content: /*
   * Copyright (C) 2018 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.android.server.backup.encryption.storage;
  
  import static com.android.server.backup.encryption.storage.BackupEncryptionDbContract.TertiaryKeysEntry;
  
  import android.content.Context;
  import android.database.sqlite.SQLiteDatabase;
  import android.database.sqlite.SQLiteException;
  import android.database.sqlite.SQLiteOpenHelper;
  
  /** Helper for creating an instance of the backup encryption database. */
  class BackupEncryptionDbHelper extends SQLiteOpenHelper {
      private static final int DATABASE_VERSION = 1;
      static final String DATABASE_NAME = "backupencryption.db";
  
      private static final String SQL_CREATE_TERTIARY_KEYS_ENTRY =
              "CREATE TABLE "
                      + TertiaryKeysEntry.TABLE_NAME
                      + " ( "
                      + TertiaryKeysEntry._ID
                      + " INTEGER PRIMARY KEY,"
                      + TertiaryKeysEntry.COLUMN_NAME_SECONDARY_KEY_ALIAS
                      + " TEXT,"
                      + TertiaryKeysEntry.COLUMN_NAME_PACKAGE_NAME
                      + " TEXT,"
                      + TertiaryKeysEntry.COLUMN_NAME_WRAPPED_KEY_BYTES
                      + " BLOB,"
                      + "UNIQUE("
                      + TertiaryKeysEntry.COLUMN_NAME_SECONDARY_KEY_ALIAS
                      + ","
                      + TertiaryKeysEntry.COLUMN_NAME_PACKAGE_NAME
                      + "))";
  
      private static final String SQL_DROP_TERTIARY_KEYS_ENTRY =
              "DROP TABLE IF EXISTS " + TertiaryKeysEntry.TABLE_NAME;
  
      BackupEncryptionDbHelper(Context context) {
          super(context, DATABASE_NAME, /*factory=*/ null, DATABASE_VERSION);
      }
  
      public void resetDatabase() throws EncryptionDbException {
          SQLiteDatabase db = getWritableDatabaseSafe();
          db.execSQL(SQL_DROP_TERTIARY_KEYS_ENTRY);
          onCreate(db);
      }
  
      @Override
      public void onCreate(SQLiteDatabase db) {
          db.execSQL(SQL_CREATE_TERTIARY_KEYS_ENTRY);
      }
  
      @Override
      public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
          db.execSQL(SQL_DROP_TERTIARY_KEYS_ENTRY);
          onCreate(db);
      }
  
      @Override
      public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
          db.execSQL(SQL_DROP_TERTIARY_KEYS_ENTRY);
          onCreate(db);
      }
  
      /**
       * Calls {@link #getWritableDatabase()}, but catches the unchecked {@link SQLiteException} and
       * rethrows {@link EncryptionDbException}.
       */
      public SQLiteDatabase getWritableDatabaseSafe() throws EncryptionDbException {
          try {
              return super.getWritableDatabase();
          } catch (SQLiteException e) {
              throw new EncryptionDbException(e);
          }
      }
  
      /**
       * Calls {@link #getReadableDatabase()}, but catches the unchecked {@link SQLiteException} and
       * rethrows {@link EncryptionDbException}.
       */
      public SQLiteDatabase getReadableDatabaseSafe() throws EncryptionDbException {
          try {
              return super.getReadableDatabase();
          } catch (SQLiteException e) {
              throw new EncryptionDbException(e);
          }
      }
  }
  