android-12 supported

Author: cxxsheng

README.md

@@ -8,10 +8,11 @@ SecurePatchedEmulator provides a prebuilt Android emulator image with the latest
 |  Version  | Security Patch |                        Download Link                         |
 | :-------: | :------------: | :----------------------------------------------------------: |
 | 14.0.0_r1 |    2024-06     | [android-14.0.0_r1.zip](https://github.com/cxxsheng/SecurePatchedEmulator/releases/download/2024-06/android-14.0.0_r1.zip) |
+| 12.0.0_r1 |    2024-06     | [android-12.0.0_r1.zip](https://github.com/cxxsheng/SecurePatchedEmulator/releases/download/2024-06/android-12.0.0_r1.zip) |
 
 ### Usage
 To set up and launch the SecurePatchedEmulator, follow these steps:
-1. Download the desired Android emulator image. For example, to launch android-14.0.0_r1:
+1. Download the desired Android emulator image. For example, to launch `android-14.0.0_r1`:
 
    ```shell
    wget https://github.com/cxxsheng/SecurePatchedEmulator/releases/download/2024-06/android-14.0.0_r1.zip
@@ -31,4 +32,70 @@ To set up and launch the SecurePatchedEmulator, follow these steps:
    emulator @YourAVDName -sysdir /path/to/emulator/x86_64
    ```
 
-   Replace `YourAVDName` with the name of your Android Virtual Device (AVD) and `/path/to/emulator` with the actual path where you extracted the emulator files.
+   Replace `YourAVDName` with the name of your Android Virtual Device (AVD) and `/path/to/emulator` with the actual path where you extracted the emulator files. Ensure that the Android version used to create `YourAVDName` matches the Android version of the emulator image.
+
+### Building
+To create a secure Android emulator image with the latest security patches, follow these steps:
+
+0. Initialize and sync the AOSP repository:
+   ```shell
+   repo init -u https://android.googlesource.com/platform/manifest -b android-14.0.0_r1
+repo sync
+   ```
+   Replace `android-14.0.0_r1` with the desired Android version.
+
+1. Identify the latest security patch tag from the[ `platform_build`](https://github.com/aosp-mirror/platform_build/tags ) repository on GitHub. For example, [`android-security-14.0.0_r9`](https://github.com/aosp-mirror/platform_build/releases/tag/android-security-14.0.0_r9):
+
+2. Fetch the security patch tag across all AOSP repositories:
+
+   ```shell
+   2. repo forall -p -c 'git fetch aosp android-security-14.0.0_r9'
+   ```
+
+   Replace `android-security-14.0.0_r9` with the actual security patch tag.
+
+3. Generate a diff file to review the changes between the current HEAD and the security patch:
+
+   ```shell
+   repo forall -p -c 'git log --oneline HEAD..FETCH_HEAD' > 14.0.0_r1-to-14.0.0_r9.diff.txt
+   ```
+
+4. Merge the security patch into the AOSP repositories:
+
+   ```shell
+   repo forall -p -c 'git merge FETCH_HEAD'
+   ```
+
+5. Modify the security patch date in the emulator image:
+
+   In the `build/make/core/version_defaults.mk` file, locate the `ro.build.version.security_patch` variable and change its value to the desired security patch date, e.g., `2024-06-05`.
+
+6. Build the Android emulator image: 
+
+   For Android 13 and above:
+
+   ```shell
+   source ./build/envsetup.sh
+   lunch sdk_phone_x86-userdebug
+   make emu_img_zip -j$(nproc)
+   ```
+
+   This generates an `sdk-repo-linux-system-images-eng.[username]].zip` file.
+
+   For Android 12 and below:
+
+   ```shell
+   source build/envsetup.sh
+   lunch sdk_phone_x86_64-userdebug
+   make -j$(nproc) sdk sdk_repo
+   ```
+
+   The `make sdk sdk_repo` command creates two files under `aosp-main/out/host/linux-x86/sdk/sdk_phone_x86_64`:
+
+   - `sdk-repo-linux-system-images-eng.[username].zip`
+   - `repo-sys-img.xml`
+
+###  Reference：
+
+1. [Merging AOSP Security Patches into Custom ROMs | Aditya Telange.](https://adityatelange.in/blog/aosp/merge-security-patches-aosp/)
+2. [Use Android Emulator virtual devices | Android Open Source Project.](https://source.android.com/docs/setup/create/avd#build_avd_images)