ArWriter.java

package org.codehaus.mojo.deb.jdpkg.ar;

import static org.codehaus.mojo.deb.jdpkg.ar.ArUtil.*;

import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;

/**
 * @author <a href="mailto:trygve.laugstol@arktekk.no">Trygve Laugstøl</a>
 * @version $Id$
 */
class ArWriter implements Closeable {
    private OutputStream output;

    static Charset charset;

    public static final String BLANKS = "               ";

    static {
        charset = Charset.forName(US_ASCII);
    }

    public ArWriter(File file) throws IOException {
        output = new FileOutputStream(file);

        output.write(toBytes(AR_ARCHIVE_MAGIC));
        output.flush();
    }

    public void add(ArFile arFile) throws IOException {
        output.write(toBytes(arFile.name, 16));
        output.write(toBytes(Long.toString(arFile.lastModified), 12));
        output.write(toBytes(Integer.toString(arFile.ownerId), 6));
        output.write(toBytes(Integer.toString(arFile.groupId), 6));
        output.write(toBytes(Integer.toOctalString(arFile.mode), 8));
        output.write(toBytes(Long.toString(arFile.size), 10));
        output.write(toBytes(AR_FILE_MAGIC));
        output.flush();

        InputStream is = null;
        try {
            is = new FileInputStream(arFile.file);
            copy(is, output, 8192);
        }
        finally {
            closeSilent(is);
        }
    }

    private byte[] toBytes(String value) {
        return toBytes(value, value.length());
    }

    private byte[] toBytes(String value, int size) {
        String s = value;

        if (s.length() > size) {
            throw new RuntimeException("Internal error. Field size (" + s.length() + ") > max size (" + size + ")");
        }

        if (s.length() < size) {
            s += BLANKS.substring(0, size - s.length());
        }

        ByteBuffer byteBuffer = charset.encode(s);
        return byteBuffer.array();
    }

    public void close() throws IOException {
        output.close();
    }
}