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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 <stddef.h> | |
8 #include <stdint.h> | |
9 | |
10 #include "base/logging.h" | |
11 #include "mojo/public/cpp/bindings/lib/serialization_util.h" | |
12 #include "mojo/public/cpp/system/handle.h" | |
13 | |
14 namespace mojo { | |
15 namespace internal { | |
16 | |
17 BoundsChecker::BoundsChecker(const void* data, | |
18 uint32_t data_num_bytes, | |
19 size_t num_handles) | |
20 : data_begin_(reinterpret_cast<uintptr_t>(data)), | |
21 data_end_(data_begin_ + data_num_bytes), | |
22 handle_begin_(0), | |
23 handle_end_(static_cast<uint32_t>(num_handles)) { | |
24 if (data_end_ < data_begin_) { | |
25 // The calculation of |data_end_| overflowed. | |
26 // It shouldn't happen but if it does, set the range to empty so | |
27 // IsValidRange() and ClaimMemory() always fail. | |
28 NOTREACHED(); | |
29 data_end_ = data_begin_; | |
30 } | |
31 if (handle_end_ < num_handles) { | |
32 // Assigning |num_handles| to |handle_end_| overflowed. | |
33 // It shouldn't happen but if it does, set the handle index range to empty. | |
34 NOTREACHED(); | |
35 handle_end_ = 0; | |
36 } | |
37 } | |
38 | |
39 BoundsChecker::~BoundsChecker() { | |
40 } | |
41 | |
42 bool BoundsChecker::ClaimMemory(const void* position, uint32_t num_bytes) { | |
43 uintptr_t begin = reinterpret_cast<uintptr_t>(position); | |
44 uintptr_t end = begin + num_bytes; | |
45 | |
46 if (!InternalIsValidRange(begin, end)) | |
47 return false; | |
48 | |
49 data_begin_ = end; | |
50 return true; | |
51 } | |
52 | |
53 bool BoundsChecker::ClaimHandle(const Handle_Data& encoded_handle) { | |
54 uint32_t index = encoded_handle.value; | |
55 if (index == kEncodedInvalidHandleValue) | |
56 return true; | |
57 | |
58 if (index < handle_begin_ || index >= handle_end_) | |
59 return false; | |
60 | |
61 // |index| + 1 shouldn't overflow, because |index| is not the max value of | |
62 // uint32_t (it is less than |handle_end_|). | |
63 handle_begin_ = index + 1; | |
64 return true; | |
65 } | |
66 | |
67 bool BoundsChecker::IsValidRange(const void* position, | |
68 uint32_t num_bytes) const { | |
69 uintptr_t begin = reinterpret_cast<uintptr_t>(position); | |
70 uintptr_t end = begin + num_bytes; | |
71 | |
72 return InternalIsValidRange(begin, end); | |
73 } | |
74 | |
75 bool BoundsChecker::InternalIsValidRange(uintptr_t begin, uintptr_t end) const { | |
76 return end > begin && begin >= data_begin_ && end <= data_end_; | |
77 } | |
78 | |
79 } // namespace internal | |
80 } // namespace mojo | |
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