/*
 *  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.commons.compress.archivers.tar;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.compress.archivers.ArchiveEntry;
import org.apache.commons.compress.archivers.ArchiveInputStream;
import org.apache.commons.compress.archivers.zip.ZipEncoding;
import org.apache.commons.compress.archivers.zip.ZipEncodingHelper;
import org.apache.commons.compress.utils.ArchiveUtils;
import org.apache.commons.compress.utils.CharsetNames;
import org.apache.commons.compress.utils.IOUtils;

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().
@NotThreadSafe
/**
 * 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().
 * @NotThreadSafe
 */
public class TarArchiveInputStream extends ArchiveInputStream {

    private static final int SMALL_BUFFER_SIZE = 256;

    private final byte[] smallBuf = new byte[SMALL_BUFFER_SIZE];

    
The size the TAR header /** The size the TAR header */
    private final int recordSize;

    
The size of a block /** The size of a block */
    private final int blockSize;

    
True if file has hit EOF /** True if file has hit EOF */
    private boolean hasHitEOF;

    
Size of the current entry /** Size of the current entry */
    private long entrySize;

    
How far into the entry the stream is at /** How far into the entry the stream is at */
    private long entryOffset;

    
An input stream to read from /** An input stream to read from */
    private final InputStream is;

    
The meta-data about the current entry /** The meta-data about the current entry */
    private TarArchiveEntry currEntry;

    
The encoding of the file /** The encoding of the file */
    private final ZipEncoding zipEncoding;

    // the provided encoding (for unit tests)
    final String encoding;

    // the global PAX header
    private Map<String, String> globalPaxHeaders = new HashMap<>();

    
Constructor for TarInputStream.
Params:
is – the input stream to use/**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     */
    public TarArchiveInputStream(final InputStream is) {
        this(is, TarConstants.DEFAULT_BLKSIZE, TarConstants.DEFAULT_RCDSIZE);
    }

    
Constructor for TarInputStream.
Params:
is – the input stream to use
encoding – name of the encoding to use for file names
Since:
1.4/**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     * @param encoding name of the encoding to use for file names
     * @since 1.4
     */
    public TarArchiveInputStream(final InputStream is, final String encoding) {
        this(is, TarConstants.DEFAULT_BLKSIZE, TarConstants.DEFAULT_RCDSIZE,
             encoding);
    }

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

    
Constructor for TarInputStream.
Params:
is – the input stream to use
blockSize – the block size to use
encoding – name of the encoding to use for file names
Since:
1.4/**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     * @param blockSize the block size to use
     * @param encoding name of the encoding to use for file names
     * @since 1.4
     */
    public TarArchiveInputStream(final InputStream is, final int blockSize,
                                 final String encoding) {
        this(is, blockSize, TarConstants.DEFAULT_RCDSIZE, encoding);
    }

    
Constructor for TarInputStream.
Params:
is – the input stream to use
blockSize – the block size to use
recordSize – the record size to use/**
     * 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 TarArchiveInputStream(final InputStream is, final int blockSize, final int recordSize) {
        this(is, blockSize, recordSize, null);
    }

    
Constructor for TarInputStream.
Params:
is – the input stream to use
blockSize – the block size to use
recordSize – the record size to use
encoding – name of the encoding to use for file names
Since:
1.4/**
     * Constructor for TarInputStream.
     * @param is the input stream to use
     * @param blockSize the block size to use
     * @param recordSize the record size to use
     * @param encoding name of the encoding to use for file names
     * @since 1.4
     */
    public TarArchiveInputStream(final InputStream is, final int blockSize, final int recordSize,
                                 final String encoding) {
        this.is = is;
        this.hasHitEOF = false;
        this.encoding = encoding;
        this.zipEncoding = ZipEncodingHelper.getZipEncoding(encoding);
        this.recordSize = recordSize;
        this.blockSize = blockSize;
    }

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

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

    
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 returned in case more than Integer.MAX_VALUE
bytes are left in the current entry in the archive.
Throws:
IOException – for signature
Returns:
The number of available bytes for the current entry./**
     * 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 returned 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
     */
    @Override
    public int available() throws IOException {
        if (isDirectory()) {
            return 0;
        }
        if (entrySize - entryOffset > Integer.MAX_VALUE) {
            return Integer.MAX_VALUE;
        }
        return (int) (entrySize - entryOffset);
    }


    
Skips over and discards n bytes of data from this input
stream. The skip method may, for a variety of reasons, end
up skipping over some smaller number of bytes, possibly 0.
This may result from any of a number of conditions; reaching end of file
or end of entry before n bytes have been skipped; are only
two possibilities. The actual number of bytes skipped is returned. If
n is negative, no bytes are skipped.
Params:
n – 
           the number of bytes to be skipped.
Throws:
IOException – 
               if some other I/O error occurs.
Returns:
the actual number of bytes skipped./**
     * Skips over and discards <code>n</code> bytes of data from this input
     * stream. The <code>skip</code> method may, for a variety of reasons, end
     * up skipping over some smaller number of bytes, possibly <code>0</code>.
     * This may result from any of a number of conditions; reaching end of file
     * or end of entry before <code>n</code> bytes have been skipped; are only
     * two possibilities. The actual number of bytes skipped is returned. If
     * <code>n</code> is negative, no bytes are skipped.
     *
     *
     * @param n
     *            the number of bytes to be skipped.
     * @return the actual number of bytes skipped.
     * @throws IOException
     *                if some other I/O error occurs.
     */
    @Override
    public long skip(final long n) throws IOException {
        if (n <= 0 || isDirectory()) {
            return 0;
        }

        final long available = entrySize - entryOffset;
        final long skipped = IOUtils.skip(is, Math.min(n, available));
        count(skipped);
        entryOffset += skipped;
        return skipped;
    }

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

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

    
Since we do not support marking just yet, we do nothing.
/**
     * Since we do not support marking just yet, we do nothing.
     */
    @Override
    public synchronized 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.
Throws:
IOException – on error
Returns:
The next TarEntry in the archive, or null./**
     * 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 TarArchiveEntry getNextTarEntry() throws IOException {
        if (isAtEOF()) {
            return null;
        }

        if (currEntry != null) {
            /* Skip will only go to the end of the current entry */
            IOUtils.skip(this, Long.MAX_VALUE);

            /* skip to the end of the last record */
            skipRecordPadding();
        }

        final byte[] headerBuf = getRecord();

        if (headerBuf == null) {
            /* hit EOF */
            currEntry = null;
            return null;
        }

        try {
            currEntry = new TarArchiveEntry(headerBuf, zipEncoding);
        } catch (final IllegalArgumentException e) {
            throw new IOException("Error detected parsing the header", e);
        }

        entryOffset = 0;
        entrySize = currEntry.getSize();

        if (currEntry.isGNULongLinkEntry()) {
            final byte[] longLinkData = getLongNameData();
            if (longLinkData == null) {
                // Bugzilla: 40334
                // Malformed tar file - long link entry name not followed by
                // entry
                return null;
            }
            currEntry.setLinkName(zipEncoding.decode(longLinkData));
        }

        if (currEntry.isGNULongNameEntry()) {
            final byte[] longNameData = getLongNameData();
            if (longNameData == null) {
                // Bugzilla: 40334
                // Malformed tar file - long entry name not followed by
                // entry
                return null;
            }
            currEntry.setName(zipEncoding.decode(longNameData));
        }

        if (currEntry.isGlobalPaxHeader()){ // Process Global Pax headers
            readGlobalPaxHeaders();
        }

        if (currEntry.isPaxHeader()){ // Process Pax headers
            paxHeaders();
        } else if (!globalPaxHeaders.isEmpty()) {
            applyPaxHeadersToCurrentEntry(globalPaxHeaders);
        }

        if (currEntry.isOldGNUSparse()){ // Process sparse files
            readOldGNUSparse();
        }

        // If the size of the next element in the archive has changed
        // due to a new size being reported in the posix header
        // information, we update entrySize here so that it contains
        // the correct value.
        entrySize = currEntry.getSize();

        return currEntry;
    }

    
The last record block should be written at the full size, so skip any
additional space used to fill a record after an entry
/**
     * The last record block should be written at the full size, so skip any
     * additional space used to fill a record after an entry
     */
    private void skipRecordPadding() throws IOException {
        if (!isDirectory() && this.entrySize > 0 && this.entrySize % this.recordSize != 0) {
            final long numRecords = (this.entrySize / this.recordSize) + 1;
            final long padding = (numRecords * this.recordSize) - this.entrySize;
            final long skipped = IOUtils.skip(is, padding);
            count(skipped);
        }
    }

    
Get the next entry in this tar archive as longname data.
Throws:
IOException – on error
Returns:
The next entry in the archive as longname data, or null./**
     * Get the next entry in this tar archive as longname data.
     *
     * @return The next entry in the archive as longname data, or null.
     * @throws IOException on error
     */
    protected byte[] getLongNameData() throws IOException {
        // read in the name
        final ByteArrayOutputStream longName = new ByteArrayOutputStream();
        int length = 0;
        while ((length = read(smallBuf)) >= 0) {
            longName.write(smallBuf, 0, length);
        }
        getNextEntry();
        if (currEntry == null) {
            // Bugzilla: 40334
            // Malformed tar file - long entry name not followed by entry
            return null;
        }
        byte[] longNameData = longName.toByteArray();
        // remove trailing null terminator(s)
        length = longNameData.length;
        while (length > 0 && longNameData[length - 1] == 0) {
            --length;
        }
        if (length != longNameData.length) {
            final byte[] l = new byte[length];
            System.arraycopy(longNameData, 0, l, 0, length);
            longNameData = l;
        }
        return longNameData;
    }

    
Get the next record 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.
If there are no more entries in the archive, null will be returned to indicate that the end of the archive has been reached. At the same time the hasHitEOF marker will be set to true.
Throws:
IOException – on error
Returns:
The next header in the archive, or null./**
     * Get the next record 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.
     *
     * <p>If there are no more entries in the archive, null will be
     * returned to indicate that the end of the archive has been
     * reached.  At the same time the {@code hasHitEOF} marker will be
     * set to true.</p>
     *
     * @return The next header in the archive, or null.
     * @throws IOException on error
     */
    private byte[] getRecord() throws IOException {
        byte[] headerBuf = readRecord();
        setAtEOF(isEOFRecord(headerBuf));
        if (isAtEOF() && headerBuf != null) {
            tryToConsumeSecondEOFRecord();
            consumeRemainderOfLastBlock();
            headerBuf = null;
        }
        return headerBuf;
    }

    
Determine if an archive record indicate End of Archive. End of
archive is indicated by a record that consists entirely of null bytes.
Params:
record – The record data to check.
Returns:
true if the record data is an End of Archive/**
     * Determine if an archive record indicate End of Archive. End of
     * archive is indicated by a record that consists entirely of null bytes.
     *
     * @param record The record data to check.
     * @return true if the record data is an End of Archive
     */
    protected boolean isEOFRecord(final byte[] record) {
        return record == null || ArchiveUtils.isArrayZero(record, recordSize);
    }

    
Read a record from the input stream and return the data.
Throws:
IOException – on error
Returns:
The record data or null if EOF has been hit./**
     * Read a record from the input stream and return the data.
     *
     * @return The record data or null if EOF has been hit.
     * @throws IOException on error
     */
    protected byte[] readRecord() throws IOException {

        final byte[] record = new byte[recordSize];

        final int readNow = IOUtils.readFully(is, record);
        count(readNow);
        if (readNow != recordSize) {
            return null;
        }

        return record;
    }

    private void readGlobalPaxHeaders() throws IOException {
        globalPaxHeaders = parsePaxHeaders(this);
        getNextEntry(); // Get the actual file entry
    }

    private void paxHeaders() throws IOException{
        final Map<String, String> headers = parsePaxHeaders(this);
        getNextEntry(); // Get the actual file entry
        applyPaxHeadersToCurrentEntry(headers);
    }

    // NOTE, using a Map here makes it impossible to ever support GNU
    // sparse files using the PAX Format 0.0, see
    // https://www.gnu.org/software/tar/manual/html_section/tar_92.html#SEC188
    Map<String, String> parsePaxHeaders(final InputStream i)
        throws IOException {
        final Map<String, String> headers = new HashMap<>(globalPaxHeaders);
        // Format is "length keyword=value\n";
        while(true){ // get length
            int ch;
            int len = 0;
            int read = 0;
            while((ch = i.read()) != -1) {
                read++;
                if (ch == '\n') { // blank line in header
                    break;
                } else if (ch == ' '){ // End of length string
                    // Get keyword
                    final ByteArrayOutputStream coll = new ByteArrayOutputStream();
                    while((ch = i.read()) != -1) {
                        read++;
                        if (ch == '='){ // end of keyword
                            final String keyword = coll.toString(CharsetNames.UTF_8);
                            // Get rest of entry
                            final int restLen = len - read;
                            if (restLen == 1) { // only NL
                                headers.remove(keyword);
                            } else {
                                final byte[] rest = new byte[restLen];
                                final int got = IOUtils.readFully(i, rest);
                                if (got != restLen) {
                                    throw new IOException("Failed to read "
                                                          + "Paxheader. Expected "
                                                          + restLen
                                                          + " bytes, read "
                                                          + got);
                                }
                                // Drop trailing NL
                                final String value = new String(rest, 0,
                                                          restLen - 1, CharsetNames.UTF_8);
                                headers.put(keyword, value);
                            }
                            break;
                        }
                        coll.write((byte) ch);
                    }
                    break; // Processed single header
                }
                len *= 10;
                len += ch - '0';
            }
            if (ch == -1){ // EOF
                break;
            }
        }
        return headers;
    }

    private void applyPaxHeadersToCurrentEntry(final Map<String, String> headers) {
        currEntry.updateEntryFromPaxHeaders(headers);

    }

    
Adds the sparse chunks from the current entry to the sparse chunks,
including any additional sparse entries following the current entry.
Throws:
IOException – on error
@todo
Sparse files get not yet really processed./**
     * Adds the sparse chunks from the current entry to the sparse chunks,
     * including any additional sparse entries following the current entry.
     *
     * @throws IOException on error
     *
     * @todo Sparse files get not yet really processed.
     */
    private void readOldGNUSparse() throws IOException {
        /* we do not really process sparse files yet
        sparses = new ArrayList();
        sparses.addAll(currEntry.getSparses());
        */
        if (currEntry.isExtended()) {
            TarArchiveSparseEntry entry;
            do {
                final byte[] headerBuf = getRecord();
                if (headerBuf == null) {
                    currEntry = null;
                    break;
                }
                entry = new TarArchiveSparseEntry(headerBuf);
                /* we do not really process sparse files yet
                sparses.addAll(entry.getSparses());
                */
            } while (entry.isExtended());
        }
    }

    private boolean isDirectory() {
        return currEntry != null && currEntry.isDirectory();
    }

    
Returns the next Archive Entry in this Stream.
Throws:
IOException – if the next entry could not be read
Returns:
the next entry, or null if there are no more entries/**
     * Returns the next Archive Entry in this Stream.
     *
     * @return the next entry,
     *         or {@code null} if there are no more entries
     * @throws IOException if the next entry could not be read
     */
    @Override
    public ArchiveEntry getNextEntry() throws IOException {
        return getNextTarEntry();
    }

    
Tries to read the next record rewinding the stream if it is not a EOF record.
This is meant to protect against cases where a tar
implementation has written only one EOF record when two are
expected.  Actually this won't help since a non-conforming
implementation likely won't fill full blocks consisting of - by
default - ten records either so we probably have already read
beyond the archive anyway.
/**
     * Tries to read the next record rewinding the stream if it is not a EOF record.
     *
     * <p>This is meant to protect against cases where a tar
     * implementation has written only one EOF record when two are
     * expected.  Actually this won't help since a non-conforming
     * implementation likely won't fill full blocks consisting of - by
     * default - ten records either so we probably have already read
     * beyond the archive anyway.</p>
     */
    private void tryToConsumeSecondEOFRecord() throws IOException {
        boolean shouldReset = true;
        final boolean marked = is.markSupported();
        if (marked) {
            is.mark(recordSize);
        }
        try {
            shouldReset = !isEOFRecord(readRecord());
        } finally {
            if (shouldReset && marked) {
                pushedBackBytes(recordSize);
            	is.reset();
            }
        }
    }

    
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.
Params:
buf – The buffer into which to place bytes read.
offset – The offset at which to place bytes read.
numToRead – The number of bytes to read.
Throws:
IOException – on error
Returns:
The number of bytes read, or -1 at EOF./**
     * 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
     */
    @Override
    public int read(final byte[] buf, final int offset, int numToRead) throws IOException {
    	int totalRead = 0;

        if (isAtEOF() || isDirectory() || entryOffset >= entrySize) {
            return -1;
        }

        if (currEntry == null) {
            throw new IllegalStateException("No current tar entry");
        }

        numToRead = Math.min(numToRead, available());

        totalRead = is.read(buf, offset, numToRead);

        if (totalRead == -1) {
            if (numToRead > 0) {
                throw new IOException("Truncated TAR archive");
            }
            setAtEOF(true);
        } else {
            count(totalRead);
            entryOffset += totalRead;
        }

        return totalRead;
    }

    
Whether this class is able to read the given entry.
May return false if the current entry is a sparse file.
/**
     * Whether this class is able to read the given entry.
     *
     * <p>May return false if the current entry is a sparse file.</p>
     */
    @Override
    public boolean canReadEntryData(final ArchiveEntry ae) {
        if (ae instanceof TarArchiveEntry) {
            final TarArchiveEntry te = (TarArchiveEntry) ae;
            return !te.isSparse();
        }
        return false;
    }

    
Get the current TAR Archive Entry that this input stream is processing
Returns:
The current Archive Entry/**
     * Get the current TAR Archive Entry that this input stream is processing
     *
     * @return The current Archive Entry
     */
    public TarArchiveEntry getCurrentEntry() {
        return currEntry;
    }

    protected final void setCurrentEntry(final TarArchiveEntry e) {
        currEntry = e;
    }

    protected final boolean isAtEOF() {
        return hasHitEOF;
    }

    protected final void setAtEOF(final boolean b) {
        hasHitEOF = b;
    }

    
This method is invoked once the end of the archive is hit, it
tries to consume the remaining bytes under the assumption that
the tool creating this archive has padded the last block.
/**
     * This method is invoked once the end of the archive is hit, it
     * tries to consume the remaining bytes under the assumption that
     * the tool creating this archive has padded the last block.
     */
    private void consumeRemainderOfLastBlock() throws IOException {
        final long bytesReadOfLastBlock = getBytesRead() % blockSize;
        if (bytesReadOfLastBlock > 0) {
            final long skipped = IOUtils.skip(is, blockSize - bytesReadOfLastBlock);
            count(skipped);
        }
    }

    
Checks if the signature matches what is expected for a tar file.
Params:
signature – 
           the bytes to check
length – 
           the number of bytes to check
Returns:
true, if this stream is a tar archive stream, false otherwise/**
     * Checks if the signature matches what is expected for a tar file.
     *
     * @param signature
     *            the bytes to check
     * @param length
     *            the number of bytes to check
     * @return true, if this stream is a tar archive stream, false otherwise
     */
    public static boolean matches(final byte[] signature, final int length) {
        if (length < TarConstants.VERSION_OFFSET+TarConstants.VERSIONLEN) {
            return false;
        }

        if (ArchiveUtils.matchAsciiBuffer(TarConstants.MAGIC_POSIX,
                signature, TarConstants.MAGIC_OFFSET, TarConstants.MAGICLEN)
            &&
            ArchiveUtils.matchAsciiBuffer(TarConstants.VERSION_POSIX,
                signature, TarConstants.VERSION_OFFSET, TarConstants.VERSIONLEN)
                ){
            return true;
        }
        if (ArchiveUtils.matchAsciiBuffer(TarConstants.MAGIC_GNU,
                signature, TarConstants.MAGIC_OFFSET, TarConstants.MAGICLEN)
            &&
            (
             ArchiveUtils.matchAsciiBuffer(TarConstants.VERSION_GNU_SPACE,
                signature, TarConstants.VERSION_OFFSET, TarConstants.VERSIONLEN)
            ||
            ArchiveUtils.matchAsciiBuffer(TarConstants.VERSION_GNU_ZERO,
                signature, TarConstants.VERSION_OFFSET, TarConstants.VERSIONLEN)
            )
                ){
            return true;
        }
        // COMPRESS-107 - recognise Ant tar files
        return ArchiveUtils.matchAsciiBuffer(TarConstants.MAGIC_ANT,
                signature, TarConstants.MAGIC_OFFSET, TarConstants.MAGICLEN)
                &&
                ArchiveUtils.matchAsciiBuffer(TarConstants.VERSION_ANT,
                        signature, TarConstants.VERSION_OFFSET, TarConstants.VERSIONLEN);
    }

}