[RFC] netx: added encoding support for UTF-16 and UTF-32

[Deepak Bhole]

* Man Wong <mwong at redhat.com> [2010-07-06 12:06]:
> Hi,
> 
> This patch adds UTF-16 and UTF-32 encoding support for netx, allowing jnlp files saved under those encoding to launch in netx [1]. Previously, when a jnlp file with UTF-16 or UTF-32 encoding is passed in, netx will throw an exception even though the jnlp file was a valid file. It would be greatly appreciated if someone can look over the code, make sure it is ok and see if additional comments are needed to make the code easier to understand.
> 
> Thanks,
> Man Lung Wong
> 
> [1] http://icedtea.classpath.org/~mwong/webstart/HelloWorld/Test.jnlp (a simple Hello World applet I created to test this patch)

InputStreamReader has a getEncoding() method[1]. Can that not be used
instead of defining our own?

1: http://download.oracle.com/docs/cd/E17476_01/javase/1.4.2/docs/api/java/io/InputStreamReader.html#getEncoding%28%29

Deepak

> diff -r 5c61be3119bb netx/net/sourceforge/jnlp/Parser.java
> --- a/netx/net/sourceforge/jnlp/Parser.java	Mon Jul 05 17:31:35 2010 +0100
> +++ b/netx/net/sourceforge/jnlp/Parser.java	Mon Jul 05 17:41:10 2010 -0400
> @@ -1168,12 +1168,16 @@
>              Node document = new Node(TinyParser.parseXML(input));
>              Node jnlpNode = getChildNode(document, "jnlp"); // skip comments
>              */
> +            
> +            //A BufferedInputStream is used to allow marking and reseting 
> +            //of a stream.    
> +            BufferedInputStream bs = new BufferedInputStream(input);
>  
>              /* NANO */
>              final XMLElement xml = new XMLElement();
>              final PipedInputStream pin = new PipedInputStream();
> -            final PipedOutputStream pout = new PipedOutputStream(pin);
> -            final InputStreamReader isr = new InputStreamReader(input);    
> +            final PipedOutputStream pout = new PipedOutputStream(pin);   
> +            final InputStreamReader isr = new InputStreamReader(bs, getEncoding(bs));    
>              // Clean the jnlp xml file of all comments before passing
>              // it to the parser.
>              new Thread(
> @@ -1196,7 +1200,69 @@
>              throw new ParseException(R("PBadXML"), ex);
>          }
>      }
> +    
> +    /**
> +     * Returns the name of the encoding used in this InputStream.
> +     *
> +     * @param input the InputStream
> +     * @return a String representation of encoding
> +     */
> +    private static String getEncoding(InputStream input) throws IOException{
> +        //Fixme: This only recognizes UTF-8, UTF-16, and 
> +        //UTF-32, which is enough to parse the prolog portion of xml to
> +        //find out the exact encoding (if it exists). The reason being
> +        //there could be other encodings, such as ISO 8859 which is 8-bits
> +        //but it supports latin characters.  
> +        //So what needs to be done is to parse the prolog and retrieve
> +        //the exact encoding from it.
>  
> +        int[] s = new int[4];
> +        String encoding = "UTF-8";
> +
> +        //Determine what the first four bytes are and store 
> +        //them into an int array.
> +        input.mark(4);
> +        for (int i = 0; i < 4; i++) {
> +            s[i] = input.read(); 
> +        }
> +        input.reset();
> +
> +        //Set the encoding base on what the first four bytes of the
> +        //inputstream turn out to be (following the information from
> +        //www.w3.org/TR/REC-xml/#sec-guessing).
> +        if (s[0] == 255) {
> +            if (s[1] == 254) {
> +                if (s[2] != 0 || s[3] != 0) {
> +                    encoding = "UnicodeLittle";
> +                } else {
> +                    encoding = "X-UTF-32LE-BOM";
> +                }
> +            }
> +        } else if (s[0] == 254 && s[1] == 255 && (s[2] != 0 || 
> +          s[3] != 0)) {
> +            encoding = "UTF-16";
> +
> +        } else if (s[0] == 0 && s[1] == 0 && s[2] == 254 && 
> +          s[3] == 255) {
> +            encoding = "X-UTF-32BE-BOM";
> +
> +        } else if (s[0] == 0 && s[1] == 0 && s[2] == 0 && 
> +          s[3] == 60) {
> +            encoding = "UTF-32BE";
> + 
> +        } else if (s[0] == 60 && s[1] == 0 && s[2] == 0 && 
> +          s[3] == 0) {
> +            encoding = "UTF-32LE";
> +
> +        } else if (s[0] == 0 && s[1] == 60 && s[2] == 0 && 
> +          s[3] == 63) { 
> +            encoding = "UTF-16BE"; 
> +        } else if (s[0] == 60 && s[1] == 0 && s[2] == 63 &&
> +          s[3] == 0) { 
> +            encoding = "UTF-16LE";
> +        }
> +
> +        return encoding;
> +    }
>  }
>  
> -