DexFileFactory.writeDexFile produces invalid files about smali HOT 5 OPEN

Hi, could you share the changes on rewriting that happen between the first and second disassembly attempts? Preferably in a minimal code snippet to try to reproduce the error on our end.

from smali.

There are no changes between loading the file and rewriting it. Simply rewriting a file without changes using DexRewriter and then writing the rewritten file produces the broken dex. The code snippet that does it is listed as the first thing in the issue.

Here are all the files needed to reproduce it locally: smali_repro.zip.

Steps:

1. Download and extract smali_repro.zip

2. Compile repro program:
   javac -cp ".;lib\*" Main.java (Windows)
   javac -cp ".:lib/*" Main.java (Linux)

3. Run repro program (it reads classes_original.dex and writes broken classes_rewritten.dex)
   java -cp ".;lib\*" Main (Windows)
   java -cp ".:lib/*" Main (Linux)

4. Disassemble original file classes_original.dex (no error):
   java -cp ".;lib\*" com.android.tools.smali.baksmali.Main dis -o out_original classes_original.dex (Windows)
   java -cp ".:lib/*" com.android.tools.smali.baksmali.Main dis -o out_original classes_original.dex (Linux)

5. Disassemble broken file classes_rewritten.dex (error as the file is broken):
   java -cp ".;lib\*" com.android.tools.smali.baksmali.Main dis -o out_rewritten classes_rewritten.dex (Windows)
   java -cp ".:lib/*" com.android.tools.smali.baksmali.Main dis -o out_rewritten classes_rewritten.dex (Linux)

The classes_rewritten.dex file is generated by using DexRewriter and then writing the file with DexFileFactory.writeDexFile.

from smali.

Actually it looks like DexFileFactory.writeDexFile is broken.

Repro:

import com.android.tools.smali.dexlib2.DexFileFactory;
import com.android.tools.smali.dexlib2.dexbacked.DexBackedDexFile;

public class Main {
    public static void main(String[] args) throws Exception {
        DexBackedDexFile dexFile = DexFileFactory.loadDexFile("classes_original.dex", null);
        DexFileFactory.writeDexFile("classes_writedexfile.dex", dexFile);
    }
}

Compile and run:

$ javac -cp ".;lib\*" Main.java

$ java -cp ".;lib\*" Main

$ md5sum classes_original.dex
73d6b886ad21105a077ba4ff8dc70a83 *classes_original.dex

$ md5sum classes_writedexfile.dex
9b638d2cf2e768c87b44a4f7dd3f3e50 *classes_writedexfile.dex

$ stat -c "%s %n" -- *.dex
2938412 classes_original.dex
3172524 classes_writedexfile.dex

$ java -cp ".;lib\*" com.android.tools.smali.baksmali.Main dis -o out classes_writedexfile.dex
Error occurred while disassembling class LFC0; - skipping class
com.android.tools.smali.util.ExceptionWithContext: Invalid uleb128 integer encountered at offset 0x110642

from smali.

Could you test with the changes in the rewriter branch?
https://github.com/google/smali/tree/rewriter

from smali.

It does not compile from command line. I've used both gradlew assemble and gradlew smali:fatJar and both fail.
If you can build the jars like the ones I can download from maven then I'll be able to test it.

> Task :smali:generateGrammarSource FAILED
error(10):  internal error:  : java.lang.Error: Error parsing smaliTreeWalker.g: 'third_party' not expected 'grammar'
org.antlr.tool.GrammarSpelunker.match(GrammarSpelunker.java:70)
org.antlr.tool.GrammarSpelunker.grammarHeader(GrammarSpelunker.java:108)
org.antlr.tool.GrammarSpelunker.parse(GrammarSpelunker.java:80)
org.antlr.Tool.sortGrammarFiles(Tool.java:585)
org.antlr.Tool.process(Tool.java:439)
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
...
> Task :smali:generateGrammarSource FAILED

> Task :dexlib2:compileJava
Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':smali:generateGrammarSource'.
> There were 19 errors during grammar generation

from smali.