[OpenJDK 2D-Dev] What is the point of CloseTTFontFileFunc?

Andrew Dinn adinn at redhat.com
Fri Jan 16 09:19:33 UTC 2015

On 15/01/15 22:53, Phil Race wrote:
> I can only suppose the author thought he was going to pass the
> platName (which would be the font file path) to some code that would
> use it to somehow close an open descriptor on that file. But clearly
> it does nothing of the sort and an up-call to the java font object
> (like in the read function) would not need that information anyway.
> So it looks redundant. I don't see how it would relate to the crash.
> That *may* be caused by some simultaneous use and/or freeing in
> different threads of files created using Font.createFont(..) and are 
> now bing released. I've also seen crashes where admins clean out the
> /tmp folder whilst the JRE is running using font files there. But
> that would probably not involve the disposer code.

The crash has been pinned down to some faulty argument passing. However,
I am glad to hear that the code appears to be redundant. My concern was
that it might be worse than that since the native code calls
JNU_ReleaseStringPlatformChars which, potentially***, can release
memory. Since platName is created by Java code (Using a combination of
String literals and String+ operations) that would be a /very bad/
thing. So, I think this callback should probably be removed (as an a
fortiori argument I'll note that it is, at best, redundant).

***n.b. I say potentially because the implementation of
JNU_ReleaseStringPlatformChars is platform-specific and has many
different code paths depending upon the type of the text the String
holds. So, I am not sure the callback will ever free memory on any
platform (Windows looks to be the most likely candidate).


Andrew Dinn

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