nptl/alloca_cutoff.c

   1 /* Determine whether block of given size can be allocated on the stack or not.
   2    Copyright (C) 2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <alloca.h>
  21 #include <stdlib.h>
  22 #include <sys/param.h>
  23 #include <pthreadP.h>
  24
  25
  26 int
  27 __libc_alloca_cutoff (size_t size)
  28 {
  29   return size <= (MIN (__MAX_ALLOCA_CUTOFF,
  30                        THREAD_GETMEM (THREAD_SELF, stackblock_size) / 4
  31                        /* The main thread, before the thread library is
  32                           initialized, has zero in the stackblock_size
  33                           element.  Since it is the main thread we can
  34                           assume the maximum available stack space.  */
  35                        ?: __MAX_ALLOCA_CUTOFF * 4));
  36 }