luni/src/main/java/org/apache/harmony/luni/internal/util/ZoneInfoDB.java - platform/libcore - Git at Google

 /*
  * Copyright (C) 2007 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 org.apache.harmony.luni.internal.util;

 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.channels.FileChannel;
 import java.nio.charset.Charsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.TimeZone;
 import libcore.io.IoUtils;

 /**
  * A class used to initialize the time zone database.  This implementation uses the
  * 'zoneinfo' database as the source of time zone information.  However, to conserve
  * disk space the data for all time zones are concatenated into a single file, and a
  * second file is used to indicate the starting position of each time zone record.  A
  * third file indicates the version of the zoneinfo database used to generate the data.
  *
  * {@hide}
  */
 public final class ZoneInfoDB {
     /**
      * The directory containing the time zone database files.
      */
     private static final String ZONE_DIRECTORY_NAME =
             System.getenv("ANDROID_ROOT") + "/usr/share/zoneinfo/";

     /**
      * The name of the file containing the concatenated time zone records.
      */
     private static final String ZONE_FILE_NAME = ZONE_DIRECTORY_NAME + "zoneinfo.dat";

     /**
      * The name of the file containing the index to each time zone record within
      * the zoneinfo.dat file.
      */
     private static final String INDEX_FILE_NAME = ZONE_DIRECTORY_NAME + "zoneinfo.idx";

     private static final Object LOCK = new Object();

     private static final String VERSION = readVersion();

     /**
      * The 'ids' array contains time zone ids sorted alphabetically, for binary searching.
      * The other two arrays are in the same order. 'byteOffsets' gives the byte offset
      * into "zoneinfo.dat" of each time zone, and 'rawUtcOffsets' gives the time zone's
      * raw UTC offset.
      */
     private static String[] ids;
     private static int[] byteOffsets;
     private static int[] rawUtcOffsets;
     static {
         readIndex();
     }

     private static ByteBuffer mappedData = mapData();

     private ZoneInfoDB() {}

     /**
      * Reads the file indicating the database version in use.  If the file is not
      * present or is unreadable, we assume a version of "2007h".
      */
     private static String readVersion() {
         RandomAccessFile versionFile = null;
         try {
             versionFile = new RandomAccessFile(ZONE_DIRECTORY_NAME + "zoneinfo.version", "r");
             byte[] buf = new byte[(int) versionFile.length()];
             versionFile.readFully(buf);
             return new String(buf, 0, buf.length, Charsets.ISO_8859_1).trim();
         } catch (IOException ex) {
             throw new RuntimeException(ex);
         } finally {
             IoUtils.closeQuietly(versionFile);
         }
     }

     /**
      * Traditionally, Unix systems have one file per time zone. We have one big data file, which
      * is just a concatenation of regular time zone files. To allow random access into this big
      * data file, we also have an index. We read the index at startup, and keep it in memory so
      * we can binary search by id when we need time zone data.
      *
      * The format of this file is, I believe, Android's own, and undocumented.
      *
      * All this code assumes strings are US-ASCII.
      */
     private static void readIndex() {
         RandomAccessFile indexFile = null;
         try {
             indexFile = new RandomAccessFile(INDEX_FILE_NAME, "r");

             // The database reserves 40 bytes for each id.
             final int SIZEOF_TZNAME = 40;
             // The database uses 32-bit (4 byte) integers.
             final int SIZEOF_TZINT = 4;

             byte[] idBytes = new byte[SIZEOF_TZNAME];

             int numEntries = (int) (indexFile.length() / (SIZEOF_TZNAME + 3*SIZEOF_TZINT));

             char[] idChars = new char[numEntries * SIZEOF_TZNAME];
             int[] idEnd = new int[numEntries];
             int idOffset = 0;

             byteOffsets = new int[numEntries];
             rawUtcOffsets = new int[numEntries];

             for (int i = 0; i < numEntries; i++) {
                 indexFile.readFully(idBytes);
                 byteOffsets[i] = indexFile.readInt();
                 int length = indexFile.readInt();
                 if (length < 44) {
                     throw new AssertionError("length in index file < sizeof(tzhead)");
                 }
                 rawUtcOffsets[i] = indexFile.readInt();

                 // Don't include null chars in the String
                 int len = idBytes.length;
                 for (int j = 0; j < len; j++) {
                     if (idBytes[j] == 0) {
                         break;
                     }
                     idChars[idOffset++] = (char) (idBytes[j] & 0xFF);
                 }

                 idEnd[i] = idOffset;
             }

             // We create one string containing all the ids, and then break that into substrings.
             // This way, all ids share a single char[] on the heap.
             String allIds = new String(idChars, 0, idOffset);
             ids = new String[numEntries];
             for (int i = 0; i < numEntries; i++) {
                 ids[i] = allIds.substring(i == 0 ? 0 : idEnd[i - 1], idEnd[i]);
             }
         } catch (IOException ex) {
             throw new RuntimeException(ex);
         } finally {
             IoUtils.closeQuietly(indexFile);
         }
     }

     /**
      * Rather than open, read, and close the big data file each time we look up a time zone,
      * we map the big data file during startup, and then just use the ByteBuffer.
      *
      * At the moment, this "big" data file is about 160 KiB. At some point, that will be small
      * enough that we'll just keep the byte[] in memory.
      */
     private static ByteBuffer mapData() {
         RandomAccessFile file = null;
         try {
             file = new RandomAccessFile(ZONE_FILE_NAME, "r");
             FileChannel channel = file.getChannel();
             ByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
             buffer.order(ByteOrder.BIG_ENDIAN);
             return buffer;
         } catch (IOException ex) {
             throw new RuntimeException(ex);
         } finally {
             IoUtils.closeQuietly(file);
         }
     }

     private static TimeZone makeTimeZone(String id) throws IOException {
         // Work out where in the big data file this time zone is.
         int index = Arrays.binarySearch(ids, id);
         if (index < 0) {
             return null;
         }
         int start = byteOffsets[index];

         // We duplicate the ByteBuffer to allow unsynchronized access to this shared data,
         // despite Buffer's implicit position.
         ByteBuffer data = mappedData.duplicate();
         data.position(start);

         // Variable names beginning tzh_ correspond to those in "tzfile.h".
         // Check tzh_magic.
         if (data.getInt() != 0x545a6966) { // "TZif"
             return null;
         }

         // Skip the uninteresting part of the header.
         data.position(start + 32);

         // Read the sizes of the arrays we're about to read.
         int tzh_timecnt = data.getInt();
         int tzh_typecnt = data.getInt();
         int tzh_charcnt = data.getInt();

         int[] transitions = new int[tzh_timecnt];
         for (int i = 0; i < tzh_timecnt; ++i) {
             transitions[i] = data.getInt();
         }

         byte[] type = new byte[tzh_timecnt];
         data.get(type);

         int[] gmtOffsets = new int[tzh_typecnt];
         byte[] isDsts = new byte[tzh_typecnt];
         byte[] abbreviationIndexes = new byte[tzh_typecnt];
         for (int i = 0; i < tzh_typecnt; ++i) {
             gmtOffsets[i] = data.getInt();
             isDsts[i] = data.get();
             abbreviationIndexes[i] = data.get();
         }

         byte[] abbreviationList = new byte[tzh_charcnt];
         data.get(abbreviationList);

         return new ZoneInfo(id, transitions, type, gmtOffsets, isDsts,
                 abbreviationIndexes, abbreviationList);
     }

     public static String[] getAvailableIDs() {
         return (String[]) ids.clone();
     }

     public static String[] getAvailableIDs(int rawOffset) {
         List<String> matches = new ArrayList<String>();
         for (int i = 0, end = rawUtcOffsets.length; i < end; i++) {
             if (rawUtcOffsets[i] == rawOffset) {
                 matches.add(ids[i]);
             }
         }
         return matches.toArray(new String[matches.size()]);
     }

     public static TimeZone getSystemDefault() {
         synchronized (LOCK) {
             TimezoneGetter tzGetter = TimezoneGetter.getInstance();
             String zoneName = tzGetter != null ? tzGetter.getId() : null;
             if (zoneName != null) {
                 zoneName = zoneName.trim();
             }
             if (zoneName == null || zoneName.isEmpty()) {
                 // use localtime for the simulator
                 // TODO: what does that correspond to?
                 zoneName = "localtime";
             }
             return TimeZone.getTimeZone(zoneName);
         }
     }

     public static TimeZone getTimeZone(String id) {
         if (id == null) {
             return null;
         }
         try {
             return makeTimeZone(id);
         } catch (IOException ignored) {
             return null;
         }
     }

     public static String getVersion() {
         return VERSION;
     }
 }
	/*
	* Copyright (C) 2007 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 org.apache.harmony.luni.internal.util;

	import java.io.IOException;
	import java.io.RandomAccessFile;
	import java.nio.ByteBuffer;
	import java.nio.ByteOrder;
	import java.nio.channels.FileChannel;
	import java.nio.charset.Charsets;
	import java.util.ArrayList;
	import java.util.Arrays;
	import java.util.List;
	import java.util.TimeZone;
	import libcore.io.IoUtils;

	/**
	* A class used to initialize the time zone database. This implementation uses the
	* 'zoneinfo' database as the source of time zone information. However, to conserve
	* disk space the data for all time zones are concatenated into a single file, and a
	* second file is used to indicate the starting position of each time zone record. A
	* third file indicates the version of the zoneinfo database used to generate the data.
	*
	* {@hide}
	*/
	public final class ZoneInfoDB {
	/**
	* The directory containing the time zone database files.
	*/
	private static final String ZONE_DIRECTORY_NAME =
	System.getenv("ANDROID_ROOT") + "/usr/share/zoneinfo/";

	/**
	* The name of the file containing the concatenated time zone records.
	*/
	private static final String ZONE_FILE_NAME = ZONE_DIRECTORY_NAME + "zoneinfo.dat";

	/**
	* The name of the file containing the index to each time zone record within
	* the zoneinfo.dat file.
	*/
	private static final String INDEX_FILE_NAME = ZONE_DIRECTORY_NAME + "zoneinfo.idx";

	private static final Object LOCK = new Object();

	private static final String VERSION = readVersion();

	/**
	* The 'ids' array contains time zone ids sorted alphabetically, for binary searching.
	* The other two arrays are in the same order. 'byteOffsets' gives the byte offset
	* into "zoneinfo.dat" of each time zone, and 'rawUtcOffsets' gives the time zone's
	* raw UTC offset.
	*/
	private static String[] ids;
	private static int[] byteOffsets;
	private static int[] rawUtcOffsets;
	static {
	readIndex();
	}

	private static ByteBuffer mappedData = mapData();

	private ZoneInfoDB() {}

	/**
	* Reads the file indicating the database version in use. If the file is not
	* present or is unreadable, we assume a version of "2007h".
	*/
	private static String readVersion() {
	RandomAccessFile versionFile = null;
	try {
	versionFile = new RandomAccessFile(ZONE_DIRECTORY_NAME + "zoneinfo.version", "r");
	byte[] buf = new byte[(int) versionFile.length()];
	versionFile.readFully(buf);
	return new String(buf, 0, buf.length, Charsets.ISO_8859_1).trim();
	} catch (IOException ex) {
	throw new RuntimeException(ex);
	} finally {
	IoUtils.closeQuietly(versionFile);
	}
	}

	/**
	* Traditionally, Unix systems have one file per time zone. We have one big data file, which
	* is just a concatenation of regular time zone files. To allow random access into this big
	* data file, we also have an index. We read the index at startup, and keep it in memory so
	* we can binary search by id when we need time zone data.
	*
	* The format of this file is, I believe, Android's own, and undocumented.
	*
	* All this code assumes strings are US-ASCII.
	*/
	private static void readIndex() {
	RandomAccessFile indexFile = null;
	try {
	indexFile = new RandomAccessFile(INDEX_FILE_NAME, "r");

	// The database reserves 40 bytes for each id.
	final int SIZEOF_TZNAME = 40;
	// The database uses 32-bit (4 byte) integers.
	final int SIZEOF_TZINT = 4;

	byte[] idBytes = new byte[SIZEOF_TZNAME];

	int numEntries = (int) (indexFile.length() / (SIZEOF_TZNAME + 3*SIZEOF_TZINT));

	char[] idChars = new char[numEntries * SIZEOF_TZNAME];
	int[] idEnd = new int[numEntries];
	int idOffset = 0;

	byteOffsets = new int[numEntries];
	rawUtcOffsets = new int[numEntries];

	for (int i = 0; i < numEntries; i++) {
	indexFile.readFully(idBytes);
	byteOffsets[i] = indexFile.readInt();
	int length = indexFile.readInt();
	if (length < 44) {
	throw new AssertionError("length in index file < sizeof(tzhead)");
	}
	rawUtcOffsets[i] = indexFile.readInt();

	// Don't include null chars in the String
	int len = idBytes.length;
	for (int j = 0; j < len; j++) {
	if (idBytes[j] == 0) {
	break;
	}
	idChars[idOffset++] = (char) (idBytes[j] & 0xFF);
	}

	idEnd[i] = idOffset;
	}

	// We create one string containing all the ids, and then break that into substrings.
	// This way, all ids share a single char[] on the heap.
	String allIds = new String(idChars, 0, idOffset);
	ids = new String[numEntries];
	for (int i = 0; i < numEntries; i++) {
	ids[i] = allIds.substring(i == 0 ? 0 : idEnd[i - 1], idEnd[i]);
	}
	} catch (IOException ex) {
	throw new RuntimeException(ex);
	} finally {
	IoUtils.closeQuietly(indexFile);
	}
	}

	/**
	* Rather than open, read, and close the big data file each time we look up a time zone,
	* we map the big data file during startup, and then just use the ByteBuffer.
	*
	* At the moment, this "big" data file is about 160 KiB. At some point, that will be small
	* enough that we'll just keep the byte[] in memory.
	*/
	private static ByteBuffer mapData() {
	RandomAccessFile file = null;
	try {
	file = new RandomAccessFile(ZONE_FILE_NAME, "r");
	FileChannel channel = file.getChannel();
	ByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());
	buffer.order(ByteOrder.BIG_ENDIAN);
	return buffer;
	} catch (IOException ex) {
	throw new RuntimeException(ex);
	} finally {
	IoUtils.closeQuietly(file);
	}
	}

	private static TimeZone makeTimeZone(String id) throws IOException {
	// Work out where in the big data file this time zone is.
	int index = Arrays.binarySearch(ids, id);
	if (index < 0) {
	return null;
	}
	int start = byteOffsets[index];

	// We duplicate the ByteBuffer to allow unsynchronized access to this shared data,
	// despite Buffer's implicit position.
	ByteBuffer data = mappedData.duplicate();
	data.position(start);

	// Variable names beginning tzh_ correspond to those in "tzfile.h".
	// Check tzh_magic.
	if (data.getInt() != 0x545a6966) { // "TZif"
	return null;
	}

	// Skip the uninteresting part of the header.
	data.position(start + 32);

	// Read the sizes of the arrays we're about to read.
	int tzh_timecnt = data.getInt();
	int tzh_typecnt = data.getInt();
	int tzh_charcnt = data.getInt();

	int[] transitions = new int[tzh_timecnt];
	for (int i = 0; i < tzh_timecnt; ++i) {
	transitions[i] = data.getInt();
	}

	byte[] type = new byte[tzh_timecnt];
	data.get(type);

	int[] gmtOffsets = new int[tzh_typecnt];
	byte[] isDsts = new byte[tzh_typecnt];
	byte[] abbreviationIndexes = new byte[tzh_typecnt];
	for (int i = 0; i < tzh_typecnt; ++i) {
	gmtOffsets[i] = data.getInt();
	isDsts[i] = data.get();
	abbreviationIndexes[i] = data.get();
	}

	byte[] abbreviationList = new byte[tzh_charcnt];
	data.get(abbreviationList);

	return new ZoneInfo(id, transitions, type, gmtOffsets, isDsts,
	abbreviationIndexes, abbreviationList);
	}

	public static String[] getAvailableIDs() {
	return (String[]) ids.clone();
	}

	public static String[] getAvailableIDs(int rawOffset) {
	List<String> matches = new ArrayList<String>();
	for (int i = 0, end = rawUtcOffsets.length; i < end; i++) {
	if (rawUtcOffsets[i] == rawOffset) {
	matches.add(ids[i]);
	}
	}
	return matches.toArray(new String[matches.size()]);
	}

	public static TimeZone getSystemDefault() {
	synchronized (LOCK) {
	TimezoneGetter tzGetter = TimezoneGetter.getInstance();
	String zoneName = tzGetter != null ? tzGetter.getId() : null;
	if (zoneName != null) {
	zoneName = zoneName.trim();
	}
	if (zoneName == null \|\| zoneName.isEmpty()) {
	// use localtime for the simulator
	// TODO: what does that correspond to?
	zoneName = "localtime";
	}
	return TimeZone.getTimeZone(zoneName);
	}
	}

	public static TimeZone getTimeZone(String id) {
	if (id == null) {
	return null;
	}
	try {
	return makeTimeZone(id);
	} catch (IOException ignored) {
	return null;
	}
	}

	public static String getVersion() {
	return VERSION;
	}
	}