From: Tom Gilbert <tom@...>
Date: 2002-08-15T01:09:40+09:00
Subject: Re: Problems with Marshal

* Berger, Daniel (djberge@qwest.com) wrote:
> Ok, I've narrowed it down partially to a newline issue with Marshal.  Here
> are a sample client and server to demonstrate.  Just start the server in one
> terminal and the client in another.  Uncomment the appropriate lines to view
> the different behavior.  More comments at end...
> 
> # SAMPLE SERVER
> 
> require 'socket'
> a = ["one","two","three"]    # -> This gets wonky results
> #a = ["one","two","three\n"] # -> This works
> #a.push("\n")                # -> This causes "marshal data too short"
> x = Marshal.dump(a)
> 
> tcpServer = TCPServer.open('localhost',8877)
> $tcpServer = tcpServer
> 
> addr = tcpServer.addr
> addr.shift # remove "AF_INET"
> 
> #puts "Server is on port: " + addr.shift.to_s
> 
> while true
>    Thread.start(tcpServer.accept) do |s|
>       puts "Accepted connection: #{s}"
>       r = s.gets
>       puts "Got #{r} from client"
>       s.puts(x)


> v = s.gets
> 
> a = Marshal.load(v)

The problem is that you're using gets and puts, which aren't appropriate
for this kind of data, e.g:

irb(main):004:0> Marshal.dump(["hello", "world\n", "\n"])
"\004\006[\010\"\nhello\"\vworld\n\"\006\n"
irb(main):005:0> puts Marshal.dump(["hello", "world\n", "\n"])
"
hello"world
"

You can imagine the problem doing a gets on a socket containing that
last string, you aren't getting your marshalled data back :)
You need to be reading all the data the client sends you, not line-wise.

Anyway, isn't there DRuby - designed specifically for this kind of task?

Tom.
-- 
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   /V\    | Tom Gilbert, London, England | http://linuxbrit.co.uk |
 /(   )\  | Open Source/UNIX consultant  | tom@linuxbrit.co.uk    |
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