Ant example source code file (TarEntry.java)

This example Ant source code file (TarEntry.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

devlen, gnamelen, io, max_namelen, millis_per_second, modtimelen, namelen, namelen, string, string, stringbuffer, stringbuffer, tarentry, tarentry, uidlen, util

The TarEntry.java source code

/*
 *  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
 * (time@ice.com) 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.
     *
     * @return This entry's name.
     */
    public String getName() {
        return this.name.toString();
    }

    /**
     * Set this entry's name.
     *
     * @param name This entry's new name.
     */
    public void setName(String name) {
        this.name = new StringBuffer(name);
    }

    /**
     * Set the mode for this entry
     *
     * @param mode the mode for this entry
     */
    public void setMode(int mode) {
        this.mode = mode;
    }

    /**
     * Get this entry's link name.
     *
     * @return This entry's link name.
     */
    public String getLinkName() {
        return this.linkName.toString();
    }

    /**
     * Get this entry's user id.
     *
     * @return This entry's user id.
     */
    public int getUserId() {
        return this.userId;
    }

    /**
     * Set this entry's user id.
     *
     * @param userId This entry's new user id.
     */
    public void setUserId(int userId) {
        this.userId = userId;
    }

    /**
     * Get this entry's group id.
     *
     * @return This entry's group id.
     */
    public int getGroupId() {
        return this.groupId;
    }

    /**
     * Set this entry's group id.
     *
     * @param groupId This entry's new group id.
     */
    public void setGroupId(int groupId) {
        this.groupId = groupId;
    }

    /**
     * Get this entry's user name.
     *
     * @return This entry's user name.
     */
    public String getUserName() {
        return this.userName.toString();
    }

    /**
     * Set this entry's user name.
     *
     * @param userName This entry's new user name.
     */
    public void setUserName(String userName) {
        this.userName = new StringBuffer(userName);
    }

    /**
     * Get this entry's group name.
     *
     * @return This entry's group name.
     */
    public String getGroupName() {
        return this.groupName.toString();
    }

    /**
     * Set this entry's group name.
     *
     * @param groupName This entry's new group name.
     */
    public void setGroupName(String groupName) {
        this.groupName = new StringBuffer(groupName);
    }

    /**
     * Convenience method to set this entry's group and user ids.
     *
     * @param userId This entry's new user id.
     * @param groupId This entry's new group id.
     */
    public void setIds(int userId, int groupId) {
        this.setUserId(userId);
        this.setGroupId(groupId);
    }

    /**
     * Convenience method to set this entry's group and user names.
     *
     * @param userName This entry's new user name.
     * @param groupName This entry's new group name.
     */
    public void setNames(String userName, String groupName) {
        this.setUserName(userName);
        this.setGroupName(groupName);
    }

    /**
     * Set this entry's modification time. The parameter passed
     * to this method is in "Java time".
     *
     * @param time This entry's new modification time.
     */
    public void setModTime(long time) {
        this.modTime = time / MILLIS_PER_SECOND;
    }

    /**
     * Set this entry's modification time.
     *
     * @param time This entry's new modification time.
     */
    public void setModTime(Date time) {
        this.modTime = time.getTime() / MILLIS_PER_SECOND;
    }

    /**
     * Set this entry's modification time.
     *
     * @return time This entry's new modification time.
     */
    public Date getModTime() {
        return new Date(this.modTime * MILLIS_PER_SECOND);
    }

    /**
     * Get this entry's file.
     *
     * @return This entry's file.
     */
    public File getFile() {
        return this.file;
    }

    /**
     * Get this entry's mode.
     *
     * @return This entry's mode.
     */
    public int getMode() {
        return this.mode;
    }

    /**
     * Get this entry's file size.
     *
     * @return This entry's file size.
     */
    public long getSize() {
        return this.size;
    }

    /**
     * Set this entry's file size.
     *
     * @param size This entry's new file size.
     */
    public void setSize(long size) {
        this.size = size;
    }


    /**
     * Indicate if this entry is a GNU long name block
     *
     * @return true if this is a long name extension provided by GNU tar
     */
    public boolean isGNULongNameEntry() {
        return linkFlag == LF_GNUTYPE_LONGNAME
                           && name.toString().equals(GNU_LONGLINK);
    }

    /**
     * Return whether or not this entry represents a directory.
     *
     * @return True if this entry is a directory.
     */
    public boolean isDirectory() {
        if (this.file != null) {
            return this.file.isDirectory();
        }

        if (this.linkFlag == LF_DIR) {
            return true;
        }

        if (this.getName().endsWith("/")) {
            return true;
        }

        return false;
    }

    /**
     * If this entry represents a file, and the file is a directory, return
     * an array of TarEntries for this entry's children.
     *
     * @return An array of TarEntry's for this entry's children.
     */
    public TarEntry[] getDirectoryEntries() {
        if (this.file == null || !this.file.isDirectory()) {
            return new TarEntry[0];
        }

        String[]   list = this.file.list();
        TarEntry[] result = new TarEntry[list.length];

        for (int i = 0; i < list.length; ++i) {
            result[i] = new TarEntry(new File(this.file, list[i]));
        }

        return result;
    }

    /**
     * Write an entry's header information to a header buffer.
     *
     * @param outbuf The tar entry header buffer to fill in.
     */
    public void writeEntryHeader(byte[] outbuf) {
        int offset = 0;

        offset = TarUtils.getNameBytes(this.name, outbuf, offset, NAMELEN);
        offset = TarUtils.getOctalBytes(this.mode, outbuf, offset, MODELEN);
        offset = TarUtils.getOctalBytes(this.userId, outbuf, offset, UIDLEN);
        offset = TarUtils.getOctalBytes(this.groupId, outbuf, offset, GIDLEN);
        offset = TarUtils.getLongOctalBytes(this.size, outbuf, offset, SIZELEN);
        offset = TarUtils.getLongOctalBytes(this.modTime, outbuf, offset, MODTIMELEN);

        int csOffset = offset;

        for (int c = 0; c < CHKSUMLEN; ++c) {
            outbuf[offset++] = (byte) ' ';
        }

        outbuf[offset++] = this.linkFlag;
        offset = TarUtils.getNameBytes(this.linkName, outbuf, offset, NAMELEN);
        offset = TarUtils.getNameBytes(this.magic, outbuf, offset, MAGICLEN);
        offset = TarUtils.getNameBytes(this.userName, outbuf, offset, UNAMELEN);
        offset = TarUtils.getNameBytes(this.groupName, outbuf, offset, GNAMELEN);
        offset = TarUtils.getOctalBytes(this.devMajor, outbuf, offset, DEVLEN);
        offset = TarUtils.getOctalBytes(this.devMinor, outbuf, offset, DEVLEN);

        while (offset < outbuf.length) {
            outbuf[offset++] = 0;
        }

        long chk = TarUtils.computeCheckSum(outbuf);

        TarUtils.getCheckSumOctalBytes(chk, outbuf, csOffset, CHKSUMLEN);
    }

    /**
     * Parse an entry's header information from a header buffer.
     *
     * @param header The tar entry header buffer to get information from.
     */
    public void parseTarHeader(byte[] header) {
        int offset = 0;

        this.name = TarUtils.parseName(header, offset, NAMELEN);
        offset += NAMELEN;
        this.mode = (int) TarUtils.parseOctal(header, offset, MODELEN);
        offset += MODELEN;
        this.userId = (int) TarUtils.parseOctal(header, offset, UIDLEN);
        offset += UIDLEN;
        this.groupId = (int) TarUtils.parseOctal(header, offset, GIDLEN);
        offset += GIDLEN;
        this.size = TarUtils.parseOctal(header, offset, SIZELEN);
        offset += SIZELEN;
        this.modTime = TarUtils.parseOctal(header, offset, MODTIMELEN);
        offset += MODTIMELEN;
        offset += CHKSUMLEN;
        this.linkFlag = header[offset++];
        this.linkName = TarUtils.parseName(header, offset, NAMELEN);
        offset += NAMELEN;
        this.magic = TarUtils.parseName(header, offset, MAGICLEN);
        offset += MAGICLEN;
        this.userName = TarUtils.parseName(header, offset, UNAMELEN);
        offset += UNAMELEN;
        this.groupName = TarUtils.parseName(header, offset, GNAMELEN);
        offset += GNAMELEN;
        this.devMajor = (int) TarUtils.parseOctal(header, offset, DEVLEN);
        offset += DEVLEN;
        this.devMinor = (int) TarUtils.parseOctal(header, offset, DEVLEN);
    }
}