JDK 10 RFR JDK-8171194: Exception "Duplicate field name&signature in class file" should report the name and signature of the field

[David Holmes]

Hi Shafi,

On 14/02/2017 11:20 PM, Shafi Ahmad wrote:
> Hi David,
>
> Thanks for reviewing it.
>
> Initially I started with fixed size of local char array but later I changed my mind and make it dynamic.
> Let me know if I have to make it local char array like.
>
> +         unsigned int siglength = sig->utf8_length();
> +         unsigned int namelength = name->utf8_length();
> +         unsigned int length = siglength + namelength + 64;
> +         char *buff = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, length);
> +         jio_snprintf(buff, length,
> +                     "Duplicate method name \"%s\" with signature \"%s\" in class file",
> +                     name->as_C_string(), sig->as_klass_external_name());
> +         classfile_parse_error("%s %s", buff, CHECK);
>        }
>
> to
>
> +         char buff[fixedsize];  // say fixedsize is 512
> +         jio_snprintf(buff, 512,
> +                     "Duplicate method name \"%s\" with signature \"%s\" in class file",
> +                     name->as_C_string(), sig->as_klass_external_name());
> +         classfile_parse_error("%s %s", buff, CHECK);
>        }

It could still be dynamic, you just need to use 
NEW_RESOURCE_ARRAY_IN_THREAD_RETURN_NULL and check for a NULL return, 
and fallback to not including the additional info. But the underlying 
Exceptions::fthrow uses a local buffer itself (1024 max), so you could 
just do the same as you propose above.

Though it is very annoying to have to allocate a buffer just to pass it 
through to classfile_parse_error which passes it through to 
Exceptions::fthrow which is a varargs method. So another possibility is 
to just add another overload of classfile_parse_error that takes in the 
two additional strings you want to print.

Thanks,
David

> Regards,
> Shafi
>
>> -----Original Message-----
>> From: David Holmes
>> Sent: Tuesday, February 14, 2017 6:34 PM
>> To: Shafi Ahmad <shafi.s.ahmad at oracle.com>; hotspot-
>> dev at openjdk.java.net
>> Subject: Re: JDK 10 RFR JDK-8171194: Exception "Duplicate field
>> name&signature in class file" should report the name and signature of the
>> field
>>
>> Hi Shafi,
>>
>> I'm concerned about the use of NEW_RESOURCE_ARRAY_IN_THREAD. If it
>> can't allocate it will abort the VM. That seems like a bad thing to happen.
>>
>> Thanks,
>> David
>>
>> On 14/02/2017 7:19 PM, Shafi Ahmad wrote:
>>> Summary: java.lang.ClassFormatError: Exception "Duplicate field
>> name&signature in class file" should report the name and signature of the
>> field.
>>>
>>> It's a very small change to single file.
>>> In the current implementation name and signature of duplicate field is
>> missing in java.lang.ClassFormatError exception message.
>>> Without a field name + signature it is hard to triggering the problem.
>>>
>>> Webrev link: http://cr.openjdk.java.net/~shshahma/8171194/webrev.00/
>>> bug link: https://bugs.openjdk.java.net/browse/JDK-8171194
>>>
>>> Testing: jprt and jtreg test.
>>>
>>> I have verified my changes with the reproduces of
>> https://bugs.openjdk.java.net/browse/JDK-8080842 on jdk8u60-b01 code
>> base as I was not able to write reproducer of current issue.
>>> With the fix I am getting below exception message.
>>>
>>> $ java CreateBadClassFile
>>> .foreach() call: Exception in thread "main" java.lang.ClassFormatError:
>> Duplicate field name "hasNext" with signature "Ljava.lang.Object;" in class
>> file WidgetCollection$1
>>> 	at java.lang.ClassLoader.defineClass1(Native Method)
>>> 	at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
>>> 	at
>> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
>>>                . . .
>>>
>>> Thanks,
>>> Coleen
>>>