text: /* Add SIG to the calling process' signal mask.
     Copyright (C) 1998-2016 Free Software Foundation, Inc.
     This file is part of the GNU C Library.
     Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998.
  
     The GNU C Library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Lesser General Public
     License as published by the Free Software Foundation; either
     version 2.1 of the License, or (at your option) any later version.
  
     The GNU C Library is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     Lesser General Public License for more details.
  
     You should have received a copy of the GNU Lesser General Public
     License along with the GNU C Library; if not, see
     <http://www.gnu.org/licenses/>.  */
  
  #define __need_NULL
  #include <stddef.h>
  #include <signal.h>
  
  int
  sighold (int sig)
  {
    sigset_t set;
  
    /* Retrieve current signal set.  */
    if (__sigprocmask (SIG_SETMASK, NULL, &set) < 0)
      return -1;
  
    /* Add the specified signal.  */
    if (sigaddset (&set, sig) < 0)
      return -1;
  
    /* Set the new mask.  */
    return __sigprocmask (SIG_SETMASK, &set, NULL);
  }
  