1 // Copyright (c) 2006, Google Inc.
2 // All rights reserved.
3 //
4 // Redistribution and use in source and binary forms, with or without
5 // modification, are permitted provided that the following conditions are
6 // met:
7 //
8 // * Redistributions of source code must retain the above copyright
9 // notice, this list of conditions and the following disclaimer.
10 // * Redistributions in binary form must reproduce the above
11 // copyright notice, this list of conditions and the following disclaimer
12 // in the documentation and/or other materials provided with the
13 // distribution.
14 // * Neither the name of Google Inc. nor the names of its
15 // contributors may be used to endorse or promote products derived from
16 // this software without specific prior written permission.
17 //
18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29 //
30 // ProtectedMemoryAllocator
31 //
32 // See the header file for documentation
33
34 #include "protected_memory_allocator.h"
35 #include <assert.h>
36
37 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
ProtectedMemoryAllocator(vm_size_t pool_size)38 ProtectedMemoryAllocator::ProtectedMemoryAllocator(vm_size_t pool_size)
39 : pool_size_(pool_size),
40 next_alloc_offset_(0),
41 valid_(false) {
42
43 kern_return_t result = vm_allocate(mach_task_self(),
44 &base_address_,
45 pool_size,
46 TRUE
47 );
48
49 valid_ = (result == KERN_SUCCESS);
50 assert(valid_);
51 }
52
53 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~ProtectedMemoryAllocator()54 ProtectedMemoryAllocator::~ProtectedMemoryAllocator() {
55 vm_deallocate(mach_task_self(),
56 base_address_,
57 pool_size_
58 );
59 }
60
61 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allocate(vm_size_t bytes)62 char *ProtectedMemoryAllocator::Allocate(vm_size_t bytes) {
63 if (valid_ && next_alloc_offset_ + bytes <= pool_size_) {
64 char *p = (char*)base_address_ + next_alloc_offset_;
65 next_alloc_offset_ += bytes;
66 return p;
67 }
68
69 return NULL; // ran out of memory in our allocation block
70 }
71
72 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Protect()73 kern_return_t ProtectedMemoryAllocator::Protect() {
74 kern_return_t result = vm_protect(mach_task_self(),
75 base_address_,
76 pool_size_,
77 FALSE,
78 VM_PROT_READ);
79
80 return result;
81 }
82
83 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unprotect()84 kern_return_t ProtectedMemoryAllocator::Unprotect() {
85 kern_return_t result = vm_protect(mach_task_self(),
86 base_address_,
87 pool_size_,
88 FALSE,
89 VM_PROT_READ | VM_PROT_WRITE);
90
91 return result;
92 }
93