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/* Copyright (C) 1991, 1995, 1996 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 General Public License as published by
the Free Software Foundation; either version 2, 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with the GNU C Library; see the file COPYING. If not, write to
the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
#include <unistd.h>
#include <errno.h>
/* Defined in brk.c. */
extern void *__curbrk;
extern int __brk (void *addr);
extern int __libc_multiple_libcs; /* Defined in init-first.c. */
/* 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 (ptrdiff_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)
{
extern void _end;
if (__brk (0) < 0) /* Initialize the break. */
return (void *) -1;
/* Align break address to page boundary if not happened before. */
if (!__libc_multiple_libcs && __curbrk == &_end)
{
size_t pg = __getpagesize ();
ptrdiff_t rest = pg - ((&_end - (void *) 0) & (pg - 1));
if (__brk (__curbrk + rest) < 0)
return (void *) -1;
}
}
if (increment == 0)
return __curbrk;
oldbrk = __curbrk;
if (__brk (oldbrk + increment) < 0)
return (void *) -1;
return oldbrk;
}
weak_alias (__sbrk, sbrk)
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