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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2013 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://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/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 packager/legal/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:
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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.imap;

import java.io.*;
import javax.mail.*;
import com.sun.mail.imap.protocol.*;
import com.sun.mail.iap.*;
import com.sun.mail.util.*;

/**
 * This class implements an IMAP data stream.
 *
 * @author  John Mani
 */

public class IMAPInputStream extends InputStream {
    private IMAPMessage msg; // this message
    private String section;  // section-id
    private int pos;	  // track the position within the IMAP datastream
    private int blksize;  // number of bytes to read in each FETCH request
    private int max;	  // the total number of bytes in this section.
			  //  -1 indicates unknown
    private byte[] buf;   // the buffer obtained from fetchBODY()
    private int bufcount; // The index one greater than the index of the
			  // last valid byte in 'buf'
    private int bufpos;   // The current position within 'buf'
    private boolean lastBuffer; // is this the last buffer of data?
    private boolean peek; // peek instead of fetch?
    private ByteArray readbuf; // reuse for each read

    // Allocate this much extra space in the read buffer to allow
    // space for the FETCH response overhead
    private static final int slop = 64;


    /**
     * Create an IMAPInputStream.
     *
     * @param	msg	the IMAPMessage the data will come from
     * @param	section	the IMAP section/part identifier for the data
     * @param	max	the number of bytes in this section
     * @param	peek	peek instead of fetch?
     */
    public IMAPInputStream(IMAPMessage msg, String section, int max,
				boolean peek) {
	this.msg = msg;
	this.section = section;
	this.max = max;
	this.peek = peek;
	pos = 0;
	blksize = msg.getFetchBlockSize();
    }

    /**
     * Do a NOOP to force any untagged EXPUNGE responses
     * and then check if this message is expunged.
     */
    private void forceCheckExpunged()
		    throws MessageRemovedIOException, FolderClosedIOException {
	synchronized (msg.getMessageCacheLock()) {
	    try {
		msg.getProtocol().noop();
	    } catch (ConnectionException cex) {
		throw new FolderClosedIOException(msg.getFolder(),
						cex.getMessage());
	    } catch (FolderClosedException fex) {
		throw new FolderClosedIOException(fex.getFolder(),
						fex.getMessage());
	    } catch (ProtocolException pex) {
		// ignore it
	    }
	}
	if (msg.isExpunged())
	    throw new MessageRemovedIOException();
    }

    /**
     * Fetch more data from the server. This method assumes that all
     * data has already been read in, hence bufpos > bufcount.
     */
    private void fill() throws IOException {
	/*
	 * If we've read the last buffer, there's no more to read.
	 * If we know the total number of bytes available from this
	 * section, let's check if we have consumed that many bytes.
	 */
	if (lastBuffer || max != -1 && pos >= max) {
	    if (pos == 0)
		checkSeen();
	    readbuf = null;	// XXX - return to pool?
	    return; // the caller of fill() will return -1.
	}

	BODY b = null;
	if (readbuf == null)
	    readbuf = new ByteArray(blksize + slop);

	ByteArray ba;
	int cnt;
	// Acquire MessageCacheLock, to freeze seqnum.
	synchronized (msg.getMessageCacheLock()) {
	    try {
		IMAPProtocol p = msg.getProtocol();

		// Check whether this message is expunged
		if (msg.isExpunged())
		    throw new MessageRemovedIOException(
				"No content for expunged message");

		int seqnum = msg.getSequenceNumber();
		cnt = blksize;
		if (max != -1 && pos + blksize > max)
		    cnt = max - pos;
		if (peek)
		    b = p.peekBody(seqnum, section, pos, cnt, readbuf);
		else
		    b = p.fetchBody(seqnum, section, pos, cnt, readbuf);
	    } catch (ProtocolException pex) {
		forceCheckExpunged();
		throw new IOException(pex.getMessage());
	    } catch (FolderClosedException fex) {
		throw new FolderClosedIOException(fex.getFolder(),
						fex.getMessage());
	    }

	    if (b == null || ((ba = b.getByteArray()) == null)) {
		forceCheckExpunged();
		throw new IOException("No content");
	    }
	}

	// make sure the SEEN flag is set after reading the first chunk
	if (pos == 0)
	    checkSeen();

	// setup new values ..
	buf = ba.getBytes();
	bufpos = ba.getStart();
	int n = ba.getCount();    // will be zero, if all data has been
				  // consumed from the server.
	// if we got less than we asked for, this is the last buffer of data
	lastBuffer = n < cnt;
	bufcount = bufpos + n;
	pos += n;
    }

    /**
     * Reads the next byte of data from this buffered input stream.
     * If no byte is available, the value -1 is returned.
     */
    public synchronized int read() throws IOException {
	if (bufpos >= bufcount) {
	    fill();
	    if (bufpos >= bufcount)
		return -1;	// EOF
	}
	return buf[bufpos++] & 0xff;
    }

    /**
     * Reads up to len bytes of data from this
     * input stream into the given buffer. 

* * Returns the total number of bytes read into the buffer, * or -1 if there is no more data.

* * Note that this method mimics the "weird !" semantics of * BufferedInputStream in that the number of bytes actually * returned may be less that the requested value. So callers * of this routine should be aware of this and must check * the return value to insure that they have obtained the * requisite number of bytes. */ public synchronized int read(byte b[], int off, int len) throws IOException { int avail = bufcount - bufpos; if (avail <= 0) { fill(); avail = bufcount - bufpos; if (avail <= 0) return -1; // EOF } int cnt = (avail < len) ? avail : len; System.arraycopy(buf, bufpos, b, off, cnt); bufpos += cnt; return cnt; } /** * Reads up to b.length bytes of data from this input * stream into an array of bytes.

* * Returns the total number of bytes read into the buffer, or * -1 is there is no more data.

* * Note that this method mimics the "weird !" semantics of * BufferedInputStream in that the number of bytes actually * returned may be less that the requested value. So callers * of this routine should be aware of this and must check * the return value to insure that they have obtained the * requisite number of bytes. */ public int read(byte b[]) throws IOException { return read(b, 0, b.length); } /** * Returns the number of bytes that can be read from this input * stream without blocking. */ public synchronized int available() throws IOException { return (bufcount - bufpos); } /** * Normally the SEEN flag will have been set by now, but if not, * force it to be set (as long as the folder isn't open read-only * and we're not peeking). * And of course, if there's no folder (e.g., a nested message) * don't do anything. */ private void checkSeen() { if (peek) // if we're peeking, don't set the SEEN flag return; try { Folder f = msg.getFolder(); if (f != null && f.getMode() != Folder.READ_ONLY && !msg.isSet(Flags.Flag.SEEN)) msg.setFlag(Flags.Flag.SEEN, true); } catch (MessagingException ex) { // ignore it } } }





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