Selinux中的APP分类

framework/base/services/core/java/com/android/oserver/pm/PackageManagerService.java         
public PackageManagerService(Context context, Installer installer,
          boolean factoryTest, boolean onlyCore) {
         ... ...
mSettings = new Settings(mPackages);
mSettings.addSharedUserLPw("android.uid.system", Process.SYSTEM_UID,
        ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.phone", RADIO_UID,
        ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.log", LOG_UID,
        ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.nfc", NFC_UID,
        ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.bluetooth", BLUETOOTH_UID,
        ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.shell", SHELL_UID,
        ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
         ... ...

/frameworks/base/services/core/java/com/android/server/pm/Settings.java
SharedUserSetting addSharedUserLPw(String name, int uid, int pkgFlags, int pkgPrivateFlags) {
    SharedUserSetting s = mSharedUsers.get(name);
    ... ...
    s = new SharedUserSetting(name, pkgFlags, pkgPrivateFlags);
    s.userId = uid;
    if (addUserIdLPw(uid, s, name)) {
        mSharedUsers.put(name, s);
        return s;
    }
    return null;
}

private boolean addUserIdLPw(int uid, Object obj, Object name) {
     ... ...
     /*
       Process.FIRST_APPLICATION_UID开始到Process.LAST_APPLICATION_UID为普通应用的uid,保存到mUserIds中
     */
    if (uid >= Process.FIRST_APPLICATION_UID) {
        int N = mUserIds.size();
        final int index = uid - Process.FIRST_APPLICATION_UID;
        while (index >= N) {
            mUserIds.add(null);
            N++;
        }
        ... ...
        mUserIds.set(index, obj);
    } else {  //将system,nfc等系统预留的uid保存到mOtherUserIds
         ... ...
        mOtherUserIds.put(uid, obj);
    }
    return true;
}

framework/base/services/core/java/com/android/oserver/pm/PackageManagerService.java
      ... ...
      // Collected privileged system packages.
      final File privilegedAppDir = new File(Environment.getRootDirectory(), "priv-app");
      scanDirTracedLI(privilegedAppDir, mDefParseFlags
              | PackageParser.PARSE_IS_SYSTEM
              | PackageParser.PARSE_IS_SYSTEM_DIR
              | PackageParser.PARSE_IS_PRIVILEGED, scanFlags, 0);

      // Collect ordinary system packages.
      final File systemAppDir = new File(Environment.getRootDirectory(), "app");
      scanDirTracedLI(systemAppDir, mDefParseFlags
              | PackageParser.PARSE_IS_SYSTEM
              | PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);

      // Collect all vendor packages.
      File vendorAppDir = new File("/vendor/app");
       ... ...
      scanDirTracedLI(vendorAppDir, mDefParseFlags
              | PackageParser.PARSE_IS_SYSTEM
              | PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);

      // Collect all OEM packages.
      final File oemAppDir = new File(Environment.getOemDirectory(), "app");
      scanDirTracedLI(oemAppDir, mDefParseFlags
              | PackageParser.PARSE_IS_SYSTEM
              | PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg,
            final int policyFlags, final int scanFlags, long currentTime, @Nullable UserHandle user)
                    throws PackageManagerException {
     ... ...

     //从前面序列1的调用逻辑已经知道，系统的sharedUserId会存储在mSharedUserId中，而通过调用mSettings.getSharedUserLPw如果这个package的 pkg.mSharedUserId不在前面的列表之中，则会创建一个新的sharedUserId，也就是说如果这个package在AndroidManefest.xml中定义了类似mSharedUserId="com.ryan.test"的shareduserid，就会在下面的函数中进行添加，并通过Settings#newUserIdLPw创建系统uid之外的shareduserid。
     synchronized (mPackages) {
         if (pkg.mSharedUserId != null) {
             // SIDE EFFECTS; may potentially allocate a new shared user
             suid = mSettings.getSharedUserLPw(
                     pkg.mSharedUserId, 0 /*pkgFlags*/, 0 /*pkgPrivateFlags*/, true /*create*/);
         }

    ... ...

    //从mPackages中获取参数信息，查看此包名的pkgSetting是否存在，查看其sharedUser是否发生了变更，如果发生了变更，则重新pkgSettings清空。PackageManagerService会在前面通过mSettings.readLPw(sUserManager.getUsers(false)将data/system/packages.xml中的信息读取出来，存到mPackages中，如果这里不存在这个mPackage，说明这个应用是新安装或者更新过的，而不是预制在系统里面的。
     pkgSetting = mSettings.getPackageLPr(pkg.packageName);
         if (pkgSetting != null && pkgSetting.sharedUser != suid) {
             pkgSetting = null;
         }
      ... ...
        //走到这里pkgSetting为null的，重新为其创建新pkgSettings
         if (pkgSetting == null) {
                        final String parentPackageName = (pkg.parentPackage != null)
                                ? pkg.parentPackage.packageName : null;
                        final boolean instantApp = (scanFlags & SCAN_AS_INSTANT_APP) != 0;
                        // REMOVE SharedUserSetting from method; update in a separate call
                        pkgSetting = Settings.createNewSetting(pkg.packageName, origPackage,
                                disabledPkgSetting, realName, suid, destCodeFile, destResourceFile,
                                pkg.applicationInfo.nativeLibraryRootDir, pkg.applicationInfo.primaryCpuAbi,
                                pkg.applicationInfo.secondaryCpuAbi, pkg.mVersionCode,
                                pkg.applicationInfo.flags, pkg.applicationInfo.privateFlags, user,
                                true /*allowInstall*/, instantApp, parentPackageName,
                                pkg.getChildPackageNames(), UserManagerService.getInstance(),
                                usesStaticLibraries, pkg.usesStaticLibrariesVersions)
      ... ...

    //进行UID的赋值
    pkg.applicationInfo.uid = pkgSetting.appId;
}

private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg,
         final int policyFlags, final int scanFlags, long currentTime, @Nullable UserHandle user)throws PackageManagerException {
          ... ...
        /* PackageManager会从下面两个路径中国年读取mac_permissions.xml文件，分为平台相关的和平台不相关的
         private static final File[] MAC_PERMISSIONS =
    { new File(Environment.getRootDirectory(), "/etc/selinux/plat_mac_permissions.xml"),
      new File(Environment.getVendorDirectory(), "/etc/selinux/nonplat_mac_permissions.xml") };
      */
          mFoundPolicyFile = SELinuxMMAC.readInstallPolicy();
          ... ...
         /*
           根据package的签名与前面读取出的mac_permission.xml文件信息将对应的seinfo
         */
          if (mFoundPolicyFile) {
              SELinuxMMAC.assignSeInfoValue(pkg);
          }
          ... ...
}