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From "Johannes Scharf (JIRA)" <j...@apache.org>
Subject [jira] Created: (VFS-295) Unsafe comparison in getParent() of AbstractFileObject
Date Fri, 08 Jan 2010 14:00:58 GMT
Unsafe comparison in getParent() of AbstractFileObject
------------------------------------------------------

                 Key: VFS-295
                 URL: https://issues.apache.org/jira/browse/VFS-295
             Project: Commons VFS
          Issue Type: Bug
    Affects Versions: 1.0
            Reporter: Johannes Scharf


When a AbstractFileObject is decorated, eg when "ON_CALL" CacheStrategy is used, a NullPointerException
is thrown.
This happens due an unsafe comparison in getParent():
{code:java}
 public FileObject getParent() throws FileSystemException {
        if (this == fs.getRoot()) // Always false when this object is decorated
        {
            if (fs.getParentLayer() != null)
            {
                // Return the parent of the parent layer
                return fs.getParentLayer().getParent();
            }
            else
            {
                // Root file has no parent
                return null;
            }
        }
// Rest of method omitted
}
{code}

*fs.getRoot()* returns the decorating object *not* the decorated. *this* is the plain decorated
(wrapped) object . So the comparison is never true. This causes the wrong code to get executed
and finally the NullPointerException (see below).

Stacktrace:
{noformat}
 java.lang.NullPointerException
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:272)
	at org.apache.commons.vfs.provider.AbstractFileSystem.resolveFile(AbstractFileSystem.java:267)
	at org.apache.commons.vfs.provider.AbstractFileObject.getParent(AbstractFileObject.java:512)
	at at.js.jtransporter.support.vfs.FtpFileObject.getInfo(FtpFileObject.java:149)
	at at.js.jtransporter.support.vfs.FtpFileObject.refresh(FtpFileObject.java:176)
	at org.apache.commons.vfs.impl.DecoratedFileObject.refresh(DecoratedFileObject.java:170)
	at org.apache.commons.vfs.cache.OnCallRefreshFileObject.resolveFile(OnCallRefreshFileObject.java:152)
	at at.js.jtransporter.transporter.VFSTransporter.createFile(VFSTransporter.java:132)
	at at.js.jtransporter.worker.resource.ResourceWorker.createFile(ResourceWorker.java:81)
	at at.js.jtransporter.worker.resource.ResourceWorker.processJob(ResourceWorker.java:52)
	at at.js.jtransporter.worker.AbstractRunnableWorker.run(AbstractRunnableWorker.java:82)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:885)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
	at java.lang.Thread.run(Thread.java:619)
{noformat}

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