[PATCH][asmtools] Fix incorrect handling of some CPX2 constant pool entries by JDIS (original) (raw)

Maxim Degtyarev mdegtyarev at gmail.com
Mon Mar 12 23:52:50 UTC 2018

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The proposed patch (see attached file jdis-cpx2-bug.diff.txt) address incorrect handling of some constant pool entries represented with CPX2 class by ASMTOOLS JDIS.

JDIS incorrectly assume that field CPX2::value1 is always used to hold index of constant pool entry of type CONSTANT_CLASS. This assumption is valid only for entries of type CONSTANT_FIELD, CONSTANT_METHOD and CONSTANT_INTERFACEMETHOD. For CONSTANT_NAMEANDTYPE, CONSTANT_METHODHANDLE, CONSTANT_DYNAMIC and CONSTANT_INVOKEDYNAMIC this assumption is wrong. As a result asmtools jdis may produce malformed output for valid input.

Example:

public class Test {

// Force `class Test` entry appear in the constant pool before

InvokeDynamic entries. public Class<?> CLASS = Test.class;

private static Runnable[] workers = {
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test"),
    () -> System.out.println("Test")
};

public static void main(String... args) {

    for(Runnable worker : workers) {
        worker.run();
    }

}

}

One of invokedynamic instructions may be rendered by jdis as

    invokedynamic    InvokeDynamic run:"()Ljava/lang/Runnable;";

instead of

    invokedynamic    InvokeDynamic

REF_invokeStatic:java/lang/invoke/LambdaMetafactory.metafactory:"(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodType;Ljava/lang/invoke/MethodHandle;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;":run:"()Ljava/lang/Runnable;" MethodType "()V", MethodHandle REF_invokeStatic:Test.lambda$static$1:"()V", MethodType "()V"; -------------- next part --------------

HG changeset patch

User maccimo

Date 1520880268 -10800

Mon Mar 12 21:44:28 2018 +0300

Node ID f5e62b0fae745f3640455513a9824c1d3a59e1be

Parent 2904229ed97ec1d90a055ad86759f867cdc5296b

Fix incorrect handling of constant pool entries of type CONSTANT_NAMEANDTYPE, CONSTANT_METHODHANDLE, CONSTANT_DYNAMIC and CONSTANT_INVOKEDYNAMIC.

diff --git a/src/org/openjdk/asmtools/jdis/ConstantPool.java b/src/org/openjdk/asmtools/jdis/ConstantPool.java --- a/src/org/openjdk/asmtools/jdis/ConstantPool.java +++ b/src/org/openjdk/asmtools/jdis/ConstantPool.java @@ -500,8 +500,9 @@ * CPX2 * * Constant entries that contain two constant-pool indices. Usually, this includes:

• * CONSTANT_FIELD CONSTANT_METHOD CONSTANT_INTERFACEMETHOD CONSTANT_NAMEANDTYPE

• * CONSTANT_METHODHANDLE CONSTANT_DYNAMIC CONSTANT_INVOKEDYNAMIC

• * CONSTANT_NAMEANDTYPE CONSTANT_METHODHANDLE CONSTANT_DYNAMIC CONSTANT_INVOKEDYNAMIC

• *

• * For constant entries referencing class members use CPX2_ClassMember instead.
  *
  */

  class CPX2 extends Constant { @@ -600,6 +601,23 @@ } }

• /**

• * CPX2_ClassMember

• *

• * Specialized subclass of CPX2 class for constant entries that contain two constant-pool indices

• * with first index pointing to the constant pool entry of type CONSTANT_CLASS.

• *

• * Usually, this includes: CONSTANT_FIELD CONSTANT_METHOD CONSTANT_INTERFACEMETHOD

• *

• */

• class CPX2_ClassMember extends CPX2 {

•    CPX2_ClassMember(TAG tagval, int cpx1, int cpx2) {

•        super(tagval, cpx1, cpx2);

•    }

• }

• /* -------------------------------------------------------- */
  /* ConstantPool Fields */
  /**

@@ -674,6 +692,8 @@ case CONSTANT_FIELD: case CONSTANT_METHOD: case CONSTANT_INTERFACEMETHOD:

•                pool.add(i, new CPX2_ClassMember(tagobj, in.readUnsignedShort(), in.readUnsignedShort()));

•                break;
             case CONSTANT_NAMEANDTYPE:
             case CONSTANT_DYNAMIC:
             case CONSTANT_INVOKEDYNAMIC:

@@ -845,13 +865,13 @@ * * getClassName *

• * Safely gets a Java class name from a ConstantClass from a CPX2 constant pool

• * Safely gets a Java class name from a ConstantClass from a CPX2_ClassMember constant pool
  * object. (eg. Method/Field/Interface Ref)
  *
  * Returns either the Java class name, or a CP index reference string.
  *
  */

• public String getClassName(CPX2 classConst) {

• public String getClassName(CPX2_ClassMember classConst) { return _getClassName(classConst.value1); }

@@ -998,17 +1018,10 @@ if (cns == null) { return "#" + cpx; }

•    switch (cns.tag) {

•        case CONSTANT_METHODHANDLE:

•        case CONSTANT_DYNAMIC:

•        case CONSTANT_INVOKEDYNAMIC:

•        case CONSTANT_METHOD:

•        case CONSTANT_INTERFACEMETHOD:

•        case CONSTANT_FIELD: {

•            CPX2 cns2 = (CPX2) cns;

•            if (cns2.value1 == cd.this_cpx) {

•                cpx = cns2.value2;

•            }

•    if (cns instanceof CPX2_ClassMember) {

•        CPX2_ClassMember cns2 = (CPX2_ClassMember) cns;

•        if (cns2.value1 == cd.this_cpx) {

•            cpx = cns2.value2;
         }
     }
     return cns.tag.tagname + " " + StringValue(cpx);

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