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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2010-2017 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://oss.oracle.com/licenses/CDDL+GPL-1.1
 * or LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
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 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
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 */

package com.sun.mail.pop3;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;
import javax.mail.util.SharedFileInputStream;

/**
 * A subclass of SharedFileInputStream that also allows writing.
 */
class WritableSharedFile extends SharedFileInputStream {

    private RandomAccessFile raf;
    private AppendStream af;

    public WritableSharedFile(File file) throws IOException {
	super(file);
	try {
	    raf = new RandomAccessFile(file, "rw");
	} catch (IOException ex) {
	    // if anything goes wrong opening the writable file,
	    // close the readable file too
	    super.close();
	}
    }

    /**
     * Return the writable version of this file.
     */
    public RandomAccessFile getWritableFile() {
	return raf;
    }

    /**
     * Close the readable and writable files.
     */
    @Override
    public void close() throws IOException {
	try {
	    super.close();
	} finally {
	    raf.close();
	}
    }

    /**
     * Update the size of the readable file after writing to the file. Updates
     * the length to be the current size of the file.
     */
    synchronized long updateLength() throws IOException {
	datalen = in.length();
	af = null;
	return datalen;
    }

    /**
     * Return a new AppendStream, but only if one isn't in active use.
     */
    public synchronized AppendStream getAppendStream() throws IOException {
	if (af != null) {
	    throw new IOException(
		    "POP3 file cache only supports single threaded access");
	}
	af = new AppendStream(this);
	return af;
    }
}