nptl/alloca_cutoff.c

   1 /* Determine whether block of given size can be allocated on the stack or not.
   2    Copyright (C) 2002-2024 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 Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, see <https://www.gnu.org/licenses/>.  */
  18
  19 #include <alloca.h>
  20 #include <stdlib.h>
  21 #include <sys/param.h>
  22 #include <pthreadP.h>
  23
  24
  25 int
  26 __libc_alloca_cutoff (size_t size)
  27 {
  28   return size <= (MIN (__MAX_ALLOCA_CUTOFF,
  29                        THREAD_GETMEM (THREAD_SELF, stackblock_size) / 4
  30                        /* The main thread, before the thread library is
  31                           initialized, has zero in the stackblock_size
  32                           element.  Since it is the main thread we can
  33                           assume the maximum available stack space.  */
  34                        ?: __MAX_ALLOCA_CUTOFF * 4));
  35 }
  36 libc_hidden_def (__libc_alloca_cutoff)