tarentry.java

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/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.
 *
 */

/*
 * This package is based on the work done by Timothy Gerard Endres
 * ([e-mail]) to whom the Ant project is very grateful for his great code.
 */

package org.apache.tools.tar;

import java.io.File;
import java.util.Date;
import java.util.Locale;

/**
 * This class represents an entry in a Tar archive. It consists
 * of the entry's header, as well as the entry's File. Entries
 * can be instantiated in one of three ways, depending on how
 * they are to be used.
 * <p>
 * TarEntries that are created from the header bytes read from
 * an archive are instantiated with the TarEntry( byte[] )
 * constructor. These entries will be used when extracting from
 * or listing the contents of an archive. These entries have their
 * header filled in using the header bytes. They also set the File
 * to null, since they reference an archive entry not a file.
 * <p>
 * TarEntries that are created from Files that are to be written
 * into an archive are instantiated with the TarEntry( File )
 * constructor. These entries have their header filled in using
 * the File's information. They also keep a reference to the File
 * for convenience when writing entries.
 * <p>
 * Finally, TarEntries can be constructed from nothing but a name.
 * This allows the programmer to construct the entry by hand, for
 * instance when only an InputStream is available for writing to
 * the archive, and the header information is constructed from
 * other information. In this case the header fields are set to
 * defaults and the File is set to null.
 *
 * <p>
 * The C structure for a Tar Entry's header is:
 * <pre>
 * struct header {
 * char name[NAMSIZ];
 * char mode[8];
 * char uid[8];
 * char gid[8];
 * char size[12];
 * char mtime[12];
 * char chksum[8];
 * char linkflag;
 * char linkname[NAMSIZ];
 * char magic[8];
 * char uname[TUNMLEN];
 * char gname[TGNMLEN];
 * char devmajor[8];
 * char devminor[8];
 * } header;
 * </pre>
 *
 */

public class TarEntry implements TarConstants {
    /** The entry's name. */
    private StringBuffer name;

    /** The entry's permission mode. */
    private int mode;

    /** The entry's user id. */
    private int userId;

    /** The entry's group id. */
    private int groupId;

    /** The entry's size. */
    private long size;

    /** The entry's modification time. */
    private long modTime;

    /** The entry's link flag. */
    private byte linkFlag;

    /** The entry's link name. */
    private StringBuffer linkName;

    /** The entry's magic tag. */
    private StringBuffer magic;

    /** The entry's user name. */
    private StringBuffer userName;

    /** The entry's group name. */
    private StringBuffer groupName;

    /** The entry's major device number. */
    private int devMajor;

    /** The entry's minor device number. */
    private int devMinor;

    /** The entry's file reference */
    private File file;

    /** Maximum length of a user's name in the tar file */
    public static final int MAX_NAMELEN = 31;

    /** Default permissions bits for directories */
    public static final int DEFAULT_DIR_MODE = 040755;

    /** Default permissions bits for files */
    public static final int DEFAULT_FILE_MODE = 0100644;

    /** Convert millis to seconds */
    public static final int MILLIS_PER_SECOND = 1000;

    /**
     * Construct an empty entry and prepares the header values.
     */
    private TarEntry () {
        this.magic = new StringBuffer(TMAGIC);
        this.name = new StringBuffer();
        this.linkName = new StringBuffer();

        String user = System.getProperty("user.name", "");

        if (user.length() > MAX_NAMELEN) {
            user = user.substring(0, MAX_NAMELEN);
        }

        this.userId = 0;
        this.groupId = 0;
        this.userName = new StringBuffer(user);
        this.groupName = new StringBuffer("");
        this.file = null;
    }

    /**
     * Construct an entry with only a name. This allows the programmer
     * to construct the entry's header "by hand". File is set to null.
     *
     * @param name the entry name
     */
    public TarEntry(String name) {
        this();

        boolean isDir = name.endsWith("/");

        this.devMajor = 0;
        this.devMinor = 0;
        this.name = new StringBuffer(name);
        this.mode = isDir ? DEFAULT_DIR_MODE : DEFAULT_FILE_MODE;
        this.linkFlag = isDir ? LF_DIR : LF_NORMAL;
        this.userId = 0;
        this.groupId = 0;
        this.size = 0;
        this.modTime = (new Date()).getTime() / MILLIS_PER_SECOND;
        this.linkName = new StringBuffer("");
        this.userName = new StringBuffer("");
        this.groupName = new StringBuffer("");
        this.devMajor = 0;
        this.devMinor = 0;

    }

    /**
     * Construct an entry with a name an a link flag.
     *
     * @param name the entry name
     * @param linkFlag the entry link flag.
     */
    public TarEntry(String name, byte linkFlag) {
        this(name);
        this.linkFlag = linkFlag;
    }

    /**
     * Construct an entry for a file. File is set to file, and the
     * header is constructed from information from the file.
     *
     * @param file The file that the entry represents.
     */
    public TarEntry(File file) {
        this();

        this.file = file;

        String fileName = file.getPath();
        String osname = System.getProperty("os.name").toLowerCase(Locale.US);

        if (osname != null) {

            // Strip off drive letters!
            // REVIEW Would a better check be "(File.separator == '\')"?

            if (osname.startsWith("windows")) {
                if (fileName.length() > 2) {
                    char ch1 = fileName.charAt(0);
                    char ch2 = fileName.charAt(1);

                    if (ch2 == ':'
                            && ((ch1 >= 'a' && ch1 <= 'z')
                                || (ch1 >= 'A' && ch1 <= 'Z'))) {
                        fileName = fileName.substring(2);
                    }
                }
            } else if (osname.indexOf("netware") > -1) {
                int colon = fileName.indexOf(':');
                if (colon != -1) {
                    fileName = fileName.substring(colon + 1);
                }
            }
        }

        fileName = fileName.replace(File.separatorChar, '/');

        // No absolute pathnames
        // Windows (and Posix?) paths can start with "\\NetworkDrive\",
        // so we loop on starting /'s.
        while (fileName.startsWith("/")) {
            fileName = fileName.substring(1);
        }

        this.linkName = new StringBuffer("");
        this.name = new StringBuffer(fileName);

        if (file.isDirectory()) {
            this.mode = DEFAULT_DIR_MODE;
            this.linkFlag = LF_DIR;

            if (this.name.charAt(this.name.length() - 1) != '/') {
                this.name.append("/");
            }
        } else {
            this.mode = DEFAULT_FILE_MODE;
            this.linkFlag = LF_NORMAL;
        }

        this.size = file.length();
        this.modTime = file.lastModified() / MILLIS_PER_SECOND;
        this.devMajor = 0;
        this.devMinor = 0;
    }

    /**
     * Construct an entry from an archive's header bytes. File is set
     * to null.
     *
     * @param headerBuf The header bytes from a tar archive entry.
     */
    public TarEntry(byte[] headerBuf) {
        this();
        this.parseTarHeader(headerBuf);
    }

    /**
     * Determine if the two entries are equal. Equality is determined
     * by the header names being equal.
     *
     * @param it Entry to be checked for equality.
     * @return True if the entries are equal.
     */
    public boolean equals(TarEntry it) {
        return this.getName().equals(it.getName());
    }

    /**
     * Determine if the two entries are equal. Equality is determined
     * by the header names being equal.
     *
     * @param it Entry to be checked for equality.
     * @return True if the entries are equal.
     */
    public boolean equals(Object it) {
        if (it == null || getClass() != it.getClass()) {
            return false;
        }
        return equals((TarEntry) it);
    }

    /**
     * Hashcodes are based on entry names.
     *
     * @return the entry hashcode
     */
    public int hashCode() {
        return getName().hashCode();
    }

    /**
     * Determine if the given entry is a descendant of this entry.
     * Descendancy is determined by the name of the descendant
     * starting with this entry's name.
     *
     * @param desc Entry to be checked as a descendent of this.
     * @return True if entry is a descendant of this.
     */
    public boolean isDescendent(TarEntry desc) {
        return desc.getName().startsWith(this.getName());
    }

    /**
     * Get this entry's name.