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Write a certain amount of data at a specified offset before returning.
template< typename SyncRandomAccessWriteDevice, typename Allocator, typename CompletionCondition> std::size_t write_at( SyncRandomAccessWriteDevice & d, uint64_t offset, basic_streambuf< Allocator > & b, CompletionCondition completion_condition);
This function is used to write a certain number of bytes of data to a random access device at a specified offset. The call will block until one of the following conditions is true:
basic_streambuf has been written.
This operation is implemented in terms of zero or more calls to the device's write_some_at function.
The device to which the data is to be written. The type must support the SyncRandomAccessWriteDevice concept.
The offset at which the data will be written.
The basic_streambuf object from
which data will be written.
The function object to be called to determine whether the write operation is complete. The signature of the function object must be:
std::size_t completion_condition( // Result of latest write_some_at operation. const asio::error_code& error, // Number of bytes transferred so far. std::size_t bytes_transferred );
A return value of 0 indicates that the write operation is complete. A non-zero return value indicates the maximum number of bytes to be written on the next call to the device's write_some_at function.
The number of bytes transferred.
Thrown on failure.