RFR (S): 8218939: vm/mlvm/anonloader/stress/byteMutation crashed on windows

[Igor Ignatyev]

I'm sorry I wasn't clear enough, I'm suggesting to harden runtime/classFileParserBug/TestBadClassName.java test, not vm/mlvm/anonloader/stress/byteMutation.
in TestBadClassName.java, we should always get CFE, so we can assert that it has the expected message.

-- Igor

> On Feb 14, 2019, at 4:36 PM, David Holmes <david.holmes at oracle.com> wrote:
> 
> Hi Igor,
> 
> Thanks for looking at this.
> 
> On 15/02/2019 10:20 am, Igor Ignatyev wrote:
>> Hi David,
>> the fix looks good to me. does it make sense to harden the test and assert the message?
> 
> In what way would you harden the test? It does random byte writes which could possibly still result in a legal classfile. You'd actually have to control the modifications to trigger specific errors that could be asserted. And I would expect such tests live somewhere in the JCK already.
> 
> Thanks,
> David
> -----
> 
>> -- Igor
>>> On Feb 14, 2019, at 2:58 PM, David Holmes <david.holmes at oracle.com> wrote:
>>> 
>>> webrev: http://cr.openjdk.java.net/~dholmes/8218939/webrev
>>> bug: https://bugs.openjdk.java.net/browse/JDK-8218939
>>> 
>>> The bytes() in a Symbol are UTF8 but do not form a NUL-terminated C-string. In a couple of places in the classfile parser we are treating it as NUL-terminated:
>>> 
>>> - in name validation we were calling strchr to find the semi-colon, but this could run off through memory if there was no semi-colon (as per the testcase). This is replaced with memchr which takes the expected length.
>>> 
>>> - in formatting the exception message we used %s but instead we need %.*s and pass the length
>>> 
>>> There's a minor change to a test to print the exception information as that exposes the fact we were doing things incorrectly e.g:
>>> 
>>> java.lang.ClassFormatError: Illegal class name "p1//BadInterface1\u00f1\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00ab\u00abU" in class file
>>> 
>>> versus (after bug fix)
>>> 
>>> java.lang.ClassFormatError: Illegal class name "p1//BadInterface1" in class file UseBadInterface1
>>> 
>>> Testing:
>>> - re-ran failing test on Windows with seeds known to have caused failures
>>> - ran ran failing test on Windows 150 times with random seeds
>>> - tiers 1-3
>>> 
>>> Thanks,
>>> David
>>> -----