mach/sbrk.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  *      File:   sbrk.c
  24  *
  25  *      Unix compatibility for sbrk system call.
  26  *
  27  * HISTORY
  28  * 09-Mar-90  Gregg Kellogg (gk) at NeXT.
  29  *      include <kern/mach_interface.h> instead of <kern/mach.h>
  30  *
  31  * 14-Feb-89  Avadis Tevanian (avie) at NeXT.
  32  *      Total rewrite using a fixed area of VM from break region.
  33  */
  34
  35 #include <mach/mach.h>          /* for vm_allocate, vm_offset_t */
  36 #include <mach/vm_statistics.h>
  37 #include <sys/types.h>          /* for caddr_t */
  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 caddr_t sbrk(size)
  44         int     size;
  45 {
  46         vm_offset_t     addr;
  47         kern_return_t   ret;
  48         caddr_t         ocurbrk;
  49         extern int      end;
  50
  51         if (sbrk_needs_init) {
  52                 sbrk_needs_init = FALSE;
  53                 /*
  54                  *      Allocate a big region to simulate break region.
  55                  */
  56                 ret =  vm_allocate(mach_task_self(), &sbrk_curbrk, sbrk_region_size,
  57                                   VM_MAKE_TAG(VM_MEMORY_SBRK)|TRUE);
  58                 if (ret != KERN_SUCCESS)
  59                         return((caddr_t)-1);
  60         }
  61
  62         if (size <= 0)
  63                 return((caddr_t)sbrk_curbrk);
  64         sbrk_curbrk += size;
  65         sbrk_region_size -= size;
  66         if (sbrk_region_size < 0)
  67                 return((caddr_t)-1);
  68         return((caddr_t)(sbrk_curbrk - size));
  69 }
  70
  71 caddr_t brk(x)
  72         caddr_t x;
  73 {
  74         return((caddr_t)-1);
  75 }
  76