sysdeps/unix/sysv/sysv4/sigaction.c

   1 /* Copyright (C) 1994,1995,1996,1997,2002 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 <stddef.h>
  22
  23 static __sighandler_t user_handlers[NSIG];
  24
  25 extern int __context_syscall (int, struct sigcontext *);
  26 extern int __sigaction_syscall (int,
  27                                 const struct sigaction *, struct sigaction *);
  28
  29 static void
  30 trampoline (int sig, int code, struct sigcontext *context)
  31 {
  32   (*(void (*) (int, int, struct sigcontext *)) user_handlers[sig])
  33     (sig, code, context);
  34   __context_syscall (1, context);
  35 }
  36
  37 /* If ACT is not NULL, change the action for SIG to *ACT.
  38    If OACT is not NULL, put the old action for SIG in *OACT.  */
  39 int
  40 __sigaction (sig, act, oact)
  41      int sig;
  42      const struct sigaction *act;
  43      struct sigaction *oact;
  44 {
  45   struct sigaction myact;
  46   __sighandler_t ohandler;
  47
  48   if (sig <= 0 || sig >= NSIG)
  49     {
  50       __set_errno (EINVAL);
  51       return -1;
  52     }
  53
  54   ohandler = user_handlers[sig];
  55
  56   if (act != NULL)
  57     {
  58       user_handlers[sig] = act->sa_handler;
  59       if (act->sa_handler != SIG_DFL && act->sa_handler != SIG_IGN)
  60         {
  61           myact = *act;
  62           act = &myact;
  63           act->sa_handler = (__sighandler_t) trampoline;
  64         }
  65     }
  66
  67   if (__sigaction_syscall (sig, act, oact) < 0)
  68     {
  69       /* The syscall got an error.  Restore the old handler and return -1.  */
  70       user_handlers[sig] = ohandler;
  71       return -1;
  72     }
  73
  74   if (oact != NULL && oact->sa_handler == (__sighandler_t) trampoline)
  75     oact->sa_handler = ohandler;
  76
  77   return 0;
  78 }
  79 libc_hidden_def (__sigaction)
  80 weak_alias (__sigaction, sigaction)