#237 Nullpointer exception while converting dex to jar

[jjongpark]

• What seems to be the problem?

NullPointerException occurs when converting a simple dex into a jar. The issue is 100% reproducible.

Steps to reproduce.

1. Prepare a simple java source file. I have attached one: Test.java
2. javac Test.java
3. dx --dex --output=classes.dex Test.class

4. d2j-dex2jar.sh classes.dex

5. What is the exact smali/baksmali command that you ran?

Custom built. I downloaded the source code from the 2.x branch today (2015-04-13) and compiled it. The build was successful and all the tests were passed.

For your reference:
version: reader-2.1-SNAPSHOT, translator-2.1-SNAPSHOT, ir-2.1-SNAPSHOT

For the Java compiler, I am using OpenJDK 7.
$ javac -version
javac 1.7.0_65
$ java -version
java version "1.7.0_65"
OpenJDK Runtime Environment (IcedTea 2.5.3) (7u71-2.5.3-0ubuntu0.12.04.1)
OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode)

• Please provide any additional information below: error messages, symptoms,
  etc.

error log:
LTest;.compare(LTest;LTest;)I
java.lang.RuntimeException: fail exe return a4
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.exec(BaseAnalyze.java:93)
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.exec(BaseAnalyze.java:1)
at com.googlecode.dex2jar.ir.ts.Cfg.dfs(Cfg.java:255)
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.analyze0(BaseAnalyze.java:75)
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.analyze(BaseAnalyze.java:69)
at com.googlecode.dex2jar.ir.ts.UnSSATransformer.transform(UnSSATransformer.java:274)
at com.googlecode.d2j.dex.Dex2jar$2.optimize(Dex2jar.java:161)
at com.googlecode.d2j.dex.Dex2Asm.convertCode(Dex2Asm.java:433)
at com.googlecode.d2j.dex.ExDex2Asm.convertCode(ExDex2Asm.java:42)
at com.googlecode.d2j.dex.Dex2jar$2.convertCode(Dex2jar.java:128)
at com.googlecode.d2j.dex.Dex2Asm.convertMethod(Dex2Asm.java:528)
at com.googlecode.d2j.dex.Dex2Asm.convertClass(Dex2Asm.java:425)
at com.googlecode.d2j.dex.Dex2Asm.convertDex(Dex2Asm.java:441)
at com.googlecode.d2j.dex.Dex2jar.doTranslate(Dex2jar.java:170)
at com.googlecode.d2j.dex.Dex2jar.to(Dex2jar.java:270)
at com.googlecode.dex2jar.tools.Dex2jarCmd.doCommandLine(Dex2jarCmd.java:108)
at com.googlecode.dex2jar.tools.BaseCmd.doMain(BaseCmd.java:290)
at com.googlecode.dex2jar.tools.Dex2jarCmd.main(Dex2jarCmd.java:32)
Caused by: java.lang.NullPointerException
at com.googlecode.dex2jar.ir.ts.UnSSATransformer$LiveA.onUseLocal(UnSSATransformer.java:552)
at com.googlecode.dex2jar.ir.ts.UnSSATransformer$LiveA.onUseLocal(UnSSATransformer.java:1)
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.onUse(BaseAnalyze.java:173)
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.onUse(BaseAnalyze.java:1)
at com.googlecode.dex2jar.ir.ts.Cfg.travel(Cfg.java:331)
at com.googlecode.dex2jar.ir.ts.Cfg.travel(Cfg.java:382)
at com.googlecode.dex2jar.ir.ts.an.BaseAnalyze.exec(BaseAnalyze.java:90)
... 17 more

.method public compare(LTest;LTest;)I
.registers 7
const/4 v1, 1
const/4 v0, -1
iget v2, p1, LTest;->x:I
iget v3, p2, LTest;->x:I
if-ge v2, v3, :L1
:L0
return v0
:L1
iget v2, p1, LTest;->x:I
iget v3, p2, LTest;->y:I
if-le v2, v3, :L2
move v0, v1
goto :L0
:L2
iget v2, p1, LTest;->y:I
iget v3, p2, LTest;->y:I
if-lt v2, v3, :L0
iget v0, p1, LTest;->y:I
iget v2, p2, LTest;->y:I
if-le v0, v2, :L3
move v0, v1
goto :L0
:L3
const/4 v0, 0
goto :L0
.end method

[Bob Pan]

This issue is fixed by rev 6fec94.
Please pull the last source and test again.
sorry for the inconvenient.

[jjongpark]

Thank you for the info. When I reset to the rev 6fec94, the problem does not occur.
However, 6fec94 is NOT the latest version. Three more commits were uploaded after 6fec94:

[90d851] (2.x, tip) by Bob Pan Bob Pan

extra indent for smali opcode
2015-04-13 13:48:37 Tree
[936811] by Bob Pan Bob Pan

implement dex weaver
2015-04-13 12:39:05 Tree
[74c27a] by Bob Pan Bob Pan

support 'invoke-x/range {}, ...'
2015-04-13 12:25:58 Tree

When I download the three more commits, the problem occurs again.

Furthermore, when I use the 6fec94 revision for converting dex file for the Android framework, following error occurred. I am attaching m-0.txt file.

[Bob Pan]

When I download the three more commits, the problem occurs again.
It is strange，I can not reproduce the problem. Please cleanup before actual build.

# for gradle
gradle clean distZip
# and for maven
mvn clean package

for the attachemnt m-0.txt,

    invoke-interface { v1, v2 }, Ljava/util/Set;->add(Ljava/lang/Object;)Z
    move-result v1 // type for v1 is boolean, aka Z
    invoke-static { v0, v1 }, // but v1 used as int, aka I
        Landroid/preference/MultiSelectListPreference;->access$076(Landroid/preference/MultiSelectListPreference;I)Z 

the problem is caused by strict type calculation, because in java syntaxt, a boolean can not assign to an inteager. so dex2jar forbid merge type Z and I. It is simple to fix
A. modify the dex by hand and add the following code

    if-eqz v1, :LZERO
    const v1, 1
    goto :Lend
:LZERO
    const v1, 0
:Lend

B. modify the dex2jar code. return TypeClass.INT when merge int and boolean at com.googlecode.dex2jar.ir.TypeClass.merge(TypeClass.java:100)

[jjongpark]

Ah, that was my mistake. As you suggested, building after cleaning up magically solved the problem. Thanks!

For the int/boolean merge issue, I do understand dex2jar forbids it, but don't understand why java compiler and dex converter allows it. Using dexdump, I analyzed classes.dex and found that it is giving boolean result to integer argument. Do you think this is a bug in javac or dx tool?

Anyway, I modified TypeClass.java as you suggested and it works. Thank you.