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, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    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;
  32 static int current_rtmax;
  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   else
  47     {
  48       current_rtmin = __SIGRTMIN;
  49       current_rtmax = __SIGRTMAX;
  50     }
  51   initialized = 1;
  52 }
  53 #endif
  54
  55 /* Return number of available real-time signal with highest priority.  */
  56 int
  57 __libc_current_sigrtmin (void)
  58 {
  59 #ifdef __SIGRTMIN
  60   if (!initialized)
  61     init ();
  62 #endif
  63   return current_rtmin;
  64 }
  65
  66 /* Return number of available real-time signal with lowest priority.  */
  67 int
  68 __libc_current_sigrtmax (void)
  69 {
  70 #ifdef __SIGRTMIN
  71   if (!initialized)
  72     init ();
  73 #endif
  74   return current_rtmax;
  75 }
  76
  77 /* Allocate real-time signal with highest/lowest available
  78    priority.  Please note that we don't use a lock since we assume
  79    this function to be called at program start.  */
  80 int
  81 __libc_allocate_rtsig (int high)
  82 {
  83 #ifndef __SIGRTMIN
  84   return -1;
  85 #else
  86   if (!initialized)
  87     init ();
  88   if (current_rtmin == -1 || current_rtmin > current_rtmax)
  89     /* We don't have anymore signal available.  */
  90     return -1;
  91
  92   return high ? current_rtmin++ : current_rtmax--;
  93 #endif
  94 }