emulated/brk.c

   1 /*
   2  * Copyright (c) 1999-2010 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  *      File:   brk.c
  30  *
  31  *      Unix compatibility for sbrk system call.
  32  *
  33  * HISTORY
  34  * 09-Mar-90  Gregg Kellogg (gk) at NeXT.
  35  *      include <kern/mach_interface.h> instead of <kern/mach.h>
  36  *
  37  * 14-Feb-89  Avadis Tevanian (avie) at NeXT.
  38  *      Total rewrite using a fixed area of VM from break region.
  39  */
  40
  41 #include <mach/mach.h>          /* for vm_allocate, vm_offset_t */
  42 #include <mach/vm_statistics.h>
  43 #include <errno.h>
  44 #include <unistd.h>
  45
  46 static int sbrk_needs_init = TRUE;
  47 static vm_size_t sbrk_region_size = 4*1024*1024; /* Well, what should it be? */
  48 static vm_address_t sbrk_curbrk;
  49
  50 void *sbrk(int size)
  51 {
  52         kern_return_t   ret;
  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                         errno = ENOMEM;
  63                         return((void *)-1);
  64                 }
  65         }
  66
  67         if (size <= 0)
  68                 return((void *)sbrk_curbrk);
  69         else if (size > sbrk_region_size) {
  70                 errno = ENOMEM;
  71                 return((void *)-1);
  72         }
  73         sbrk_curbrk += size;
  74         sbrk_region_size -= size;
  75         return((void *)(sbrk_curbrk - size));
  76 }
  77
  78 void *brk(const void *x)
  79 {
  80         errno = ENOMEM;
  81         return((void *)-1);
  82 }