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aapt2-build

Source of the bionic-static libaapt2.so binaries that ship inside the apktool-android AAR. Binaries are produced from a vendored copy of ReVanced/aapt2's CMake recipe, with iBotPeaches/Tumbleson PR #3130 layered on top so the result handles the modern <item type="layout" format="..."> resource patterns that ReVanced's v1.1.0 prebuilts reject.

Layout

aapt2-build/
├── README.md                — this file
├── SELF_BUILD_PLAN.md       — full execution plan + recipe gotchas
├── patches/                 — Apktool leniency patches (see patches/README.md)
│   ├── 0001-aapt2-port-changes-for-apktool.patch
│   └── 0002-aapt2-unrestrict-item-tag-value-format.patch
└── recipe/                  — vendored ReVanced/aapt2 build recipe
    ├── CMakeLists.txt
    ├── build.sh             — host-aware, lightly patched
    ├── patch.sh             — host-aware, switched to patch -p1
    ├── cmake/
    ├── misc/
    ├── patches/             — recipe-local patch set; sees both
    │   │                       ReVanced's patches AND our 0002
    │   ├── apktool_ibotpeaches.patch   — ReVanced (kept verbatim)
    │   ├── protobuf.patch              — ReVanced (build adaptation)
    │   ├── 32bsystem_on_armv8.patch    — ReVanced (armv7 BusError)
    │   └── 0002-aapt2-unrestrict-item-tag-value-format.patch
    └── README.md            — upstream ReVanced README + our delta

recipe/submodules/ (the AOSP source roots) is intentionally NOT checked in; developers symlink it from a scratch clone of ReVanced/aapt2. recipe/build/ and recipe/out/ are also gitignored.

Output contract

The end state is the three files Gradle picks up:

brut.apktool/apktool-android/src/main/jniLibs/arm64-v8a/libaapt2.so
brut.apktool/apktool-android/src/main/jniLibs/armeabi-v7a/libaapt2.so
brut.apktool/apktool-android/src/main/jniLibs/x86_64/libaapt2.so

Each .so MUST be statically linked (no DT_NEEDED entries). Verify with the NDK's llvm-readelf:

"$ANDROID_NDK/toolchains/llvm/prebuilt/$NDK_HOST/bin/llvm-readelf" \
    -d brut.apktool/apktool-android/src/main/jniLibs/arm64-v8a/libaapt2.so \
    | grep NEEDED
# (no output expected — fully static)

file brut.apktool/apktool-android/src/main/jniLibs/arm64-v8a/libaapt2.so
# ELF 64-bit LSB executable, ARM aarch64, ..., statically linked, stripped

If NEEDED entries do appear (e.g. libc++_shared.so, libprotobuf-lite.so, libpng16.so), the binary will fail to load from nativeLibraryDir on stock Android. The recipe's CMakeLists.txt sets CMAKE_EXE_LINKER_FLAGS "-static" and PNG_SHARED=OFF; if you end up with dynamic deps, that flag isn't reaching every dep.

How to (re)build

Five steps, ~5 minutes once the deps are installed.

1. One-time: clone ReVanced's recipe with submodules

The 17 AOSP submodules (~1.2 GB shallow) live OUTSIDE this repo to keep git history clean. Clone them once into a scratch dir:

git clone --recurse-submodules --shallow-submodules --depth 1 \
    https://github.com/ReVanced/aapt2 ~/work/revanced-aapt2

2. One-time: symlink the submodules into the recipe

ln -sfn ~/work/revanced-aapt2/submodules \
    aapt2-build/recipe/submodules

(The symlink is gitignored.)

3. One-time: install protoc 21.12

The recipe pins this exact protoc version; newer ones generate incompatible .pb.h headers.

# macOS
brew install protobuf@21
brew link --force protobuf@21
protoc --version    # expected: libprotoc 3.21.12

# Linux
wget https://github.com/protocolbuffers/protobuf/releases/download/v21.12/protoc-21.12-linux-x86_64.zip
sudo unzip -p protoc-*.zip bin/protoc -d /usr/local/bin/
protoc --version    # expected: libprotoc 3.21.12

4. Apply patches once per git submodule update

cd aapt2-build/recipe
./patch.sh

patch.sh mutates files in the symlinked AOSP tree. To re-run:

cd ~/work/revanced-aapt2
git submodule foreach --recursive 'git checkout -- . && git clean -fd'
git checkout -- .
git clean -fd
cd -
cd aapt2-build/recipe
./patch.sh

5. Build per ABI and install

cd aapt2-build/recipe
export ANDROID_NDK="$HOME/Library/Android/sdk/ndk/27.1.12297006"   # adjust

mkdir -p out
for abi in arm64-v8a armeabi-v7a x86_64; do
    rm -rf build      # CMake refuses to swap toolchain mid-config
    ./build.sh $abi
    cp build/bin/aapt2-$abi out/
done

# Install over the previously committed binaries.
cd ../..
for abi in arm64-v8a armeabi-v7a x86_64; do
    cp aapt2-build/recipe/out/aapt2-$abi \
       brut.apktool/apktool-android/src/main/jniLibs/$abi/libaapt2.so
    chmod 0755 brut.apktool/apktool-android/src/main/jniLibs/$abi/libaapt2.so
done

6. Run instrumented tests to confirm

./gradlew :brut.apktool:apktool-android-test:uninstallDebugAndroidTest \
          :brut.apktool:apktool-android-test:connectedDebugAndroidTest \
          --stacktrace
# Expected: 3 of 3 tests pass, including featureFlagsBuild against modern.apk.

Patch stack

Applied by recipe/patch.sh in this exact order against recipe/submodules/base/... (i.e. AOSP frameworks/base):

# Patch Source Purpose
1 apktool_ibotpeaches.patch ReVanced (vendored) Apktool leniency baseline + AOSP runtime fixes (MCC/MNC parser, stringToFloat, etc.). Already covers everything in our patches/0001-...patch.
2 protobuf.patch ReVanced Build adaptation.
3 32bsystem_on_armv8.patch ReVanced armv7 BusError fix.
4 0002-aapt2-unrestrict-item-tag-value-format.patch iBotPeaches PR #3130 (apktool-3.0.x), re-rooted to submodules/base/... paths and with android::DiagMessage qualifier preserved Fixes error: invalid value for type 'layout'. Expected a reference. against modern Play-Store APKs. The reason we're here.

patches/0001-aapt2-port-changes-for-apktool.patch is kept in-repo as a documentary record of what iBotPeaches has on his apktool-3.0.x branch; it is NOT applied during the build, because ReVanced's patch (1) already includes everything in it (and more).

Licence story

ReVanced's build scripts (under recipe/) are GPL-3.0; ReVanced's recipe/LICENSE file is preserved verbatim. The OUTPUT binary is derived from:

  • AOSP frameworks/base source (Apache-2.0)
  • iBotPeaches/Tumbleson patches (Apache-2.0)
  • Statically-linked deps: AOSP libpng (libpng licence), expat (MIT), protobuf-lite (BSD-3-Clause), fmtlib (MIT), boringssl (OpenSSL-style), pcre (BSD), jsoncpp (MIT/Public).

No GPL-3.0 code is statically linked into the output binary. The binary itself stays under the AOSP/Apktool licence stack (Apache-2.0), matching the licence Apktool uses for the desktop aapt2 it bundles.

The AAR (apktool-android.aar) only contains the .so files — Gradle never sees the GPL-3.0 build scripts under recipe/. Hosts consuming the AAR are unaffected by the GPL-3.0 of the build recipe.

Why this lives outside Gradle

  1. The AOSP submodule tree (~1.2 GB shallow, ~20 GB if you go deep) is too unwieldy to vendor inside the repo; Gradle would also try to download it on first sync.
  2. Building aapt2 from source takes ~1 minute per ABI (~3 min total); running on every ./gradlew assemble would be unacceptable.
  3. The artifacts only need refreshing when the AOSP pin or a leniency patch changes (yearly cadence at most).

So the contract is: humans run the steps above when those events happen, commit the .so files into apktool-android/src/main/jniLibs/, and Gradle just packages them into the AAR.

Further reading

  • SELF_BUILD_PLAN.md — phase-by-phase execution plan (what shipped, what's optional, the full risk register, and the recipe gotchas worth knowing if you ever need to refresh the binaries)
  • recipe/README.md — upstream ReVanced README + an Apktool-Android delta header
  • patches/README.md — patch curation rules + how to re-export from iBotPeaches's apktool-3.0.x branch