/* Copyright (C) 1991-2018 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

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

#include <errno.h>

#include <stdint.h>

#include <unistd.h>

#include <libc-internal.h>

/* Defined in brk.c.  */

extern void *__curbrk;

extern int __brk (void *addr);

/* Extend the process's data space by INCREMENT.

   If INCREMENT is negative, shrink data space by - INCREMENT.

   Return start of new space allocated, or -1 for errors.  */

void *

__sbrk (intptr_t increment)

{

  void *oldbrk;

  /* If this is not part of the dynamic library or the library is used

     via dynamic loading in a statically linked program update

     __curbrk from the kernel's brk value.  That way two separate

     instances of __brk and __sbrk can share the heap, returning

     interleaved pieces of it.  */

  if (__curbrk == NULL || __libc_multiple_libcs)

    if (__brk (0) < 0)		/* Initialize the break.  */

      return (void *) -1;

  if (increment == 0)

    return __curbrk;

  oldbrk = __curbrk;

  if (increment > 0

      ? ((uintptr_t) oldbrk + (uintptr_t) increment < (uintptr_t) oldbrk)

      : ((uintptr_t) oldbrk < (uintptr_t) -increment))

    {

      __set_errno (ENOMEM);

      return (void *) -1;

    }

  if (__brk (oldbrk + increment) < 0)

    return (void *) -1;

  return oldbrk;

}

libc_hidden_def (__sbrk)

weak_alias (__sbrk, sbrk)