feat: add validate-elf-alignment command (#23)

Author: LukasMod

README.md

@@ -70,6 +70,7 @@ jobs:
 | `rock-build-extra-params` | Extra parameters for rock build:android  | No       | -                  |
 | `comment-bot`             | Whether to comment PR with build link    | No       | `true`             |
 | `custom-identifier`       | Custom identifier used in artifact naming for re-sign and ad-hoc flows to distinguish builds with the same native fingerprint     | No       | -           |
+| `validate-elf-alignment`  | Validate 16KB ELF alignment of native libraries (Google Play compliance) | No       | `false`     |
 
 ## Artifact Naming
 
@@ -150,6 +151,27 @@ The following mappings are set:
 
 Both conventions are set simultaneously, so the action works with any existing build configuration.
 
+## ELF Alignment Validation
+
+When `validate-elf-alignment: true`, the action verifies that all native shared libraries (`.so` files) in the APK are 16KB page-size aligned, as required by [Google Play for Android 15+ devices](https://developer.android.com/guide/practices/page-sizes).
+
+The check runs **only on fresh builds** (not on cached/downloaded artifacts) and **before** re-signing or uploading. It performs two levels of verification:
+
+1. **Zip-level alignment** via `zipalign -P 16` — checks that `.so` entries are correctly aligned within the APK archive
+2. **ELF-level alignment** via `objdump` — inspects each shared library's LOAD segment to confirm `2**14` (16KB) or higher alignment
+
+The command only supports APK files. If the build produces an AAB, the step will fail with a clear error. If any 64-bit library (`arm64-v8a`, `x86_64`) is misaligned, the workflow fails with a list of affected libraries.
+
+Internally this uses `npx rock validate-elf-alignment`, which requires `objdump` available on the runner. `zipalign` from Android build-tools 35.0.0+ is optional but recommended for zip-level checks.
+
+```yaml
+- uses: callstackincubator/android@v3
+  with:
+    github-token: ${{ secrets.GITHUB_TOKEN }}
+    variant: 'release'
+    validate-elf-alignment: true
+```
+
 ## Prerequisites
 
 - Ubuntu runner

action.yml

@@ -71,6 +71,10 @@ inputs:
   custom-identifier:
     description: 'Custom identifier used in artifact naming for re-sign and ad-hoc flows to distinguish builds with the same native fingerprint'
     required: false
+  validate-elf-alignment:
+    description: 'Validate ELF alignment of native libraries (16KB page size compliance for Google Play)'
+    required: false
+    default: 'false'
 
 outputs:
   artifact-url:
@@ -270,6 +274,13 @@ runs:
         echo "ARTIFACT_PATH=$BINARY_PATH" >> $GITHUB_ENV
       shell: bash
 
+    - name: Validate ELF Alignment
+      if: ${{ inputs.validate-elf-alignment == 'true' && !env.ARTIFACT_URL && env.ARTIFACT_PATH }}
+      run: |
+        npx rock validate-elf-alignment "${{ env.ARTIFACT_PATH }}"
+      shell: bash
+      working-directory: ${{ inputs.working-directory }}
+
     - name: Download and Unpack Binary
       if: ${{ env.ARTIFACT_URL && inputs.re-sign == 'true' }}
       run: |