Ant example source code file (TarInputStream.java)

This example Ant source code file (TarInputStream.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

eof, filterinputstream, io, ioexception, ioexception, off, string, stringbuffer, sz, tarbuffer, tarbuffer, tarentry, tarentry, tarinputstream, tarinputstream

The TarInputStream.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.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * The TarInputStream reads a UNIX tar archive as an InputStream.
 * methods are provided to position at each successive entry in
 * the archive, and the read each entry as a normal input stream
 * using read().
 *
 */
public class TarInputStream extends FilterInputStream {

    // CheckStyle:VisibilityModifier OFF - bc
    protected boolean debug;
    protected boolean hasHitEOF;
    protected long entrySize;
    protected long entryOffset;
    protected byte[] readBuf;
    protected TarBuffer buffer;
    protected TarEntry currEntry;

    /**
     * This contents of this array is not used at all in this class,
     * it is only here to avoid repreated object creation during calls
     * to the no-arg read method.
     */
    protected byte[] oneBuf;

    // CheckStyle:VisibilityModifier ON

    /**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     */
    public TarInputStream(InputStream is) {
        this(is, TarBuffer.DEFAULT_BLKSIZE, TarBuffer.DEFAULT_RCDSIZE);
    }

    /**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     * @param blockSize the block size to use
     */
    public TarInputStream(InputStream is, int blockSize) {
        this(is, blockSize, TarBuffer.DEFAULT_RCDSIZE);
    }

    /**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     * @param blockSize the block size to use
     * @param recordSize the record size to use
     */
    public TarInputStream(InputStream is, int blockSize, int recordSize) {
        super(is);

        this.buffer = new TarBuffer(is, blockSize, recordSize);
        this.readBuf = null;
        this.oneBuf = new byte[1];
        this.debug = false;
        this.hasHitEOF = false;
    }

    /**
     * Sets the debugging flag.
     *
     * @param debug True to turn on debugging.
     */
    public void setDebug(boolean debug) {
        this.debug = debug;
        this.buffer.setDebug(debug);
    }

    /**
     * Closes this stream. Calls the TarBuffer's close() method.
     * @throws IOException on error
     */
    public void close() throws IOException {
        this.buffer.close();
    }

    /**
     * Get the record size being used by this stream's TarBuffer.
     *
     * @return The TarBuffer record size.
     */
    public int getRecordSize() {
        return this.buffer.getRecordSize();
    }

    /**
     * Get the available data that can be read from the current
     * entry in the archive. This does not indicate how much data
     * is left in the entire archive, only in the current entry.
     * This value is determined from the entry's size header field
     * and the amount of data already read from the current entry.
     * Integer.MAX_VALUE is returen in case more than Integer.MAX_VALUE
     * bytes are left in the current entry in the archive.
     *
     * @return The number of available bytes for the current entry.
     * @throws IOException for signature
     */
    public int available() throws IOException {
        if (this.entrySize - this.entryOffset > Integer.MAX_VALUE) {
            return Integer.MAX_VALUE;
        }
        return (int) (this.entrySize - this.entryOffset);
    }

    /**
     * Skip bytes in the input buffer. This skips bytes in the
     * current entry's data, not the entire archive, and will
     * stop at the end of the current entry's data if the number
     * to skip extends beyond that point.
     *
     * @param numToSkip The number of bytes to skip.
     * @return the number actually skipped
     * @throws IOException on error
     */
    public long skip(long numToSkip) throws IOException {
        // REVIEW
        // This is horribly inefficient, but it ensures that we
        // properly skip over bytes via the TarBuffer...
        //
        byte[] skipBuf = new byte[8 * 1024];
        long skip = numToSkip;
        while (skip > 0) {
            int realSkip = (int) (skip > skipBuf.length ? skipBuf.length : skip);
            int numRead = this.read(skipBuf, 0, realSkip);
            if (numRead == -1) {
                break;
            }
            skip -= numRead;
        }
        return (numToSkip - skip);
    }

    /**
     * Since we do not support marking just yet, we return false.
     *
     * @return False.
     */
    public boolean markSupported() {
        return false;
    }

    /**
     * Since we do not support marking just yet, we do nothing.
     *
     * @param markLimit The limit to mark.
     */
    public void mark(int markLimit) {
    }

    /**
     * Since we do not support marking just yet, we do nothing.
     */
    public void reset() {
    }

    /**
     * Get the next entry in this tar archive. This will skip
     * over any remaining data in the current entry, if there
     * is one, and place the input stream at the header of the
     * next entry, and read the header and instantiate a new
     * TarEntry from the header bytes and return that entry.
     * If there are no more entries in the archive, null will
     * be returned to indicate that the end of the archive has
     * been reached.
     *
     * @return The next TarEntry in the archive, or null.
     * @throws IOException on error
     */
    public TarEntry getNextEntry() throws IOException {
        if (this.hasHitEOF) {
            return null;
        }

        if (this.currEntry != null) {
            long numToSkip = this.entrySize - this.entryOffset;

            if (this.debug) {
                System.err.println("TarInputStream: SKIP currENTRY '"
                        + this.currEntry.getName() + "' SZ "
                        + this.entrySize + " OFF "
                        + this.entryOffset + "  skipping "
                        + numToSkip + " bytes");
            }

            if (numToSkip > 0) {
                this.skip(numToSkip);
            }

            this.readBuf = null;
        }

        byte[] headerBuf = this.buffer.readRecord();

        if (headerBuf == null) {
            if (this.debug) {
                System.err.println("READ NULL RECORD");
            }
            this.hasHitEOF = true;
        } else if (this.buffer.isEOFRecord(headerBuf)) {
            if (this.debug) {
                System.err.println("READ EOF RECORD");
            }
            this.hasHitEOF = true;
        }

        if (this.hasHitEOF) {
            this.currEntry = null;
        } else {
            this.currEntry = new TarEntry(headerBuf);

            if (this.debug) {
                System.err.println("TarInputStream: SET CURRENTRY '"
                        + this.currEntry.getName()
                        + "' size = "
                        + this.currEntry.getSize());
            }

            this.entryOffset = 0;

            this.entrySize = this.currEntry.getSize();
        }

        if (this.currEntry != null && this.currEntry.isGNULongNameEntry()) {
            // read in the name
            StringBuffer longName = new StringBuffer();
            byte[] buf = new byte[256];
            int length = 0;
            while ((length = read(buf)) >= 0) {
                longName.append(new String(buf, 0, length));
            }
            getNextEntry();
            if (this.currEntry == null) {
                // Bugzilla: 40334
                // Malformed tar file - long entry name not followed by entry
                return null;
            }
            // remove trailing null terminator
            if (longName.length() > 0
                && longName.charAt(longName.length() - 1) == 0) {
                longName.deleteCharAt(longName.length() - 1);
            }
            this.currEntry.setName(longName.toString());
        }

        return this.currEntry;
    }

    /**
     * Reads a byte from the current tar archive entry.
     *
     * This method simply calls read( byte[], int, int ).
     *
     * @return The byte read, or -1 at EOF.
     * @throws IOException on error
     */
    public int read() throws IOException {
        int num = this.read(this.oneBuf, 0, 1);
        return num == -1 ? -1 : ((int) this.oneBuf[0]) & 0xFF;
    }

    /**
     * Reads bytes from the current tar archive entry.
     *
     * This method is aware of the boundaries of the current
     * entry in the archive and will deal with them as if they
     * were this stream's start and EOF.
     *
     * @param buf The buffer into which to place bytes read.
     * @param offset The offset at which to place bytes read.
     * @param numToRead The number of bytes to read.
     * @return The number of bytes read, or -1 at EOF.
     * @throws IOException on error
     */
    public int read(byte[] buf, int offset, int numToRead) throws IOException {
        int totalRead = 0;

        if (this.entryOffset >= this.entrySize) {
            return -1;
        }

        if ((numToRead + this.entryOffset) > this.entrySize) {
            numToRead = (int) (this.entrySize - this.entryOffset);
        }

        if (this.readBuf != null) {
            int sz = (numToRead > this.readBuf.length) ? this.readBuf.length
                    : numToRead;

            System.arraycopy(this.readBuf, 0, buf, offset, sz);

            if (sz >= this.readBuf.length) {
                this.readBuf = null;
            } else {
                int newLen = this.readBuf.length - sz;
                byte[] newBuf = new byte[newLen];

                System.arraycopy(this.readBuf, sz, newBuf, 0, newLen);

                this.readBuf = newBuf;
            }

            totalRead += sz;
            numToRead -= sz;
            offset += sz;
        }

        while (numToRead > 0) {
            byte[] rec = this.buffer.readRecord();

            if (rec == null) {
                // Unexpected EOF!
                throw new IOException("unexpected EOF with " + numToRead
                        + " bytes unread");
            }

            int sz = numToRead;
            int recLen = rec.length;

            if (recLen > sz) {
                System.arraycopy(rec, 0, buf, offset, sz);

                this.readBuf = new byte[recLen - sz];

                System.arraycopy(rec, sz, this.readBuf, 0, recLen - sz);
            } else {
                sz = recLen;

                System.arraycopy(rec, 0, buf, offset, recLen);
            }

            totalRead += sz;
            numToRead -= sz;
            offset += sz;
        }

        this.entryOffset += totalRead;

        return totalRead;
    }

    /**
     * Copies the contents of the current tar archive entry directly into
     * an output stream.
     *
     * @param out The OutputStream into which to write the entry's data.
     * @throws IOException on error
     */
    public void copyEntryContents(OutputStream out) throws IOException {
        byte[] buf = new byte[32 * 1024];

        while (true) {
            int numRead = this.read(buf, 0, buf.length);

            if (numRead == -1) {
                break;
            }

            out.write(buf, 0, numRead);
        }
    }
}