Question

When I was reading from a usocket stream using the code below:

(let ((stream (socket-stream sk)) line)
  (loop for line = (read-line stream)
     while line do (format t line)))

when read-line meets an non-ascii charactor, it throw out an exception:

decoding error on stream
#<SB-SYS:FD-STREAM
  for "socket 118.229.141.195:52946, peer: 119.75.217.109..."
  {BCA02F1}>
(:EXTERNAL-FORMAT :UTF-8):
  the octet sequence (176) cannot be decoded.
   [Condition of type SB-INT:STREAM-DECODING-ERROR]

Neither read-line nor read-byte works, so I tried to use trivial-utf-8 to read utf-8 string
using read-utf-8-string, but It only accepts a binary stream, it seems socket-stream does not create a binary stream, so I was confused how to read from a socket stream that has non-ascii charactors?

Answer 1

You can first read-sequence (if you know the length ahead of time) or read-bytes while there are some, and then convert them to string with (babel:octets-to-string octets :encoding :utf-8)) (where octets is (make-array expected-length :element-type '(unsigned-byte 8))).