<AWT Dev> JAWT Breakage in OpenJDK 7/8

[Artem Ananiev]

Hi, Omair,

I don't remember the exact reason for LD_LIBRARY_PATH changes, but it's 
very unlikely they can be reverted. Your proposed patch will probably 
solve the problem (I haven't checked, though), but it has major 
side-effect: increased startup time.

That's why I vote for just updating JAWT documentation to include 
System.loadLibrary() call in the application code.

Thanks,

Artem

On 7/24/2012 8:44 PM, Omair Majid wrote:
> Hi,
>
> I recently discovered that a number of applications making use of JAWT
> [1] are broken on OpenJDK 7 and 8, while they were working with OpenJDK6.
>
> The docs for JAWT state [1]:
> """
> The final step ­ the most interesting one ­ is to write the native
> rendering method, with an interface that conforms to the header file
> that javah generated, and build it as a standard shared library (called
> myRenderingLib in the above example) by linking it, for the Solaris
> operating environment, against the jre/lib/sparc/libjawt.so library.
> """
>
> In other words, JAWT expects third-party native libraries to be linked
> against libjawt.so. However, nowhere on that page does it say that
> something like System.loadLibrary("jawt") is needed. In practice, this
> means that most existing applications rely on libjawt.so being magically
> found and loaded by the JVM. In OpenJDK6, LD_LIBRARY_PATH was set to a
> value such that the linker could resolve libjawt.so when a library
> depending on it was loaded. LD_LIBRARY_PATH was removed for OpenJDK7
> [2]. So a number of existing applications fail to work with OpenJDK7
> because they can not load libjawt.so. Some applications have been
> patched to load libjawt.so manually [3], but others haven't (or cant be).
>
> The most backwards-compatible fix is to undo the effects of the
> LD_LIBRARY_PATH change - by setting RUNPATH of the launcher, for
> example. The build-dev folks suggested that I only do that as a last
> resort [4].
>
> An alternate fix seems to be to always load libjawt when awt starts up.
> There might be a small window of time where a third-party library fails
> to link against libjawt.so but this can happen only if awt has not
> started up. I would think such a case would not work with OpenJDK6 too
> since libjawt.so will not be able to resolve the dependency on
> libxawt.so. libxawt.so is only loaded after awt is started up, and can
> not be resolved through LD_LIBRARY_PATH.
>
> The attached patches for OpenJDK8 and OpenJDK7 attempt this approach.
> Does anyone have any thoughts or comments?
>
> I suspect something like this might be needed for Windows too, but I
> don't have access to a windows box to verify it.
>
> As an aside, should the docs for JAWT [1] be updated?
>
> Thanks,
> Omair
>
> [1]
> http://download.java.net/jdk8/docs/technotes/guides/awt/AWT_Native_Interface.html
> [2] https://blogs.oracle.com/darcy/entry/purging_ld_library_path
> [3]
> http://java-game-lib.svn.sourceforge.net/viewvc/java-game-lib/trunk/LWJGL/src/java/org/lwjgl/LinuxSysImplementation.java?r1=3418&r2=3604
> [4] http://mail.openjdk.java.net/pipermail/build-dev/2012-July/006492.html