- read message fid-value reply! error!procedure
This corresponds to a 9P Tread request. The message is a list of three elements, the fid of the file, the offset to read from, and the number of bytes to read. fid-value is the value bound to the fid.
If the read succeeds, reply! should be called with a list of one argument, that being a u8vector of bytes of the desired length or less.
If the read fails, error! should be called with a suitable error message.
The default implementation calls error! with a message stating that reading is not supported.