mach/sbrk.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  *      File:   sbrk.c
  27  *
  28  *      Unix compatibility for sbrk system call.
  29  *
  30  * HISTORY
  31  * 09-Mar-90  Gregg Kellogg (gk) at NeXT.
  32  *      include <kern/mach_interface.h> instead of <kern/mach.h>
  33  *
  34  * 14-Feb-89  Avadis Tevanian (avie) at NeXT.
  35  *      Total rewrite using a fixed area of VM from break region.
  36  */
  37
  38 #include <mach/mach.h>          /* for vm_allocate, vm_offset_t */
  39 #include <mach/vm_statistics.h>
  40 #include <sys/types.h>          /* for caddr_t */
  41
  42 static int sbrk_needs_init = TRUE;
  43 static vm_size_t sbrk_region_size = 4*1024*1024; /* Well, what should it be? */
  44 static vm_address_t sbrk_curbrk;
  45
  46 caddr_t sbrk(size)
  47         int     size;
  48 {
  49         vm_offset_t     addr;
  50         kern_return_t   ret;
  51         caddr_t         ocurbrk;
  52         extern int      end;
  53
  54         if (sbrk_needs_init) {
  55                 sbrk_needs_init = FALSE;
  56                 /*
  57                  *      Allocate a big region to simulate break region.
  58                  */
  59                 ret =  vm_allocate(mach_task_self(), &sbrk_curbrk, sbrk_region_size,
  60                                   VM_MAKE_TAG(VM_MEMORY_SBRK)|TRUE);
  61                 if (ret != KERN_SUCCESS)
  62                         return((caddr_t)-1);
  63         }
  64
  65         if (size <= 0)
  66                 return((caddr_t)sbrk_curbrk);
  67         sbrk_curbrk += size;
  68         sbrk_region_size -= size;
  69         if (sbrk_region_size < 0)
  70                 return((caddr_t)-1);
  71         return((caddr_t)(sbrk_curbrk - size));
  72 }
  73
  74 caddr_t brk(x)
  75         caddr_t x;
  76 {
  77         return((caddr_t)-1);
  78 }
  79