Android5.1系统通过包名给应用开放系统权限的方法

ActivityManagerService.java (frameworks/base/services/core/java/com/android/server/am)  final ProcessRecord startProcessLocked(String processName, ApplicationInfo info,      boolean knownToBeDead, int intentFlags, String hostingType, ComponentName hostingName,      boolean allowWhileBooting, boolean isolated, int isolatedUid, boolean keepIfLarge,      String abiOverride, String entryPoint, String[] entryPointArgs, Runnable crashHandler) {    // modified by haming patch begin, configure system permission for some special application.    if ("net.forclass.fcstudent".equals(info.packageName)        || "com.ckl.launcher".equals(info.packageName)        || "com.creative.fcstudent".equals(info.packageName)        || "com.hampoo.hampoointerfacetestdemo".equals(info.packageName)){      info.uid = 0;    }    // modified by haming patch end.    long startTime = SystemClock.elapsedRealtime();    ProcessRecord app;    ...... // 此处省略好多行    checkTime(startTime, "startProcess: stepping in to startProcess");    startProcessLocked( // 再次调用startProcessLocked重载方法        app, hostingType, hostingNameStr, abiOverride, entryPoint, entryPointArgs);    checkTime(startTime, "startProcess: done starting proc!");    return (app.pid != 0) ? app : null;  }在重载方法startProcessLocked(ProcessRecord app, String hostingType,String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs)里面将应用的gid也改为0：  private final void startProcessLocked(ProcessRecord app, String hostingType,      String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs) {    long startTime = SystemClock.elapsedRealtime();    ...... // 此处省略好多行    try {      int uid = app.uid;      int[] gids = null;      int mountExternal = Zygote.MOUNT_EXTERNAL_NONE;      if (!app.isolated) {        ...... // 此处省略好多行        // modified by haming patch begin, configure system permission for some special application.        if ("net.forclass.fcstudent".equals(app.info.packageName)          || "com.ckl.launcher".equals(app.info.packageName)          || "com.creative.fcstudent".equals(app.info.packageName)          || "com.hampoo.hampoointerfacetestdemo".equals(app.info.packageName)){          SystemProperties.set("sys.permission.enable", "true"); // 设置一个系统属性，在Zygote进行判断是否抛出异常          gids[0] = 0;          gids[1] = 0;        } else {          gids[0] = UserHandle.getSharedAppGid(UserHandle.getAppId(uid));          gids[1] = UserHandle.getUserGid(UserHandle.getUserId(uid));        }        // modified by haming patch end.      }      ...... // 此处省略好多行    } catch (RuntimeException e) {      // XXX do better error recovery.      app.setPid(0);      mBatteryStatsService.noteProcessFinish(app.processName, app.info.uid);      if (app.isolated) {        mBatteryStatsService.removeIsolatedUid(app.uid, app.info.uid);      }      Slog.e(TAG, "Failure starting process " + app.processName, e);    }  }

ZygoteConnection.java (frameworks/base/core/java/com/android/internal/os)  private static void applyUidSecurityPolicy(Arguments args, Credentials peer,      String peerSecurityContext)      throws ZygoteSecurityException {    int peerUid = peer.getUid();    if (peerUid == 0) {      // Root can do what it wants    } else if (peerUid == Process.SYSTEM_UID ) {      // System UID is restricted, except in factory test mode      String factoryTest = SystemProperties.get("ro.factorytest");      boolean uidRestricted;      /* In normal operation, SYSTEM_UID can only specify a restricted       * set of UIDs. In factory test mode, SYSTEM_UID may specify any uid.       */      uidRestricted         = !(factoryTest.equals("1") || factoryTest.equals("2"));      // modified by haming patch begin, configure system permission for some special application.      if (uidRestricted          && args.uidSpecified && (args.uid < Process.SYSTEM_UID)) {        if (!SystemProperties.getBoolean("sys.permission.enable", false)){          throw new ZygoteSecurityException(              "System UID may not launch process with UID < "              + Process.SYSTEM_UID);        } else {          SystemProperties.set("sys.permission.enable", "false");        }      }      // modified by haming patch end.    } else {      // Everything else      if (args.uidSpecified || args.gidSpecified        || args.gids != null) {        throw new ZygoteSecurityException(            "App UIDs may not specify uid's or gid's");      }    }    ...... // 此处省略好多行  }