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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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