/*
 * 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.
 */
package org.apache.commons.compress.archivers.cpio;

import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;

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;

CpioArchiveInputStream is a stream for reading cpio streams. All formats of
cpio are supported (old ascii, old binary, new portable format and the new
portable format with crc).

The stream can be read by extracting a cpio entry (containing all
informations about a entry) and afterwards reading from the stream the file
specified by the entry.

CpioArchiveInputStream cpioIn = new CpioArchiveInputStream(
        Files.newInputStream(Paths.get("test.cpio")));
CpioArchiveEntry cpioEntry;
while ((cpioEntry = cpioIn.getNextEntry()) != null) {
    System.out.println(cpioEntry.getName());
    int tmp;
    StringBuilder buf = new StringBuilder();
    while ((tmp = cpIn.read()) != -1) {
        buf.append((char) tmp);
    }
    System.out.println(buf.toString());
}
cpioIn.close();


Note: This implementation should be compatible to cpio 2.5
This class uses mutable fields and is not considered to be threadsafe.
Based on code from the jRPM project (jrpm.sourceforge.net)
/**
 * CpioArchiveInputStream is a stream for reading cpio streams. All formats of
 * cpio are supported (old ascii, old binary, new portable format and the new
 * portable format with crc).
 *
 * <p>
 * The stream can be read by extracting a cpio entry (containing all
 * informations about a entry) and afterwards reading from the stream the file
 * specified by the entry.
 * </p>
 * <pre>
 * CpioArchiveInputStream cpioIn = new CpioArchiveInputStream(
 *         Files.newInputStream(Paths.get(&quot;test.cpio&quot;)));
 * CpioArchiveEntry cpioEntry;
 *
 * while ((cpioEntry = cpioIn.getNextEntry()) != null) {
 *     System.out.println(cpioEntry.getName());
 *     int tmp;
 *     StringBuilder buf = new StringBuilder();
 *     while ((tmp = cpIn.read()) != -1) {
 *         buf.append((char) tmp);
 *     }
 *     System.out.println(buf.toString());
 * }
 * cpioIn.close();
 * </pre>
 * <p>
 * Note: This implementation should be compatible to cpio 2.5
 *
 * <p>This class uses mutable fields and is not considered to be threadsafe.
 *
 * <p>Based on code from the jRPM project (jrpm.sourceforge.net)
 */

public class CpioArchiveInputStream extends ArchiveInputStream implements
        CpioConstants {

    private boolean closed = false;

    private CpioArchiveEntry entry;

    private long entryBytesRead = 0;

    private boolean entryEOF = false;

    private final byte tmpbuf[] = new byte[4096];

    private long crc = 0;

    private final InputStream in;

    // cached buffers - must only be used locally in the class (COMPRESS-172 - reduce garbage collection)
    private final byte[] twoBytesBuf = new byte[2];
    private final byte[] fourBytesBuf = new byte[4];
    private final byte[] sixBytesBuf = new byte[6];

    private final int blockSize;

    
The encoding to use for filenames and labels.
/**
     * The encoding to use for filenames and labels.
     */
    private final ZipEncoding zipEncoding;

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

    
Construct the cpio input stream with a blocksize of BLOCK_SIZE and expecting ASCII file names. 
Params:
in – 
           The cpio stream/**
     * Construct the cpio input stream with a blocksize of {@link
     * CpioConstants#BLOCK_SIZE BLOCK_SIZE} and expecting ASCII file
     * names.
     *
     * @param in
     *            The cpio stream
     */
    public CpioArchiveInputStream(final InputStream in) {
        this(in, BLOCK_SIZE, CharsetNames.US_ASCII);
    }

    
Construct the cpio input stream with a blocksize of BLOCK_SIZE. 
Params:
in – 
           The cpio stream
encoding – 
           The encoding of file names to expect - use null for
           the platform's default.
Since:
1.6/**
     * Construct the cpio input stream with a blocksize of {@link
     * CpioConstants#BLOCK_SIZE BLOCK_SIZE}.
     *
     * @param in
     *            The cpio stream
     * @param encoding
     *            The encoding of file names to expect - use null for
     *            the platform's default.
     * @since 1.6
     */
    public CpioArchiveInputStream(final InputStream in, final String encoding) {
        this(in, BLOCK_SIZE, encoding);
    }

    
Construct the cpio input stream with a blocksize of BLOCK_SIZE expecting ASCII file names. 
Params:
in – 
           The cpio stream
blockSize – 
           The block size of the archive.
Since:
1.5/**
     * Construct the cpio input stream with a blocksize of {@link
     * CpioConstants#BLOCK_SIZE BLOCK_SIZE} expecting ASCII file
     * names.
     *
     * @param in
     *            The cpio stream
     * @param blockSize
     *            The block size of the archive.
     * @since 1.5
     */
    public CpioArchiveInputStream(final InputStream in, final int blockSize) {
        this(in, blockSize, CharsetNames.US_ASCII);
    }

    
Construct the cpio input stream with a blocksize of BLOCK_SIZE. 
Params:
in – 
           The cpio stream
blockSize – 
           The block size of the archive.
encoding – 
           The encoding of file names to expect - use null for
           the platform's default.
Since:
1.6/**
     * Construct the cpio input stream with a blocksize of {@link CpioConstants#BLOCK_SIZE BLOCK_SIZE}.
     *
     * @param in
     *            The cpio stream
     * @param blockSize
     *            The block size of the archive.
     * @param encoding
     *            The encoding of file names to expect - use null for
     *            the platform's default.
     * @since 1.6
     */
    public CpioArchiveInputStream(final InputStream in, final int blockSize, final String encoding) {
        this.in = in;
        this.blockSize = blockSize;
        this.encoding = encoding;
        this.zipEncoding = ZipEncodingHelper.getZipEncoding(encoding);
    }

    
Returns 0 after EOF has reached for the current entry data, otherwise
always return 1.

Programs should not count on this method to return the actual number of
bytes that could be read without blocking.
Throws:
IOException – 
            if an I/O error has occurred or if a CPIO file error has
            occurred
Returns:
1 before EOF and 0 after EOF has reached for current entry./**
     * Returns 0 after EOF has reached for the current entry data, otherwise
     * always return 1.
     * <p>
     * Programs should not count on this method to return the actual number of
     * bytes that could be read without blocking.
     *
     * @return 1 before EOF and 0 after EOF has reached for current entry.
     * @throws IOException
     *             if an I/O error has occurred or if a CPIO file error has
     *             occurred
     */
    @Override
    public int available() throws IOException {
        ensureOpen();
        if (this.entryEOF) {
            return 0;
        }
        return 1;
    }

    
Closes the CPIO input stream.
Throws:
IOException – 
            if an I/O error has occurred/**
     * Closes the CPIO input stream.
     *
     * @throws IOException
     *             if an I/O error has occurred
     */
    @Override
    public void close() throws IOException {
        if (!this.closed) {
            in.close();
            this.closed = true;
        }
    }

    
Closes the current CPIO entry and positions the stream for reading the
next entry.
Throws:
IOException – 
            if an I/O error has occurred or if a CPIO file error has
            occurred/**
     * Closes the current CPIO entry and positions the stream for reading the
     * next entry.
     *
     * @throws IOException
     *             if an I/O error has occurred or if a CPIO file error has
     *             occurred
     */
    private void closeEntry() throws IOException {
        // the skip implementation of this class will not skip more
        // than Integer.MAX_VALUE bytes
        while (skip((long) Integer.MAX_VALUE) == Integer.MAX_VALUE) { // NOPMD
            // do nothing
        }
    }

    
Check to make sure that this stream has not been closed
Throws:
IOException – 
            if the stream is already closed/**
     * Check to make sure that this stream has not been closed
     *
     * @throws IOException
     *             if the stream is already closed
     */
    private void ensureOpen() throws IOException {
        if (this.closed) {
            throw new IOException("Stream closed");
        }
    }

    
Reads the next CPIO file entry and positions stream at the beginning of
the entry data.
Throws:
IOException – 
            if an I/O error has occurred or if a CPIO file error has
            occurred
Returns:
the CpioArchiveEntry just read/**
     * Reads the next CPIO file entry and positions stream at the beginning of
     * the entry data.
     *
     * @return the CpioArchiveEntry just read
     * @throws IOException
     *             if an I/O error has occurred or if a CPIO file error has
     *             occurred
     */
    public CpioArchiveEntry getNextCPIOEntry() throws IOException {
        ensureOpen();
        if (this.entry != null) {
            closeEntry();
        }
        readFully(twoBytesBuf, 0, twoBytesBuf.length);
        if (CpioUtil.byteArray2long(twoBytesBuf, false) == MAGIC_OLD_BINARY) {
            this.entry = readOldBinaryEntry(false);
        } else if (CpioUtil.byteArray2long(twoBytesBuf, true)
                   == MAGIC_OLD_BINARY) {
            this.entry = readOldBinaryEntry(true);
        } else {
            System.arraycopy(twoBytesBuf, 0, sixBytesBuf, 0,
                             twoBytesBuf.length);
            readFully(sixBytesBuf, twoBytesBuf.length,
                      fourBytesBuf.length);
            final String magicString = ArchiveUtils.toAsciiString(sixBytesBuf);
            switch (magicString) {
                case MAGIC_NEW:
                    this.entry = readNewEntry(false);
                    break;
                case MAGIC_NEW_CRC:
                    this.entry = readNewEntry(true);
                    break;
                case MAGIC_OLD_ASCII:
                    this.entry = readOldAsciiEntry();
                    break;
                default:
                    throw new IOException("Unknown magic [" + magicString + "]. Occured at byte: " + getBytesRead());
            }
        }

        this.entryBytesRead = 0;
        this.entryEOF = false;
        this.crc = 0;

        if (this.entry.getName().equals(CPIO_TRAILER)) {
            this.entryEOF = true;
            skipRemainderOfLastBlock();
            return null;
        }
        return this.entry;
    }

    private void skip(final int bytes) throws IOException{
        // bytes cannot be more than 3 bytes
        if (bytes > 0) {
            readFully(fourBytesBuf, 0, bytes);
        }
    }

    
Reads from the current CPIO entry into an array of bytes. Blocks until
some input is available.
Params:
b – 
           the buffer into which the data is read
off – 
           the start offset of the data
len – 
           the maximum number of bytes read
Throws:
IOException – 
            if an I/O error has occurred or if a CPIO file error has
            occurred
Returns:
the actual number of bytes read, or -1 if the end of the entry is
        reached/**
     * Reads from the current CPIO entry into an array of bytes. Blocks until
     * some input is available.
     *
     * @param b
     *            the buffer into which the data is read
     * @param off
     *            the start offset of the data
     * @param len
     *            the maximum number of bytes read
     * @return the actual number of bytes read, or -1 if the end of the entry is
     *         reached
     * @throws IOException
     *             if an I/O error has occurred or if a CPIO file error has
     *             occurred
     */
    @Override
    public int read(final byte[] b, final int off, final int len)
            throws IOException {
        ensureOpen();
        if (off < 0 || len < 0 || off > b.length - len) {
            throw new IndexOutOfBoundsException();
        } else if (len == 0) {
            return 0;
        }

        if (this.entry == null || this.entryEOF) {
            return -1;
        }
        if (this.entryBytesRead == this.entry.getSize()) {
            skip(entry.getDataPadCount());
            this.entryEOF = true;
            if (this.entry.getFormat() == FORMAT_NEW_CRC
                && this.crc != this.entry.getChksum()) {
                throw new IOException("CRC Error. Occured at byte: "
                                      + getBytesRead());
            }
            return -1; // EOF for this entry
        }
        final int tmplength = (int) Math.min(len, this.entry.getSize()
                - this.entryBytesRead);
        if (tmplength < 0) {
            return -1;
        }

        final int tmpread = readFully(b, off, tmplength);
        if (this.entry.getFormat() == FORMAT_NEW_CRC) {
            for (int pos = 0; pos < tmpread; pos++) {
                this.crc += b[pos] & 0xFF;
                this.crc &= 0xFFFFFFFFL;
            }
        }
        if (tmpread > 0) {
            this.entryBytesRead += tmpread;
        }

        return tmpread;
    }

    private final int readFully(final byte[] b, final int off, final int len)
            throws IOException {
        final int count = IOUtils.readFully(in, b, off, len);
        count(count);
        if (count < len) {
            throw new EOFException();
        }
        return count;
    }

    private long readBinaryLong(final int length, final boolean swapHalfWord)
            throws IOException {
        final byte tmp[] = new byte[length];
        readFully(tmp, 0, tmp.length);
        return CpioUtil.byteArray2long(tmp, swapHalfWord);
    }

    private long readAsciiLong(final int length, final int radix)
            throws IOException {
        final byte tmpBuffer[] = new byte[length];
        readFully(tmpBuffer, 0, tmpBuffer.length);
        return Long.parseLong(ArchiveUtils.toAsciiString(tmpBuffer), radix);
    }

    private CpioArchiveEntry readNewEntry(final boolean hasCrc)
            throws IOException {
        CpioArchiveEntry ret;
        if (hasCrc) {
            ret = new CpioArchiveEntry(FORMAT_NEW_CRC);
        } else {
            ret = new CpioArchiveEntry(FORMAT_NEW);
        }

        ret.setInode(readAsciiLong(8, 16));
        final long mode = readAsciiLong(8, 16);
        if (CpioUtil.fileType(mode) != 0){ // mode is initialised to 0
            ret.setMode(mode);
        }
        ret.setUID(readAsciiLong(8, 16));
        ret.setGID(readAsciiLong(8, 16));
        ret.setNumberOfLinks(readAsciiLong(8, 16));
        ret.setTime(readAsciiLong(8, 16));
        ret.setSize(readAsciiLong(8, 16));
        ret.setDeviceMaj(readAsciiLong(8, 16));
        ret.setDeviceMin(readAsciiLong(8, 16));
        ret.setRemoteDeviceMaj(readAsciiLong(8, 16));
        ret.setRemoteDeviceMin(readAsciiLong(8, 16));
        final long namesize = readAsciiLong(8, 16);
        ret.setChksum(readAsciiLong(8, 16));
        final String name = readCString((int) namesize);
        ret.setName(name);
        if (CpioUtil.fileType(mode) == 0 && !name.equals(CPIO_TRAILER)){
            throw new IOException("Mode 0 only allowed in the trailer. Found entry name: "
                                  + ArchiveUtils.sanitize(name)
                                  + " Occured at byte: " + getBytesRead());
        }
        skip(ret.getHeaderPadCount(namesize - 1));

        return ret;
    }

    private CpioArchiveEntry readOldAsciiEntry() throws IOException {
        final CpioArchiveEntry ret = new CpioArchiveEntry(FORMAT_OLD_ASCII);

        ret.setDevice(readAsciiLong(6, 8));
        ret.setInode(readAsciiLong(6, 8));
        final long mode = readAsciiLong(6, 8);
        if (CpioUtil.fileType(mode) != 0) {
            ret.setMode(mode);
        }
        ret.setUID(readAsciiLong(6, 8));
        ret.setGID(readAsciiLong(6, 8));
        ret.setNumberOfLinks(readAsciiLong(6, 8));
        ret.setRemoteDevice(readAsciiLong(6, 8));
        ret.setTime(readAsciiLong(11, 8));
        final long namesize = readAsciiLong(6, 8);
        ret.setSize(readAsciiLong(11, 8));
        final String name = readCString((int) namesize);
        ret.setName(name);
        if (CpioUtil.fileType(mode) == 0 && !name.equals(CPIO_TRAILER)){
            throw new IOException("Mode 0 only allowed in the trailer. Found entry: "
                                  + ArchiveUtils.sanitize(name)
                                  + " Occured at byte: " + getBytesRead());
        }

        return ret;
    }

    private CpioArchiveEntry readOldBinaryEntry(final boolean swapHalfWord)
            throws IOException {
        final CpioArchiveEntry ret = new CpioArchiveEntry(FORMAT_OLD_BINARY);

        ret.setDevice(readBinaryLong(2, swapHalfWord));
        ret.setInode(readBinaryLong(2, swapHalfWord));
        final long mode = readBinaryLong(2, swapHalfWord);
        if (CpioUtil.fileType(mode) != 0){
            ret.setMode(mode);
        }
        ret.setUID(readBinaryLong(2, swapHalfWord));
        ret.setGID(readBinaryLong(2, swapHalfWord));
        ret.setNumberOfLinks(readBinaryLong(2, swapHalfWord));
        ret.setRemoteDevice(readBinaryLong(2, swapHalfWord));
        ret.setTime(readBinaryLong(4, swapHalfWord));
        final long namesize = readBinaryLong(2, swapHalfWord);
        ret.setSize(readBinaryLong(4, swapHalfWord));
        final String name = readCString((int) namesize);
        ret.setName(name);
        if (CpioUtil.fileType(mode) == 0 && !name.equals(CPIO_TRAILER)){
            throw new IOException("Mode 0 only allowed in the trailer. Found entry: "
                                  + ArchiveUtils.sanitize(name)
                                  + "Occured at byte: " + getBytesRead());
        }
        skip(ret.getHeaderPadCount(namesize - 1));

        return ret;
    }

    private String readCString(final int length) throws IOException {
        // don't include trailing NUL in file name to decode
        final byte tmpBuffer[] = new byte[length - 1];
        readFully(tmpBuffer, 0, tmpBuffer.length);
        this.in.read();
        return zipEncoding.decode(tmpBuffer);
    }

    
Skips specified number of bytes in the current CPIO entry.
Params:
n – 
           the number of bytes to skip
Throws:
IOException – 
            if an I/O error has occurred
IllegalArgumentException – 
            if n < 0
Returns:
the actual number of bytes skipped/**
     * Skips specified number of bytes in the current CPIO entry.
     *
     * @param n
     *            the number of bytes to skip
     * @return the actual number of bytes skipped
     * @throws IOException
     *             if an I/O error has occurred
     * @throws IllegalArgumentException
     *             if n &lt; 0
     */
    @Override
    public long skip(final long n) throws IOException {
        if (n < 0) {
            throw new IllegalArgumentException("negative skip length");
        }
        ensureOpen();
        final int max = (int) Math.min(n, Integer.MAX_VALUE);
        int total = 0;

        while (total < max) {
            int len = max - total;
            if (len > this.tmpbuf.length) {
                len = this.tmpbuf.length;
            }
            len = read(this.tmpbuf, 0, len);
            if (len == -1) {
                this.entryEOF = true;
                break;
            }
            total += len;
        }
        return total;
    }

    @Override
    public ArchiveEntry getNextEntry() throws IOException {
        return getNextCPIOEntry();
    }

    
Skips the padding zeros written after the TRAILER!!! entry.
/**
     * Skips the padding zeros written after the TRAILER!!! entry.
     */
    private void skipRemainderOfLastBlock() throws IOException {
        final long readFromLastBlock = getBytesRead() % blockSize;
        long remainingBytes = readFromLastBlock == 0 ? 0
            : blockSize - readFromLastBlock;
        while (remainingBytes > 0) {
            final long skipped = skip(blockSize - readFromLastBlock);
            if (skipped <= 0) {
                break;
            }
            remainingBytes -= skipped;
        }
    }

    
Checks if the signature matches one of the following magic values:
Strings:
"070701" - MAGIC_NEW
"070702" - MAGIC_NEW_CRC
"070707" - MAGIC_OLD_ASCII
Octal Binary value:
070707 - MAGIC_OLD_BINARY (held as a short) = 0x71C7 or 0xC771
Params:
signature – data to match
length – length of data
Returns:
whether the buffer seems to contain CPIO data/**
     * Checks if the signature matches one of the following magic values:
     *
     * Strings:
     *
     * "070701" - MAGIC_NEW
     * "070702" - MAGIC_NEW_CRC
     * "070707" - MAGIC_OLD_ASCII
     *
     * Octal Binary value:
     *
     * 070707 - MAGIC_OLD_BINARY (held as a short) = 0x71C7 or 0xC771
     * @param signature data to match
     * @param length length of data
     * @return whether the buffer seems to contain CPIO data
     */
    public static boolean matches(final byte[] signature, final int length) {
        if (length < 6) {
            return false;
        }

        // Check binary values
        if (signature[0] == 0x71 && (signature[1] & 0xFF) == 0xc7) {
            return true;
        }
        if (signature[1] == 0x71 && (signature[0] & 0xFF) == 0xc7) {
            return true;
        }

        // Check Ascii (String) values
        // 3037 3037 30nn
        if (signature[0] != 0x30) {
            return false;
        }
        if (signature[1] != 0x37) {
            return false;
        }
        if (signature[2] != 0x30) {
            return false;
        }
        if (signature[3] != 0x37) {
            return false;
        }
        if (signature[4] != 0x30) {
            return false;
        }
        // Check last byte
        if (signature[5] == 0x31) {
            return true;
        }
        if (signature[5] == 0x32) {
            return true;
        }
        if (signature[5] == 0x37) {
            return true;
        }

        return false;
    }
}