Source/WebKit/Platform/IPC/ArgumentCoders.h

/*
 * Copyright (C) 2010-2017 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "Decoder.h"
#include "Encoder.h"
#include <utility>
#include <wtf/Forward.h>
#include <wtf/MonotonicTime.h>
#include <wtf/SHA1.h>
#include <wtf/WallTime.h>

namespace IPC {

// An argument coder works on POD types
template<typename T> struct SimpleArgumentCoder {
    static void encode(Encoder& encoder, const T& t)
    {
        encoder.encodeFixedLengthData(reinterpret_cast<const uint8_t*>(&t), sizeof(T), alignof(T));
    }

    static bool decode(Decoder& decoder, T& t)
    {
        return decoder.decodeFixedLengthData(reinterpret_cast<uint8_t*>(&t), sizeof(T), alignof(T));
    }
};

template<typename T> struct ArgumentCoder<OptionSet<T>> {
    static void encode(Encoder& encoder, const OptionSet<T>& optionSet)
    {
        encoder << (static_cast<uint64_t>(optionSet.toRaw()));
    }

    static bool decode(Decoder& decoder, OptionSet<T>& optionSet)
    {
        uint64_t value;
        if (!decoder.decode(value))
            return false;

        optionSet = OptionSet<T>::fromRaw(value);
        return true;
    }

    static std::optional<OptionSet<T>> decode(Decoder& decoder)
    {
        std::optional<uint64_t> value;
        decoder >> value;
        if (!value)
            return std::nullopt;
        return OptionSet<T>::fromRaw(*value);
    }
};

template<typename T> struct ArgumentCoder<std::optional<T>> {
    static void encode(Encoder& encoder, const std::optional<T>& optional)
    {
        if (!optional) {
            encoder << false;
            return;
        }

        encoder << true;
        encoder << optional.value();
    }

    static bool decode(Decoder& decoder, std::optional<T>& optional)
    {
        bool isEngaged;
        if (!decoder.decode(isEngaged))
            return false;

        if (!isEngaged) {
            optional = std::nullopt;
            return true;
        }

        T value;
        if (!decoder.decode(value))
            return false;

        optional = WTFMove(value);
        return true;
    }
    
    static std::optional<std::optional<T>> decode(Decoder& decoder)
    {
        std::optional<bool> isEngaged;
        decoder >> isEngaged;
        if (!isEngaged)
            return std::nullopt;
        if (*isEngaged) {
            std::optional<T> value;
            decoder >> value;
            if (!value)
                return std::nullopt;
            return std::optional<std::optional<T>>(WTFMove(*value));
        }
        return std::optional<std::optional<T>>(std::optional<T>(std::nullopt));
    }
};

template<typename T, typename U> struct ArgumentCoder<std::pair<T, U>> {
    static void encode(Encoder& encoder, const std::pair<T, U>& pair)
    {
        encoder << pair.first << pair.second;
    }

    static bool decode(Decoder& decoder, std::pair<T, U>& pair)
    {
        T first;
        if (!decoder.decode(first))
            return false;

        U second;
        if (!decoder.decode(second))
            return false;

        pair.first = first;
        pair.second = second;
        return true;
    }

    static std::optional<std::pair<T, U>> decode(Decoder& decoder)
    {
        std::optional<T> first;
        decoder >> first;
        if (!first)
            return std::nullopt;
        
        std::optional<U> second;
        decoder >> second;
        if (!second)
            return std::nullopt;
        
        return {{ WTFMove(*first), WTFMove(*second) }};
    }
};

template<size_t index, typename... Elements>
struct TupleCoder {
    static void encode(Encoder& encoder, const std::tuple<Elements...>& tuple)
    {
        encoder << std::get<sizeof...(Elements) - index>(tuple);
        TupleCoder<index - 1, Elements...>::encode(encoder, tuple);
    }

    template<typename U = typename std::remove_reference<typename std::tuple_element<sizeof...(Elements) - index, std::tuple<Elements...>>::type>::type, std::enable_if_t<!UsesModernDecoder<U>::value>* = nullptr>
    static bool decode(Decoder& decoder, std::tuple<Elements...>& tuple)
    {
        if (!decoder.decode(std::get<sizeof...(Elements) - index>(tuple)))
            return false;
        return TupleCoder<index - 1, Elements...>::decode(decoder, tuple);
    }
    
    template<typename U = typename std::remove_reference<typename std::tuple_element<sizeof...(Elements) - index, std::tuple<Elements...>>::type>::type, std::enable_if_t<UsesModernDecoder<U>::value>* = nullptr>
    static bool decode(Decoder& decoder, std::tuple<Elements...>& tuple)
    {
        std::optional<U> optional;
        decoder >> optional;
        if (!optional)
            return false;
        std::get<sizeof...(Elements) - index>(tuple) = WTFMove(*optional);
        return TupleCoder<index - 1, Elements...>::decode(decoder, tuple);
    }
};

template<typename... Elements>
struct TupleCoder<0, Elements...> {
    static void encode(Encoder&, const std::tuple<Elements...>&)
    {
    }

    static bool decode(Decoder&, std::tuple<Elements...>&)
    {
        return true;
    }
};

template<typename... Elements> struct ArgumentCoder<std::tuple<Elements...>> {
    static void encode(Encoder& encoder, const std::tuple<Elements...>& tuple)
    {
        TupleCoder<sizeof...(Elements), Elements...>::encode(encoder, tuple);
    }

    static bool decode(Decoder& decoder, std::tuple<Elements...>& tuple)
    {
        return TupleCoder<sizeof...(Elements), Elements...>::decode(decoder, tuple);
    }
};


template<typename KeyType, typename ValueType> struct ArgumentCoder<WTF::KeyValuePair<KeyType, ValueType>> {
    static void encode(Encoder& encoder, const WTF::KeyValuePair<KeyType, ValueType>& pair)
    {
        encoder << pair.key << pair.value;
    }

    static bool decode(Decoder& decoder, WTF::KeyValuePair<KeyType, ValueType>& pair)
    {
        KeyType key;
        if (!decoder.decode(key))
            return false;

        ValueType value;
        if (!decoder.decode(value))
            return false;

        pair.key = key;
        pair.value = value;
        return true;
    }
};

template<bool fixedSizeElements, typename T, size_t inlineCapacity> struct VectorArgumentCoder;

template<typename T, size_t inlineCapacity> struct VectorArgumentCoder<false, T, inlineCapacity> {
    static void encode(Encoder& encoder, const Vector<T, inlineCapacity>& vector)
    {
        encoder << static_cast<uint64_t>(vector.size());
        for (size_t i = 0; i < vector.size(); ++i)
            encoder << vector[i];
    }

    static bool decode(Decoder& decoder, Vector<T, inlineCapacity>& vector)
    {
        std::optional<Vector<T, inlineCapacity>> optional;
        decoder >> optional;
        if (!optional)
            return false;
        vector = WTFMove(*optional);
        return true;
    }

    static std::optional<Vector<T, inlineCapacity>> decode(Decoder& decoder)
    {
        uint64_t size;
        if (!decoder.decode(size))
            return std::nullopt;

        Vector<T, inlineCapacity> vector;
        for (size_t i = 0; i < size; ++i) {
            std::optional<T> element;
            decoder >> element;
            if (!element)
                return std::nullopt;
            vector.append(WTFMove(*element));
        }
        vector.shrinkToFit();
        return WTFMove(vector);
    }
};

template<typename T, size_t inlineCapacity> struct VectorArgumentCoder<true, T, inlineCapacity> {
    static void encode(Encoder& encoder, const Vector<T, inlineCapacity>& vector)
    {
        encoder << static_cast<uint64_t>(vector.size());
        encoder.encodeFixedLengthData(reinterpret_cast<const uint8_t*>(vector.data()), vector.size() * sizeof(T), alignof(T));
    }
    
    static bool decode(Decoder& decoder, Vector<T, inlineCapacity>& vector)
    {
        uint64_t size;
        if (!decoder.decode(size))
            return false;

        // Since we know the total size of the elements, we can allocate the vector in
        // one fell swoop. Before allocating we must however make sure that the decoder buffer
        // is big enough.
        if (!decoder.bufferIsLargeEnoughToContain<T>(size)) {
            decoder.markInvalid();
            return false;
        }

        Vector<T, inlineCapacity> temp;
        temp.grow(size);

        decoder.decodeFixedLengthData(reinterpret_cast<uint8_t*>(temp.data()), size * sizeof(T), alignof(T));

        vector.swap(temp);
        return true;
    }
    
    static std::optional<Vector<T, inlineCapacity>> decode(Decoder& decoder)
    {
        uint64_t size;
        if (!decoder.decode(size))
            return std::nullopt;
        
        // Since we know the total size of the elements, we can allocate the vector in
        // one fell swoop. Before allocating we must however make sure that the decoder buffer
        // is big enough.
        if (!decoder.bufferIsLargeEnoughToContain<T>(size)) {
            decoder.markInvalid();
            return std::nullopt;
        }
        
        Vector<T, inlineCapacity> vector;
        vector.grow(size);
        
        decoder.decodeFixedLengthData(reinterpret_cast<uint8_t*>(vector.data()), size * sizeof(T), alignof(T));
        
        return vector;
    }
};

template<typename T, size_t inlineCapacity> struct ArgumentCoder<Vector<T, inlineCapacity>> : VectorArgumentCoder<std::is_arithmetic<T>::value, T, inlineCapacity> { };

template<typename KeyArg, typename MappedArg, typename HashArg, typename KeyTraitsArg, typename MappedTraitsArg> struct ArgumentCoder<HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg>> {
    typedef HashMap<KeyArg, MappedArg, HashArg, KeyTraitsArg, MappedTraitsArg> HashMapType;

    static void encode(Encoder& encoder, const HashMapType& hashMap)
    {
        encoder << static_cast<uint64_t>(hashMap.size());
        for (typename HashMapType::const_iterator it = hashMap.begin(), end = hashMap.end(); it != end; ++it)
            encoder << *it;
    }

    static bool decode(Decoder& decoder, HashMapType& hashMap)
    {
        uint64_t hashMapSize;
        if (!decoder.decode(hashMapSize))
            return false;

        HashMapType tempHashMap;
        for (uint64_t i = 0; i < hashMapSize; ++i) {
            KeyArg key;
            MappedArg value;
            if (!decoder.decode(key))
                return false;
            if (!decoder.decode(value))
                return false;

            if (!tempHashMap.add(key, value).isNewEntry) {
                // The hash map already has the specified key, bail.
                decoder.markInvalid();
                return false;
            }
        }

        hashMap.swap(tempHashMap);
        return true;
    }

    static std::optional<HashMapType> decode(Decoder& decoder)
    {
        uint64_t hashMapSize;
        if (!decoder.decode(hashMapSize))
            return std::nullopt;

        HashMapType hashMap;
        for (uint64_t i = 0; i < hashMapSize; ++i) {
            std::optional<KeyArg> key;
            decoder >> key;
            if (!key)
                return std::nullopt;

            std::optional<MappedArg> value;
            decoder >> value;
            if (!value)
                return std::nullopt;

            if (!hashMap.add(WTFMove(key.value()), WTFMove(value.value())).isNewEntry) {
                // The hash map already has the specified key, bail.
                decoder.markInvalid();
                return std::nullopt;
            }
        }

        return WTFMove(hashMap);
    }
};

template<typename KeyArg, typename HashArg, typename KeyTraitsArg> struct ArgumentCoder<HashSet<KeyArg, HashArg, KeyTraitsArg>> {
    typedef HashSet<KeyArg, HashArg, KeyTraitsArg> HashSetType;

    static void encode(Encoder& encoder, const HashSetType& hashSet)
    {
        encoder << static_cast<uint64_t>(hashSet.size());
        for (typename HashSetType::const_iterator it = hashSet.begin(), end = hashSet.end(); it != end; ++it)
            encoder << *it;
    }

    static bool decode(Decoder& decoder, HashSetType& hashSet)
    {
        std::optional<HashSetType> tempHashSet;
        decoder >> tempHashSet;
        if (!tempHashSet)
            return false;

        hashSet.swap(tempHashSet.value());
        return true;
    }

    static std::optional<HashSetType> decode(Decoder& decoder)
    {
        uint64_t hashSetSize;
        if (!decoder.decode(hashSetSize))
            return std::nullopt;

        HashSetType hashSet;
        for (uint64_t i = 0; i < hashSetSize; ++i) {
            std::optional<KeyArg> key;
            decoder >> key;
            if (!key)
                return std::nullopt;

            if (!hashSet.add(WTFMove(key.value())).isNewEntry) {
                // The hash set already has the specified key, bail.
                decoder.markInvalid();
                return std::nullopt;
            }
        }

        return WTFMove(hashSet);
    }
};

template<typename KeyArg, typename HashArg, typename KeyTraitsArg> struct ArgumentCoder<HashCountedSet<KeyArg, HashArg, KeyTraitsArg>> {
    typedef HashCountedSet<KeyArg, HashArg, KeyTraitsArg> HashCountedSetType;
    
    static void encode(Encoder& encoder, const HashCountedSetType& hashCountedSet)
    {
        encoder << static_cast<uint64_t>(hashCountedSet.size());
        
        for (auto entry : hashCountedSet) {
            encoder << entry.key;
            encoder << entry.value;
        }
    }
    
    static bool decode(Decoder& decoder, HashCountedSetType& hashCountedSet)
    {
        uint64_t hashCountedSetSize;
        if (!decoder.decode(hashCountedSetSize))
            return false;
        
        HashCountedSetType tempHashCountedSet;
        for (uint64_t i = 0; i < hashCountedSetSize; ++i) {
            KeyArg key;
            if (!decoder.decode(key))
                return false;
            
            unsigned count;
            if (!decoder.decode(count))
                return false;
            
            if (!tempHashCountedSet.add(key, count).isNewEntry) {
                // The hash counted set already has the specified key, bail.
                decoder.markInvalid();
                return false;
            }
        }
        
        hashCountedSet.swap(tempHashCountedSet);
        return true;
    }
};

template<typename ValueType, typename ErrorType> struct ArgumentCoder<Expected<ValueType, ErrorType>> {
    static void encode(Encoder& encoder, const Expected<ValueType, ErrorType>& expected)
    {
        if (!expected.has_value()) {
            encoder << false;
            encoder << expected.error();
            return;
        }
        encoder << true;
        encoder << expected.value();
    }

    static std::optional<Expected<ValueType, ErrorType>> decode(Decoder& decoder)
    {
        std::optional<bool> hasValue;
        decoder >> hasValue;
        if (!hasValue)
            return std::nullopt;
        
        if (*hasValue) {
            std::optional<ValueType> value;
            decoder >> value;
            if (!value)
                return std::nullopt;
            
            Expected<ValueType, ErrorType> expected(WTFMove(*value));
            return WTFMove(expected);
        }
        std::optional<ErrorType> error;
        decoder >> error;
        if (!error)
            return std::nullopt;
        return { makeUnexpected(WTFMove(*error)) };
    }
};

template<> struct ArgumentCoder<WallTime> {
    static void encode(Encoder&, const WallTime&);
    static bool decode(Decoder&, WallTime&);
    static std::optional<WallTime> decode(Decoder&);
};

template<> struct ArgumentCoder<AtomicString> {
    static void encode(Encoder&, const AtomicString&);
    static bool decode(Decoder&, AtomicString&);
};

template<> struct ArgumentCoder<CString> {
    static void encode(Encoder&, const CString&);
    static bool decode(Decoder&, CString&);
};

template<> struct ArgumentCoder<String> {
    static void encode(Encoder&, const String&);
    static bool decode(Decoder&, String&);
    static std::optional<String> decode(Decoder&);
};

template<> struct ArgumentCoder<SHA1::Digest> {
    static void encode(Encoder&, const SHA1::Digest&);
    static bool decode(Decoder&, SHA1::Digest&);
};

} // namespace IPC