[rfc]Stream doesn't reset mark in finally

[Jiri Vanek]

Hello!

Looking to imageIO.java (if this is bad thread, please redirect me!) when 
reading images
http://hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/share/classes/javax/imageio/ImageIO.java#l543
and ending at:

                // Perform mark/reset as a defensive measure
                // even though plug-ins are supposed to take
                // care of it.
                boolean canDecode = false;
                if (stream != null) {
                    stream.mark();
                }
                canDecode = spi.canDecodeInput(input);
                if (stream != null) {
                    stream.reset();
                }
                return canDecode;

I'm wondering, why  stream.reset(); is not in finaly  block:

// Perform mark/reset as a defensive measure
// even though plug-ins are supposed to take
// care of it.
boolean canDecode = false;
if (stream != null) {
stream.mark();
}
try{
    canDecode = spi.canDecodeInput(input);
} finally {
    if (stream != null) {
        stream.reset();
    }
}
return canDecode;


Eg png and bmp decoders can are throwing IIOException when header is corrutped. 
That pretty definitely sure killer of  stream mark stacks.
You yourselves write  : //Perform mark/reset as a defensive measure even though 
plug-ins are supposed to take care of it.
So if densive, then try/finaly please.

I did not check if this changed in 9 but if not....Please. This is makig work 
on custom image plugins, for image formats which just wraps another bmp/png and 
are expecting corrupted headers preatty hards.


J.