ChunkedStream returns null on EOF causing ChunkedWriteHandler to fail, 4.0.2.Final

[tantaman]

Using ChunkedStream to read an empty file and ChunkedWriteHandler to write it to a channel results in a null pointer exception.

It appears that the problem is that ChunkedStream returns null once it reaches the end of the stream: https://github.com/netty/netty/blob/netty-4.0.2.Final/handler/src/main/java/io/netty/handler/stream/ChunkedStream.java#L99

and ChunkedWriteHandler then attempts to write the null message to the channel: https://github.com/netty/netty/blob/netty-4.0.2.Final/handler/src/main/java/io/netty/handler/stream/ChunkedWriteHandler.java#L260

Of course this is only a problem for empty files otherwise a non-null chunk is returned and subsequent reads in the ChunkedWriteHandler are correctly guarded by the isEndOfInput check.

This problem also occurs with ChunkedNioStream.

java.lang.NullPointerException: msg
    at io.netty.channel.DefaultChannelHandlerContext.write(DefaultChannelHandlerContext.java:674)
    at io.netty.channel.DefaultChannelHandlerContext.write(DefaultChannelHandlerContext.java:668)
    at io.netty.handler.stream.ChunkedWriteHandler.doFlush(ChunkedWriteHandler.java:260)
    at io.netty.handler.stream.ChunkedWriteHandler.flush(ChunkedWriteHandler.java:145)
    at io.netty.channel.DefaultChannelHandlerContext.invokeFlush0(DefaultChannelHandlerContext.java:730)
    at io.netty.channel.DefaultChannelHandlerContext.invokeFlush(DefaultChannelHandlerContext.java:713)
    at io.netty.channel.DefaultChannelHandlerContext.flush(DefaultChannelHandlerContext.java:706)
    at com.tantaman.ferox.priv.Response$FineGrainedControl.write(Response.java:253)
    at com.tantaman.ferox.remotestorage.route_handlers.ReadRouteHandler.returnDocument(ReadRouteHandler.java:133)
    at com.tantaman.ferox.remotestorage.route_handlers.ReadRouteHandler.respondWithResource(ReadRouteHandler.java:89)
    at com.tantaman.ferox.remotestorage.route_handlers.ReadRouteHandler.access$2(ReadRouteHandler.java:85)
    at com.tantaman.ferox.remotestorage.route_handlers.ReadRouteHandler$2.run(ReadRouteHandler.java:76)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:353)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:366)
    at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:101)
    at java.lang.Thread.run(Thread.java:722)

[normanmaurer]

@tantaman thanks for reporting. Could you please retest with 4.0.5.Final-SNAPSHOT ? I just fixed it here...