signal/allocrtsig.c

   1 /* Handle real-time signal allocation.  Generic version.
   2    Copyright (C) 1997-2019 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    <https://www.gnu.org/licenses/>.  */
  19
  20 #include <signal.h>
  21
  22 /* Another sysdeps file can #define this and then #include this file.  */
  23 #ifndef RESERVED_SIGRT
  24 # define RESERVED_SIGRT 0
  25 #endif
  26
  27 /* In these variables we keep track of the used variables.  If the
  28    platform does not support any real-time signals we will define the
  29    values to some unreasonable value which will signal failing of all
  30    the functions below.  */
  31 #ifdef __SIGRTMIN
  32 static int current_rtmin = __SIGRTMIN + RESERVED_SIGRT;
  33 static int current_rtmax = __SIGRTMAX;
  34 #endif
  35
  36 /* Return number of available real-time signal with highest priority.  */
  37 int
  38 __libc_current_sigrtmin (void)
  39 {
  40 #ifdef __SIGRTMIN
  41   return current_rtmin;
  42 #else
  43   return -1;
  44 #endif
  45 }
  46 libc_hidden_def (__libc_current_sigrtmin)
  47 strong_alias (__libc_current_sigrtmin, __libc_current_sigrtmin_private)
  48
  49 /* Return number of available real-time signal with lowest priority.  */
  50 int
  51 __libc_current_sigrtmax (void)
  52 {
  53 #ifdef __SIGRTMIN
  54   return current_rtmax;
  55 #else
  56   return -1;
  57 #endif
  58 }
  59 libc_hidden_def (__libc_current_sigrtmax)
  60 strong_alias (__libc_current_sigrtmax, __libc_current_sigrtmax_private)
  61
  62 /* Allocate real-time signal with highest/lowest available
  63    priority.  Please note that we don't use a lock since we assume
  64    this function to be called at program start.  */
  65 int
  66 __libc_allocate_rtsig (int high)
  67 {
  68 #ifndef __SIGRTMIN
  69   return -1;
  70 #else
  71   if (current_rtmin == -1 || current_rtmin > current_rtmax)
  72     /* We don't have any more signals available.  */
  73     return -1;
  74
  75   return high ? current_rtmin++ : current_rtmax--;
  76 #endif
  77 }
  78 strong_alias (__libc_allocate_rtsig, __libc_allocate_rtsig_private)