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

/* brk system call for Linux/i386.
   Copyright (C) 1995-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   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
   <https://www.gnu.org/licenses/>.  */

#if BUILD_PIE_DEFAULT
/* Can't use "call *%gs:SYSINFO_OFFSET" during statup in static PIE.  */
# define I386_USE_SYSENTER 0
#endif

#include <errno.h>
#include <unistd.h>
#include <sysdep.h>

/* This must be initialized data because commons can't have aliases.  */
void *__curbrk = 0;

/* Old braindamage in GCC's crtstuff.c requires this symbol in an attempt
   to work around different old braindamage in the old Linux ELF dynamic
   linker.  */
weak_alias (__curbrk, ___brk_addr)

int
__brk (void *addr)
{
  void *newbrk = (void *) INTERNAL_SYSCALL_CALL (brk, addr);
  __curbrk = newbrk;
  if (newbrk < addr)
    return INLINE_SYSCALL_ERROR_RETURN_VALUE (ENOMEM);
  return 0;
}
weak_alias (__brk, brk)