signal/allocrtsig.c

   1 /* Handle real-time signal allocation.
   2    Copyright (C) 1997, 1998 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 Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    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    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <signal.h>
  22
  23 /* In these variables we keep track of the used variables.  If the
  24    platform does not support any real-time signals we will define the
  25    values to some unreasonable value which will signal failing of all
  26    the functions below.  */
  27 #ifndef __SIGRTMIN
  28 static int current_rtmin = -1;
  29 static int current_rtmax = -1;
  30 #else
  31 static int current_rtmin = __SIGRTMIN;
  32 static int current_rtmax = __SIGRTMAX;
  33
  34 static int initialized;
  35
  36 #include "testrtsig.h"
  37
  38 static void
  39 init (void)
  40 {
  41   if (!kernel_has_rtsig ())
  42     {
  43       current_rtmin = -1;
  44       current_rtmax = -1;
  45     }
  46   initialized = 1;
  47 }
  48 #endif
  49
  50 /* Return number of available real-time signal with highest priority.  */
  51 int
  52 __libc_current_sigrtmin (void)
  53 {
  54 #ifdef __SIGRTMIN
  55   if (!initialized)
  56     init ();
  57 #endif
  58   return current_rtmin;
  59 }
  60
  61 /* Return number of available real-time signal with lowest priority.  */
  62 int
  63 __libc_current_sigrtmax (void)
  64 {
  65 #ifdef __SIGRTMIN
  66   if (!initialized)
  67     init ();
  68 #endif
  69   return current_rtmax;
  70 }
  71
  72 /* Allocate real-time signal with highest/lowest available
  73    priority.  Please note that we don't use a lock since we assume
  74    this function to be called at program start.  */
  75 int
  76 __libc_allocate_rtsig (int high)
  77 {
  78 #ifndef __SIGRTMIN
  79   return -1;
  80 #else
  81   if (!initialized)
  82     init ();
  83   if (current_rtmin == -1 || current_rtmin > current_rtmax)
  84     /* We don't have anymore signal available.  */
  85     return -1;
  86
  87   return high ? current_rtmin++ : current_rtmax--;
  88 #endif
  89 }