104 lines
3.8 KiB
Markdown
104 lines
3.8 KiB
Markdown
# Installing a Platform-Signed APK on the MG4 Head Unit
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This documents the reliable way to install a (platform-signed) APK onto the
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MG4 SWI69 head unit (Android 9 / SAIC MT2712) over ADB.
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The head unit rejects the standard `adb install` / `pm install` flow with:
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```
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java.io.IOException: Not allowed to install non-system apps on internal storage
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at com.android.internal.content.PackageHelper.resolveInstallVolume(...)
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```
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This is not a signature problem — the same `platform.pk8` / `platform.x509.pem`
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that signs the already-installed `com.mg4.*` apps signs our APK too (verified by
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matching SHA-256 cert digests). The PackageManager simply will not let the
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shell UID (2000) stage a non-system package onto internal storage through its
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default install path, and `--install-location`, `--force-uuid internal`, `-l`
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(forward lock) and session-based `install-create`/`install-write`/`install-commit`
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all hit the same wall or fail to open the file (SELinux denies `system_server`
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read access to shell-owned files in some flag combinations).
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## Prerequisites
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- The MG4 head unit connected over ADB (`adb devices` lists it).
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- A built APK. For a platform-signed build see
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[`MG4_PLATFORM_BUILD.md`](./MG4_PLATFORM_BUILD.md) (DiPlay) — the same
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`zipalign` + `apksigner sign --key tools/platform.pk8 --cert
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tools/platform.x509.pem` step applies here.
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- The platform keys in `tools/` (`platform.pk8`, `platform.x509.pem`).
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## The Install Command
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The only flag combination that works on this unit is:
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```bash
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adb push <your-app>.apk /data/local/tmp/update.apk
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adb shell "pm install -r -f -d -t /data/local/tmp/update.apk"
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```
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Flags:
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- `-r` — replace the existing package if one is installed.
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- `-f` — force install on internal flash (`/data/app/`).
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- `-d` — allow a version-code downgrade (debuggable packages only). The
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unstable channel bumps `versionCode` per CI build, so a locally built APK
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is almost always lower than whatever the OTA last pushed; without `-d` the
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install silently fails on a version mismatch.
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- `-t` — allow test packages. Unstable/debug builds are marked debuggable,
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which the PackageManager treats as a test package.
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The file **must** be pushed as (or renamed to) something under
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`/data/local/tmp/`. Other locations (`/sdcard/`, a custom cache dir) fail with
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`Can't open file` because `system_server` has no SELinux read access to those
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contexts. A failed `pm install` attempt can delete the staged file, so if a
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later install says `No such file or directory`, re-push.
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## Verifying the Install
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```bash
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adb shell pm path com.evsuite.abrp.unstable
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# -> package:/data/app/com.evsuite.abrp.unstable-.../base.apk
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```
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To confirm the platform signature matches the system:
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```bash
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BUILD_TOOLS="$ANDROID_HOME/build-tools/36.0.0"
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adb pull "$(adb shell pm path com.evsuite.abrp.unstable | sed 's/package://')" /tmp/installed.apk
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"$BUILD_TOOLS/apksigner" verify --print-certs /tmp/installed.apk
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# SHA-256 cert digest should match tools/platform.x509.pem
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```
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## Uninstalling
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```bash
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adb uninstall com.evsuite.abrp.unstable
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```
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Add `-k` to keep data/cache around (useful when re-installing to test without
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wiping the local consumption store).
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## End-to-End: Build → Sign → Install
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From the repository root:
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```bash
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# 1. Build
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./gradlew :app:assembleUnstableDebug
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# 2. Align + platform-sign
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SDK="$HOME/Library/Android/sdk"
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BT="$SDK/build-tools/36.0.0"
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IN=app/build/outputs/apk/unstable/debug/app-unstable-debug.apk
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ALIGNED=app/build/outputs/apk/unstable/debug/app-unstable-debug-aligned.apk
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OUT=FatihsMG4-unstable-platform.apk
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"$BT/zipalign" -f 4 "$IN" "$ALIGNED"
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"$BT/apksigner" sign --key tools/platform.pk8 --cert tools/platform.x509.pem --out "$OUT" "$ALIGNED"
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"$BT/apksigner" verify --verbose "$OUT"
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# 3. Install on the head unit
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adb push "$OUT" /data/local/tmp/update.apk
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adb shell "pm install -r -f -d -t /data/local/tmp/update.apk"
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```
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