Write a certain amount of data at a specified offset before returning.

template<
    typename SyncRandomAccessWriteDevice,
    typename ConstBufferSequence>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    boost::uint64_t offset,
    const ConstBufferSequence & buffers);

template<
    typename SyncRandomAccessWriteDevice,
    typename ConstBufferSequence,
    typename CompletionCondition>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    boost::uint64_t offset,
    const ConstBufferSequence & buffers,
    CompletionCondition completion_condition);

template<
    typename SyncRandomAccessWriteDevice,
    typename ConstBufferSequence,
    typename CompletionCondition>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    boost::uint64_t offset,
    const ConstBufferSequence & buffers,
    CompletionCondition completion_condition,
    boost::system::error_code & ec);

template<
    typename SyncRandomAccessWriteDevice,
    typename Allocator>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    boost::uint64_t offset,
    basic_streambuf< Allocator > & b);

template<
    typename SyncRandomAccessWriteDevice,
    typename Allocator,
    typename CompletionCondition>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    boost::uint64_t offset,
    basic_streambuf< Allocator > & b,
    CompletionCondition completion_condition);

template<
    typename SyncRandomAccessWriteDevice,
    typename Allocator,
    typename CompletionCondition>
std::size_t write_at(
    SyncRandomAccessWriteDevice & d,
    boost::uint64_t offset,
    basic_streambuf< Allocator > & b,
    CompletionCondition completion_condition,
    boost::system::error_code & ec);