extendable_binary_details.hpp

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/*
  Copyright (c) 2016, Randolph Voorhies, Shane Grant, Michal Breiter
  All rights reserved.

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:
      * Redistributions of source code must retain the above copyright
        notice, this list of conditions and the following disclaimer.
      * 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.
      * Neither the name of cereal nor the
        names of its contributors may be used to endorse or promote products
        derived from this software without specific prior written permission.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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 RANDOLPH VOORHIES OR SHANE GRANT OR MICHAL BREITER 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 CEREAL_DETAILS_EXTENDABLE_BINARY_DETAILS_HPP_
#define CEREAL_DETAILS_EXTENDABLE_BINARY_DETAILS_HPP_

#include <cereal/cereal.hpp>
#include <limits>
#include <sstream>
#include <queue>
#include <assert.h>

namespace cereal
{
  namespace extendable_binary_detail
  {

    inline std::uint8_t is_little_endian()
    {
      static std::int32_t test = 1;
      return *reinterpret_cast<std::int8_t*>( &test ) == 1;
    }


    template <std::size_t DataSize>
    inline void swap_bytes( std::uint8_t * data )
    {
      for( std::size_t i = 0, end = DataSize / 2; i < end; ++i )
        std::swap( data[i], data[DataSize - i - 1] );
    }


    enum class FieldType
    {
            omitted_field = 0x0,
            positive_integer = 0x1,
            negative_integer = 0x2,
            floating_point = 0x3,
            integer_packed = 0x4,
            class_t = 0x5,
            pointer = 0x6,
            size_tag = 0x7,
            packed_array = 0x8,
            packed_struct = 0x9,
            last_field = 0xa,
        LAST_RESERVED_UNUSED
    };


    enum class ClassMarkers : std::uint8_t
    {
            None = 0,
            EmptyClass = 0x1 << 0,
            HasVersion = 0x1 << 1,
    };

    ClassMarkers& operator|=(ClassMarkers& l, ClassMarkers r)
    {
      l = static_cast<ClassMarkers>(static_cast<std::uint8_t>(l) | static_cast<std::uint8_t>(r));
      return l;
    }

    std::uint8_t operator&(ClassMarkers l, ClassMarkers r)
    {
      return static_cast<std::uint8_t>(l) & static_cast<std::uint8_t>(r);
    }


    enum class PointerMarkers : std::uint8_t
    {
            None = 0,
            Empty = 0x1 << 0, // None (0) can be used
            IsSharedPtr = 0x1 << 1,
            IsPolymorphicPointer = 0x1 << 2
    };

    PointerMarkers& operator|=(PointerMarkers& l, PointerMarkers r)
    {
      l = static_cast<PointerMarkers>(static_cast<std::uint8_t>(l) | static_cast<std::uint8_t>(r));
      return l;
    }

    std::uint8_t operator&(PointerMarkers l, PointerMarkers r)
    {
      return static_cast<std::uint8_t>(l) & static_cast<std::uint8_t>(r);
    }


    enum { maxVarintSize = 10 };

    inline std::uint8_t writeType(FieldType fieldType, std::uint8_t other) {
      return (static_cast<std::uint8_t>(fieldType) << 4) | (0xf & other);
    }

    inline std::pair<FieldType, std::uint8_t> readType(std::uint8_t input) {
      std::uint8_t fieldType = (input >> 4);
      if(static_cast<std::uint8_t>(fieldType) >= static_cast<std::uint8_t>(FieldType::LAST_RESERVED_UNUSED)) {
        throw Exception("FieldType has unknown value " + std::to_string(fieldType) + " all:" + std::to_string(input));
      }
      return std::make_pair(static_cast<FieldType>(fieldType), (0xf & input));
    }


    template <class T> inline
    std::uint8_t getHighestBit(T v)
    {
      // TODO fix for big endian
      std::uint8_t n = 0;
      while( v != 0 ) {
        v >>= 8;
        n++;
      }
      return n;
    }


    inline std::uint8_t getHighestBit(std::uint8_t)
    {
      return 1;
    }

    template <class T> inline
    T getqNaN();

    template <> inline
    float getqNaN()
    {
      union { float f; std::uint32_t i; } f;
      f.i = 0x7fc00000;
      return f.f;
    }

    template <> inline
    double getqNaN()
    {
      union { double d; std::uint64_t i; } d;
      d.i = 0x7FF8000000000000ull;
      return d.d;
    }

    template <class T> inline
    T getqNaN()
    {
      static_assert(traits::detail::delay_static_assert<T>::value, "unknown qNaN value");
    }

    inline std::uint8_t getFloatSizeFromTagSize(std::uint8_t tagSize)
    {
      switch (tagSize) {
        case 1:
          return 4;
        case 2:
          return 8;
        default:
          throw Exception("Unsupported floating point size");
      }
    }


    template <class T> inline
    std::uint8_t getTagSizeFromFloatType()
    {
      static_assert(sizeof(T) == 4 || sizeof(T) == 8, "unsupported floating point type");
      static_assert(std::is_floating_point<T>::value, "expected floating point type");
      switch (sizeof(T)) {
        case 4:
          return 1;
        case 8:
          return 2;
      }
    }

    inline std::uint8_t getIntSizeFromTagSize(std::uint8_t tagSize)
    {
      switch (tagSize) {
        case 0:
        case 1:
        case 2:
        case 3:
        case 4:
        case 5:
        case 6:
        case 7:
        case 8:
          return tagSize;
        case 9:
          return 16;
        case 10:
          return 32;
        default:
          throw Exception("Unsupported int size");
      }
    }


    inline std::uint8_t getIntSizeTagFromByteCount(unsigned int byteCount) {
      if(byteCount <= 8) {
        return byteCount;
      } else if(byteCount <= 16) {
        return 9;
      } else if(byteCount <= 32) {
        return 10;
      } else {
        throw Exception("Unsupported int size");
      }
    }

    struct StreamPos
    {
      std::streamoff start;
      std::streamoff end;
    };


    class StreamAdapter
    {
      public:

        StreamAdapter(std::istream & stream, std::stringstream & sharedObjectStream, std::size_t maxBytesInSharedStream)
            : nowReading(nullptr), bytesLeft(0), endOfWritingStream(0), startOfStream(sharedObjectStream.tellg()),
              mainStream(stream), backStream(sharedObjectStream), maxBytesSharedStream(maxBytesInSharedStream)
        {}


        void pushReadingPos(StreamPos & streamPos)
        {
          if (nowReading == nullptr) {
            // save backStream pos for restoration
            endOfWritingStream = backStream.tellg();
          } else {
            // save current position when we get back to this level
            backStreams.push(std::make_pair(backStream.tellg(), nowReading));
          }
          backStream.seekg(streamPos.start);
          nowReading = &streamPos;
          bytesLeft = streamPos.end - streamPos.start;
        }


        inline std::size_t readBinary(void *const data, std::size_t size)
        {
          std::size_t readSize;
          if (nowReading == nullptr) {
            readSize = static_cast<std::size_t>( mainStream.rdbuf()->sgetn(reinterpret_cast<char *>( data ), size));
          } else {
            if (size > bytesLeft) {
              throw Exception("went to far reading skipped shared object stream");
            }
            readSize = static_cast<std::size_t>( backStream.rdbuf()->sgetn(reinterpret_cast<char *>( data ), size));
            bytesLeft -= readSize;
            if (0 == bytesLeft) {
              popStream();
            }
          }
          return readSize;
        }


        inline void skipData(std::size_t size)
        {
          bool streamError;
          if (nowReading == nullptr) {
            mainStream.ignore(size);
            streamError = !mainStream; // we don't care about eof here
          } else {
            if (size > bytesLeft) {
              throw Exception("went to far reading skipped shared object stream");
            }
            backStream.ignore(size);
            streamError = !backStream; // we don't care about eof here
            bytesLeft -= size;
            if (0 == bytesLeft) {
              popStream();
            }
          }
          if (streamError)
            throw Exception("Failed to skip " + std::to_string(size) + " bytes from input stream!");
        }


        inline void checkIfMaxSize(std::size_t size, std::ostream& stream)
        {
          std::size_t posNow = static_cast<std::size_t>(stream.tellp());
          if (posNow - startOfStream + size > maxBytesSharedStream) {
            throw Exception("Shared obiect shared data limit hit");
          }
        }


        inline void readToOtherStream(std::size_t size, std::ostream & stream)
        {
          checkIfMaxSize(size, stream);
          auto copyN = [](std::istream & from, std::size_t sizeToCopy, std::ostream & to) {
            auto start = std::istreambuf_iterator<char>(from);
            auto end = std::istreambuf_iterator<char>();
            auto dest = std::ostreambuf_iterator<char>(to);
            for (; sizeToCopy > 0 && start != end; ++start, ++dest, --sizeToCopy) {
              *dest = *start;
            }
            if (0 != sizeToCopy)
              throw Exception("Failed to skip data from input stream!");
          };

          if (nowReading == nullptr) {
            copyN(mainStream, size, stream);
          } else {
            // shouldn't be here, there is no point in copying data if we are reading from backStream
            assert(false);
            if (size > bytesLeft) {
              throw Exception("went to far reading skipped shared object stream");
            }
            copyN(mainStream, size, stream);
            bytesLeft -= size;
            if (0 == bytesLeft) {
              popStream();
            }
          }
        }

      private:

        void popStream()
        {
          if (backStreams.empty()) {
            // move backStream back where it was for writing
            backStream.seekg(endOfWritingStream);
            nowReading = nullptr;
            bytesLeft = 0;
          } else {
            const auto & next = backStreams.back();
            backStream.seekg(next.first);
            // we read something before so next.first has to be used
            bytesLeft = next.second->end - next.first;
            nowReading = next.second;
            backStreams.pop();
          }
        }

      private:
        StreamPos *nowReading; 
        std::size_t bytesLeft; 
        std::size_t endOfWritingStream; 
        const std::size_t startOfStream; 
        std::queue<std::pair<std::size_t, StreamPos *>> backStreams;
        std::istream & mainStream; 
        std::istream & backStream; 
        const std::size_t maxBytesSharedStream; 
    };
  } // namespace extendable_binary_detail
} // namespace cereal
#endif