RFR (S) 8042660: vm/mlvm/anonloader/stress/byteMutation failed with: assert(index >=0 && index < _length) failed: symbol index overflow

[harold seigel]

Hi,

Please review this small change to fix bug 8042660 
<https://bugs.openjdk.java.net/browse/JDK-8042660>.

The code in ClassFileParser::parse_constant_pool() that handles 
CONSTANT_NameAndType and CONSTANT_*Ref assumes that the constant pool 
strings they reference are valid names and signatures because they are 
valid Utf8 strings.  But, "" is a valid Utf8 string but not a valid name 
or signature.  Assuming that the strings were of non-zero length caused 
crashes when test byteMutation specified zero length strings.  This fix 
adds checks for strings of zero length and throws ClassFormatError 
exceptions, preventing the JVM crashes.

Open webrev: http://cr.openjdk.java.net/~hseigel/bug_8042660/

JBS Bug: https://bugs.openjdk.java.net/browse/JDK-8042660

The fix was tested with JCK Lang, VM, and API java_lang tests, the UTE 
quick and split verifier tests, and the hotspot, JDK vm, java/io, 
java/lang, and java/util JTreg tests, and the tests included in this RFR.

Thanks, Harold