44   (flags & SA_SIGINFO) ? __default_rt_sa_restorer               \
  45   : __default_sa_restorer
  46 #else
  47 #define choose_restorer(flags)                                  \
  48   __default_sa_restorer
  49 #endif
  50
  51 /* If ACT is not NULL, change the action for SIG to *ACT.
  52    If OACT is not NULL, put the old action for SIG in *OACT.  */
  53 int
  54 __libc_sigaction (sig, act, oact)
  55      int sig;
  56      const struct sigaction *act;
  57      struct sigaction *oact;
  58 {
  59 #ifndef __ASSUME_REALTIME_SIGNALS
  60   struct old_kernel_sigaction k_sigact, k_osigact;
  61 #endif
  62   int result;
  63
  64 #ifdef __NR_rt_sigaction
  65   /* First try the RT signals.  */
  66 # ifndef __ASSUME_REALTIME_SIGNALS
  67   if (!__libc_missing_rt_sigs)
  68 # endif
  69     {
  70       struct kernel_sigaction kact, koact;
  71 # ifndef __ASSUME_REALTIME_SIGNALS
  72       int saved_errno = errno;
  73 # endif
  74
  75       if (act)
  76         {
  77           kact.k_sa_handler = act->sa_handler;
  78           memcpy (&kact.sa_mask, &act->sa_mask, sizeof (sigset_t));
  79           kact.sa_flags = act->sa_flags;
  80 # ifdef HAVE_SA_RESTORER
  81           /* If the user specified SA_ONSTACK this means she is trying to
  82              use the old-style stack switching.  Unfortunately this
  83              requires the sa_restorer field so we cannot install our own
  84              handler.  (In fact the user is likely to be out of luck anyway
  85              since the kernel currently only supports stack switching via
  86              the X/Open sigaltstack interface, but we allow for the
  87              possibility that this might change in the future.)  */
  88           if (kact.sa_flags & (SA_RESTORER | SA_ONSTACK))
  89             kact.sa_restorer = act->sa_restorer;
  90           else
  91             {
  92               kact.sa_restorer = choose_restorer (kact.sa_flags);
  93               kact.sa_flags |= SA_RESTORER;
  94             }
  95 # endif
  96         }
  97
  98       /* XXX The size argument hopefully will have to be changed to the
  99          real size of the user-level sigset_t.  */
 100       result = INLINE_SYSCALL (rt_sigaction, 4, sig,
 101                                act ? __ptrvalue (&kact) : NULL,
 102                                oact ? __ptrvalue (&koact) : NULL, _NSIG / 8);
 103
 104 # ifndef __ASSUME_REALTIME_SIGNALS
 105       if (result >= 0 || errno != ENOSYS)
 106 # endif
 107         {
 108           if (oact && result >= 0)
 109             {
 110               oact->sa_handler = koact.k_sa_handler;
 111               memcpy (&oact->sa_mask, &koact.sa_mask, sizeof (sigset_t));
 112               oact->sa_flags = koact.sa_flags;
 113 # ifdef HAVE_SA_RESTORER
 114               oact->sa_restorer = koact.sa_restorer;
 115 # endif
 116             }
 117           return result;
 118         }
 119
 120 # ifndef __ASSUME_REALTIME_SIGNALS
 121       __set_errno (saved_errno);
 122       __libc_missing_rt_sigs = 1;
 123 # endif
 124     }
 125 #endif
 126
 127 #ifndef __ASSUME_REALTIME_SIGNALS
 128   if (act)
 129     {
 130       k_sigact.k_sa_handler = act->sa_handler;
 131       k_sigact.sa_mask = act->sa_mask.__val[0];
 132       k_sigact.sa_flags = act->sa_flags;
 133 # ifdef HAVE_SA_RESTORER
 134       /* See the comments above for why we test SA_ONSTACK.  */
 135       if (k_sigact.sa_flags & (SA_RESTORER | SA_ONSTACK))
 136         k_sigact.sa_restorer = act->sa_restorer;
 137       else
 138         {
 139           k_sigact.sa_restorer = choose_restorer (k_sigact.sa_flags);
 140           k_sigact.sa_flags |= SA_RESTORER;
 141         }
 142 # endif
 143     }
 144   result = INLINE_SYSCALL (sigaction, 3, sig,
 145                            act ? __ptrvalue (&k_sigact) : NULL,
 146                            oact ? __ptrvalue (&k_osigact) : NULL);
 147   if (oact && result >= 0)
 148     {
 149       oact->sa_handler = k_osigact.k_sa_handler;
 150       oact->sa_mask.__val[0] = k_osigact.sa_mask;
 151       oact->sa_flags = k_osigact.sa_flags;
 152 # ifdef HAVE_SA_RESTORER
 153       oact->sa_restorer = k_osigact.sa_restorer;
 154 # endif
 155     }
 156   return result;
 157 #endif
 158 }
 159 libc_hidden_def (__libc_sigaction)
 160
 161 #ifndef LIBC_SIGACTION
 162 weak_alias (__libc_sigaction, __sigaction)
 163 libc_hidden_weak (__sigaction)
 164 weak_alias (__libc_sigaction, sigaction)
 165 #endif