malloc/morecore.c

   1 /* Copyright (C) 1991-2021 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #if defined(SHARED) || defined(USE_MTAG)
  19 static bool __always_fail_morecore = false;
  20 #endif
  21
  22 /* Allocate INCREMENT more bytes of data space,
  23    and return the start of data space, or NULL on errors.
  24    If INCREMENT is negative, shrink data space.  */
  25 void *
  26 __glibc_morecore (ptrdiff_t increment)
  27 {
  28 #if defined(SHARED) || defined(USE_MTAG)
  29   if (__always_fail_morecore)
  30     return NULL;
  31 #endif
  32
  33   void *result = (void *) __sbrk (increment);
  34   if (result == (void *) -1)
  35     return NULL;
  36
  37   return result;
  38 }
  39 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
  40 compat_symbol (libc, __glibc_morecore, __default_morecore, GLIBC_2_0);
  41 #endif