Android 源码集成可卸载 APP

android系统包含三类APP: 1、可自由卸载APP安装在 /data/app目录下。 2、系统APP放在 /system/app目录。 3、特权APP放在 /system/priv-app目录。

系统编译后，打包前， /data分区不起作用，因此系统打包前，可以先将APP全部拷贝到 /system分区的 /system/usr/app目录下。

1、拷贝APP暂存到 /system/usr/app 目录

 在 /build/target/product/base_product.mk中添加如下命令， 会将 /apps/apps目录下的所有文件拷贝到 /system/usr/app ，将 shell脚本拷贝到 /system/bin目录

# 拷贝APP
PRODUCT_COPY_FILES += $(call find-copy-subdir-files,*,/data1/rom/android/lineageOS2/apps/apps,/system/usr/app)
# 拷贝shell
PRODUCT_COPY_FILES += $(call find-copy-subdir-files,*,/data1/rom/android/lineageOS2/apps/shell,/system/bin)

2、绕过拷贝 .apk文件时校验

 注释 /build/core/Makefile 如下 apk拷贝报错代码

define check-product-copy-files
$(if $(filter %.apk, $(1)),$(error \Prebuilt apk found in PRODUCT_COPY_FILES: $(1), use BUILD_PREBUILT instead!))
endef

3、系统启动执行init.rc脚本时，拷贝APP到 /data分区

在 init.rc文件中定义如下service , 并在 on boot 事件中 执行 preinstall

service preinstall /system/bin/preinstall.shclass mainuser rootgroup rootoneshoton bootxxxxxxxxxx.....start preinstall

4、shell 脚本文件如下 

#!/system/bin/shCUSTOMIZED_APK=/system/usr/app
DATA_APK=/data/appecho "CUSTOMIZED_APK=${CUSTOMIZED_APK}"
#获取是否已经预安装过标记位
PREINSTALL_RESULT=`getprop persist.sys.preinstall.value`
echo "PREINSTALL_RESULT=${PREINSTALL_RESULT}"
apk_files=""
#判断标记位是否为空，为空则没有预装过。然后将所有apk均copy到data/app下面。if [ -z "${PREINSTALL_RESULT}" ]; thencd ${CUSTOMIZED_APK}apk_files=$(ls *.apk )echo "apks files = ${apk_files}"for apkfile in $apk_filesdoecho " apkfiles = ${apkfile} "cp -vf ${CUSTOMIZED_APK}/${apkfile} ${DATA_APK}/${apkfile}echo "start copy "chmod 777 ${DATA_APK}/${apkfile}done#设置标记位
setprop persist.sys.preinstall.value 1# 拷贝 设备改机文件
cp /system/etc/device.json /data/system/device.json
chmod 666 /data/system/device.json
# 拷贝adb公钥
cp /system/etc/adb_keys /data/system/adb_keys
chown -R shell:shell /data/system/adb_keys
chmod 666 /data/system/adb_keyscd ../..fi

5、添加selinux权限

file_contexts文件： system/sepolicy/private/file_contexts 添加下面一行：

/system/bin/preinstall.sh  u:object_r:preinstall_exec:s0

同目录新建文件 preinstall.te 内容如下：

type preinstall, domain;
type preinstall_exec, exec_type, file_type;init_daemon_domain(preinstall)
#全部默认允许
permissive preinstall;

修改 init.te 允许读取并执行 preinstall:

#默认全部允许
allow init preinstall_exec:file {read open getattr execute};

android 11 系统 在 system/sepolicy/prebuilts/api/30.0/private 目录同步修改

TODO

最后一次拉取的android11源码 将 apk拷贝到 /data/app目录后开机没有扫描安装，原因待分析

FIXED : 

在 PackageManagerService. assertPackageIsValid 方法中 ，如下代码段：

// If we're only installing presumed-existing packages, require that the
// scanned APK is both already known and at the path previously established
// for it.  Previously unknown packages we pick up normally, but if we have an
// a priori expectation about this package's install presence, enforce it.
// With a singular exception for new system packages. When an OTA contains
// a new system package, we allow the codepath to change from a system location
// to the user-installed location. If we don't allow this change, any newer,
// user-installed version of the application will be ignored.
if ((scanFlags & SCAN_REQUIRE_KNOWN) != 0) {if (mExpectingBetter.containsKey(pkg.getPackageName())) {logCriticalInfo(Log.WARN,"Relax SCAN_REQUIRE_KNOWN requirement for package "+ pkg.getPackageName());} else {PackageSetting known = mSettings.getPackageLPr(pkg.getPackageName());if (known != null) {if (DEBUG_PACKAGE_SCANNING) {Log.d(TAG, "Examining " + pkg.getCodePath()+ " and requiring known paths " + known.codePathString+ " & " + known.resourcePathString);}if (!pkg.getCodePath().equals(known.codePathString)|| !pkg.getCodePath().equals(known.resourcePathString)) {throw new PackageManagerException(INSTALL_FAILED_PACKAGE_CHANGED,"Application package " + pkg.getPackageName()+ " found at " + pkg.getCodePath()+ " but expected at " + known.codePathString+ "; ignoring.");}} else {// throw new PackageManagerException(INSTALL_FAILED_INVALID_INSTALL_LOCATION,//         "Application package " + pkg.getPackageName()//         + " not found; ignoring.");}}
}

注释掉  INSTALL_FAILED_INVALID_INSTALL_LOCATION 异常。

同时，修改selinux权限: untrusted_app_all 增加 execute 权限：

#允许app读取/data/system目录文件 允许app 执行 data/app-libm目录下的可执行文件
allow untrusted_app_all system_data_file:file { open read execute};