sysdeps/unix/sysv/sigaction.c

   1 /* Copyright (C) 1992, 1994, 1995, 1996, 1997 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 <sysdep.h>
  20 #include <errno.h>
  21 #include <stddef.h>
  22 #include <signal.h>
  23
  24
  25 /* If ACT is not NULL, change the action for SIG to *ACT.
  26    If OACT is not NULL, put the old action for SIG in *OACT.  */
  27 int
  28 __sigaction (sig, act, oact)
  29      int sig;
  30      const struct sigaction *act;
  31      struct sigaction *oact;
  32 {
  33   sighandler_t handler;
  34   int save;
  35
  36   if (sig <= 0 || sig >= NSIG)
  37     {
  38       __set_errno (EINVAL);
  39       return -1;
  40     }
  41
  42   if (act == NULL)
  43     {
  44       if (oact == NULL)
  45         return 0;
  46       /* Race condition, but this is the only way to do it.  */
  47       handler = signal (sig, SIG_IGN);
  48       if (handler == SIG_ERR)
  49         return -1;
  50       save = errno;
  51       (void) signal (sig, handler);
  52       __set_errno (save);
  53     }
  54   else
  55     {
  56       int i;
  57
  58       if (act->sa_flags != 0)
  59         {
  60         unimplemented:
  61           __set_errno (ENOSYS);
  62           return -1;
  63         }
  64
  65       for (i = 1; i < NSIG; ++i)
  66         if (__sigismember (&act->sa_mask, i))
  67           goto unimplemented;
  68
  69       handler = signal (sig, act->sa_handler);
  70       if (handler == SIG_ERR)
  71         return -1;
  72     }
  73
  74   if (oact != NULL)
  75     {
  76       oact->sa_handler = handler;
  77       __sigemptyset (&oact->sa_mask);
  78       oact->sa_flags = 0;
  79     }
  80
  81   return 0;
  82 }
  83
  84 weak_alias (__sigaction, sigaction)