cannot setExceptionBreakpoints about java-debug

[akaroml]

This is a bug we must fix in 0.1.0

[Eskibear]

I've found the root cause. It's a JDT bug.
When calling request.enable(), it constructs the command bytes, and sends to VM. The differences are as:

bytes(4100018xy)  <--- this causes error
bytes(410001800000000xy) <--- this is ok

'x' controls caught exceptions
'y' controls uncaught exceptions

In command bytes construction, look at
org.eclipse.jdi.internal.request.EventRequestImpl

@Override
public synchronized void enable() {
    ......
    writeModifiers(outData);   <--- here it construct command bytes. 
    JdwpReplyPacket replyPacket = requestVM(JdwpCommandPacket.ER_SET,
        outBytes);   <--- here it send the command.
    defaultReplyErrorHandler(replyPacket.errorCode());   <--- here it parses the error code.
    ......
}

In calling writeModifiers(outData), there a part writing JdwpID:

/**
* Writes ID.
*/
public void write(DataOutputStream outStream) throws IOException {
	int size = getSize();     <--- vm.fReferenceTypeIDSize, should be 8, but is 0.
	for (int i = size - 1; i >= 0; i--) {
		byte b = (byte) (fValue >>> 8 * i); 
		outStream.write(b);
	}
}

However, vm.fReferenceTypeIDSize is set to default value 0. vm.fGotIDSizes is false, meaning that vm.getIDSizes() has not been called yet.

[Eskibear]

there're many solutions, PR #25 works well, but not easy to understand. I'm looking for a more elegant one.

[Eskibear]

Since fReferenceTypeIDSize is only modified in getIDSizes(), as shown in the call hierarchy, we now can only fix it via sending another command calling requestVM.

[Eskibear]

fixed by call vm.version() after launching the vm.