Bug: SystemFlavorMap.addFlavorForUnencodedNative ineffective on MacOS

Eirik Bakke ebakke at mit.edu
Fri Sep 18 19:50:32 UTC 2015

I can see the bug now at http://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8136781 . Thanks again!

-- Eirik

On 9/18/15, 3:01 PM, "macosx-port-dev on behalf of Eirik Bakke" <macosx-port-dev-bounces at openjdk.java.net<mailto:macosx-port-dev-bounces at openjdk.java.net> on behalf of ebakke at mit.edu<mailto:ebakke at mit.edu>> wrote:

Hi, Sergey.

I've filed the bug and received review ID JI-9024567 for now. Thanks!

-- Eirik

On 9/18/15, 2:58 PM, "Bug-Report-Daemon_WW at ORACLE.COM<mailto:Bug-Report-Daemon_WW at ORACLE.COM>"
<Bug-Report-Daemon_WW at ORACLE.COM<mailto:Bug-Report-Daemon_WW at ORACLE.COM>> wrote:

Dear Java Developer,
Thank you for reporting this issue.

We are evaluating this report and have assigned it a Review ID:
JI-9024567. In the event this report is determined to be a defect or
enhancement request, it will be referenced with a new Bug ID and will be
listed on Bugs.java.com. For other related issues, please visit our Bug
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We try to process all newly posted bugs in a timely manner, but make no
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On 9/18/15, 2:35 PM, "Sergey Bylokhov" <Sergey.Bylokhov at oracle.com<mailto:Sergey.Bylokhov at oracle.com>> wrote:

Hi, Eirik.
Thanks for report! Please file a new bug at
http://bugreport.sun.com/bugreport , don't forget to add a steps to
reproduce, then send me a bugid.

On 18.09.15 21:18, Eirik Bakke wrote:
Hi, macosx-port-dev.

There seems to be a bug in the MacOS implementation underlying
SystemFlavorMap.addFlavorForUnencodedNative. Where would the best place
to report this be? Is this the relevant mailing list?

The bug report follows:

My Java application allows users to paste selections from Microsoft
Excel. The data is retrieved using Excel's binary BIFF8 format rather
than in plain text format in order to reliably detect date formatting,
preserve numerical precision, and such. On Windows, getting to the
relevant clipboard InputStream can be achieved by calling
SystemFlavorMap.addUnencodedNativeForFlavor to map a new DataFlavor to a
native data type identifier. On MacOS, however, there seems to be a bug
that renders SystemFlavorMap.addUnencodedNativeForFlavor ineffective.

Looking at the JDK source code, the bug seems to be that
sun.lwawt.macosx.CDataTransferer.registerFormatWithPasteboard is never
called when SystemFlavorMap.addUnencodedNativeForFlavor/
addFlavorForUnencodedNative is used to register a new native clipboard
data format. This leads
Java_sun_lwawt_macosx_CClipboard_getClipboardFormats in
macosx/native/sun/awt/CClipboard.m to never return formats of the new
type, because indexForFormat (in CDataTransferer.m) will always return

The observation above lead me to a workaround for the bug, which is to
ewFlavor, (SystemFlavorMap) SystemFlavorMap.getDefaultFlavorMap()) once
after first mapping the flavor using addUnencodedNativeForFlavor and
addFlavorForUnencodedNative. This works because the call to
getFormatsForFlavor forces DataTransferer.getFormatForNativeAsLong to be
called with the new native data type identifier, which in turn causes
registerFormatWithPasteboard to be called in CDataTransferer.m. I'm
worried that the workaround will cease to work in the future, however,
since it relies on an obscure side-effect of a method in a private API
from the sun.awt package.

I've assembled a minimal example here:

-- Eirik

Best regards, Sergey.

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