libc/signal/sysv_signal.c

   1 /* Copyright (C) 1991, 1992, 1996, 1997, 2005 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, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <signal.h>
  20
  21 /* Tolerate non-threads versions of Posix */
  22 #ifndef SA_ONESHOT
  23 #define SA_ONESHOT 0
  24 #endif
  25 #ifndef SA_NOMASK
  26 #define SA_NOMASK 0
  27 #endif
  28 #ifndef SA_INTERRUPT
  29 #define SA_INTERRUPT 0
  30 #endif
  31
  32 /* Set the handler for the signal SIG to HANDLER,
  33    returning the old handler, or SIG_ERR on error.  */
  34 __sighandler_t __sysv_signal (int sig, __sighandler_t handler)
  35 {
  36   struct sigaction act, oact;
  37
  38   /* Check signal extents to protect __sigismember.  */
  39   if (handler == SIG_ERR || sig < 1 || sig >= NSIG)
  40     {
  41       __set_errno (EINVAL);
  42       return SIG_ERR;
  43     }
  44
  45   act.sa_handler = handler;
  46   __sigemptyset (&act.sa_mask);
  47   act.sa_flags = (SA_ONESHOT | SA_NOMASK | SA_INTERRUPT) & ~SA_RESTART;
  48   /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
  49   if (sigaction (sig, &act, &oact) < 0)
  50     return SIG_ERR;
  51
  52   return oact.sa_handler;
  53 }
  54 strong_alias(__sysv_signal,sysv_signal)