g_io_channel_read with the new API.
a buffer to read data into
The number of bytes read. This may be zero even on success if count < 6 and the channel's encoding is non- null. This indicates that the next UTF-8 character is too wide for the buffer.
the size of the buffer. Note that the buffer may not be completely filled even if there is data in the buffer if the remaining data is not a complete character.
the status of the operation.