[JEXL-217] Interpreter.getAttribute() raises exception in non-strict mode when cached property resolver is used

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.0
• Fix Version/s: 3.1
• Assignee: Henri Biestro
• Reporter: Dmitri Blinov
• Created: 27/Aug/16 14:24
• Updated: 29/Jun/21 06:59
• Resolved: 31/Aug/16 10:25

Description

I'm chasing strange bug where regardless of the JexlContext operating in non-strict mode the ArrayIndexOutOfBoundsException is thrown in the script like this

entity = args[0]; @lenient {copy = args[1]; xwsp = args[2]}

here is the stack trace

Caused by: java.lang.ArrayIndexOutOfBoundsException
at java.lang.reflect.Array.get(Native Method)
at org.apache.commons.jexl3.internal.introspection.ListGetExecutor.tryInvoke(ListGetExecutor.java:88)
at org.apache.commons.jexl3.internal.Interpreter.getAttribute(Interpreter.java:1700)
at org.apache.commons.jexl3.internal.Interpreter.visit(Interpreter.java:945)
at org.apache.commons.jexl3.parser.ASTArrayAccess.jjtAccept(ASTArrayAccess.java:18)
at org.apache.commons.jexl3.internal.Interpreter.visit(Interpreter.java:1013)
at org.apache.commons.jexl3.parser.ASTReference.jjtAccept(ASTReference.java:18)
at org.apache.commons.jexl3.internal.Interpreter.executeAssign(Interpreter.java:1119)
at org.apache.commons.jexl3.internal.Interpreter.visit(Interpreter.java:1062)
at org.apache.commons.jexl3.parser.ASTAssignment.jjtAccept(ASTAssignment.java:18)
at org.apache.commons.jexl3.internal.Interpreter.visit(Interpreter.java:578)
at org.apache.commons.jexl3.parser.ASTBlock.jjtAccept(ASTBlock.java:18)
at org.apache.commons.jexl3.internal.Interpreter.processAnnotation(Interpreter.java:1848)
at org.apache.commons.jexl3.internal.Interpreter$1.call(Interpreter.java:1856)

Unfortunately I haven't managed to create and provide reproducible test case, but from looking into the code I think the problem fires when the Interpreter tries to call cached method ListGetExecutor.tryInvoke() but does not catch subsequent exception.

I rewrote the code as follows and the problem seemed to go away

Interpreter.java

        ...
        Exception xcause = null;

        // attempt to reuse last executor cached in volatile JexlNode.value
        if (node != null && cache) {
            Object cached = node.jjtGetValue();
            if (cached instanceof JexlPropertyGet) {
                JexlPropertyGet vg = (JexlPropertyGet) cached;

                try {

                   Object value = vg.tryInvoke(object, attribute);
                   if (!vg.tryFailed(value)) {
                       return value;
                   }

                } catch (Exception xany) {
                    xcause = xany;
                }

            }
        }

        if (xcause == null) {

           // resolve that property

           List<PropertyResolver> resolvers = uberspect.getResolvers(operator, object);
           JexlPropertyGet vg = uberspect.getPropertyGet(resolvers, object, attribute);
           if (vg != null) {
               try {
                   Object value = vg.invoke(object);
                   // cache executor in volatile JexlNode.value
                   if (node != null && cache && vg.isCacheable()) {
                       node.jjtSetValue(vg);
                   }
                   return value;
               } catch (Exception xany) {
                   xcause = xany;
               }
           }
        }
        ...