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

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