Platform/CoreIPC/ArgumentCoders.h

/*
 * Copyright (C) 2010 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
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * 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.
 */

#ifndef SimpleArgumentCoder_h
#define SimpleArgumentCoder_h

#include "ArgumentDecoder.h"
#include "ArgumentEncoder.h"
#include <utility>
#include <wtf/HashMap.h>
#include <wtf/TypeTraits.h>
#include <wtf/Vector.h>
#include <wtf/text/AtomicString.h>
#include <wtf/text/CString.h>
#include <wtf/text/WTFString.h>

namespace CoreIPC {

// An argument coder works on POD types
template<typename T> struct SimpleArgumentCoder {
    static void encode(ArgumentEncoder* encoder, const T& t)
    {
        encoder->encodeBytes(reinterpret_cast<const uint8_t*>(&t), sizeof(T));
    }
    static bool decode(ArgumentDecoder* decoder, T& t)
    {
        return decoder->decodeBytes(reinterpret_cast<uint8_t*>(&t), sizeof(T));
    }
};

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

    static bool decode(ArgumentDecoder* 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;
    }
};

template<bool fixedSizeElements, typename T> struct VectorArgumentCoder;

template<typename T> struct VectorArgumentCoder<false, T> {
    static void encode(ArgumentEncoder* encoder, const Vector<T>& vector)
    {
        encoder->encodeUInt64(vector.size());
        for (size_t i = 0; i < vector.size(); ++i)
            encoder->encode(vector[i]);
    }

    static bool decode(ArgumentDecoder* decoder, Vector<T>& vector)
    {
        uint64_t size;
        if (!decoder->decodeUInt64(size))
            return false;

        Vector<T> tmp;
        for (size_t i = 0; i < size; ++i) {
            T element;
            if (!decoder->decode(element))
                return false;

            tmp.append(element);
        }

        tmp.shrinkToFit();
        vector.swap(tmp);
        return true;
    }
};

template<typename T> struct VectorArgumentCoder<true, T> {
    static void encode(ArgumentEncoder* encoder, const Vector<T>& vector)
    {
        encoder->encodeUInt64(vector.size());
        // FIXME: If we could tell the encoder to align the buffer, we could just do an encodeBytes here.
        for (size_t i = 0; i < vector.size(); ++i)
            encoder->encode(vector[i]);
    }

    static bool decode(ArgumentDecoder* decoder, Vector<T>& vector)
    {
        uint64_t size;
        if (!decoder->decodeUInt64(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> tmp;
        tmp.reserveCapacity(size);

        for (size_t i = 0; i < size; ++i) {
            T element;
            if (!decoder->decode(element))
                return false;

            tmp.uncheckedAppend(element);
        }

        vector.swap(tmp);
        return true;
    }
};

template<typename T> struct ArgumentCoder<Vector<T> > : VectorArgumentCoder<WTF::IsArithmetic<T>::value, T> { };

// Specialization for Vector<uint8_t>
template<> struct ArgumentCoder<Vector<uint8_t> > {
    static void encode(ArgumentEncoder* encoder, const Vector<uint8_t>& vector)
    {
        encoder->encodeBytes(vector.data(), vector.size());
    }

    static bool decode(ArgumentDecoder* decoder, Vector<uint8_t>& vector)
    {
        return decoder->decodeBytes(vector);
    }
};

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(ArgumentEncoder* encoder, const HashMapType& hashMap)
    {
        encoder->encodeUInt64(hashMap.size());
        for (typename HashMapType::const_iterator it = hashMap.begin(), end = hashMap.end(); it != end; ++it)
            encoder->encode(*it);
    }

    static bool decode(ArgumentDecoder* 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).second) {
                // The hash map already has the specified key, bail.
                decoder->markInvalid();
                return false;
            }
        }

        hashMap.swap(tempHashMap);
        return true;
    }
};

template<> struct ArgumentCoder<CString> {
    static void encode(ArgumentEncoder* encoder, const CString& string)
    {
        // Special case the null string.
        if (string.isNull()) {
            encoder->encodeUInt32(std::numeric_limits<uint32_t>::max());
            return;
        }

        uint32_t length = string.length();
        encoder->encode(length);
        encoder->encodeBytes(reinterpret_cast<const uint8_t*>(string.data()), length);
    }

    static bool decode(ArgumentDecoder* decoder, CString& result)
    {
        uint32_t length;
        if (!decoder->decode(length))
            return false;

        if (length == std::numeric_limits<uint32_t>::max()) {
            // This is the null string.
            result = CString();
            return true;
        }

        // Before allocating the string, make sure that the decoder buffer is big enough.
        if (!decoder->bufferIsLargeEnoughToContain<char>(length)) {
            decoder->markInvalid();
            return false;
        }

        char* buffer;
        CString string = CString::newUninitialized(length, buffer);
        if (!decoder->decodeBytes(reinterpret_cast<uint8_t*>(buffer), length))
            return false;

        result = string;
        return true;
    }
};

template<> struct ArgumentCoder<String> {
    static void encode(ArgumentEncoder* encoder, const String& string)
    {
        // Special case the null string.
        if (string.isNull()) {
            encoder->encodeUInt32(std::numeric_limits<uint32_t>::max());
            return;
        }

        uint32_t length = string.length();
        encoder->encode(length);
        encoder->encodeBytes(reinterpret_cast<const uint8_t*>(string.characters()), length * sizeof(UChar));
    }

    static bool decode(ArgumentDecoder* decoder, String& result)
    {
        uint32_t length;
        if (!decoder->decode(length))
            return false;

        if (length == std::numeric_limits<uint32_t>::max()) {
            // This is the null string.
            result = String();
            return true;
        }

        // Before allocating the string, make sure that the decoder buffer is big enough.
        if (!decoder->bufferIsLargeEnoughToContain<UChar>(length)) {
            decoder->markInvalid();
            return false;
        }

        UChar* buffer;
        String string = String::createUninitialized(length, buffer);
        if (!decoder->decodeBytes(reinterpret_cast<uint8_t*>(buffer), length * sizeof(UChar)))
            return false;

        result = string;
        return true;
    }
};

template<> struct ArgumentCoder<AtomicString> {
    static void encode(ArgumentEncoder* encoder, const AtomicString& atomicString)
    {
        encoder->encode(atomicString.string());
    }

    static bool decode(ArgumentDecoder* decoder, AtomicString& atomicString)
    {
        String string;
        if (!decoder->decode(string))
            return false;

        atomicString = string;
        return true;
    }
};

} // namespace CoreIPC

#endif // SimpleArgumentCoder_h