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From "Andrew Cornwall (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5654) [classlib][pack200] Init methods cannot be synchronized
Date Wed, 26 Mar 2008 22:33:25 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5654?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12582458#action_12582458
] 

Andrew Cornwall commented on HARMONY-5654:
------------------------------------------

This does look like an encoding issue to me. Using the attached pack200.pack.gz and unpacking,
I find that parseFlags("method_flags"...) is returning 131104 (0x20020) for methodFlags[19][2],
which corresponds to NewAttributeBands$LayoutElement.<init>(NewAttributeBands, NewAttributeBands$LayoutElement).
In the original JAR (which I exported from my pack200 project in Eclipse), this method has
an access_flags of 0x0.

Some useful code snippets for debugging:

>From ClassBands.parseMethodAttrBands:
    private void parseMethodAttrBands(InputStream in) throws IOException, Pack200Exception
{
        methodFlags = parseFlags("method_flags", in, classMethodCount,
                Codec.UNSIGNED5, options.hasMethodFlagsHi());
        try {
            if(((methodFlags[19][2]) & 0x20) == 0x20) {
                System.out.println("Halt here: methodFlags[19][2] is "+ methodFlags[19][2]);
            }
        } catch (ArrayIndexOutOfBoundsException ex) {
            // do nothing
        }
...


>From Segment.buildClassFile:
		// add methods
		ClassFileEntry cfMethods[] = new ClassFileEntry[classBands.getClassMethodCount()[classNum]];
		// fieldDescr and fieldFlags used to create this
		for (i = 0; i < cfMethods.length; i++) {
            String descriptorStr = classBands.getMethodDescr()[classNum][i];
            int colon = descriptorStr.indexOf(':');
            CPUTF8 name = cpBands.cpUTF8Value(descriptorStr.substring(0,colon), ClassConstantPool.DOMAIN_NORMALASCIIZ);
            CPUTF8 descriptor = cpBands.cpUTF8Value(descriptorStr.substring(colon+1), ClassConstantPool.DOMAIN_SIGNATUREASCIIZ);
            if((classNum == 19) && (i==2)) {
                System.out.println("self halt");
            }
			cfMethods[i] = cp.add(new CPMethod(name, descriptor, classBands
                    .getMethodFlags()[classNum][i], classBands
                    .getMethodAttributes()[classNum][i]));
		}

(Also incidentally, shouldn't the comment be:
 		// methodDescr and methodFlags used to create this
instead of fieldFlags? Looks like a cut & paste error from the code above.)

> [classlib][pack200] Init methods cannot be synchronized
> -------------------------------------------------------
>
>                 Key: HARMONY-5654
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5654
>             Project: Harmony
>          Issue Type: Bug
>          Components: Classlib
>         Environment: All pack200
>            Reporter: Andrew Cornwall
>         Attachments: pack200.pack.gz
>
>
> In the current code, it's possible for a CPMethod  <init> to be emitted as synchronized.
This will not pass Sun's verification. For instance, if you run pack200 on itself, NewAttributeBands$LayoutElement
in the following will be emitted with a synchronized <init>.
> I've temporarily hacked this with the following code in CPMethod:
> 	public CPMethod(CPUTF8 name, CPUTF8 descriptor, long flags, List attributes) {
> 		// TODO Check that we only pass these on, or remap
>         super(name, descriptor, 0x7FFF & flags, attributes);
> 	    if(name.underlyingString().equals("<init>")) {
> 	        // hack hack - init should never be synchronized
> 	        SegmentUtils.debug("Hacking off synchronized on an init method");
> 	        this.flags = (short)(this.flags & 0x7FDF);
> 	    }
> 	}
> but I really need to look into it more deeply and find out why the 0x20 flag is being
passed in. (This may end up being an encoding issue, but I need to look more first).

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