mach/sbrk.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23 /*
  24  *      File:   sbrk.c
  25  *
  26  *      Unix compatibility for sbrk system call.
  27  *
  28  * HISTORY
  29  * 09-Mar-90  Gregg Kellogg (gk) at NeXT.
  30  *      include <kern/mach_interface.h> instead of <kern/mach.h>
  31  *
  32  * 14-Feb-89  Avadis Tevanian (avie) at NeXT.
  33  *      Total rewrite using a fixed area of VM from break region.
  34  */
  35
  36 #include <mach/mach.h>          /* for vm_allocate, vm_offset_t */
  37 #include <mach/vm_statistics.h>
  38
  39 static int sbrk_needs_init = TRUE;
  40 static vm_size_t sbrk_region_size = 4*1024*1024; /* Well, what should it be? */
  41 static vm_address_t sbrk_curbrk;
  42
  43 void *sbrk(size)
  44         int     size;
  45 {
  46         kern_return_t   ret;
  47
  48         if (sbrk_needs_init) {
  49                 sbrk_needs_init = FALSE;
  50                 /*
  51                  *      Allocate a big region to simulate break region.
  52                  */
  53                 ret =  vm_allocate(mach_task_self(), &sbrk_curbrk, sbrk_region_size,
  54                                   VM_MAKE_TAG(VM_MEMORY_SBRK)|TRUE);
  55                 if (ret != KERN_SUCCESS)
  56                         return((void *)-1);
  57         }
  58
  59         if (size <= 0)
  60                 return((void *)sbrk_curbrk);
  61         else if (size > sbrk_region_size)
  62                 return((void *)-1);
  63         sbrk_curbrk += size;
  64         sbrk_region_size -= size;
  65         return((void *)(sbrk_curbrk - size));
  66 }
  67
  68 void *brk(x)
  69         void *x;
  70 {
  71         return((void *)-1);
  72 }
  73