158 lines
4.0 KiB
C++
158 lines
4.0 KiB
C++
/*
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* Copyright (C) 2010-2021 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "config.h"
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#include <wtf/persistence/PersistentDecoder.h>
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#include <wtf/persistence/PersistentEncoder.h>
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namespace WTF {
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namespace Persistence {
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Decoder::Decoder(Span<const uint8_t> span)
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: m_buffer(span)
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, m_bufferPosition(span.begin())
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{
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}
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Decoder::~Decoder()
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{
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}
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bool Decoder::bufferIsLargeEnoughToContain(size_t size) const
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{
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return size <= static_cast<size_t>(m_buffer.end() - m_bufferPosition);
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}
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const uint8_t* Decoder::bufferPointerForDirectRead(size_t size)
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{
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if (!bufferIsLargeEnoughToContain(size))
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return nullptr;
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auto data = m_bufferPosition;
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m_bufferPosition += size;
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Encoder::updateChecksumForData(m_sha1, { data, size });
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return data;
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}
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bool Decoder::decodeFixedLengthData(Span<uint8_t> span)
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{
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auto buffer = bufferPointerForDirectRead(span.size());
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if (!buffer)
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return false;
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memcpy(span.data(), buffer, span.size());
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return true;
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}
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bool Decoder::rewind(size_t size)
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{
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if (size <= static_cast<size_t>(m_bufferPosition - m_buffer.begin())) {
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m_bufferPosition -= size;
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return true;
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}
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return false;
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}
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template<typename T>
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Decoder& Decoder::decodeNumber(std::optional<T>& optional)
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{
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if (!bufferIsLargeEnoughToContain(sizeof(T)))
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return *this;
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T value;
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memcpy(&value, m_bufferPosition, sizeof(T));
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m_bufferPosition += sizeof(T);
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Encoder::updateChecksumForNumber(m_sha1, value);
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optional = value;
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return *this;
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}
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Decoder& Decoder::operator>>(std::optional<bool>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<uint8_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<uint16_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<int16_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<uint32_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<uint64_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<int32_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<int64_t>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<float>& result)
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{
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return decodeNumber(result);
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}
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Decoder& Decoder::operator>>(std::optional<double>& result)
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{
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return decodeNumber(result);
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}
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bool Decoder::verifyChecksum()
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{
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SHA1::Digest computedHash;
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m_sha1.computeHash(computedHash);
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SHA1::Digest savedHash;
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if (!decodeFixedLengthData({ savedHash.data(), sizeof(savedHash) }))
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return false;
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return computedHash == savedHash;
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}
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} // namespace Persistence
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} // namespace WTF
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