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      1 /*
      2  * [The "BSD licence"]
      3  * Copyright (c) 2011 Ben Gruver
      4  * All rights reserved.
      5  *
      6  * Redistribution and use in source and binary forms, with or without
      7  * modification, are permitted provided that the following conditions
      8  * are met:
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote products
     15  *    derived from this software without specific prior written permission.
     16  *
     17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     19  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     20  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     21  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     22  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     23  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     24  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     25  * INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     26  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     27  */
     28 
     29 package org.jf.dexlib.Code.Analysis;
     30 
     31 import org.jf.dexlib.*;
     32 import org.jf.dexlib.Code.Format.Instruction22c;
     33 import org.jf.dexlib.Code.Instruction;
     34 import org.jf.dexlib.Code.InstructionWithReference;
     35 import org.jf.dexlib.Util.AccessFlags;
     36 
     37 import java.util.HashMap;
     38 
     39 public class SyntheticAccessorResolver {
     40     public static final int METHOD = 0;
     41     public static final int GETTER = 1;
     42     public static final int SETTER = 2;
     43 
     44     private final DexFileClassMap classMap;
     45     private final HashMap<MethodIdItem, AccessedMember> resolvedAccessors = new HashMap<MethodIdItem, AccessedMember>();
     46 
     47     public SyntheticAccessorResolver(DexFile dexFile) {
     48         classMap = new DexFileClassMap(dexFile);
     49     }
     50 
     51     public static boolean looksLikeSyntheticAccessor(MethodIdItem methodIdItem) {
     52         return methodIdItem.getMethodName().getStringValue().startsWith("access$");
     53     }
     54 
     55     public AccessedMember getAccessedMember(MethodIdItem methodIdItem) {
     56         AccessedMember accessedMember = resolvedAccessors.get(methodIdItem);
     57         if (accessedMember != null) {
     58             return accessedMember;
     59         }
     60 
     61         ClassDefItem classDefItem = classMap.getClassDefByType(methodIdItem.getContainingClass());
     62         if (classDefItem == null) {
     63             return null;
     64         }
     65 
     66         ClassDataItem classDataItem = classDefItem.getClassData();
     67         if (classDataItem == null) {
     68             return null;
     69         }
     70 
     71         ClassDataItem.EncodedMethod encodedMethod = classDataItem.findDirectMethodByMethodId(methodIdItem);
     72         if (encodedMethod == null) {
     73             return null;
     74         }
     75 
     76         //A synthetic accessor will be marked synthetic
     77         if ((encodedMethod.accessFlags & AccessFlags.SYNTHETIC.getValue()) == 0) {
     78             return null;
     79         }
     80 
     81         Instruction[] instructions = encodedMethod.codeItem.getInstructions();
     82 
     83         //TODO: add support for odexed formats
     84         switch (instructions[0].opcode.format) {
     85             case Format35c:
     86             case Format3rc: {
     87                 //a synthetic method access should be either 2 or 3 instructions, depending on if the method returns
     88                 //anything or not
     89                 if (instructions.length < 2 || instructions.length > 3) {
     90                     return null;
     91                 }
     92                 InstructionWithReference instruction = (InstructionWithReference)instructions[0];
     93                 Item referencedItem = instruction.getReferencedItem();
     94                 if (!(referencedItem instanceof  MethodIdItem)) {
     95                     return null;
     96                 }
     97                 MethodIdItem referencedMethodIdItem = (MethodIdItem)referencedItem;
     98 
     99                 accessedMember = new AccessedMember(METHOD, referencedMethodIdItem);
    100                 resolvedAccessors.put(methodIdItem, accessedMember);
    101                 return accessedMember;
    102             }
    103             case Format22c: {
    104                 //a synthetic field access should be exactly 2 instructions. The set/put, and then the return
    105                 if (instructions.length != 2) {
    106                     return null;
    107                 }
    108                 Instruction22c instruction = (Instruction22c)instructions[0];
    109                 Item referencedItem = instruction.getReferencedItem();
    110                 if (!(referencedItem instanceof FieldIdItem)) {
    111                     return null;
    112                 }
    113                 FieldIdItem referencedFieldIdItem = (FieldIdItem)referencedItem;
    114 
    115                 if (instruction.opcode.setsRegister() || instruction.opcode.setsWideRegister()) {
    116                     //If the instruction sets a register, that means it is a getter - it gets the field value and
    117                     //stores it in the register
    118                     accessedMember = new AccessedMember(GETTER, referencedFieldIdItem);
    119                 } else {
    120                     accessedMember = new AccessedMember(SETTER, referencedFieldIdItem);
    121                 }
    122 
    123                 resolvedAccessors.put(methodIdItem, accessedMember);
    124                 return accessedMember;
    125             }
    126             default:
    127                 return null;
    128         }
    129     }
    130 
    131     public static class AccessedMember {
    132         public final int accessedMemberType;
    133         public final Item accessedMember;
    134 
    135         public AccessedMember(int accessedMemberType, Item accessedMember) {
    136             this.accessedMemberType = accessedMemberType;
    137             this.accessedMember = accessedMember;
    138         }
    139     }
    140 }
    141