BacktraceFieldTest.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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/**
 * @test
 * @bug 4446677
 * @bug 8158237
 * @summary debuggee used to crash when debugging under jbuilder
 * @author jjh
 *
 * @run build TestScaffold VMConnection TargetListener TargetAdapter
 * @run compile -g BacktraceFieldTest.java
 * @run driver BacktraceFieldTest
 */

/*
 * The fix for this bug filters out the backtrace field from the list
 * of fields for java.lang.Throwable.
 * This test verifies that this really happens, and also verifies that the fix
 * doesn't incorrectly discard other fields.
 */

import com.sun.jdi.*;
import com.sun.jdi.event.*;
import com.sun.jdi.request.*;

import java.util.*;

/********** target program **********/

class Testy {
    /*
     * This is used to verify that the fix doesn't filter out fields that it
     * shouldn't.  7 is an abitrary number, and this isn't a definitive
     * test; the fix could conceivably filter out the 89th field of a class
     * named Foo.
     * To verify that this part of this test works, first uncomment the field8
     * line and verify that the test fails, and then rename a field to xxx and
     * verify that the test fails.
     */
    int field1;
    int field2;
    int field3;
    int field4;
    int field5;
    int field6;
    final static int field7 = 7;  // Value is the number of fields.
    //int field8;

    Testy() {
    }
}


class BacktraceFieldTarg {
    public static void gus() {
    }

    public static void main(String[] args) {
        Testy myTesty = new Testy();
        try {
            throw new RuntimeException("jjException");
        } catch (Exception ee) {
            gus();
            System.out.println("debuggee: Exception: " + ee);
        }
    }
}

/********** test program **********/

public class BacktraceFieldTest extends TestScaffold {
    ThreadReference mainThread;

    BacktraceFieldTest (String args[]) {
        super(args);
    }

    public static void main(String[] args)      throws Exception {
        new BacktraceFieldTest(args).startTests();
    }

    private void printval(ArrayReference backTraceVal, int index) throws Exception {
        ArrayReference val = (ArrayReference)backTraceVal.getValue(index);
        println("BT: val at " + index + " = " + val);

        // The segv used to happen here for index = 0
        // Now all objects in the backtrace are objects.
        Object xVal = (Object)val.getValue(0);
        println("BT: xVal = " + xVal);
    }

    /********** test core **********/

    protected void runTests() throws Exception {
        /*
         * Get to the top of gus()
         * to determine mainThread
         */
        BreakpointEvent bpe = startTo("BacktraceFieldTarg", "gus", "()V");
        mainThread = bpe.thread();

        /*
         * We are now one frame below the exception frame that contains
         * our ee var.
         */
        StackFrame myFrame = mainThread.frame(1);

        LocalVariable lv = myFrame.visibleVariableByName("ee");
        println("BT: lv = " + lv);
        println("BT: lvType = " + lv.typeName());

        List allFields = ((ReferenceType)(lv.type())).allFields();
        println("BT: allFields = " + allFields);

        /*
         * Search through the fields of ee to verify that
         * java.lang.Throwable.backtrace isn't there.
         */
        boolean backtrace_found = false;
        Iterator iter = allFields.iterator();
        while(iter.hasNext()) {
            Field ff = (Field)iter.next();
            if (ff.toString().equals("java.lang.Throwable.backtrace")) {
                backtrace_found = true;
                println("java.lang.Throwable.backtrace field not filtered out.");

                /*
                 * If you want to experience the segv this bug causes, change
                 * this test to 1 == 1 and run it with jdk 1.4, build 74 or earlier
                 */
                if (1 == 1) {
                    // The following code will show the segv that this can cause.
                    ObjectReference myVal = (ObjectReference)myFrame.getValue(lv);
                    println("BT: myVal = " + myVal);

                    ArrayReference backTraceVal = (ArrayReference)myVal.getValue(ff);
                    println("BT: backTraceVal = " + backTraceVal);

                    printval(backTraceVal, 0);
                    printval(backTraceVal, 1);
                    printval(backTraceVal, 2);
                    printval(backTraceVal, 3);  // backtrace has 4 elements

                    try {
                        printval(backTraceVal, 4);
                    } catch (Exception e) {
                        println("Exception " + e);
                    }
                }
                break;
            }
        }

        if (!backtrace_found) {
            failure("ERROR: java.lang.Throwable.backtrace field filtered out.");
        }

        // Next, verify that we don't accidently discard a field that we shouldn't

        if (!testFailed) {
            lv = myFrame.visibleVariableByName("myTesty");

            allFields = ((ReferenceType)(lv.type())).allFields();
            println("BT: allFields = " + allFields);

            if (allFields.size() != Testy.field7) {
                failure("ERROR: wrong number of fields; expected " + Testy.field7 + ", Got " + allFields.size());
            } else {
                iter = allFields.iterator();
                while(iter.hasNext()) {
                    String fieldName = ((Field)iter.next()).toString();
                    if (!fieldName.startsWith("Testy.field", 0)) {
                        failure("ERROR: Found bogus field: " + fieldName.toString());
                    }
                }
            }
        }

        listenUntilVMDisconnect();

        /*
         * deal with results of test
         * if anything has called failure("foo") testFailed will be true
         */
        if (!testFailed) {
            println("BacktraceFieldTest: passed");
        } else {
            throw new Exception("BacktraceFieldTest: failed");
        }
    }
}