signal/allocrtsig.c

   1 /* Handle real-time signal allocation.
   2    Copyright (C) 1997-2015 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 <signal.h>
  21
  22 /* In these variables we keep track of the used variables.  If the
  23    platform does not support any real-time signals we will define the
  24    values to some unreasonable value which will signal failing of all
  25    the functions below.  */
  26 #ifndef __SIGRTMIN
  27 static int current_rtmin = -1;
  28 static int current_rtmax = -1;
  29 #else
  30 static int current_rtmin;
  31 static int current_rtmax;
  32
  33 static int initialized;
  34
  35 #include <testrtsig.h>
  36
  37 static void
  38 init (void)
  39 {
  40   if (!kernel_has_rtsig ())
  41     {
  42       current_rtmin = -1;
  43       current_rtmax = -1;
  44     }
  45   else
  46     {
  47       current_rtmin = __SIGRTMIN;
  48       current_rtmax = __SIGRTMAX;
  49     }
  50   initialized = 1;
  51 }
  52 #endif
  53
  54 /* Return number of available real-time signal with highest priority.  */
  55 int
  56 __libc_current_sigrtmin (void)
  57 {
  58 #ifdef __SIGRTMIN
  59   if (!initialized)
  60     init ();
  61 #endif
  62   return current_rtmin;
  63 }
  64 libc_hidden_def (__libc_current_sigrtmin)
  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 libc_hidden_def (__libc_current_sigrtmax)
  77
  78 /* Allocate real-time signal with highest/lowest available
  79    priority.  Please note that we don't use a lock since we assume
  80    this function to be called at program start.  */
  81 int
  82 __libc_allocate_rtsig (int high)
  83 {
  84 #ifndef __SIGRTMIN
  85   return -1;
  86 #else
  87   if (!initialized)
  88     init ();
  89   if (current_rtmin == -1 || current_rtmin > current_rtmax)
  90     /* We don't have anymore signal available.  */
  91     return -1;
  92
  93   return high ? current_rtmin++ : current_rtmax--;
  94 #endif
  95 }