[RFC]: backport to fix PR655

[Denis Lila]

Hi.

> I can reproduce this bug using the testcase at the end of:
> http://bugs.sun.com/view_bug.do?bug_id=6934977
> 
> But hmm.. the test still fail for me with this backport applied..
> although in a different way. Do this backport need something that can
> handle the thrown InternalError Exception to work?

Thanks for testing this.

The InternalError you're seeing is exactly what is supposed to happen.
If you run the jtreg tests included in the patch (Basic.java and
Truncate.java) you'll see that without the patch, Basic will fail
with an IOException, and Truncate will fail with a SIGBUS. With the
backport applied, neither of them will fail (because Truncate.java has
some logic to ignore the Error).

Regards,
Denis.

----- Original Message -----
> Hi!
> On 2011-03-01 00:07, Denis Lila wrote:
> > Hi.
> >
> > The attached patch would backport this changeset:
> > http://hg.openjdk.java.net/jdk7/jdk7/jdk/rev/24741c4bf300
> > which fixes S6934977. PR655 seems to be a duplicate of that
> > (but I don't have a reproducer for PR655 so I can't say for
> > certain; however, looking at the 2 bug descriptions, there
> > is little doubt).
> 

> 
> With backport applied:
> java TruncateTest
> Creating test file...done
> Creating mapped buffer from test file...done
> Attempting to truncate the file...done
> Attempting to load mapped buffer...
> Exception in thread "main" java.lang.InternalError: a fault occurred
> in
> a recent unsafe memory access operation in compiled Java code
> at sun.nio.cs.UTF_8$Encoder.encodeArrayLoop(UTF_8.java:360)
> at sun.nio.cs.UTF_8$Encoder.encodeLoop(UTF_8.java:466)
> at java.nio.charset.CharsetEncoder.encode(CharsetEncoder.java:561)
> at sun.nio.cs.StreamEncoder.implWrite(StreamEncoder.java:270)
> at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:124)
> at java.io.OutputStreamWriter.write(OutputStreamWriter.java:207)
> at java.io.BufferedWriter.flushBuffer(BufferedWriter.java:128)
> at java.io.PrintStream.write(PrintStream.java:493)
> at java.io.PrintStream.print(PrintStream.java:636)
> at java.io.PrintStream.println(PrintStream.java:773)
> at TruncateTest.main(TruncateTest.java:30)
> 
> 
> Unpatched without backport applied:
> java TruncateTest
> Creating test file...done
> Creating mapped buffer from test file...done
> Attempting to truncate the file...done
> Attempting to load mapped buffer...
> #
> # A fatal error has been detected by the Java Runtime Environment:
> #
> # SIGBUS (0x7) at pc=0x00007fccd4874f48, pid=17748,
> tid=140518804694800
> #
> # JRE version: 6.0_20-b20
> # Java VM: OpenJDK 64-Bit Server VM (19.0-b09 mixed mode linux-amd64 )
> # Derivative: IcedTea6 1.9.2
> # Distribution: Ubuntu 10.04.1 LTS, package
> 6b20-1.9.2-0ubuntu1~10.04.1
> # Problematic frame:
> # C [libnio.so+0x4f48] Java_java_nio_MappedByteBuffer_load0+0x48
> #
> # An error report file with more information is saved as:
> # /home/xranby/hs_err_pid17748.log
> #
> # If you would like to submit a bug report, please include
> # instructions how to reproduce the bug and visit:
> # https://bugs.launchpad.net/ubuntu/+source/openjdk-6/
> # The crash happened outside the Java Virtual Machine in native code.
> # See problematic frame for where to report the bug.
> #
> Avbruten (SIGABRT)
> 
> 
> 
> >
> > Ok to push?
> 
> Since this fix only alter the return type of private JNI methods makes
> me think this are a suitable back-port to IcedTea6.
> 
> Please verify that this fix passes the reproducer on your machine.
> 
> >
> > Thank you,
> > Denis.
> 
> Cheers, and have a great day!
> Xerxes