/*
 * Copyright (c) 1997, 2023 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package jakarta.mail.internet;

import jakarta.activation.DataSource;
import jakarta.mail.BodyPart;
import jakarta.mail.IllegalWriteException;
import jakarta.mail.MessageAware;
import jakarta.mail.MessageContext;
import jakarta.mail.MessagingException;
import jakarta.mail.Multipart;
import jakarta.mail.MultipartDataSource;
import jakarta.mail.util.LineInputStream;
import jakarta.mail.util.LineOutputStream;

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


/**
 * The MimeMultipart class is an implementation of the abstract Multipart
 * class that uses MIME conventions for the multipart data. <p>
 *
 * A MimeMultipart is obtained from a MimePart whose primary type
 * is "multipart" (by invoking the part's <code>getContent()</code> method)
 * or it can be created by a client as part of creating a new MimeMessage. <p>
 *
 * The default multipart subtype is "mixed".  The other multipart
 * subtypes, such as "alternative", "related", and so on, can be
 * implemented as subclasses of MimeMultipart with additional methods
 * to implement the additional semantics of that type of multipart
 * content. The intent is that service providers, mail JavaBean writers
 * and mail clients will write many such subclasses and their Command
 * Beans, and will install them into the JavaBeans Activation
 * Framework, so that any Jakarta Mail implementation and its clients can
 * transparently find and use these classes. Thus, a MIME multipart
 * handler is treated just like any other type handler, thereby
 * decoupling the process of providing multipart handlers from the
 * Jakarta Mail API. Lacking these additional MimeMultipart subclasses,
 * all subtypes of MIME multipart data appear as MimeMultipart objects. <p>
 *
 * An application can directly construct a MIME multipart object of any
 * subtype by using the <code>MimeMultipart(String subtype)</code>
 * constructor.  For example, to create a "multipart/alternative" object,
 * use <code>new MimeMultipart("alternative")</code>. <p>
 *
 * The <code>mail.mime.multipart.ignoremissingendboundary</code>
 * property may be set to <code>false</code> to cause a
 * <code>MessagingException</code> to be thrown if the multipart
 * data does not end with the required end boundary line.  If this
 * property is set to <code>true</code> or not set, missing end
 * boundaries are not considered an error and the final body part
 * ends at the end of the data. <p>
 *
 * The <code>mail.mime.multipart.ignoremissingboundaryparameter</code>
 * System property may be set to <code>false</code> to cause a
 * <code>MessagingException</code> to be thrown if the Content-Type
 * of the MimeMultipart does not include a <code>boundary</code> parameter.
 * If this property is set to <code>true</code> or not set, the multipart
 * parsing code will look for a line that looks like a bounary line and
 * use that as the boundary separating the parts. <p>
 *
 * The <code>mail.mime.multipart.ignoreexistingboundaryparameter</code>
 * System property may be set to <code>true</code> to cause any boundary
 * to be ignored and instead search for a boundary line in the message
 * as with <code>mail.mime.multipart.ignoremissingboundaryparameter</code>. <p>
 *
 * Normally, when writing out a MimeMultipart that contains no body
 * parts, or when trying to parse a multipart message with no body parts,
 * a <code>MessagingException</code> is thrown.  The MIME spec does not allow
 * multipart content with no body parts.  The
 * <code>mail.mime.multipart.allowempty</code> System property may be set to
 * <code>true</code> to override this behavior.
 * When writing out such a MimeMultipart, a single empty part will be
 * included.  When reading such a multipart, a MimeMultipart will be created
 * with no body parts.
 *
 * @author John Mani
 * @author Bill Shannon
 * @author Max Spivak
 */

public class MimeMultipart extends Multipart {

    /**
     * The DataSource supplying our InputStream.
     */
    protected DataSource ds = null;

    /**
     * Have we parsed the data from our InputStream yet?
     * Defaults to true; set to false when our constructor is
     * given a DataSource with an InputStream that we need to
     * parse.
     */
    protected boolean parsed = true;

    /**
     * Have we seen the final bounary line?
     *
     * @since JavaMail 1.5
     */
    protected boolean complete = true;

    /**
     * The MIME multipart preamble text, the text that
     * occurs before the first boundary line.
     *
     * @since JavaMail 1.5
     */
    protected String preamble = null;

    /**
     * Flag corresponding to the "mail.mime.multipart.ignoremissingendboundary"
     * property, set in the {@link #initializeProperties} method called from
     * constructors and the parse method.
     *
     * @since JavaMail 1.5
     */
    protected boolean ignoreMissingEndBoundary = true;

    /**
     * Flag corresponding to the
     * "mail.mime.multipart.ignoremissingboundaryparameter"
     * property, set in the {@link #initializeProperties} method called from
     * constructors and the parse method.
     *
     * @since JavaMail 1.5
     */
    protected boolean ignoreMissingBoundaryParameter = true;

    /**
     * Flag corresponding to the
     * "mail.mime.multipart.ignoreexistingboundaryparameter"
     * property, set in the {@link #initializeProperties} method called from
     * constructors and the parse method.
     *
     * @since JavaMail 1.5
     */
    protected boolean ignoreExistingBoundaryParameter = false;

    /**
     * Flag corresponding to the "mail.mime.multipart.allowempty"
     * property, set in the {@link #initializeProperties} method called from
     * constructors and the parse method.
     *
     * @since JavaMail 1.5
     */
    protected boolean allowEmpty = false;

    /**
     * Default constructor. An empty MimeMultipart object
     * is created. Its content type is set to "multipart/mixed".
     * A unique boundary string is generated and this string is
     * setup as the "boundary" parameter for the
     * <code>contentType</code> field. <p>
     *
     * MimeBodyParts may be added later.
     */
    public MimeMultipart() {
        this("mixed");
    }

    /**
     * Construct a MimeMultipart object of the given subtype.
     * A unique boundary string is generated and this string is
     * setup as the "boundary" parameter for the
     * <code>contentType</code> field.
     * Calls the {@link #initializeProperties} method.<p>
     *
     * MimeBodyParts may be added later.
     *
     * @param subtype the MIME content subtype
     */
    public MimeMultipart(String subtype) {
        super();
        /*
         * Compute a boundary string.
         */
        String boundary = UniqueValue.getUniqueBoundaryValue();
        ContentType cType = new ContentType("multipart", subtype, null);
        cType.setParameter("boundary", boundary);
        contentType = cType.toString();
        initializeProperties();
    }

    /**
     * Construct a MimeMultipart object of the default "mixed" subtype,
     * and with the given body parts.  More body parts may be added later.
     *
     * @param parts the body parts
     * @throws MessagingException for failures
     * @since JavaMail 1.5
     */
    public MimeMultipart(BodyPart... parts) throws MessagingException {
        this();
        for (BodyPart bp : parts)
            super.addBodyPart(bp);
    }

    /**
     * Construct a MimeMultipart object of the given subtype
     * and with the given body parts.  More body parts may be added later.
     *
     * @param subtype the MIME content subtype
     * @param parts   the body parts
     * @throws MessagingException for failures
     * @since JavaMail 1.5
     */
    public MimeMultipart(String subtype, BodyPart... parts)
            throws MessagingException {
        this(subtype);
        for (BodyPart bp : parts)
            super.addBodyPart(bp);
    }

    /**
     * Constructs a MimeMultipart object and its bodyparts from the
     * given DataSource. <p>
     *
     * This constructor handles as a special case the situation where the
     * given DataSource is a MultipartDataSource object.  In this case, this
     * method just invokes the superclass (i.e., Multipart) constructor
     * that takes a MultipartDataSource object. <p>
     *
     * Otherwise, the DataSource is assumed to provide a MIME multipart
     * byte stream.  The <code>parsed</code> flag is set to false.  When
     * the data for the body parts are needed, the parser extracts the
     * "boundary" parameter from the content type of this DataSource,
     * skips the 'preamble' and reads bytes till the terminating
     * boundary and creates MimeBodyParts for each part of the stream.
     *
     * @param ds DataSource, can be a MultipartDataSource
     * @throws ParseException     for failures parsing the message
     * @throws MessagingException for other failures
     */
    public MimeMultipart(DataSource ds) throws MessagingException {
        super();

        if (ds instanceof MessageAware) {
            MessageContext mc = ((MessageAware) ds).getMessageContext();
            setParent(mc.getPart());
        }

        if (ds instanceof MultipartDataSource) {
            // ask super to do this for us.
            setMultipartDataSource((MultipartDataSource) ds);
            return;
        }

        // 'ds' was not a MultipartDataSource, we have
        // to parse this ourself.
        parsed = false;
        this.ds = ds;
        contentType = ds.getContentType();
    }

    /**
     * Initialize flags that control parsing behavior,
     * based on System properties described above in
     * the class documentation.
     *
     * @since JavaMail 1.5
     */
    protected void initializeProperties() {
        // read properties that control parsing

        // default to true
        ignoreMissingEndBoundary = MimeUtility.getBooleanSystemProperty(
                "mail.mime.multipart.ignoremissingendboundary", true);
        // default to true
        ignoreMissingBoundaryParameter = MimeUtility.getBooleanSystemProperty(
                "mail.mime.multipart.ignoremissingboundaryparameter", true);
        // default to false
        ignoreExistingBoundaryParameter = MimeUtility.getBooleanSystemProperty(
                "mail.mime.multipart.ignoreexistingboundaryparameter", false);
        // default to false
        allowEmpty = MimeUtility.getBooleanSystemProperty(
                "mail.mime.multipart.allowempty", false);
    }

    /**
     * Set the subtype. This method should be invoked only on a new
     * MimeMultipart object created by the client. The default subtype
     * of such a multipart object is "mixed".
     *
     * @param subtype Subtype
     * @throws MessagingException for failures
     */
    public synchronized void setSubType(String subtype)
            throws MessagingException {
        ContentType cType = new ContentType(contentType);
        cType.setSubType(subtype);
        contentType = cType.toString();
    }

    /**
     * Return the number of enclosed BodyPart objects.
     *
     * @return number of parts
     */
    @Override
    public synchronized int getCount() throws MessagingException {
        parse();
        return super.getCount();
    }

    /**
     * Get the specified BodyPart.  BodyParts are numbered starting at 0.
     *
     * @param index the index of the desired BodyPart
     * @return the Part
     * @throws MessagingException if no such BodyPart exists
     */
    @Override
    public synchronized BodyPart getBodyPart(int index)
            throws MessagingException {
        parse();
        return super.getBodyPart(index);
    }

    /**
     * Get the MimeBodyPart referred to by the given ContentID (CID).
     * Returns null if the part is not found.
     *
     * @param CID the ContentID of the desired part
     * @return the Part
     * @throws MessagingException for failures
     */
    public synchronized BodyPart getBodyPart(String CID)
            throws MessagingException {
        parse();

        int count = getCount();
        for (int i = 0; i < count; i++) {
            MimeBodyPart part = (MimeBodyPart) getBodyPart(i);
            String s = part.getContentID();
            if (s != null && s.equals(CID))
                return part;
        }
        return null;
    }

    /**
     * Remove the specified part from the multipart message.
     * Shifts all the parts after the removed part down one.
     *
     * @param part The part to remove
     * @return true if part removed, false otherwise
     * @throws MessagingException    if no such Part exists
     * @throws IllegalWriteException if the underlying
     *                                  implementation does not support modification
     *                                  of existing values
     */
    @Override
    public boolean removeBodyPart(BodyPart part) throws MessagingException {
        parse();
        return super.removeBodyPart(part);
    }

    /**
     * Remove the part at specified location (starting from 0).
     * Shifts all the parts after the removed part down one.
     *
     * @param index Index of the part to remove
     * @throws IndexOutOfBoundsException if the given index
     *                                      is out of range.
     * @throws IllegalWriteException     if the underlying
     *                                      implementation does not support modification
     *                                      of existing values
     * @throws MessagingException        for other failures
     */
    @Override
    public void removeBodyPart(int index) throws MessagingException {
        parse();
        super.removeBodyPart(index);
    }

    /**
     * Adds a Part to the multipart.  The BodyPart is appended to
     * the list of existing Parts.
     *
     * @param part The Part to be appended
     * @throws IllegalWriteException if the underlying
     *                                  implementation does not support modification
     *                                  of existing values
     * @throws MessagingException    for other failures
     */
    @Override
    public synchronized void addBodyPart(BodyPart part)
            throws MessagingException {
        parse();
        super.addBodyPart(part);
    }

    /**
     * Adds a BodyPart at position <code>index</code>.
     * If <code>index</code> is not the last one in the list,
     * the subsequent parts are shifted up. If <code>index</code>
     * is larger than the number of parts present, the
     * BodyPart is appended to the end.
     *
     * @param part  The BodyPart to be inserted
     * @param index Location where to insert the part
     * @throws IllegalWriteException if the underlying
     *                                  implementation does not support modification
     *                                  of existing values
     * @throws MessagingException    for other failures
     */
    @Override
    public synchronized void addBodyPart(BodyPart part, int index)
            throws MessagingException {
        parse();
        super.addBodyPart(part, index);
    }

    /**
     * Return true if the final boundary line for this
     * multipart was seen.  When parsing multipart content,
     * this class will (by default) terminate parsing with
     * no error if the end of input is reached before seeing
     * the final multipart boundary line.  In such a case,
     * this method will return false.  (If the System property
     * "mail.mime.multipart.ignoremissingendboundary" is set to
     * false, parsing such a message will instead throw a
     * MessagingException.)
     *
     * @return true if the final boundary line was seen
     * @throws MessagingException for failures
     * @since JavaMail 1.4
     */
    public synchronized boolean isComplete() throws MessagingException {
        parse();
        return complete;
    }

    /**
     * Get the preamble text, if any, that appears before the
     * first body part of this multipart.  Some protocols,
     * such as IMAP, will not allow access to the preamble text.
     *
     * @return the preamble text, or null if no preamble
     * @throws MessagingException for failures
     * @since JavaMail 1.4
     */
    public synchronized String getPreamble() throws MessagingException {
        parse();
        return preamble;
    }

    /**
     * Set the preamble text to be included before the first
     * body part.  Applications should generally not include
     * any preamble text.  In some cases it may be helpful to
     * include preamble text with instructions for users of
     * pre-MIME software.  The preamble text should be complete
     * lines, including newlines.
     *
     * @param preamble the preamble text
     * @throws MessagingException for failures
     * @since JavaMail 1.4
     */
    public synchronized void setPreamble(String preamble)
            throws MessagingException {
        this.preamble = preamble;
    }

    /**
     * Update headers. The default implementation here just
     * calls the <code>updateHeaders</code> method on each of its
     * children BodyParts. <p>
     *
     * Note that the boundary parameter is already set up when
     * a new and empty MimeMultipart object is created. <p>
     *
     * This method is called when the <code>saveChanges</code>
     * method is invoked on the Message object containing this
     * Multipart. This is typically done as part of the Message
     * send process, however note that a client is free to call
     * it any number of times. So if the header updating process is
     * expensive for a specific MimeMultipart subclass, then it
     * might itself want to track whether its internal state actually
     * did change, and do the header updating only if necessary.
     *
     * @throws MessagingException for failures
     */
    protected synchronized void updateHeaders() throws MessagingException {
        parse();
        for (int i = 0; i < parts.size(); i++)
            ((MimeBodyPart) parts.elementAt(i)).updateHeaders();
    }

    /**
     * Iterates through all the parts and outputs each MIME part
     * separated by a boundary.
     */
    @Override
    public synchronized void writeTo(OutputStream os)
            throws IOException, MessagingException {
        parse();

        String boundary = "--" +
                (new ContentType(contentType)).getParameter("boundary");
        LineOutputStream los = streamProvider.outputLineStream(os, false);
        // if there's a preamble, write it out
        if (preamble != null) {
            byte[] pb = MimeUtility.getBytes(preamble);
            los.write(pb);
            // make sure it ends with a newline
            if (pb.length > 0 &&
                    !(pb[pb.length - 1] == '\r' || pb[pb.length - 1] == '\n')) {
                los.writeln();
            }
            // XXX - could force a blank line before start boundary
        }

        if (parts.size() == 0) {
            if (allowEmpty) {
                // write out a single empty body part
                los.writeln(boundary); // put out boundary
                los.writeln(); // put out empty line
            } else {
                throw new MessagingException("Empty multipart: " + contentType);
            }
        } else {
            for (int i = 0; i < parts.size(); i++) {
                los.writeln(boundary); // put out boundary
                parts.elementAt(i).writeTo(os);
                los.writeln(); // put out empty line
            }
        }

        // put out last boundary
        los.writeln(boundary + "--");
    }

    /**
     * Parse the InputStream from our DataSource, constructing the
     * appropriate MimeBodyParts.  The <code>parsed</code> flag is
     * set to true, and if true on entry nothing is done.  This
     * method is called by all other methods that need data for
     * the body parts, to make sure the data has been parsed.
     * The {@link #initializeProperties} method is called before
     * parsing the data.
     *
     * @throws ParseException     for failures parsing the message
     * @throws MessagingException for other failures
     * @since JavaMail 1.2
     */
    protected synchronized void parse() throws MessagingException {
        if (parsed)
            return;

        initializeProperties();

        InputStream in = null;
        SharedInputStream sin = null;
        long start = 0, end = 0;

        try {
            in = ds.getInputStream();
            if (!(in instanceof ByteArrayInputStream) &&
                    !(in instanceof BufferedInputStream) &&
                    !(in instanceof SharedInputStream))
                in = new BufferedInputStream(in);
        } catch (Exception ex) {
            throw new MessagingException("No inputstream from datasource", ex);
        }
        if (in instanceof SharedInputStream)
            sin = (SharedInputStream) in;

        ContentType cType = new ContentType(contentType);
        String boundary = null;
        if (!ignoreExistingBoundaryParameter) {
            String bp = cType.getParameter("boundary");
            if (bp != null)
                boundary = "--" + bp;
        }
        if (boundary == null && !ignoreMissingBoundaryParameter &&
                !ignoreExistingBoundaryParameter)
            throw new ParseException("Missing boundary parameter");

        try {
            // Skip and save the preamble
            LineInputStream lin = streamProvider.inputLineStream(in, false);
            StringBuilder preamblesb = null;
            String line;
            while ((line = lin.readLine()) != null) {
                /*
                 * Strip trailing whitespace.  Can't use trim method
                 * because it's too aggressive.  Some bogus MIME
                 * messages will include control characters in the
                 * boundary string.
                 */
                int i;
                for (i = line.length() - 1; i >= 0; i--) {
                    char c = line.charAt(i);
                    if (!(c == ' ' || c == '\t'))
                        break;
                }
                line = line.substring(0, i + 1);
                if (boundary != null) {
                    if (line.equals(boundary))
                        break;
                    if (line.length() == boundary.length() + 2 &&
                            line.startsWith(boundary) && line.endsWith("--")) {
                        line = null;    // signal end of multipart
                        break;
                    }
                } else {
                    /*
                     * Boundary hasn't been defined, does this line
                     * look like a boundary?  If so, assume it is
                     * the boundary and save it.
                     */
                    if (line.length() > 2 && line.startsWith("--")) {
                        if (line.length() > 4 && allDashes(line)) {
                            /*
                             * The first boundary-like line we find is
                             * probably *not* the end-of-multipart boundary
                             * line.  More likely it's a line full of dashes
                             * in the preamble text.  Just keep reading.
                             */
                        } else {
                            boundary = line;
                            break;
                        }
                    }
                }

                // save the preamble after skipping blank lines
                if (line.length() > 0) {
                    // accumulate the preamble
                    if (preamblesb == null)
                        preamblesb = new StringBuilder(line.length() + 2);
                    preamblesb.append(line).append(System.lineSeparator());
                }
            }

            if (preamblesb != null)
                preamble = preamblesb.toString();

            if (line == null) {
                if (allowEmpty)
                    return;
                else
                    throw new ParseException("Missing start boundary");
            }

            // save individual boundary bytes for comparison later
            byte[] bndbytes = MimeUtility.getBytes(boundary);
            int bl = bndbytes.length;

            /*
             * Compile Boyer-Moore parsing tables.
             */

            // initialize Bad Character Shift table
            int[] bcs = new int[256];
            for (int i = 0; i < bl; i++)
                bcs[bndbytes[i] & 0xff] = i + 1;

            // initialize Good Suffix Shift table
            int[] gss = new int[bl];
            NEXT:
            for (int i = bl; i > 0; i--) {
                int j;    // the beginning index of the suffix being considered
                for (j = bl - 1; j >= i; j--) {
                    // Testing for good suffix
                    if (bndbytes[j] == bndbytes[j - i]) {
                        // bndbytes[j..len] is a good suffix
                        gss[j - 1] = i;
                    } else {
                        // No match. The array has already been
                        // filled up with correct values before.
                        continue NEXT;
                    }
                }
                while (j > 0)
                    gss[--j] = i;
            }
            gss[bl - 1] = 1;

            /*
             * Read and process body parts until we see the
             * terminating boundary line (or EOF).
             */
            boolean done = false;
            getparts:
            while (!done) {
                InternetHeaders headers = null;
                if (sin != null) {
                    start = sin.getPosition();
                    // skip headers
                    while ((line = lin.readLine()) != null && line.length() > 0)
                        ;
                    if (line == null) {
                        if (!ignoreMissingEndBoundary)
                            throw new ParseException(
                                    "missing multipart end boundary");
                        // assume there's just a missing end boundary
                        complete = false;
                        break getparts;
                    }
                } else {
                    // collect the headers for this body part
                    headers = createInternetHeaders(in);
                }

                if (!in.markSupported())
                    throw new MessagingException("Stream doesn't support mark");

                ByteArrayOutputStream buf = null;
                // if we don't have a shared input stream, we copy the data
                if (sin == null)
                    buf = new ByteArrayOutputStream();
                else
                    end = sin.getPosition();
                int b;

                /*
                 * These buffers contain the bytes we're checking
                 * for a match.  inbuf is the current buffer and
                 * previnbuf is the previous buffer.  We need the
                 * previous buffer to check that we're preceeded
                 * by an EOL.
                 */
                // XXX - a smarter algorithm would use a sliding window
                //	 over a larger buffer
                byte[] inbuf = new byte[bl];
                byte[] previnbuf = new byte[bl];
                int inSize = 0;        // number of valid bytes in inbuf
                int prevSize = 0;    // number of valid bytes in previnbuf
                int eolLen;
                boolean first = true;

                /*
                 * Read and save the content bytes in buf.
                 */
                for (; ; ) {
                    in.mark(bl + 4 + 1000); // bnd + "--\r\n" + lots of LWSP
                    eolLen = 0;
                    inSize = readFully(in, inbuf, 0, bl);
                    if (inSize < bl) {
                        // hit EOF
                        if (!ignoreMissingEndBoundary)
                            throw new ParseException(
                                    "missing multipart end boundary");
                        if (sin != null)
                            end = sin.getPosition();
                        complete = false;
                        done = true;
                        break;
                    }
                    // check whether inbuf contains a boundary string
                    int i;
                    for (i = bl - 1; i >= 0; i--) {
                        if (inbuf[i] != bndbytes[i])
                            break;
                    }
                    if (i < 0) {    // matched all bytes
                        eolLen = 0;
                        if (!first) {
                            // working backwards, find out if we were preceeded
                            // by an EOL, and if so find its length
                            b = previnbuf[prevSize - 1];
                            if (b == '\r' || b == '\n') {
                                eolLen = 1;
                                if (b == '\n' && prevSize >= 2) {
                                    b = previnbuf[prevSize - 2];
                                    if (b == '\r')
                                        eolLen = 2;
                                }
                            }
                        }
                        if (first || eolLen > 0) {    // yes, preceed by EOL
                            if (sin != null) {
                                // update "end", in case this really is
                                // a valid boundary
                                end = sin.getPosition() - bl - eolLen;
                            }
                            // matched the boundary, check for last boundary
                            int b2 = in.read();
                            if (b2 == '-') {
                                if (in.read() == '-') {
                                    complete = true;
                                    done = true;
                                    break;    // ignore trailing text
                                }
                            }
                            // skip linear whitespace
                            while (b2 == ' ' || b2 == '\t')
                                b2 = in.read();
                            // check for end of line
                            if (b2 == '\n')
                                break;    // got it!  break out of the loop
                            if (b2 == '\r') {
                                in.mark(1);
                                if (in.read() != '\n')
                                    in.reset();
                                break;    // got it!  break out of the loop
                            }
                        }
                        i = 0;
                    }

                    /*
                     * Get here if boundary didn't match,
                     * wasn't preceeded by EOL, or wasn't
                     * followed by whitespace or EOL.
                     */

                    // compute how many bytes we can skip
                    int skip = Math.max(i + 1 - bcs[inbuf[i] & 0xff], gss[i]);
                    // want to keep at least two characters
                    if (skip < 2) {
                        // only skipping one byte, save one byte
                        // from previous buffer as well
                        // first, write out bytes we're done with
                        if (sin == null && prevSize > 1)
                            buf.write(previnbuf, 0, prevSize - 1);
                        in.reset();
                        skipFully(in, 1);
                        if (prevSize >= 1) {    // is there a byte to save?
                            // yes, save one from previous and one from current
                            previnbuf[0] = previnbuf[prevSize - 1];
                            previnbuf[1] = inbuf[0];
                            prevSize = 2;
                        } else {
                            // no previous bytes to save, can only save current
                            previnbuf[0] = inbuf[0];
                            prevSize = 1;
                        }
                    } else {
                        // first, write out data from previous buffer before
                        // we dump it
                        if (prevSize > 0 && sin == null)
                            buf.write(previnbuf, 0, prevSize);
                        // all the bytes we're skipping are saved in previnbuf
                        prevSize = skip;
                        in.reset();
                        skipFully(in, prevSize);
                        // swap buffers
                        byte[] tmp = inbuf;
                        inbuf = previnbuf;
                        previnbuf = tmp;
                    }
                    first = false;
                }

                /*
                 * Create a MimeBody element to represent this body part.
                 */
                MimeBodyPart part;
                if (sin != null) {
                    part = createMimeBodyPartIs(sin.newStream(start, end));
                } else {
                    // write out data from previous buffer, not including EOL
                    if (prevSize - eolLen > 0)
                        buf.write(previnbuf, 0, prevSize - eolLen);
                    // if we didn't find a trailing boundary,
                    // the current buffer has data we need too
                    if (!complete && inSize > 0)
                        buf.write(inbuf, 0, inSize);
                    part = createMimeBodyPart(headers, buf.toByteArray());
                }
                super.addBodyPart(part);
            }
        } catch (IOException ioex) {
            throw new MessagingException("IO Error", ioex);
        } finally {
            try {
                in.close();
            } catch (IOException cex) {
                // ignore
            }
        }

        parsed = true;
    }

    /**
     * Is the string all dashes ('-')?
     */
    private static boolean allDashes(String s) {
        for (int i = 0; i < s.length(); i++) {
            if (s.charAt(i) != '-')
                return false;
        }
        return true;
    }

    /**
     * Read data from the input stream to fill the buffer starting
     * at the specified offset with the specified number of bytes.
     * If len is zero, return zero.  If at EOF, return -1.  Otherwise,
     * return the number of bytes read.  Call the read method on the
     * input stream as many times as necessary to read len bytes.
     *
     * @param in  InputStream to read from
     * @param buf buffer to read into
     * @param off offset in the buffer for first byte
     * @param len number of bytes to read
     * @return -1 on EOF, otherwise number of bytes read
     * @throws IOException on I/O errors
     */
    private static int readFully(InputStream in, byte[] buf, int off, int len)
            throws IOException {
        if (len == 0)
            return 0;
        int total = 0;
        while (len > 0) {
            int bsize = in.read(buf, off, len);
            if (bsize <= 0)    // should never be zero
                break;
            off += bsize;
            total += bsize;
            len -= bsize;
        }
        return total > 0 ? total : -1;
    }

    /**
     * Skip the specified number of bytes, repeatedly calling
     * the skip method as necessary.
     */
    private void skipFully(InputStream in, long offset) throws IOException {
        while (offset > 0) {
            long cur = in.skip(offset);
            if (cur <= 0)
                throw new EOFException("can't skip");
            offset -= cur;
        }
    }

    /**
     * Create and return an InternetHeaders object that loads the
     * headers from the given InputStream.  Subclasses can override
     * this method to return a subclass of InternetHeaders, if
     * necessary.  This implementation simply constructs and returns
     * an InternetHeaders object.
     *
     * @param is the InputStream to read the headers from
     * @return an InternetHeaders object
     * @throws MessagingException for failures
     * @since JavaMail 1.2
     */
    protected InternetHeaders createInternetHeaders(InputStream is)
            throws MessagingException {
        return new InternetHeaders(is);
    }

    /**
     * Create and return a MimeBodyPart object to represent a
     * body part parsed from the InputStream.  Subclasses can override
     * this method to return a subclass of MimeBodyPart, if
     * necessary.  This implementation simply constructs and returns
     * a MimeBodyPart object.
     *
     * @param headers the headers for the body part
     * @param content the content of the body part
     * @return a MimeBodyPart
     * @throws MessagingException for failures
     * @since JavaMail 1.2
     */
    protected MimeBodyPart createMimeBodyPart(InternetHeaders headers,
                                              byte[] content) throws MessagingException {
        return new MimeBodyPart(headers, content);
    }

    /**
     * Create and return a MimeBodyPart object to represent a
     * body part parsed from the InputStream.  Subclasses can override
     * this method to return a subclass of MimeBodyPart, if
     * necessary.  This implementation simply constructs and returns
     * a MimeBodyPart object.
     *
     * @param is InputStream containing the body part
     * @return a MimeBodyPart
     * @throws MessagingException for failures
     * @since JavaMail 1.2
     */
    protected MimeBodyPart createMimeBodyPart(InputStream is)
            throws MessagingException {
        return new MimeBodyPart(is);
    }

    private MimeBodyPart createMimeBodyPartIs(InputStream is)
            throws MessagingException {
        try {
            return createMimeBodyPart(is);
        } finally {
            try {
                is.close();
            } catch (IOException ex) {
                // ignore it
            }
        }
    }
}
