[apple/libc.git] / emulated / brk.c

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 * Copyright (c) 1999-2010 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
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 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
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/*
 *      File:   brk.c
 *
 *      Unix compatibility for sbrk system call.
 *
 * HISTORY
 * 09-Mar-90  Gregg Kellogg (gk) at NeXT.
 *      include <kern/mach_interface.h> instead of <kern/mach.h>
 *
 * 14-Feb-89  Avadis Tevanian (avie) at NeXT.
 *      Total rewrite using a fixed area of VM from break region.
 */

#include <mach/mach.h>          /* for vm_allocate, vm_offset_t */
#include <mach/vm_statistics.h>
#include <errno.h>
#include <unistd.h>

static int sbrk_needs_init = TRUE;
static vm_size_t sbrk_region_size = 4*1024*1024; /* Well, what should it be? */
static vm_address_t sbrk_curbrk;

void *sbrk(int size)
{
        kern_return_t   ret;

        if (sbrk_needs_init) {
                sbrk_needs_init = FALSE;
                /*
                 *      Allocate a big region to simulate break region.
                 */
                ret =  vm_allocate(mach_task_self(), &sbrk_curbrk, sbrk_region_size,
                                  VM_MAKE_TAG(VM_MEMORY_SBRK)|TRUE);
                if (ret != KERN_SUCCESS) {
                        errno = ENOMEM;
                        return((void *)-1);
                }
        }
        
        if (size <= 0)
                return((void *)sbrk_curbrk);
        else if (size > sbrk_region_size) {
                errno = ENOMEM;
                return((void *)-1);
        }
        sbrk_curbrk += size;
        sbrk_region_size -= size;
        return((void *)(sbrk_curbrk - size));
}

void *brk(const void *x)
{
        errno = ENOMEM;
        return((void *)-1);
}