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      1 /*
      2  * Copyright (C) 2017 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package libcore.util;
     18 
     19 /**
     20  * Utility methods associated with finding updateable time zone data files.
     21  */
     22 public final class TimeZoneDataFiles {
     23 
     24     private static final String ANDROID_ROOT_ENV = "ANDROID_ROOT";
     25     private static final String ANDROID_DATA_ENV = "ANDROID_DATA";
     26 
     27     private TimeZoneDataFiles() {}
     28 
     29     /**
     30      * Returns two time zone file paths for the specified file name in an array in the order they
     31      * should be tried. See {@link #generateIcuDataPath()} for ICU files instead.
     32      * <ul>
     33      * <li>[0] - the location of the file in the /data partition (may not exist).</li>
     34      * <li>[1] - the location of the file in the /system partition (should exist).</li>
     35      * </ul>
     36      */
     37     // VisibleForTesting
     38     public static String[] getTimeZoneFilePaths(String fileName) {
     39         return new String[] {
     40                 getDataTimeZoneFile(fileName),
     41                 getSystemTimeZoneFile(fileName)
     42         };
     43     }
     44 
     45     private static String getDataTimeZoneFile(String fileName) {
     46         return System.getenv(ANDROID_DATA_ENV) + "/misc/zoneinfo/current/" + fileName;
     47     }
     48 
     49     // VisibleForTesting
     50     public static String getSystemTimeZoneFile(String fileName) {
     51         return System.getenv(ANDROID_ROOT_ENV) + "/usr/share/zoneinfo/" + fileName;
     52     }
     53 
     54     public static String generateIcuDataPath() {
     55         StringBuilder icuDataPathBuilder = new StringBuilder();
     56         // ICU should first look in ANDROID_DATA. This is used for (optional) timezone data.
     57         String dataIcuDataPath = getEnvironmentPath(ANDROID_DATA_ENV, "/misc/zoneinfo/current/icu");
     58         if (dataIcuDataPath != null) {
     59             icuDataPathBuilder.append(dataIcuDataPath);
     60         }
     61 
     62         // ICU should always look in ANDROID_ROOT.
     63         String systemIcuDataPath = getEnvironmentPath(ANDROID_ROOT_ENV, "/usr/icu");
     64         if (systemIcuDataPath != null) {
     65             if (icuDataPathBuilder.length() > 0) {
     66                 icuDataPathBuilder.append(":");
     67             }
     68             icuDataPathBuilder.append(systemIcuDataPath);
     69         }
     70         return icuDataPathBuilder.toString();
     71     }
     72 
     73     /**
     74      * Creates a path by combining the value of an environment variable with a relative path.
     75      * Returns {@code null} if the environment variable is not set.
     76      */
     77     private static String getEnvironmentPath(String environmentVariable, String path) {
     78         String variable = System.getenv(environmentVariable);
     79         if (variable == null) {
     80             return null;
     81         }
     82         return variable + path;
     83     }
     84 }
     85