    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 * http://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.commons.compress.archivers.zip;
    020
    021import static org.apache.commons.compress.archivers.zip.ZipConstants.SHORT;
    022import static org.apache.commons.compress.archivers.zip.ZipConstants.WORD;
    023
    024import java.nio.charset.Charset;
    025import java.util.zip.CRC32;
    026import java.util.zip.ZipException;
    027
    028/**
    029 * Adds Unix file permission and UID/GID fields as well as symbolic
    030 * link handling.
    031 *
    032 * <p>This class uses the ASi extra field in the format:</p>
    033 * <pre>
    034 *         Value         Size            Description
    035 *         -----         ----            -----------
    036 * (Unix3) 0x756e        Short           tag for this extra block type
    037 *         TSize         Short           total data size for this block
    038 *         CRC           Long            CRC-32 of the remaining data
    039 *         Mode          Short           file permissions
    040 *         SizDev        Long            symlink'd size OR major/minor dev num
    041 *         UID           Short           user ID
    042 *         GID           Short           group ID
    043 *         (var.)        variable        symbolic link file name
    044 * </pre>
    045 * <p>taken from appnote.iz (Info-ZIP note, 981119) found at <a
    046 * href="ftp://ftp.uu.net/pub/archiving/zip/doc/">ftp://ftp.uu.net/pub/archiving/zip/doc/</a></p>
    047 *
    048 * <p>Short is two bytes and Long is four bytes in big endian byte and
    049 * word order, device numbers are currently not supported.</p>
    050 * @NotThreadSafe
    051 *
    052 * <p>Since the documentation this class is based upon doesn't mention
    053 * the character encoding of the file name at all, it is assumed that
    054 * it uses the current platform's default encoding.</p>
    055 */
    056public class AsiExtraField implements ZipExtraField, UnixStat, Cloneable {
    057
    058    private static final ZipShort HEADER_ID = new ZipShort(0x756E);
    059    private static final int      MIN_SIZE = WORD + SHORT + WORD + SHORT + SHORT;
    060    /**
    061     * Standard Unix stat(2) file mode.
    062     */
    063    private int mode;
    064    /**
    065     * User ID.
    066     */
    067    private int uid;
    068    /**
    069     * Group ID.
    070     */
    071    private int gid;
    072    /**
    073     * File this entry points to, if it is a symbolic link.
    074     *
    075     * <p>empty string - if entry is not a symbolic link.</p>
    076     */
    077    private String link = "";
    078    /**
    079     * Is this an entry for a directory?
    080     */
    081    private boolean dirFlag;
    082
    083    /**
    084     * Instance used to calculate checksums.
    085     */
    086    private CRC32 crc = new CRC32();
    087
    088    /** Constructor for AsiExtraField. */
    089    public AsiExtraField() {
    090    }
    091
    092    @Override
    093    public Object clone() {
    094        try {
    095            final AsiExtraField cloned = (AsiExtraField) super.clone();
    096            cloned.crc = new CRC32();
    097            return cloned;
    098        } catch (final CloneNotSupportedException cnfe) {
    099            // impossible
    100            throw new UnsupportedOperationException(cnfe); //NOSONAR
    101        }
    102    }
    103
    104    /**
    105     * Delegate to local file data.
    106     * @return the local file data
    107     */
    108    @Override
    109    public byte[] getCentralDirectoryData() {
    110        return getLocalFileDataData();
    111    }
    112
    113    /**
    114     * Delegate to local file data.
    115     * @return the centralDirectory length
    116     */
    117    @Override
    118    public ZipShort getCentralDirectoryLength() {
    119        return getLocalFileDataLength();
    120    }
    121
    122    /**
    123     * Get the group id.
    124     * @return the group id
    125     */
    126    public int getGroupId() {
    127        return gid;
    128    }
    129
    130    /**
    131     * The Header-ID.
    132     * @return the value for the header id for this extrafield
    133     */
    134    @Override
    135    public ZipShort getHeaderId() {
    136        return HEADER_ID;
    137    }
    138
    139    /**
    140     * Name of linked file
    141     *
    142     * @return name of the file this entry links to if it is a
    143     *         symbolic link, the empty string otherwise.
    144     */
    145    public String getLinkedFile() {
    146        return link;
    147    }
    148
    149    /**
    150     * The actual data to put into local file data - without Header-ID
    151     * or length specifier.
    152     * @return get the data
    153     */
    154    @Override
    155    public byte[] getLocalFileDataData() {
    156        // CRC will be added later
    157        final byte[] data = new byte[getLocalFileDataLength().getValue() - WORD];
    158        System.arraycopy(ZipShort.getBytes(getMode()), 0, data, 0, 2);
    159
    160        final byte[] linkArray = getLinkedFile().getBytes(Charset.defaultCharset()); // Uses default charset - see class Javadoc
    161        // CheckStyle:MagicNumber OFF
    162        System.arraycopy(ZipLong.getBytes(linkArray.length), 0, data, 2, WORD);
    163
    164        System.arraycopy(ZipShort.getBytes(getUserId()), 0, data, 6, 2);
    165        System.arraycopy(ZipShort.getBytes(getGroupId()), 0, data, 8, 2);
    166
    167        System.arraycopy(linkArray, 0, data, 10, linkArray.length);
    168        // CheckStyle:MagicNumber ON
    169
    170        crc.reset();
    171        crc.update(data);
    172        final long checksum = crc.getValue();
    173
    174        final byte[] result = new byte[data.length + WORD];
    175        System.arraycopy(ZipLong.getBytes(checksum), 0, result, 0, WORD);
    176        System.arraycopy(data, 0, result, WORD, data.length);
    177        return result;
    178    }
    179
    180    /**
    181     * Length of the extra field in the local file data - without
    182     * Header-ID or length specifier.
    183     * @return a {@code ZipShort} for the length of the data of this extra field
    184     */
    185    @Override
    186    public ZipShort getLocalFileDataLength() {
    187        // @formatter:off
    188        return new ZipShort(WORD      // CRC
    189                          + 2         // Mode
    190                          + WORD      // SizDev
    191                          + 2         // UID
    192                          + 2         // GID
    193                          + getLinkedFile().getBytes(Charset.defaultCharset()).length);
    194                          // Uses default charset - see class Javadoc
    195        // @formatter:on
    196    }
    197
    198    /**
    199     * File mode of this file.
    200     * @return the file mode
    201     */
    202    public int getMode() {
    203        return mode;
    204    }
    205
    206    /**
    207     * Get the file mode for given permissions with the correct file type.
    208     * @param mode the mode
    209     * @return the type with the mode
    210     */
    211    protected int getMode(final int mode) {
    212        int type = FILE_FLAG;
    213        if (isLink()) {
    214            type = LINK_FLAG;
    215        } else if (isDirectory()) {
    216            type = DIR_FLAG;
    217        }
    218        return type | (mode & PERM_MASK);
    219    }
    220
    221    /**
    222     * Get the user id.
    223     * @return the user id
    224     */
    225    public int getUserId() {
    226        return uid;
    227    }
    228
    229    /**
    230     * Is this entry a directory?
    231     * @return true if this entry is a directory
    232     */
    233    public boolean isDirectory() {
    234        return dirFlag && !isLink();
    235    }
    236
    237    /**
    238     * Is this entry a symbolic link?
    239     * @return true if this is a symbolic link
    240     */
    241    public boolean isLink() {
    242        return !getLinkedFile().isEmpty();
    243    }
    244
    245    /**
    246     * Doesn't do anything special since this class always uses the
    247     * same data in central directory and local file data.
    248     */
    249    @Override
    250    public void parseFromCentralDirectoryData(final byte[] buffer, final int offset,
    251                                              final int length)
    252        throws ZipException {
    253        parseFromLocalFileData(buffer, offset, length);
    254    }
    255
    256    /**
    257     * Populate data from this array as if it was in local file data.
    258     * @param data an array of bytes
    259     * @param offset the start offset
    260     * @param length the number of bytes in the array from offset
    261     * @throws ZipException on error
    262     */
    263    @Override
    264    public void parseFromLocalFileData(final byte[] data, final int offset, final int length)
    265        throws ZipException {
    266        if (length < MIN_SIZE) {
    267            throw new ZipException("The length is too short, only "
    268                    + length + " bytes, expected at least " + MIN_SIZE);
    269        }
    270
    271        final long givenChecksum = ZipLong.getValue(data, offset);
    272        final byte[] tmp = new byte[length - WORD];
    273        System.arraycopy(data, offset + WORD, tmp, 0, length - WORD);
    274        crc.reset();
    275        crc.update(tmp);
    276        final long realChecksum = crc.getValue();
    277        if (givenChecksum != realChecksum) {
    278            throw new ZipException("Bad CRC checksum, expected "
    279                                   + Long.toHexString(givenChecksum)
    280                                   + " instead of "
    281                                   + Long.toHexString(realChecksum));
    282        }
    283
    284        final int newMode = ZipShort.getValue(tmp, 0);
    285        // CheckStyle:MagicNumber OFF
    286        final int linkArrayLength = (int) ZipLong.getValue(tmp, 2);
    287        if (linkArrayLength < 0 || linkArrayLength > tmp.length - 10) {
    288            throw new ZipException("Bad symbolic link name length " + linkArrayLength
    289                + " in ASI extra field");
    290        }
    291        uid = ZipShort.getValue(tmp, 6);
    292        gid = ZipShort.getValue(tmp, 8);
    293        if (linkArrayLength == 0) {
    294            link = "";
    295        } else {
    296            final byte[] linkArray = new byte[linkArrayLength];
    297            System.arraycopy(tmp, 10, linkArray, 0, linkArrayLength);
    298            link = new String(linkArray, Charset.defaultCharset()); // Uses default charset - see class Javadoc
    299        }
    300        // CheckStyle:MagicNumber ON
    301        setDirectory((newMode & DIR_FLAG) != 0);
    302        setMode(newMode);
    303    }
    304
    305    /**
    306     * Indicate whether this entry is a directory.
    307     * @param dirFlag if true, this entry is a directory
    308     */
    309    public void setDirectory(final boolean dirFlag) {
    310        this.dirFlag = dirFlag;
    311        mode = getMode(mode);
    312    }
    313
    314    /**
    315     * Set the group id.
    316     * @param gid the group id
    317     */
    318    public void setGroupId(final int gid) {
    319        this.gid = gid;
    320    }
    321
    322    /**
    323     * Indicate that this entry is a symbolic link to the given file name.
    324     *
    325     * @param name Name of the file this entry links to, empty String
    326     *             if it is not a symbolic link.
    327     */
    328    public void setLinkedFile(final String name) {
    329        link = name;
    330        mode = getMode(mode);
    331    }
    332
    333    /**
    334     * File mode of this file.
    335     * @param mode the file mode
    336     */
    337    public void setMode(final int mode) {
    338        this.mode = getMode(mode);
    339    }
    340
    341    /**
    342     * Set the user id.
    343     * @param uid the user id
    344     */
    345    public void setUserId(final int uid) {
    346        this.uid = uid;
    347    }
    348}