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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "mojo/public/cpp/bindings/lib/bounds_checker.h"
#include "mojo/public/cpp/bindings/lib/bindings_serialization.h"
#include "mojo/public/cpp/environment/logging.h"
#include "mojo/public/cpp/system/handle.h"
namespace mojo {
namespace internal {
BoundsChecker::BoundsChecker(const void* data,
uint32_t data_num_bytes,
size_t num_handles)
: data_begin_(reinterpret_cast<uintptr_t>(data)),
data_end_(data_begin_ + data_num_bytes),
handle_begin_(0),
handle_end_(static_cast<uint32_t>(num_handles)) {
if (data_end_ < data_begin_) {
// The calculation of |data_end_| overflowed.
// It shouldn't happen but if it does, set the range to empty so
// IsValidRange() and ClaimMemory() always fail.
MOJO_DCHECK(false) << "Not reached";
data_end_ = data_begin_;
}
if (handle_end_ < num_handles) {
// Assigning |num_handles| to |handle_end_| overflowed.
// It shouldn't happen but if it does, set the handle index range to empty.
MOJO_DCHECK(false) << "Not reached";
handle_end_ = 0;
}
}
BoundsChecker::~BoundsChecker() {
}
bool BoundsChecker::ClaimMemory(const void* position, uint32_t num_bytes) {
uintptr_t begin = reinterpret_cast<uintptr_t>(position);
uintptr_t end = begin + num_bytes;
if (!InternalIsValidRange(begin, end))
return false;
data_begin_ = end;
return true;
}
bool BoundsChecker::ClaimHandle(const Handle& encoded_handle) {
uint32_t index = encoded_handle.value();
if (index == kEncodedInvalidHandleValue)
return true;
if (index < handle_begin_ || index >= handle_end_)
return false;
// |index| + 1 shouldn't overflow, because |index| is not the max value of
// uint32_t (it is less than |handle_end_|).
handle_begin_ = index + 1;
return true;
}
bool BoundsChecker::IsValidRange(const void* position,
uint32_t num_bytes) const {
uintptr_t begin = reinterpret_cast<uintptr_t>(position);
uintptr_t end = begin + num_bytes;
return InternalIsValidRange(begin, end);
}
bool BoundsChecker::InternalIsValidRange(uintptr_t begin, uintptr_t end) const {
return end > begin && begin >= data_begin_ && end <= data_end_;
}
} // namespace internal
} // namespace mojo
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