sysdeps/unix/sysv/linux/i386/brk.c

   1 /* brk system call for Linux/i386.
   2    Copyright (C) 1995-2020 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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #if BUILD_PIE_DEFAULT
  20 /* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */
  21 # define I386_USE_SYSENTER 0
  22 #endif
  23
  24 #include <errno.h>
  25 #include <unistd.h>
  26 #include <sysdep.h>
  27
  28 /* This must be initialized data because commons can't have aliases.  */
  29 void *__curbrk = 0;
  30
  31 /* Old braindamage in GCC's crtstuff.c requires this symbol in an attempt
  32    to work around different old braindamage in the old Linux ELF dynamic
  33    linker.  */
  34 weak_alias (__curbrk, ___brk_addr)
  35
  36 int
  37 __brk (void *addr)
  38 {
  39   INTERNAL_SYSCALL_DECL (err);
  40   void *newbrk = (void *) INTERNAL_SYSCALL (brk, err, 1, addr);
  41   __curbrk = newbrk;
  42   if (newbrk < addr)
  43     return INLINE_SYSCALL_ERROR_RETURN_VALUE (ENOMEM);
  44   return 0;
  45 }
  46 weak_alias (__brk, brk)