View of xos/usr/lib/libc/brk.c

/* Copyright (C) 2008  Emmanuel Varoquaux
 
   This file is part of XOS.
 
   This program 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 3 of the License, or
   (at your option) any later version.
 
   This program 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 this program.  If not, see <http://www.gnu.org/licenses/>. */
 
#include "unistd.h"
 
#include "xos.h"
 
static void *curbrk = (void *)-1;
 
static void init_curbrk()
{
  __syscall_sbrk(0, &curbrk);
}
 
static int sbrk_internal(int incr)
{
  void *_brk;
 
  if (__syscall_sbrk(incr, &_brk) == -1)
    return -1;
  curbrk = _brk;
  return 0;
}
 
int __attribute__ ((weak, visibility ("default"))) brk(void *addr)
{
  if (curbrk == (void *)-1)
    init_curbrk();
 
  return sbrk_internal(addr - curbrk);
}
typeof (brk) __brk __attribute__ ((alias ("brk")));
 
void __attribute__ ((weak, visibility ("default"))) *sbrk(intptr_t incr)
{
  void *oldbrk;
 
  if (curbrk == (void *)-1)
    init_curbrk();
 
  if (incr == 0)
    return curbrk;
 
  oldbrk = curbrk;
  if (sbrk_internal(incr) == -1)
    return (void *)-1;
  return oldbrk;
}
typeof (sbrk) __sbrk __attribute__ ((alias ("sbrk")));