/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * particular file as subject to the "Classpath" exception as provided

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 */

package sun.util.calendar;

import  java.io.File;

import  java.io.FileInputStream;

import  java.io.FileNotFoundException;

import  java.io.IOException;

import  java.lang.ref.SoftReference;

import  java.security.AccessController;

import  java.security.PrivilegedAction;

import  java.security.PrivilegedActionException;

import  java.security.PrivilegedExceptionAction;

import  java.util.ArrayList;

import  java.util.HashMap;

import  java.util.List;

import  java.util.Map;

/**

 * <code>ZoneInfoFile</code> reads Zone information files in the

 * <java.home>/lib/zi directory and provides time zone

 * information in the form of a {@link ZoneInfo} object. Also, it

 * reads the ZoneInfoMappings file to obtain time zone IDs information

 * that is used by the {@link ZoneInfo} class. The directory layout

 * and data file formats are as follows.

 *

 * <p><strong>Directory layout</strong><p>

 *

 * All zone data files and ZoneInfoMappings are put under the

 * <java.home>/lib/zi directory. A path name for a given time

 * zone ID is a concatenation of <java.home>/lib/zi/ and the

 * time zone ID. (The file separator is replaced with the platform

 * dependent value. e.g., '\' for Win32.) An example layout will look

 * like as follows.

 * <blockquote>

 * <pre>

 * <java.home>/lib/zi/Africa/Addis_Ababa

 *                   /Africa/Dakar

 *                   /America/Los_Angeles

 *                   /Asia/Singapore

 *                   /EET

 *                   /Europe/Oslo

 *                   /GMT

 *                   /Pacific/Galapagos

 *                       ...

 *                   /ZoneInfoMappings

 * </pre>

 * </blockquote>

 *

 * A zone data file has specific information of each zone.

 * <code>ZoneInfoMappings</code> has global information of zone IDs so

 * that the information can be obtained without instantiating all time

 * zones.

 *

 * <p><strong>File format</strong><p>

 *

 * Two binary-file formats based on a simple Tag-Length-Value format are used

 * to describe TimeZone information. The generic format of a data file is:

 * <blockquote>

 * <pre>

 *    DataFile {

 *      u1              magic[7];

 *      u1              version;

 *      data_item       data[];

 *    }

 * </pre>

 * </blockquote>

 * where <code>magic</code> is a magic number identifying a file

 * format, <code>version</code> is the format version number, and

 * <code>data</code> is one or more <code>data_item</code>s. The

 * <code>data_item</code> structure is:

 * <blockquote>

 * <pre>

 *    data_item {

 *      u1              tag;

 *      u2              length;

 *      u1              value[length];

 *    }

 * </pre>

 * </blockquote>

 * where <code>tag</code> indicates the data type of the item,

 * <code>length</code> is a byte count of the following

 * <code>value</code> that is the content of item data.

 * <p>

 * All data is stored in the big-endian order. There is no boundary

 * alignment between date items.

 *

 * <p><strong>1. ZoneInfo data file</strong><p>

 *

 * Each ZoneInfo data file consists of the following members.

 * <br>

 * <blockquote>

 * <pre>

 *    ZoneInfoDataFile {

 *      u1              magic[7];

 *      u1              version;

 *      SET OF<sup>1</sup> {

 *        transition            transitions<sup>2</sup>;

 *        offset_table          offsets<sup>2</sup>;

 *        simpletimezone        stzparams<sup>2</sup>;

 *        raw_offset            rawoffset;

 *        dstsaving             dst;

 *        checksum              crc32;

 *        gmtoffsetwillchange   gmtflag<sup>2</sup>;

 *      }

 *   }

 *   1: an unordered collection of zero or one occurrences of each item

 *   2: optional item

 * </pre>

 * </blockquote>

 * <code>magic</code> is a byte-string constant identifying the

 * ZoneInfo data file.  This field must be <code>"javazi&#92;0"</code>

 * defined as {@link #JAVAZI_LABEL}.

 * <p>

 * <code>version</code> is the version number of the file format. This

 * will be used for compatibility check. This field must be

 * <code>0x01</code> in this version.

 * <p>

 * <code>transition</code>, <code>offset_table</code> and

 * <code>simpletimezone</code> have information of time transition

 * from the past to the future.  Therefore, these structures don't

 * exist if the zone didn't change zone names and haven't applied DST in

 * the past, and haven't planned to apply it.  (e.g. Asia/Tokyo zone)

 * <p>

 * <code>raw_offset</code>, <code>dstsaving</code> and <code>checksum</code>

 * exist in every zoneinfo file. They are used by TimeZone.class indirectly.

 *

 * <p><strong>1.1 <code>transition</code> structure</strong><p><a name="transition"></a>

 * <blockquote>

 * <pre>

 *    transition {

 *      u1      tag;              // 0x04 : constant

 *      u2      length;           // byte length of whole values

 *      s8      value[length/8];  // transitions in `long'

 *    }

 * </pre>

 * </blockquote>

 * See {@link ZoneInfo#transitions ZoneInfo.transitions} about the value.

 *

 * <p><strong>1.2 <code>offset_table</code> structure</strong><p>

 * <blockquote>

 * <pre>

 *    offset_table {

 *      u1      tag;              // 0x05 : constant

 *      u2      length;           // byte length of whole values

 *      s4      value[length/4];  // offset values in `int'

 *    }

 * </pre>

 * </blockquote>

 *

 * <p><strong>1.3 <code>simpletimezone</code> structure</strong><p>

 * See {@link ZoneInfo#simpleTimeZoneParams ZoneInfo.simpleTimeZoneParams}

 * about the value.

 * <blockquote>

 * <pre>

 *    simpletimezone {

 *      u1      tag;              // 0x06 : constant

 *      u2      length;           // byte length of whole values

 *      s4      value[length/4];  // SimpleTimeZone parameters

 *    }

 * </pre>

 * </blockquote>

 * See {@link ZoneInfo#offsets ZoneInfo.offsets} about the value.

 *

 * <p><strong>1.4 <code>raw_offset</code> structure</strong><p>

 * <blockquote>

 * <pre>

 *    raw_offset {

 *      u1      tag;              // 0x01 : constant

 *      u2      length;           // must be 4.

 *      s4      value;            // raw GMT offset [millisecond]

 *    }

 * </pre>

 * </blockquote>

 * See {@link ZoneInfo#rawOffset ZoneInfo.rawOffset} about the value.

 *

 * <p><strong>1.5 <code>dstsaving</code> structure</strong><p>

 * Value has dstSaving in seconds.

 * <blockquote>

 * <pre>

 *    dstsaving {

 *      u1      tag;              // 0x02 : constant

 *      u2      length;           // must be 2.

 *      s2      value;            // DST save value [second]

 *    }

 * </pre>

 * </blockquote>

 * See {@link ZoneInfo#dstSavings ZoneInfo.dstSavings} about value.

 *

 * <p><strong>1.6 <code>checksum</code> structure</strong><p>

 * <blockquote>

 * <pre>

 *    checksum {

 *      u1      tag;              // 0x03 : constant

 *      u2      length;           // must be 4.

 *      s4      value;            // CRC32 value of transitions

 *    }

 * </pre>

 * </blockquote>

 * See {@link ZoneInfo#checksum ZoneInfo.checksum}.

 *

 * <p><strong>1.7 <code>gmtoffsetwillchange</code> structure</strong><p>

 * This record has a flag value for {@link ZoneInfo#rawOffsetWillChange}.

 * If this record is not present in a zoneinfo file, 0 is assumed for

 * the value.

 * <blockquote>

 * <pre>

 *    gmtoffsetwillchange {

 *      u1      tag;             // 0x07 : constant

 *      u2      length;          // must be 1.

 *      u1      value;           // 1: if the GMT raw offset will change

 *                               // in the future, 0, otherwise.

 *     }

 * </pre>

 * </blockquote>

 *

 *

 * <p><strong>2. ZoneInfoMappings file</strong><p>

 *

 * The ZoneInfoMappings file consists of the following members.

 * <br>

 * <blockquote>

 * <pre>

 *    ZoneInfoMappings {

 *      u1      magic[7];

 *      u1      version;

 *      SET OF {

 *        versionName                   version;

 *        zone_id_table                 zoneIDs;

 *        raw_offset_table              rawoffsets;

 *        raw_offset_index_table        rawoffsetindices;

 *        alias_table                   aliases;

 *        excluded_list                 excludedList;

 *      }

 *   }

 * </pre>

 * </blockquote>

 *

 * <code>magic</code> is a byte-string constant which has the file type.

 * This field must be <code>"javazm&#92;0"</code> defined as {@link #JAVAZM_LABEL}.

 * <p>

 * <code>version</code> is the version number of this file

 * format. This will be used for compatibility check. This field must

 * be <code>0x01</code> in this version.

 * <p>

 * <code>versionName</code> shows which version of Olson's data has been used

 * to generate this ZoneInfoMappings. (e.g. <code>tzdata2000g</code>) <br>

 * This field is for trouble-shooting and isn't usually used in runtime.

 * <p>

 * <code>zone_id_table</code>, <code>raw_offset_index_table</code> and

 * <code>alias_table</code> are general information of supported

 * zones.

 *

 * <p><strong>2.1 <code>zone_id_table</code> structure</strong><p>

 * The list of zone IDs included in the zi database. The list does

 * <em>not</em> include zone IDs, if any, listed in excludedList.

 * <br>

 * <blockquote>

 * <pre>

 *    zone_id_table {

 *      u1      tag;              // 0x40 : constant

 *      u2      length;           // byte length of whole values

 *      u2      zone_id_count;

 *      zone_id value[zone_id_count];

 *    }

 *

 *    zone_id {

 *      u1      byte_length;      // byte length of id

 *      u1      id[byte_length];  // zone name string

 *    }

 * </pre>

 * </blockquote>

 *

 * <p><strong>2.2 <code>raw_offset_table</code> structure</strong><p>

 * <br>

 * <blockquote>

 * <pre>

 *    raw_offset_table {

 *      u1      tag;              // 0x41 : constant

 *      u2      length;           // byte length of whole values

 *      s4      value[length/4];  // raw GMT offset in milliseconds

 *   }

 * </pre>

 * </blockquote>

 *

 * <p><strong>2.3 <code>raw_offset_index_table</code> structure</strong><p>

 * <br>

 * <blockquote>

 * <pre>

 *    raw_offset_index_table {

 *      u1      tag;              // 0x42 : constant

 *      u2      length;           // byte length of whole values

 *      u1      value[length];

 *    }

 * </pre>

 * </blockquote>

 *

 * <p><strong>2.4 <code>alias_table</code> structure</strong><p>

 * <br>

 * <blockquote>

 * <pre>

 *   alias_table {

 *      u1      tag;              // 0x43 : constant

 *      u2      length;           // byte length of whole values

 *      u2      nentries;         // number of id-pairs

 *      id_pair value[nentries];

 *   }

 *

 *   id_pair {

 *      zone_id aliasname;

 *      zone_id ID;

 *   }

 * </pre>

 * </blockquote>

 *

 * <p><strong>2.5 <code>versionName</code> structure</strong><p>

 * <br>

 * <blockquote>

 * <pre>

 *   versionName {

 *      u1      tag;              // 0x44 : constant

 *      u2      length;           // byte length of whole values

 *      u1      value[length];

 *   }

 * </pre>

 * </blockquote>

 *

 * <p><strong>2.6 <code>excludeList</code> structure</strong><p>

 * The list of zone IDs whose zones will change their GMT offsets

 * (a.k.a. raw offsets) some time in the future. Those IDs must be

 * added to the list of zone IDs for getAvailableIDs(). Also they must

 * be examined for getAvailableIDs(int) to determine the

 * <em>current</em> GMT offsets.

 * <br>

 * <blockquote>

 * <pre>

 *   excluded_list {

 *      u1      tag;              // 0x45 : constant

 *      u2      length;           // byte length of whole values

 *      u2      nentries;         // number of zone_ids

 *      zone_id value[nentries];  // excluded zone IDs

 *   }

 * </pre>

 * </blockquote>

 *

 * @since 1.4

 */

public class ZoneInfoFile {

    /**

     * The magic number for the ZoneInfo data file format.

     */

    public static final byte[]  JAVAZI_LABEL = {

        (byte)'j', (byte)'a', (byte)'v', (byte)'a', (byte)'z', (byte)'i', (byte)'\0'

    };

    private static final int    JAVAZI_LABEL_LENGTH = JAVAZI_LABEL.length;

    /**

     * The ZoneInfo data file format version number. Must increase

     * one when any incompatible change has been made.

     */

    public static final byte    JAVAZI_VERSION = 0x01;

    /**

     * Raw offset data item tag.

     */

    public static final byte    TAG_RawOffset = 1;

    /**

     * Known last Daylight Saving Time save value data item tag.

     */

    public static final byte    TAG_LastDSTSaving = 2;

    /**

     * Checksum data item tag.

     */

    public static final byte    TAG_CRC32 = 3;

    /**

     * Transition data item tag.

     */

    public static final byte    TAG_Transition = 4;

    /**

     * Offset table data item tag.

     */

    public static final byte    TAG_Offset = 5;

    /**

     * SimpleTimeZone parameters data item tag.

     */

    public static final byte    TAG_SimpleTimeZone = 6;

    /**

     * Raw GMT offset will change in the future.

     */

    public static final byte    TAG_GMTOffsetWillChange = 7;

    /**

     * The ZoneInfoMappings file name.

     */

    public static final String  JAVAZM_FILE_NAME = "ZoneInfoMappings";

    /**

     * The magic number for the ZoneInfoMappings file format.

     */

    public static final byte[]  JAVAZM_LABEL = {

        (byte)'j', (byte)'a', (byte)'v', (byte)'a', (byte)'z', (byte)'m', (byte)'\0'

    };

    private static final int    JAVAZM_LABEL_LENGTH = JAVAZM_LABEL.length;

    /**

     * The ZoneInfoMappings file format version number. Must increase

     * one when any incompatible change has been made.

     */

    public static final byte    JAVAZM_VERSION = 0x01;

    /**

     * Time zone IDs data item tag.

     */

    public static final byte    TAG_ZoneIDs = 64;

    /**

     * Raw GMT offsets table data item tag.

     */

    public static final byte    TAG_RawOffsets = 65;

    /**

     * Indices to the raw GMT offset table data item tag.

     */

    public static final byte    TAG_RawOffsetIndices = 66;

    /**

     * Time zone aliases table data item tag.

     */

    public static final byte    TAG_ZoneAliases = 67;

    /**

     * Olson's public zone information version tag.

     */

    public static final byte    TAG_TZDataVersion = 68;

    /**

     * Excluded zones item tag. (Added in Mustang)

     */

    public static final byte    TAG_ExcludedZones = 69;

    private static Map<String, ZoneInfo> zoneInfoObjects = null;

    private static final String ziDir;

    static {

        String zi = (String) AccessController.doPrivileged(

                         new sun.security.action.GetPropertyAction("java.home"))

                    + File.separator + "lib" + File.separator + "zi";

        try {

            zi = new File(zi).getCanonicalPath();

        } catch (Exception e) {

        }

        ziDir = zi;

    }

    /**

     * Converts the given time zone ID to a platform dependent path

     * name. For example, "America/Los_Angeles" is converted to

     * "America\Los_Angeles" on Win32.

     * @return a modified ID replacing '/' with {@link

     * java.io.File#separatorChar File.separatorChar} if needed.

     */

    public static String getFileName(String ID) {

        if (File.separatorChar == '/') {

            return ID;

        }

        return ID.replace('/', File.separatorChar);

    }

    /**

     * Gets a ZoneInfo with the given GMT offset. The object

     * has its ID in the format of GMT{+|-}hh:mm.

     *

     * @param originalId the given custom id (before normalized such as "GMT+9")

     * @param gmtOffset GMT offset <em>in milliseconds</em>

     * @return a ZoneInfo constructed with the given GMT offset

     */

    public static ZoneInfo getCustomTimeZone(String originalId, int gmtOffset) {

        String id = toCustomID(gmtOffset);

        ZoneInfo zi = getFromCache(id);

        if (zi == null) {

            zi = new ZoneInfo(id, gmtOffset);

            zi = addToCache(id, zi);

            if (!id.equals(originalId)) {

                zi = addToCache(originalId, zi);

            }

        }

        return (ZoneInfo) zi.clone();

    }

    public static String toCustomID(int gmtOffset) {

        char sign;

        int offset = gmtOffset / 60000;

        if (offset >= 0) {