uclibc-ng/libc/signal/allocrtsig.c

/* Handle real-time signal allocation.
   Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.

   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <features.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/syscall.h>
 
/* Only enable rt signals when it is supported at compile time */
#ifndef __NR_rt_sigaction
/* In these variables we keep track of the used variables.  If the
   platform does not support any real-time signals we will define the
   values to some unreasonable value which will signal failing of all
   the functions below.  */
static int current_rtmin = -1;
static int current_rtmax = -1;
#else
static int current_rtmin = __SIGRTMIN;
static int current_rtmax = __SIGRTMAX;
#endif

/* Return number of available real-time signal with highest priority.  */
int __libc_current_sigrtmin (void)
{
  return current_rtmin;
}

/* Return number of available real-time signal with lowest priority.  */
int __libc_current_sigrtmax (void)
{
  return current_rtmax;
}

/* Allocate real-time signal with highest/lowest available
   priority.  Please note that we don't use a lock since we assume
   this function to be called at program start.  */
int __libc_allocate_rtsig (int high)
{
  if (current_rtmin == -1 || current_rtmin > current_rtmax)
    /* We don't have anymore signal available.  */
    return -1;

  return high ? current_rtmin++ : current_rtmax--;
}