001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.commons.fileupload;
018    
019    import java.io.ByteArrayOutputStream;
020    import java.io.IOException;
021    import java.io.InputStream;
022    import java.io.OutputStream;
023    import java.io.UnsupportedEncodingException;
024    
025    import org.apache.commons.fileupload.util.Closeable;
026    import org.apache.commons.fileupload.util.Streams;
027    
028    /**
029     * <p> Low level API for processing file uploads.
030     *
031     * <p> This class can be used to process data streams conforming to MIME
032     * 'multipart' format as defined in
033     * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>. Arbitrarily
034     * large amounts of data in the stream can be processed under constant
035     * memory usage.
036     *
037     * <p> The format of the stream is defined in the following way:<br>
038     *
039     * <code>
040     *   multipart-body := preamble 1*encapsulation close-delimiter epilogue<br>
041     *   encapsulation := delimiter body CRLF<br>
042     *   delimiter := "--" boundary CRLF<br>
043     *   close-delimiter := "--" boudary "--"<br>
044     *   preamble := &lt;ignore&gt;<br>
045     *   epilogue := &lt;ignore&gt;<br>
046     *   body := header-part CRLF body-part<br>
047     *   header-part := 1*header CRLF<br>
048     *   header := header-name ":" header-value<br>
049     *   header-name := &lt;printable ascii characters except ":"&gt;<br>
050     *   header-value := &lt;any ascii characters except CR & LF&gt;<br>
051     *   body-data := &lt;arbitrary data&gt;<br>
052     * </code>
053     *
054     * <p>Note that body-data can contain another mulipart entity.  There
055     * is limited support for single pass processing of such nested
056     * streams.  The nested stream is <strong>required</strong> to have a
057     * boundary token of the same length as the parent stream (see {@link
058     * #setBoundary(byte[])}).
059     *
060     * <p>Here is an example of usage of this class.<br>
061     *
062     * <pre>
063     *    try {
064     *        MultipartStream multipartStream = new MultipartStream(input,
065     *                                                              boundary);
066     *        boolean nextPart = multipartStream.skipPreamble();
067     *        OutputStream output;
068     *        while(nextPart) {
069     *            header = chunks.readHeader();
070     *            // process headers
071     *            // create some output stream
072     *            multipartStream.readBodyPart(output);
073     *            nextPart = multipartStream.readBoundary();
074     *        }
075     *    } catch(MultipartStream.MalformedStreamException e) {
076     *          // the stream failed to follow required syntax
077     *    } catch(IOException) {
078     *          // a read or write error occurred
079     *    }
080     *
081     * </pre>
082     *
083     * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
084     * @author <a href="mailto:martinc@apache.org">Martin Cooper</a>
085     * @author Sean C. Sullivan
086     *
087     * @version $Id: MultipartStream.java 607869 2008-01-01 16:42:17Z jochen $
088     */
089    public class MultipartStream {
090        /**
091         * Internal class, which is used to invoke the
092         * {@link ProgressListener}.
093         */
094        static class ProgressNotifier {
095            /** The listener to invoke.
096             */
097            private final ProgressListener listener;
098            /** Number of expected bytes, if known, or -1.
099             */
100            private final long contentLength;
101            /** Number of bytes, which have been read so far.
102             */
103            private long bytesRead;
104            /** Number of items, which have been read so far.
105             */
106            private int items;
107            /** Creates a new instance with the given listener
108             * and content length.
109             * @param pListener The listener to invoke.
110             * @param pContentLength The expected content length.
111             */
112            ProgressNotifier(ProgressListener pListener, long pContentLength) {
113                listener = pListener;
114                contentLength = pContentLength;
115            }
116            /** Called to indicate that bytes have been read.
117             * @param pBytes Number of bytes, which have been read.
118             */
119            void noteBytesRead(int pBytes) {
120                /* Indicates, that the given number of bytes have been read from
121                 * the input stream.
122                 */
123                bytesRead += pBytes;
124                notifyListener();
125            }
126            /** Called to indicate, that a new file item has been detected.
127             */
128            void noteItem() {
129                ++items;
130            }
131            /** Called for notifying the listener.
132             */
133            private void notifyListener() {
134                if (listener != null) {
135                    listener.update(bytesRead, contentLength, items);
136                }
137            }
138        }
139    
140        // ----------------------------------------------------- Manifest constants
141    
142    
143        /**
144         * The Carriage Return ASCII character value.
145         */
146        public static final byte CR = 0x0D;
147    
148    
149        /**
150         * The Line Feed ASCII character value.
151         */
152        public static final byte LF = 0x0A;
153    
154    
155        /**
156         * The dash (-) ASCII character value.
157         */
158        public static final byte DASH = 0x2D;
159    
160    
161        /**
162         * The maximum length of <code>header-part</code> that will be
163         * processed (10 kilobytes = 10240 bytes.).
164         */
165        public static final int HEADER_PART_SIZE_MAX = 10240;
166    
167    
168        /**
169         * The default length of the buffer used for processing a request.
170         */
171        protected static final int DEFAULT_BUFSIZE = 4096;
172    
173    
174        /**
175         * A byte sequence that marks the end of <code>header-part</code>
176         * (<code>CRLFCRLF</code>).
177         */
178        protected static final byte[] HEADER_SEPARATOR = {
179            CR, LF, CR, LF };
180    
181    
182        /**
183         * A byte sequence that that follows a delimiter that will be
184         * followed by an encapsulation (<code>CRLF</code>).
185         */
186        protected static final byte[] FIELD_SEPARATOR = {
187            CR, LF};
188    
189    
190        /**
191         * A byte sequence that that follows a delimiter of the last
192         * encapsulation in the stream (<code>--</code>).
193         */
194        protected static final byte[] STREAM_TERMINATOR = {
195            DASH, DASH};
196    
197    
198        /**
199         * A byte sequence that precedes a boundary (<code>CRLF--</code>).
200         */
201        protected static final byte[] BOUNDARY_PREFIX = {
202            CR, LF, DASH, DASH};
203    
204    
205        // ----------------------------------------------------------- Data members
206    
207    
208        /**
209         * The input stream from which data is read.
210         */
211        private final InputStream input;
212    
213    
214        /**
215         * The length of the boundary token plus the leading <code>CRLF--</code>.
216         */
217        private int boundaryLength;
218    
219    
220        /**
221         * The amount of data, in bytes, that must be kept in the buffer in order
222         * to detect delimiters reliably.
223         */
224        private int keepRegion;
225    
226    
227        /**
228         * The byte sequence that partitions the stream.
229         */
230        private byte[] boundary;
231    
232    
233        /**
234         * The length of the buffer used for processing the request.
235         */
236        private final int bufSize;
237    
238    
239        /**
240         * The buffer used for processing the request.
241         */
242        private final byte[] buffer;
243    
244    
245        /**
246         * The index of first valid character in the buffer.
247         * <br>
248         * 0 <= head < bufSize
249         */
250        private int head;
251    
252    
253        /**
254         * The index of last valid characer in the buffer + 1.
255         * <br>
256         * 0 <= tail <= bufSize
257         */
258        private int tail;
259    
260    
261        /**
262         * The content encoding to use when reading headers.
263         */
264        private String headerEncoding;
265    
266    
267        /**
268         * The progress notifier, if any, or null.
269         */
270        private final ProgressNotifier notifier;
271    
272        // ----------------------------------------------------------- Constructors
273    
274        /**
275         * Creates a new instance.
276         * @deprecated Use {@link #MultipartStream(InputStream, byte[],
277         * org.apache.commons.fileupload.MultipartStream.ProgressNotifier)},
278         * or {@link #MultipartStream(InputStream, byte[], int,
279         * org.apache.commons.fileupload.MultipartStream.ProgressNotifier)}
280         */
281        public MultipartStream() {
282            this(null, null, null);
283        }
284    
285        /**
286         * <p> Constructs a <code>MultipartStream</code> with a custom size buffer
287         * and no progress notifier.
288         *
289         * <p> Note that the buffer must be at least big enough to contain the
290         * boundary string, plus 4 characters for CR/LF and double dash, plus at
291         * least one byte of data.  Too small a buffer size setting will degrade
292         * performance.
293         *
294         * @param input    The <code>InputStream</code> to serve as a data source.
295         * @param boundary The token used for dividing the stream into
296         *                 <code>encapsulations</code>.
297         * @param bufSize  The size of the buffer to be used, in bytes.
298         *
299         * @see #MultipartStream(InputStream, byte[],
300         *   MultipartStream.ProgressNotifier)
301         * @deprecated Use {@link #MultipartStream(InputStream, byte[], int,
302         *  org.apache.commons.fileupload.MultipartStream.ProgressNotifier)}.
303         */
304        public MultipartStream(InputStream input, byte[] boundary, int bufSize) {
305            this(input, boundary, bufSize, null);
306        }
307    
308        /**
309         * <p> Constructs a <code>MultipartStream</code> with a custom size buffer.
310         *
311         * <p> Note that the buffer must be at least big enough to contain the
312         * boundary string, plus 4 characters for CR/LF and double dash, plus at
313         * least one byte of data.  Too small a buffer size setting will degrade
314         * performance.
315         *
316         * @param input    The <code>InputStream</code> to serve as a data source.
317         * @param boundary The token used for dividing the stream into
318         *                 <code>encapsulations</code>.
319         * @param bufSize  The size of the buffer to be used, in bytes.
320         * @param pNotifier The notifier, which is used for calling the
321         *                  progress listener, if any.
322         *
323         * @see #MultipartStream(InputStream, byte[],
324         *     MultipartStream.ProgressNotifier)
325         */
326        MultipartStream(InputStream input,
327                byte[] boundary,
328                int bufSize,
329                ProgressNotifier pNotifier) {
330            this.input = input;
331            this.bufSize = bufSize;
332            this.buffer = new byte[bufSize];
333            this.notifier = pNotifier;
334    
335            // We prepend CR/LF to the boundary to chop trailng CR/LF from
336            // body-data tokens.
337            this.boundary = new byte[boundary.length + BOUNDARY_PREFIX.length];
338            this.boundaryLength = boundary.length + BOUNDARY_PREFIX.length;
339            this.keepRegion = this.boundary.length;
340            System.arraycopy(BOUNDARY_PREFIX, 0, this.boundary, 0,
341                    BOUNDARY_PREFIX.length);
342            System.arraycopy(boundary, 0, this.boundary, BOUNDARY_PREFIX.length,
343                    boundary.length);
344    
345            head = 0;
346            tail = 0;
347        }
348    
349    
350        /**
351         * <p> Constructs a <code>MultipartStream</code> with a default size buffer.
352         *
353         * @param input    The <code>InputStream</code> to serve as a data source.
354         * @param boundary The token used for dividing the stream into
355         *                 <code>encapsulations</code>.
356         * @param pNotifier An object for calling the progress listener, if any.
357         *
358         *
359         * @see #MultipartStream(InputStream, byte[], int,
360         *     MultipartStream.ProgressNotifier)
361         */
362        MultipartStream(InputStream input,
363                byte[] boundary,
364                ProgressNotifier pNotifier) {
365            this(input, boundary, DEFAULT_BUFSIZE, pNotifier);
366        }
367    
368        /**
369         * <p> Constructs a <code>MultipartStream</code> with a default size buffer.
370         *
371         * @param input    The <code>InputStream</code> to serve as a data source.
372         * @param boundary The token used for dividing the stream into
373         *                 <code>encapsulations</code>.
374         *
375         * @deprecated Use {@link #MultipartStream(InputStream, byte[],
376         *  MultipartStream.ProgressNotifier)}.
377         * @see #MultipartStream(InputStream, byte[], int,
378         *  MultipartStream.ProgressNotifier)
379         */
380        public MultipartStream(InputStream input,
381                byte[] boundary) {
382            this(input, boundary, DEFAULT_BUFSIZE, null);
383        }
384    
385        // --------------------------------------------------------- Public methods
386    
387    
388        /**
389         * Retrieves the character encoding used when reading the headers of an
390         * individual part. When not specified, or <code>null</code>, the platform
391         * default encoding is used.
392    
393         *
394         * @return The encoding used to read part headers.
395         */
396        public String getHeaderEncoding() {
397            return headerEncoding;
398        }
399    
400    
401        /**
402         * Specifies the character encoding to be used when reading the headers of
403         * individual parts. When not specified, or <code>null</code>, the platform
404         * default encoding is used.
405         *
406         * @param encoding The encoding used to read part headers.
407         */
408        public void setHeaderEncoding(String encoding) {
409            headerEncoding = encoding;
410        }
411    
412    
413        /**
414         * Reads a byte from the <code>buffer</code>, and refills it as
415         * necessary.
416         *
417         * @return The next byte from the input stream.
418         *
419         * @throws IOException if there is no more data available.
420         */
421        public byte readByte() throws IOException {
422            // Buffer depleted ?
423            if (head == tail) {
424                head = 0;
425                // Refill.
426                tail = input.read(buffer, head, bufSize);
427                if (tail == -1) {
428                    // No more data available.
429                    throw new IOException("No more data is available");
430                }
431                if (notifier != null) {
432                    notifier.noteBytesRead(tail);
433                }
434            }
435            return buffer[head++];
436        }
437    
438    
439        /**
440         * Skips a <code>boundary</code> token, and checks whether more
441         * <code>encapsulations</code> are contained in the stream.
442         *
443         * @return <code>true</code> if there are more encapsulations in
444         *         this stream; <code>false</code> otherwise.
445         *
446         * @throws MalformedStreamException if the stream ends unexpecetedly or
447         *                                  fails to follow required syntax.
448         */
449        public boolean readBoundary()
450                throws MalformedStreamException {
451            byte[] marker = new byte[2];
452            boolean nextChunk = false;
453    
454            head += boundaryLength;
455            try {
456                marker[0] = readByte();
457                if (marker[0] == LF) {
458                    // Work around IE5 Mac bug with input type=image.
459                    // Because the boundary delimiter, not including the trailing
460                    // CRLF, must not appear within any file (RFC 2046, section
461                    // 5.1.1), we know the missing CR is due to a buggy browser
462                    // rather than a file containing something similar to a
463                    // boundary.
464                    return true;
465                }
466    
467                marker[1] = readByte();
468                if (arrayequals(marker, STREAM_TERMINATOR, 2)) {
469                    nextChunk = false;
470                } else if (arrayequals(marker, FIELD_SEPARATOR, 2)) {
471                    nextChunk = true;
472                } else {
473                    throw new MalformedStreamException(
474                    "Unexpected characters follow a boundary");
475                }
476            } catch (IOException e) {
477                throw new MalformedStreamException("Stream ended unexpectedly");
478            }
479            return nextChunk;
480        }
481    
482    
483        /**
484         * <p>Changes the boundary token used for partitioning the stream.
485         *
486         * <p>This method allows single pass processing of nested multipart
487         * streams.
488         *
489         * <p>The boundary token of the nested stream is <code>required</code>
490         * to be of the same length as the boundary token in parent stream.
491         *
492         * <p>Restoring the parent stream boundary token after processing of a
493         * nested stream is left to the application.
494         *
495         * @param boundary The boundary to be used for parsing of the nested
496         *                 stream.
497         *
498         * @throws IllegalBoundaryException if the <code>boundary</code>
499         *                                  has a different length than the one
500         *                                  being currently parsed.
501         */
502        public void setBoundary(byte[] boundary)
503                throws IllegalBoundaryException {
504            if (boundary.length != boundaryLength - BOUNDARY_PREFIX.length) {
505                throw new IllegalBoundaryException(
506                "The length of a boundary token can not be changed");
507            }
508            System.arraycopy(boundary, 0, this.boundary, BOUNDARY_PREFIX.length,
509                    boundary.length);
510        }
511    
512    
513        /**
514         * <p>Reads the <code>header-part</code> of the current
515         * <code>encapsulation</code>.
516         *
517         * <p>Headers are returned verbatim to the input stream, including the
518         * trailing <code>CRLF</code> marker. Parsing is left to the
519         * application.
520         *
521         * <p><strong>TODO</strong> allow limiting maximum header size to
522         * protect against abuse.
523         *
524         * @return The <code>header-part</code> of the current encapsulation.
525         *
526         * @throws MalformedStreamException if the stream ends unexpecetedly.
527         */
528        public String readHeaders()
529        throws MalformedStreamException {
530            int i = 0;
531            byte b;
532            // to support multi-byte characters
533            ByteArrayOutputStream baos = new ByteArrayOutputStream();
534            int size = 0;
535            while (i < HEADER_SEPARATOR.length) {
536                try {
537                    b = readByte();
538                } catch (IOException e) {
539                    throw new MalformedStreamException("Stream ended unexpectedly");
540                }
541                if (++size > HEADER_PART_SIZE_MAX) {
542                    throw new MalformedStreamException(
543                            "Header section has more than " + HEADER_PART_SIZE_MAX
544                            + " bytes (maybe it is not properly terminated)");
545                }
546                if (b == HEADER_SEPARATOR[i]) {
547                    i++;
548                } else {
549                    i = 0;
550                }
551                baos.write(b);
552            }
553    
554            String headers = null;
555            if (headerEncoding != null) {
556                try {
557                    headers = baos.toString(headerEncoding);
558                } catch (UnsupportedEncodingException e) {
559                    // Fall back to platform default if specified encoding is not
560                    // supported.
561                    headers = baos.toString();
562                }
563            } else {
564                headers = baos.toString();
565            }
566    
567            return headers;
568        }
569    
570    
571        /**
572         * <p>Reads <code>body-data</code> from the current
573         * <code>encapsulation</code> and writes its contents into the
574         * output <code>Stream</code>.
575         *
576         * <p>Arbitrary large amounts of data can be processed by this
577         * method using a constant size buffer. (see {@link
578         * #MultipartStream(InputStream,byte[],int,
579         *   MultipartStream.ProgressNotifier) constructor}).
580         *
581         * @param output The <code>Stream</code> to write data into. May
582         *               be null, in which case this method is equivalent
583         *               to {@link #discardBodyData()}.
584         *
585         * @return the amount of data written.
586         *
587         * @throws MalformedStreamException if the stream ends unexpectedly.
588         * @throws IOException              if an i/o error occurs.
589         */
590        public int readBodyData(OutputStream output)
591                throws MalformedStreamException, IOException {
592            final InputStream istream = newInputStream();
593            return (int) Streams.copy(istream, output, false);
594        }
595    
596        /**
597         * Creates a new {@link ItemInputStream}.
598         * @return A new instance of {@link ItemInputStream}.
599         */
600        ItemInputStream newInputStream() {
601            return new ItemInputStream();
602        }
603    
604        /**
605         * <p> Reads <code>body-data</code> from the current
606         * <code>encapsulation</code> and discards it.
607         *
608         * <p>Use this method to skip encapsulations you don't need or don't
609         * understand.
610         *
611         * @return The amount of data discarded.
612         *
613         * @throws MalformedStreamException if the stream ends unexpectedly.
614         * @throws IOException              if an i/o error occurs.
615         */
616        public int discardBodyData()
617        throws MalformedStreamException,
618        IOException {
619            return readBodyData(null);
620        }
621    
622    
623        /**
624         * Finds the beginning of the first <code>encapsulation</code>.
625         *
626         * @return <code>true</code> if an <code>encapsulation</code> was found in
627         *         the stream.
628         *
629         * @throws IOException if an i/o error occurs.
630         */
631        public boolean skipPreamble()
632        throws IOException {
633            // First delimiter may be not preceeded with a CRLF.
634            System.arraycopy(boundary, 2, boundary, 0, boundary.length - 2);
635            boundaryLength = boundary.length - 2;
636            try {
637                // Discard all data up to the delimiter.
638                discardBodyData();
639    
640                // Read boundary - if succeded, the stream contains an
641                // encapsulation.
642                return readBoundary();
643            } catch (MalformedStreamException e) {
644                return false;
645            } finally {
646                // Restore delimiter.
647                System.arraycopy(boundary, 0, boundary, 2, boundary.length - 2);
648                boundaryLength = boundary.length;
649                boundary[0] = CR;
650                boundary[1] = LF;
651            }
652        }
653    
654    
655        /**
656         * Compares <code>count</code> first bytes in the arrays
657         * <code>a</code> and <code>b</code>.
658         *
659         * @param a     The first array to compare.
660         * @param b     The second array to compare.
661         * @param count How many bytes should be compared.
662         *
663         * @return <code>true</code> if <code>count</code> first bytes in arrays
664         *         <code>a</code> and <code>b</code> are equal.
665         */
666        public static boolean arrayequals(byte[] a,
667                byte[] b,
668                int count) {
669            for (int i = 0; i < count; i++) {
670                if (a[i] != b[i]) {
671                    return false;
672                }
673            }
674            return true;
675        }
676    
677    
678        /**
679         * Searches for a byte of specified value in the <code>buffer</code>,
680         * starting at the specified <code>position</code>.
681         *
682         * @param value The value to find.
683         * @param pos   The starting position for searching.
684         *
685         * @return The position of byte found, counting from beginning of the
686         *         <code>buffer</code>, or <code>-1</code> if not found.
687         */
688        protected int findByte(byte value,
689                int pos) {
690            for (int i = pos; i < tail; i++) {
691                if (buffer[i] == value) {
692                    return i;
693                }
694            }
695    
696            return -1;
697        }
698    
699    
700        /**
701         * Searches for the <code>boundary</code> in the <code>buffer</code>
702         * region delimited by <code>head</code> and <code>tail</code>.
703         *
704         * @return The position of the boundary found, counting from the
705         *         beginning of the <code>buffer</code>, or <code>-1</code> if
706         *         not found.
707         */
708        protected int findSeparator() {
709            int first;
710            int match = 0;
711            int maxpos = tail - boundaryLength;
712            for (first = head;
713            (first <= maxpos) && (match != boundaryLength);
714            first++) {
715                first = findByte(boundary[0], first);
716                if (first == -1 || (first > maxpos)) {
717                    return -1;
718                }
719                for (match = 1; match < boundaryLength; match++) {
720                    if (buffer[first + match] != boundary[match]) {
721                        break;
722                    }
723                }
724            }
725            if (match == boundaryLength) {
726                return first - 1;
727            }
728            return -1;
729        }
730    
731        /**
732         * Thrown to indicate that the input stream fails to follow the
733         * required syntax.
734         */
735        public static class MalformedStreamException
736        extends IOException {
737            /**
738             * Constructs a <code>MalformedStreamException</code> with no
739             * detail message.
740             */
741            public MalformedStreamException() {
742                super();
743            }
744    
745            /**
746             * Constructs an <code>MalformedStreamException</code> with
747             * the specified detail message.
748             *
749             * @param message The detail message.
750             */
751            public MalformedStreamException(String message) {
752                super(message);
753            }
754        }
755    
756    
757        /**
758         * Thrown upon attempt of setting an invalid boundary token.
759         */
760        public static class IllegalBoundaryException
761                extends IOException {
762            /**
763             * Constructs an <code>IllegalBoundaryException</code> with no
764             * detail message.
765             */
766            public IllegalBoundaryException() {
767                super();
768            }
769    
770            /**
771             * Constructs an <code>IllegalBoundaryException</code> with
772             * the specified detail message.
773             *
774             * @param message The detail message.
775             */
776            public IllegalBoundaryException(String message) {
777                super(message);
778            }
779        }
780    
781        /**
782         * An {@link InputStream} for reading an items contents.
783         */
784        public class ItemInputStream extends InputStream implements Closeable {
785            /** The number of bytes, which have been read so far.
786             */
787            private long total;
788            /** The number of bytes, which must be hold, because
789             * they might be a part of the boundary.
790             */
791            private int pad;
792            /** The current offset in the buffer.
793             */
794            private int pos;
795            /** Whether the stream is already closed.
796             */
797            private boolean closed;
798    
799            /**
800             * Creates a new instance.
801             */
802            ItemInputStream() {
803                findSeparator();
804            }
805    
806            /**
807             * Called for finding the separator.
808             */
809            private void findSeparator() {
810                pos = MultipartStream.this.findSeparator();
811                if (pos == -1) {
812                    if (tail - head > keepRegion) {
813                        pad = keepRegion;
814                    } else {
815                        pad = tail - head;
816                    }
817                }
818            }
819    
820            /**
821             * Returns the number of bytes, which have been read
822             * by the stream.
823             * @return Number of bytes, which have been read so far.
824             */
825            public long getBytesRead() {
826                return total;
827            }
828    
829            /**
830             * Returns the number of bytes, which are currently
831             * available, without blocking.
832             * @throws IOException An I/O error occurs.
833             * @return Number of bytes in the buffer.
834             */
835            public int available() throws IOException {
836                if (pos == -1) {
837                    return tail - head - pad;
838                }
839                return pos - head;
840            }
841    
842            /** Offset when converting negative bytes to integers.
843             */
844            private static final int BYTE_POSITIVE_OFFSET = 256;
845    
846            /**
847             * Returns the next byte in the stream.
848             * @return The next byte in the stream, as a non-negative
849             *   integer, or -1 for EOF.
850             * @throws IOException An I/O error occurred.
851             */
852            public int read() throws IOException {
853                if (closed) {
854                    throw new FileItemStream.ItemSkippedException();
855                }
856                if (available() == 0) {
857                    if (makeAvailable() == 0) {
858                        return -1;
859                    }
860                }
861                ++total;
862                int b = buffer[head++];
863                if (b >= 0) {
864                    return b;
865                }
866                return b + BYTE_POSITIVE_OFFSET;
867            }
868    
869            /**
870             * Reads bytes into the given buffer.
871             * @param b The destination buffer, where to write to.
872             * @param off Offset of the first byte in the buffer.
873             * @param len Maximum number of bytes to read.
874             * @return Number of bytes, which have been actually read,
875             *   or -1 for EOF.
876             * @throws IOException An I/O error occurred.
877             */
878            public int read(byte[] b, int off, int len) throws IOException {
879                if (closed) {
880                    throw new FileItemStream.ItemSkippedException();
881                }
882                if (len == 0) {
883                    return 0;
884                }
885                int res = available();
886                if (res == 0) {
887                    res = makeAvailable();
888                    if (res == 0) {
889                        return -1;
890                    }
891                }
892                res = Math.min(res, len);
893                System.arraycopy(buffer, head, b, off, res);
894                head += res;
895                total += res;
896                return res;
897            }
898    
899            /**
900             * Closes the input stream.
901             * @throws IOException An I/O error occurred.
902             */
903            public void close() throws IOException {
904                close(false);
905            }
906    
907            /**
908             * Closes the input stream.
909             * @param pCloseUnderlying Whether to close the underlying stream
910             *   (hard close)
911             * @throws IOException An I/O error occurred.
912             */
913            public void close(boolean pCloseUnderlying) throws IOException {
914                if (closed) {
915                    return;
916                }
917                if (pCloseUnderlying) {
918                    closed = true;
919                    input.close();
920                } else {
921                    for (;;) {
922                        int av = available();
923                        if (av == 0) {
924                            av = makeAvailable();
925                            if (av == 0) {
926                                break;
927                            }
928                        }
929                        skip(av);
930                    }
931                }
932                closed = true;
933            }
934    
935            /**
936             * Skips the given number of bytes.
937             * @param bytes Number of bytes to skip.
938             * @return The number of bytes, which have actually been
939             *   skipped.
940             * @throws IOException An I/O error occurred.
941             */
942            public long skip(long bytes) throws IOException {
943                if (closed) {
944                    throw new FileItemStream.ItemSkippedException();
945                }
946                int av = available();
947                if (av == 0) {
948                    av = makeAvailable();
949                    if (av == 0) {
950                        return 0;
951                    }
952                }
953                long res = Math.min(av, bytes);
954                head += res;
955                return res;
956            }
957    
958            /**
959             * Attempts to read more data.
960             * @return Number of available bytes
961             * @throws IOException An I/O error occurred.
962             */
963            private int makeAvailable() throws IOException {
964                if (pos != -1) {
965                    return 0;
966                }
967    
968                // Move the data to the beginning of the buffer.
969                total += tail - head - pad;
970                System.arraycopy(buffer, tail - pad, buffer, 0, pad);
971    
972                // Refill buffer with new data.
973                head = 0;
974                tail = pad;
975    
976                for (;;) {
977                    int bytesRead = input.read(buffer, tail, bufSize - tail);
978                    if (bytesRead == -1) {
979                        // The last pad amount is left in the buffer.
980                        // Boundary can't be in there so signal an error
981                        // condition.
982                        final String msg = "Stream ended unexpectedly";
983                        throw new MalformedStreamException(msg);
984                    }
985                    if (notifier != null) {
986                        notifier.noteBytesRead(bytesRead);
987                    }
988                    tail += bytesRead;
989    
990                    findSeparator();
991                    int av = available();
992    
993                    if (av > 0 || pos != -1) {
994                        return av;
995                    }
996                }
997            }
998    
999            /**
1000             * Returns, whether the stream is closed.
1001             * @return True, if the stream is closed, otherwise false.
1002             */
1003            public boolean isClosed() {
1004                return closed;
1005            }
1006        }
1007    
1008        // ------------------------------------------------------ Debugging methods
1009    
1010    
1011        // These are the methods that were used to debug this stuff.
1012        /*
1013    
1014        // Dump data.
1015        protected void dump()
1016        {
1017            System.out.println("01234567890");
1018            byte[] temp = new byte[buffer.length];
1019            for(int i=0; i<buffer.length; i++)
1020            {
1021                if (buffer[i] == 0x0D || buffer[i] == 0x0A)
1022                {
1023                    temp[i] = 0x21;
1024                }
1025                else
1026                {
1027                    temp[i] = buffer[i];
1028                }
1029            }
1030            System.out.println(new String(temp));
1031            int i;
1032            for (i=0; i<head; i++)
1033                System.out.print(" ");
1034            System.out.println("h");
1035            for (i=0; i<tail; i++)
1036                System.out.print(" ");
1037            System.out.println("t");
1038            System.out.flush();
1039        }
1040    
1041        // Main routine, for testing purposes only.
1042        //
1043        // @param args A String[] with the command line arguments.
1044        // @throws Exception, a generic exception.
1045        public static void main( String[] args )
1046            throws Exception
1047        {
1048            File boundaryFile = new File("boundary.dat");
1049            int boundarySize = (int)boundaryFile.length();
1050            byte[] boundary = new byte[boundarySize];
1051            FileInputStream input = new FileInputStream(boundaryFile);
1052            input.read(boundary,0,boundarySize);
1053    
1054            input = new FileInputStream("multipart.dat");
1055            MultipartStream chunks = new MultipartStream(input, boundary);
1056    
1057            int i = 0;
1058            String header;
1059            OutputStream output;
1060            boolean nextChunk = chunks.skipPreamble();
1061            while (nextChunk)
1062            {
1063                header = chunks.readHeaders();
1064                System.out.println("!"+header+"!");
1065                System.out.println("wrote part"+i+".dat");
1066                output = new FileOutputStream("part"+(i++)+".dat");
1067                chunks.readBodyData(output);
1068                nextChunk = chunks.readBoundary();
1069            }
1070        }
1071    
1072         */
1073    }