IO#readlines/IO#getc hangs while reading over TCPSocket

[bkutil]

👋

Since commit 992ba47, the following script hangs until the other side closes the connection:

server = TCPServer.new 9292

while session = server.accept
    puts "Request"

    while line = session.readline("\r\n")
      puts line.inspect
      break if line == "\r\n"
    end

    puts "Response"

    session.write "HTTP/1.1 200 OK\r\n\r\nOK\n"
    session.flush
    session.close
end

With mruby-io and mruby-socket core mrbgems compiled in, running the above script and then e.g. curl 'http://localhost:9292/' outputs:

Before 992ba47:

Request
"GET / HTTP/1.1\r\n"
"Host: localhost:9292\r\n"
"User-Agent: curl/7.58.0\r\n"
"Accept: */*\r\n"
"\r\n"
Response

After:

Request
"GET / HTTP/1.1\r\n"
"Host: localhost:9292\r\n"
"User-Agent: curl/7.58.0\r\n"
"Accept: */*\r\n"
...

Same happens while calling session.getc in the inner loop. Is this expected behavior? It also doesn't happen with MRI Ruby.

[dearblue]

😿 I made a mistake.
Thanks @bkutil for the report!
Thanks @matz for the fix!