RFR: JDK-8245432: Lookup::defineHiddenClass should throw UnsupportedClassVersionError if the given bytes are of an unsupported major or minor version

[David Holmes]

Hi Mandy,

On 27/05/2020 7:46 am, Mandy Chung wrote:
> Lookup::defineHiddenClass currently throws IAE by ASM if the given bytes 
> are of unsupported class file version.  The implementation should catch 
> and throw UnsupportedClassVersionError instead.
> 
> webrev:
> http://cr.openjdk.java.net/~mchung/jdk15/webrevs/8245432/webrev.00/

What happened to the check:

if ((reader.getAccess() & Opcodes.ACC_MODULE) != 0) {

?

2036                 if (msg.startsWith("Unsupported class file major 
version")) {

Is that too strict - what if the issue is with the minor version? In 
general having to parse the ASM exception seems fragile.

This code:

if (msg.startsWith("Unsupported class file major version")) {
     UnsupportedClassVersionError ucve = new 
UnsupportedClassVersionError(msg);
     ucve.initCause(e);
     throw ucve;
} else {
     ClassFormatError cfe = new ClassFormatError();
     cfe.initCause(e);
     throw cfe;
}

could be simplified to:

ClassFormatError cfe;
if (msg.startsWith("Unsupported class file major version")) {
     cfe = new UnsupportedClassVersionError(msg);
} else {
     cfe = new ClassFormatError();
}
cfe.initCause(e);
throw cfe;

> This patch also includes a spec clarification of @throws IAE if the
> the bytes has ACC_MODULE flag set to fix JDK-8245596.

Until I saw what the code did the old versus new text did not seem like 
a clarification. Might I suggest augmenting rather than replacing the 
existing text:

@throws IllegalArgumentException if {@code bytes} is not a class or 
interface (the ACC_MODULE flag is set in the value of the {@code 
access_flags} item) or


Note:

1927          * in the value of the {@coode access_flags} item or

Typo: coode

Also should same change be made to defineHiddenClassWithClassData docs.

Thanks,
David
-----

> thanks
> Mandy