libc/signal/signal.c

   1 /* BSD-like signal function.
   2    Copyright (C) 1991,1992,1996,1997,2000,2002,2005
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <errno.h>
  21 #include <signal.h>
  22 #include <string.h>     /* For the real memset prototype.  */
  23
  24 sigset_t _sigintr;      /* Set by siginterrupt.  */
  25
  26 /* Set the handler for the signal SIG to HANDLER,
  27    returning the old handler, or SIG_ERR on error.  */
  28 __sighandler_t
  29 signal (int sig, __sighandler_t handler)
  30 {
  31   struct sigaction act, oact;
  32
  33   /* Check signal extents to protect __sigismember.  */
  34   if (handler == SIG_ERR || sig < 1 || sig >= NSIG)
  35     {
  36       __set_errno (EINVAL);
  37       return SIG_ERR;
  38     }
  39
  40   act.sa_handler = handler;
  41   __sigemptyset (&act.sa_mask);
  42   __sigaddset (&act.sa_mask, sig);
  43   act.sa_flags = __sigismember (&_sigintr, sig) ? 0 : SA_RESTART;
  44   /* In Linux (as of 2.6.25), fails only if sig is SIGKILL or SIGSTOP */
  45   if (sigaction (sig, &act, &oact) < 0)
  46     return SIG_ERR;
  47
  48   return oact.sa_handler;
  49 }
  50 libc_hidden_def(signal)
  51 #ifdef __UCLIBC_SUSV3_LEGACY__
  52 strong_alias(signal,bsd_signal)
  53 #endif