libc/signal/allocrtsig.c

   1 /* Handle real-time signal allocation.
   2    Copyright (C) 1997, 1998, 1999 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
   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 <features.h>
  21 #include <signal.h>
  22 #include <sys/syscall.h>
  23
  24 /* Only enable rt signals when it is supported at compile time */
  25 #ifndef __NR_rt_sigaction
  26 /* In these variables we keep track of the used variables.  If the
  27    platform does not support any real-time signals we will define the
  28    values to some unreasonable value which will signal failing of all
  29    the functions below.  */
  30 static int current_rtmin = -1;
  31 static int current_rtmax = -1;
  32 #else
  33 # ifdef __UCLIBC_HAS_THREADS_NATIVE__
  34 static int current_rtmin = __SIGRTMIN + 2;
  35 # elif defined __UCLIBC_HAS_THREADS__ && !defined __UCLIBC_HAS_LINUXTHREADS__
  36 /* psm: might be good for LT old as well, do not want to break it for now */
  37 /* Sanity check */
  38 #  if !defined __SIGRTMIN || (__SIGRTMAX - __SIGRTMIN) < 3
  39 #   error "This must not happen"
  40 #  endif
  41 static int current_rtmin = __SIGRTMIN + 3;
  42 # else
  43 static int current_rtmin = __SIGRTMIN;
  44 # endif
  45 static int current_rtmax = __SIGRTMAX;
  46 #endif
  47
  48 /* Return number of available real-time signal with highest priority.  */
  49 int __libc_current_sigrtmin (void)
  50 {
  51   return current_rtmin;
  52 }
  53
  54 /* Return number of available real-time signal with lowest priority.  */
  55 int __libc_current_sigrtmax (void)
  56 {
  57   return current_rtmax;
  58 }
  59
  60 #if 0
  61 /* Allocate real-time signal with highest/lowest available
  62    priority.  Please note that we don't use a lock since we assume
  63    this function to be called at program start.  */
  64 int __libc_allocate_rtsig (int high);
  65 int __libc_allocate_rtsig (int high)
  66 {
  67   if (current_rtmin == -1 || current_rtmin > current_rtmax)
  68     /* We don't have anymore signal available.  */
  69     return -1;
  70
  71   return high ? current_rtmin++ : current_rtmax--;
  72 }
  73 #endif