src/main/java/org/apache/commons/compress/archivers/ar/ArArchiveOutputStream.java

/*
 * 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.ar;

import java.io.IOException;
import java.io.OutputStream;

import org.apache.commons.compress.archivers.ArchiveEntry;
import org.apache.commons.compress.archivers.ArchiveOutputStream;

/**
 * Implements the "ar" archive format as an output stream.
 * 
 * @NotThreadSafe
 */
public class ArArchiveOutputStream extends ArchiveOutputStream {

    private final OutputStream out;
    private long archiveOffset = 0;
    private long entryOffset = 0;
    private ArArchiveEntry prevEntry;
    private boolean haveUnclosedEntry = true;

    public ArArchiveOutputStream( final OutputStream pOut ) {
        this.out = pOut;
    }

    private long writeArchiveHeader() throws IOException {
        byte [] header = ArArchiveEntry.HEADER.getBytes();
        out.write(header);
        return header.length;
    }

    public void closeArchiveEntry() throws IOException {
        if (prevEntry != null && haveUnclosedEntry && (entryOffset % 2) != 0) {
            out.write('\n'); // Pad byte
            archiveOffset++;
        }
        haveUnclosedEntry = false;
    }

    public void putArchiveEntry( final ArchiveEntry pEntry ) throws IOException {
        ArArchiveEntry pArEntry = (ArArchiveEntry)pEntry;
        if (prevEntry == null) {
            archiveOffset += writeArchiveHeader();
        } else {
            if (prevEntry.getLength() != entryOffset) {
                throw new IOException("length does not match entry (" + prevEntry.getLength() + " != " + entryOffset);
            }

            closeArchiveEntry();
        }

        prevEntry = pArEntry;

        archiveOffset += writeEntryHeader(pArEntry);

        entryOffset = 0;
        haveUnclosedEntry = true;
    }

    private long fill( final long pOffset, final long pNewOffset, final char pFill ) throws IOException { 
        final long diff = pNewOffset - pOffset;

        if (diff > 0) {
            for (int i = 0; i < diff; i++) {
                write(pFill);
            }
        }

        return pNewOffset;
    }

    private long write( final String data ) throws IOException {
        final byte[] bytes = data.getBytes("ascii");
        write(bytes);
        return bytes.length;
    }

    private long writeEntryHeader( final ArArchiveEntry pEntry ) throws IOException {

        long offset = 0;

        final String n = pEntry.getName();
        if (n.length() > 16) {
            throw new IOException("filename too long");
        }
        offset += write(n);

        offset = fill(offset, 16, ' ');
        final String m = "" + (pEntry.getLastModified() / 1000);
        if (m.length() > 12) {
            throw new IOException("modified too long");
        }
        offset += write(m);

        offset = fill(offset, 28, ' ');
        final String u = "" + pEntry.getUserId();
        if (u.length() > 6) {
            throw new IOException("userid too long");
        }
        offset += write(u);

        offset = fill(offset, 34, ' ');
        final String g = "" + pEntry.getGroupId();
        if (g.length() > 6) {
            throw new IOException("groupid too long");
        }
        offset += write(g);

        offset = fill(offset, 40, ' ');
        final String fm = "" + Integer.toString(pEntry.getMode(), 8);
        if (fm.length() > 8) {
            throw new IOException("filemode too long");
        }
        offset += write(fm);

        offset = fill(offset, 48, ' ');
        final String s = "" + pEntry.getLength();
        if (s.length() > 10) {
            throw new IOException("size too long");
        }
        offset += write(s);

        offset = fill(offset, 58, ' ');

        offset += write(ArArchiveEntry.TRAILER);

        return offset;
    }

    public void write(int b) throws IOException {
        out.write(b);
        entryOffset++;
    }

    public void write(byte[] b, int off, int len) throws IOException {
        out.write(b, off, len);
        entryOffset += len;
    }

    public void write(byte[] b) throws IOException {
        out.write(b);
        entryOffset += b.length;
    }

    public void close() throws IOException {
        closeArchiveEntry();
        out.close();
        prevEntry = null;
    }

}