About lpdiff

lpdiff - a tool for creating LuckyPatcher patch lines from original and patched .smali files.

It is intended to automatize the creation of LuckyPatcher custom patch pattern lines which may survive small changes in app code.

Usage

Create files

1. Save original .smali as origin.smali
2. Patch .smali.
3. Save patched .smali as result.smali

File names may be arbitrary, but must have .smali at their ends

Start lpdiff

Change EDITOR variable in lpdiff.sh to your favorite editor and start the script:

./lpdiff.sh origin.smali result.smali

Edit dump files

lpdiff will open editor for origin_filtered.dump, result_filtered.dump and origin-result.diff files.

origin-result.diff is for reference only, look there to see changes.

Edit origin_filtered.dump and result_filtered.dump to keep only changes for single patch pattern:

1. Find line code_item: Lpatched/class;->patchedMethod()V
2. Find the instructions: line below it.
3. Remove all lines above this line (including the instructions: line).
4. This is the start of the method code.
5. Find the end of the method code (usually return, return-void or return-object) and remove all lines below.
6. Verify that all HEX instructions were properly filtered (operands that may change between app builds should be masked by ** symbols). Generally, the second byte of almost all opcodes should be masked
7. Save dump files and close the editor.
8. Press ENTER in lpdiff's terminal to continue.
9. lpdiff will open EDITOR with the resulting LuckyPatcher custom patch pattern

Adding opcode masking data

You should edit the write_sed_commands function in lpdiff.sh if you need to mask opcodes that are not yet added to lpdiff.

The opcodes masking list currently is not comprehensive and will be updated during lpdiff usage in real life - feel free to submit pull requests here.