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1 // Copyright 2014 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "mojo/public/cpp/bindings/lib/bounds_checker.h" | |
6 | |
7 #include "mojo/public/cpp/bindings/lib/bindings_serialization.h" | |
8 #include "mojo/public/cpp/environment/logging.h" | |
9 #include "mojo/public/cpp/system/handle.h" | |
10 | |
11 namespace mojo { | |
12 namespace internal { | |
13 | |
14 BoundsChecker::BoundsChecker(const void* data, | |
15 uint32_t data_num_bytes, | |
16 size_t num_handles) | |
17 : data_begin_(reinterpret_cast<uintptr_t>(data)), | |
18 data_end_(data_begin_ + data_num_bytes), | |
19 handle_begin_(0), | |
20 handle_end_(static_cast<uint32_t>(num_handles)) { | |
21 if (data_end_ < data_begin_) { | |
22 // The calculation of |data_end_| overflowed. | |
23 // It shouldn't happen but if it does, set the range to empty so | |
24 // IsValidRange() and ClaimMemory() always fail. | |
25 MOJO_DCHECK(false) << "Not reached"; | |
26 data_end_ = data_begin_; | |
27 } | |
28 if (handle_end_ < num_handles) { | |
29 // Assigning |num_handles| to |handle_end_| overflowed. | |
30 // It shouldn't happen but if it does, set the handle index range to empty. | |
31 MOJO_DCHECK(false) << "Not reached"; | |
32 handle_end_ = 0; | |
33 } | |
34 } | |
35 | |
36 BoundsChecker::~BoundsChecker() { | |
37 } | |
38 | |
39 bool BoundsChecker::ClaimMemory(const void* position, uint32_t num_bytes) { | |
40 uintptr_t begin = reinterpret_cast<uintptr_t>(position); | |
41 uintptr_t end = begin + num_bytes; | |
42 | |
43 if (!InternalIsValidRange(begin, end)) | |
44 return false; | |
45 | |
46 data_begin_ = end; | |
47 return true; | |
48 } | |
49 | |
50 bool BoundsChecker::ClaimHandle(const Handle& encoded_handle) { | |
51 uint32_t index = encoded_handle.value(); | |
52 if (index == kEncodedInvalidHandleValue) | |
53 return true; | |
54 | |
55 if (index < handle_begin_ || index >= handle_end_) | |
56 return false; | |
57 | |
58 // |index| + 1 shouldn't overflow, because |index| is not the max value of | |
59 // uint32_t (it is less than |handle_end_|). | |
60 handle_begin_ = index + 1; | |
61 return true; | |
62 } | |
63 | |
64 bool BoundsChecker::IsValidRange(const void* position, | |
65 uint32_t num_bytes) const { | |
66 uintptr_t begin = reinterpret_cast<uintptr_t>(position); | |
67 uintptr_t end = begin + num_bytes; | |
68 | |
69 return InternalIsValidRange(begin, end); | |
70 } | |
71 | |
72 bool BoundsChecker::InternalIsValidRange(uintptr_t begin, uintptr_t end) const { | |
73 return end > begin && begin >= data_begin_ && end <= data_end_; | |
74 } | |
75 | |
76 } // namespace internal | |
77 } // namespace mojo | |
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