glibc/signal/allocrtsig.c

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/* Handle real-time signal allocation.
Copyright (C) 1997-2014 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <signal.h>
/* In these variables we keep track of the used variables. If the
platform does not support any real-time signals we will define the
values to some unreasonable value which will signal failing of all
the functions below. */
#ifndef __SIGRTMIN
static int current_rtmin = -1;
static int current_rtmax = -1;
#else
static int current_rtmin;
static int current_rtmax;
static int initialized;
#include <testrtsig.h>
static void
init (void)
{
if (!kernel_has_rtsig ())
{
current_rtmin = -1;
current_rtmax = -1;
}
else
{
current_rtmin = __SIGRTMIN;
current_rtmax = __SIGRTMAX;
}
initialized = 1;
}
#endif
/* Return number of available real-time signal with highest priority. */
int
__libc_current_sigrtmin (void)
{
#ifdef __SIGRTMIN
if (!initialized)
init ();
#endif
return current_rtmin;
}
libc_hidden_def (__libc_current_sigrtmin)
/* Return number of available real-time signal with lowest priority. */
int
__libc_current_sigrtmax (void)
{
#ifdef __SIGRTMIN
if (!initialized)
init ();
#endif
return current_rtmax;
}
libc_hidden_def (__libc_current_sigrtmax)
/* Allocate real-time signal with highest/lowest available
priority. Please note that we don't use a lock since we assume
this function to be called at program start. */
int
__libc_allocate_rtsig (int high)
{
#ifndef __SIGRTMIN
return -1;
#else
if (!initialized)
init ();
if (current_rtmin == -1 || current_rtmin > current_rtmax)
/* We don't have anymore signal available. */
return -1;
return high ? current_rtmin++ : current_rtmax--;
#endif
}