Fixed failure when instrumenting classes with an annotation containing an Enum-type value

[katherine-hough]

Failure Description

Phosphor instrumentation throws an IllegalArgumentException when processing a class containing an annotation with a value of an Enum type.

Stack Trace

java.lang.IllegalArgumentException: value edu.columbia.cs.psl.phosphor.struct.TaggedReferenceArray@770d3326
        at java.base/edu.columbia.cs.psl.phosphor.org.objectweb.asm.SymbolTable.addConstant(SymbolTable.java:525)
        at java.base/edu.columbia.cs.psl.phosphor.org.objectweb.asm.AnnotationWriter.visit(AnnotationWriter.java:259)
        at java.base/edu.columbia.cs.psl.phosphor.org.objectweb.asm.tree.AnnotationNode.accept(AnnotationNode.java:226)
        at java.base/edu.columbia.cs.psl.phosphor.org.objectweb.asm.tree.AnnotationNode.accept(AnnotationNode.java:193)
        at java.base/edu.columbia.cs.psl.phosphor.org.objectweb.asm.tree.MethodNode.accept(MethodNode.java:674)
        at java.base/edu.columbia.cs.psl.phosphor.instrumenter.TaintLoadCoercer$UninstTaintLoadCoercerMN.visitEnd(TaintLoadCoercer.java:235)

Cause

ASM's AnnotationNode class is not instrumented by Phosphor. AnnotationNode uses an instance of the Java Class Library class java.util.ArrayList to store name-value pairs for an annotation. java.util.ArrayList is instrumented by Phosphor. Enum values are stored by AnnotationNode as String arrays. ArrayList will wrap these String arrays into TaggedReferenceArray instances and before storing them. When the AnnotationNode goes to process the Enum value, it receives a TaggedReferenceArray from the ArrayList instead of a String array.

Changes

• Added previously failing test case demonstrating instrumentation failure when processing annotations containing Enum values.
• Fixed instrumentation failure when processing annotations containing Enum values by adding a class visitor to PhosphorPatcher to unwrap TaggedReferenceArray instances returned by certain JCL methods in ASM classes.