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

[Shafi Ahmad]

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);
       }

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
> >