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

Shafi Ahmad shafi.s.ahmad at oracle.com
Thu Feb 16 08:35:36 UTC 2017 

Hi Coleen,

I don't have test case. I tried to write one but couldn't able to.  

I have verified it with reproducer of old fixed bug https://bugs.openjdk.java.net/browse/JDK-8080842. 
I applied my changes on the revision just before the fix of  JDK-8080842. 

Without the fix:
java CreateBadClassFile 
.foreach() call: Exception in thread "main" java.lang.ClassFormatError: Duplicate field name&signature in class file WidgetCollection$1 
        at java.lang.ClassLoader.defineClass1(Native Method) 
        at java.lang.ClassLoader.defineClass(ClassLoader.java:759) 
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) 
        . . .

With the fix:
.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)
               . . .

Regards,
Shafi

> -----Original Message-----
> From: Coleen Phillimore
> Sent: Thursday, February 16, 2017 2:42 AM
> To: 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
> 
> 
> Yes this looks very good.  Do you have a test for it?  Or is it in the jck tests and
> verified manually for each case?
> 
> Thanks,
> Coleen
> 
> On 2/15/17 1:29 AM, Shafi Ahmad wrote:
> > Thank you David for reviewing it.
> >
> > All,
> >
> > May I get second reviewer for this trivial change.
> >
> > Regards,
> > Shafi
> >
> >
> >
> >> -----Original Message-----
> >> From: David Holmes
> >> Sent: Wednesday, February 15, 2017 11:54 AM
> >> 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
> >>
> >> Looks good to me! Nice and neat.
> >>
> >> Thanks,
> >> David
> >>
> >> On 15/02/2017 4:02 PM, Shafi Ahmad wrote:
> >>> Hi David,
> >>>
> >>> Please find updated webrev at
> >>> http://cr.openjdk.java.net/~shshahma/8171194/webrev.01/
> >>> Added overloaded method classfile_parse_error.
> >>>
> >>> Regards,
> >>> Shafi
> >>>
> >>>> -----Original Message-----
> >>>> From: David Holmes
> >>>> Sent: Wednesday, February 15, 2017 3:55 AM
> >>>> 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,
> >>>>
> >>>> 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:
> >>>>>> 14
> >>>>>> 2)
>

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