# FileUploadBase.java

    /*
     * Licensed to the Apache Software Foundation (ASF) under one or more
     * contributor license agreements.  See the NOTICE file distributed with
     * this work for additional information regarding copyright ownership.
     * The ASF licenses this file to You under the Apache License, Version 2.0
     * (the "License"); you may not use this file except in compliance with
     * the License.  You may obtain a copy of the License at
     *
     *      http://www.apache.org/licenses/LICENSE-2.0
     *
     * Unless required by applicable law or agreed to in writing, software
     * distributed under the License is distributed on an "AS IS" BASIS,
     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     * See the License for the specific language governing permissions and
     * limitations under the License.
     */
    package org.apache.commons.fileupload;

    import static java.lang.String.format;

    import java.io.IOException;
    import java.io.InputStream;
    import java.nio.charset.StandardCharsets;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Locale;
    import java.util.Map;
    import java.util.NoSuchElementException;
    import java.util.Objects;

    import javax.servlet.http.HttpServletRequest;

    import org.apache.commons.fileupload.MultipartStream.ItemInputStream;
    import org.apache.commons.fileupload.servlet.ServletFileUpload;
    import org.apache.commons.fileupload.servlet.ServletRequestContext;
    import org.apache.commons.fileupload.util.Closeable;
    import org.apache.commons.fileupload.util.FileItemHeadersImpl;
    import org.apache.commons.fileupload.util.LimitedInputStream;
    import org.apache.commons.fileupload.util.Streams;
    import org.apache.commons.io.IOUtils;

    /**
     * High level API for processing file uploads.
     *
     * <p>
     * This class handles multiple files per single HTML widget, sent using {@code multipart/mixed} encoding type, as specified by
     * <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>. Use {@link #parseRequest(RequestContext)} to acquire a list of
     * {@link org.apache.commons.fileupload.FileItem}s associated with a given HTML widget.
     * </p>
     *
     * <p>
     * How the data for individual parts is stored is determined by the factory used to create them; a given part may be in memory, on disk, or somewhere else.
     * </p>
     */
    public abstract class FileUploadBase {

        /**
         * The iterator, which is returned by
         * {@link FileUploadBase#getItemIterator(RequestContext)}.
         */
        private class FileItemIteratorImpl implements FileItemIterator {

            /**
             * Default implementation of {@link FileItemStream}.
             */
            private final class FileItemStreamImpl implements FileItemStream {

                /**
                 * The file items content type.
                 */
                private final String contentType;

                /**
                 * The file items field name.
                 */
                private final String fieldName;

                /**
                 * The file items file name.
                 */
                private final String name;

                /**
                 * Whether the file item is a form field.
                 */
                private final boolean formField;

                /**
                 * The file items input stream.
                 */
                private final InputStream inputStream;

                /**
                 * The headers, if any.
                 */
                private FileItemHeaders headers;

                /**
                 * Creates a new instance.
                 *
                 * @param name          The items file name, or null.
                 * @param fieldName     The items field name.
                 * @param contentType   The items content type, or null.
                 * @param formField     Whether the item is a form field.
                 * @param contentLength The items content length, if known, or -1
                 * @throws IOException Creating the file item failed.
                 */
                FileItemStreamImpl(final String name, final String fieldName, final String contentType, final boolean formField, final long contentLength)
                        throws IOException {
                    this.name = name;
                    this.fieldName = fieldName;
                    this.contentType = contentType;
                    this.formField = formField;
                    // Check if limit is already exceeded
                    if (fileSizeMax != -1 && contentLength != -1 && contentLength > fileSizeMax) {
                        final FileSizeLimitExceededException e = new FileSizeLimitExceededException(
                                format("The field %s exceeds its maximum permitted size of %s bytes.", fieldName, Long.valueOf(fileSizeMax)), contentLength,
                                fileSizeMax);
                        e.setFileName(name);
                        e.setFieldName(fieldName);
                        throw new FileUploadIOException(e);
                    }
                    // OK to construct stream now
                    final ItemInputStream itemStream = multi.newInputStream();
                    InputStream istream = itemStream;
                    if (fileSizeMax != -1) {
                        istream = new LimitedInputStream(istream, fileSizeMax) {

                            @Override
                            protected void raiseError(final long sizeMax, final long count) throws IOException {
                                itemStream.close(true);
                                final FileSizeLimitExceededException e = new FileSizeLimitExceededException(
                                        format("The field %s exceeds its maximum permitted size of %s bytes.", fieldName, Long.valueOf(sizeMax)), count, sizeMax);
                                e.setFieldName(fieldName);
                                e.setFileName(name);
                                throw new FileUploadIOException(e);
                            }
                        };
                    }
                    inputStream = istream;
                }

                /**
                 * Closes the file item.
                 *
                 * @throws IOException An I/O error occurred.
                 */
                void close() throws IOException {
                    inputStream.close();
                }

                /**
                 * Returns the items content type, or null.
                 *
                 * @return Content type, if known, or null.
                 */
                @Override
                public String getContentType() {
                    return contentType;
                }

                /**
                 * Returns the items field name.
                 *
                 * @return Field name.
                 */
                @Override
                public String getFieldName() {
                    return fieldName;
                }

                /**
                 * Returns the file item headers.
                 *
                 * @return The items header object
                 */
                @Override
                public FileItemHeaders getHeaders() {
                    return headers;
                }

                /**
                 * Returns the items file name.
                 *
                 * @return File name, if known, or null.
                 * @throws InvalidFileNameException The file name contains a NUL character,
                 *   which might be an indicator of a security attack. If you intend to
                 *   use the file name anyways, catch the exception and use
                 *   InvalidFileNameException#getName().
                 */
                @Override
                public String getName() {
                    return Streams.checkFileName(name);
                }

                /**
                 * Returns, whether this is a form field.
                 *
                 * @return True, if the item is a form field,
                 *   otherwise false.
                 */
                @Override
                public boolean isFormField() {
                    return formField;
                }

                /**
                 * Returns an input stream, which may be used to
                 * read the items contents.
                 *
                 * @return Opened input stream.
                 * @throws IOException An I/O error occurred.
                 */
                @Override
                public InputStream openStream() throws IOException {
                    if (((Closeable) inputStream).isClosed()) {
                        throw new FileItemStream.ItemSkippedException();
                    }
                    return inputStream;
                }

                /**
                 * Sets the file item headers.
                 *
                 * @param headers The items header object
                 */
                @Override
                public void setHeaders(final FileItemHeaders headers) {
                    this.headers = headers;
                }

            }

            /**
             * The multi part stream to process.
             */
            private final MultipartStream multi;

            /**
             * The notifier, which used for triggering the
             * {@link ProgressListener}.
             */
            private final MultipartStream.ProgressNotifier notifier;

            /**
             * The boundary, which separates the various parts.
             */
            private final byte[] boundary;

            /**
             * The item, which we currently process.
             */
            private FileItemStreamImpl currentItem;

            /**
             * The current items field name.
             */
            private String currentFieldName;

            /**
             * Whether we are currently skipping the preamble.
             */
            private boolean skipPreamble;

            /**
             * Whether the current item may still be read.
             */
            private boolean itemValid;

            /**
             * Whether we have seen the end of the file.
             */
            private boolean eof;

            /**
             * Is this a multipart/related Request.
             */
            private final boolean multipartRelated;

            /**
             * Creates a new instance.
             *
             * @param ctx The request context.
             * @throws FileUploadException An error occurred while
             *   parsing the request.
             * @throws IOException An I/O error occurred.
             */
            FileItemIteratorImpl(final RequestContext ctx) throws FileUploadException, IOException {
                Objects.requireNonNull(ctx, "ctx");
                final String contentType = ctx.getContentType();
                if (null == contentType || !contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART)) {
                    throw new InvalidContentTypeException(format("the request neither contains a %s nor a %s nor a %s stream, content type header is %s",
                            MULTIPART_FORM_DATA, MULTIPART_MIXED, MULTIPART_RELATED, contentType));
                }
                multipartRelated = contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART_RELATED);
                @SuppressWarnings("deprecation") // still has to be backward compatible
                final int contentLengthInt = ctx.getContentLength();
                final long requestSize = UploadContext.class.isAssignableFrom(ctx.getClass())
                        // Inline conditional is OK here CHECKSTYLE:OFF
                        ? ((UploadContext) ctx).contentLength()
                        : contentLengthInt;
                // CHECKSTYLE:ON
                final InputStream input; // this is eventually closed in MultipartStream processing
                if (sizeMax >= 0) {
                    if (requestSize != -1 && requestSize > sizeMax) {
                        throw new SizeLimitExceededException(format("the request was rejected because its size (%s) exceeds the configured maximum (%s)",
                                Long.valueOf(requestSize), Long.valueOf(sizeMax)), requestSize, sizeMax);
                    }
                    // this is eventually closed in MultipartStream processing
                    input = new LimitedInputStream(ctx.getInputStream(), sizeMax) {

                        @Override
                        protected void raiseError(final long sizeMax, final long count) throws IOException {
                            final FileUploadException ex = new SizeLimitExceededException(
                                    format("the request was rejected because its size (%s) exceeds the configured maximum (%s)", Long.valueOf(count),
                                            Long.valueOf(sizeMax)),
                                    count, sizeMax);
                            throw new FileUploadIOException(ex);
                        }
                    };
                } else {
                    input = ctx.getInputStream();
                }
                String charEncoding = headerEncoding;
                if (charEncoding == null) {
                    charEncoding = ctx.getCharacterEncoding();
                }
                boundary = getBoundary(contentType);
                if (boundary == null) {
                    IOUtils.closeQuietly(input); // avoid possible resource leak
                    throw new FileUploadException("the request was rejected because no multipart boundary was found");
                }
                notifier = new MultipartStream.ProgressNotifier(listener, requestSize);
                try {
                    multi = new MultipartStream(input, boundary, notifier);
                } catch (final IllegalArgumentException iae) {
                    IOUtils.closeQuietly(input); // avoid possible resource leak
                    throw new InvalidContentTypeException(format("The boundary specified in the %s header is too long", CONTENT_TYPE), iae);
                }
                multi.setHeaderEncoding(charEncoding);
                multi.setPartHeaderSizeMax(getPartHeaderSizeMax());
                skipPreamble = true;
                findNextItem();
            }

            /**
             * Called for finding the next item, if any.
             *
             * @return True, if an next item was found, otherwise false.
             * @throws IOException An I/O error occurred.
             */
            private boolean findNextItem() throws IOException {
                if (eof) {
                    return false;
                }
                if (currentItem != null) {
                    currentItem.close();
                    currentItem = null;
                }
                for (;;) {
                    final boolean nextPart;
                    if (skipPreamble) {
                        nextPart = multi.skipPreamble();
                    } else {
                        nextPart = multi.readBoundary();
                    }
                    if (!nextPart) {
                        if (currentFieldName == null) {
                            // Outer multipart terminated -> No more data
                            eof = true;
                            return false;
                        }
                        // Inner multipart terminated -> Return to parsing the outer
                        multi.setBoundary(boundary);
                        currentFieldName = null;
                        continue;
                    }
                    final FileItemHeaders headers = getParsedHeaders(multi.readHeaders());
                    if (multipartRelated) {
                        currentFieldName = "";
                        currentItem = new FileItemStreamImpl(null, null, headers.getHeader(CONTENT_TYPE), false, getContentLength(headers));
                        currentItem.setHeaders(headers);
                        notifier.noteItem();
                        itemValid = true;
                        return true;
                    }
                    if (currentFieldName == null) {
                        // We're parsing the outer multipart
                        final String fieldName = getFieldName(headers);
                        if (fieldName != null) {
                            final String subContentType = headers.getHeader(CONTENT_TYPE);
                            if (subContentType != null && subContentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART_MIXED)) {
                                currentFieldName = fieldName;
                                // Multiple files associated with this field name
                                final byte[] subBoundary = getBoundary(subContentType);
                                multi.setBoundary(subBoundary);
                                skipPreamble = true;
                                continue;
                            }
                            final String fileName = getFileName(headers);
                            currentItem = new FileItemStreamImpl(fileName, fieldName, headers.getHeader(CONTENT_TYPE), fileName == null, getContentLength(headers));
                            currentItem.setHeaders(headers);
                            notifier.noteItem();
                            itemValid = true;
                            return true;
                        }
                    } else {
                        final String fileName = getFileName(headers);
                        if (fileName != null) {
                            currentItem = new FileItemStreamImpl(fileName, currentFieldName, headers.getHeader(CONTENT_TYPE), false, getContentLength(headers));
                            currentItem.setHeaders(headers);
                            notifier.noteItem();
                            itemValid = true;
                            return true;
                        }
                    }
                    multi.discardBodyData();
                }
            }

            private long getContentLength(final FileItemHeaders headers) {
                try {
                    return Long.parseLong(headers.getHeader(CONTENT_LENGTH));
                } catch (final Exception e) {
                    return -1;
                }
            }

            /**
             * Returns, whether another instance of {@link FileItemStream}
             * is available.
             *
             * @throws FileUploadException Parsing or processing the
             *   file item failed.
             * @throws IOException Reading the file item failed.
             * @return True, if one or more additional file items
             *   are available, otherwise false.
             */
            @Override
            public boolean hasNext() throws FileUploadException, IOException {
                if (eof) {
                    return false;
                }
                if (itemValid) {
                    return true;
                }
                try {
                    return findNextItem();
                } catch (final FileUploadIOException e) {
                    // unwrap encapsulated SizeException
                    throw (FileUploadException) e.getCause();
                }
            }

            /**
             * Returns the next available {@link FileItemStream}.
             *
             * @throws java.util.NoSuchElementException No more items are
             *   available. Use {@link #hasNext()} to prevent this exception.
             * @throws FileUploadException Parsing or processing the
             *   file item failed.
             * @throws IOException Reading the file item failed.
             * @return FileItemStream instance, which provides
             *   access to the next file item.
             */
            @Override
            public FileItemStream next() throws FileUploadException, IOException {
                if (eof || !itemValid && !hasNext()) {
                    throw new NoSuchElementException();
                }
                itemValid = false;
                return currentItem;
            }

        }

        /**
         * Thrown to indicate that A files size exceeds the configured maximum.
         */
        public static class FileSizeLimitExceededException
                extends SizeException {

            /**
             * The exceptions UID, for serializing an instance.
             */
            private static final long serialVersionUID = 8150776562029630058L;

            /**
             * File name of the item, which caused the exception.
             */
            private String fileName;

            /**
             * Field name of the item, which caused the exception.
             */
            private String fieldName;

            /**
             * Constructs a {@code SizeExceededException} with
             * the specified detail message, and actual and permitted sizes.
             *
             * @param message   The detail message.
             * @param actual    The actual request size.
             * @param permitted The maximum permitted request size.
             */
            public FileSizeLimitExceededException(final String message, final long actual,
                    final long permitted) {
                super(message, actual, permitted);
            }

            /**
             * Returns the field name of the item, which caused the
             * exception.
             *
             * @return Field name, if known, or null.
             */
            public String getFieldName() {
                return fieldName;
            }

            /**
             * Returns the file name of the item, which caused the
             * exception.
             *
             * @return File name, if known, or null.
             */
            public String getFileName() {
                return fileName;
            }

            /**
             * Sets the field name of the item, which caused the
             * exception.
             *
             * @param fieldName the field name of the item,
             *        which caused the exception.
             */
            public void setFieldName(final String fieldName) {
                this.fieldName = fieldName;
            }

            /**
             * Sets the file name of the item, which caused the
             * exception.
             *
             * @param fileName the file name of the item, which caused the exception.
             */
            public void setFileName(final String fileName) {
                this.fileName = fileName;
            }

        }

        /**
         * Signals that a FileUpload I/O exception of some sort has occurred. This class is the general class of exceptions produced by failed or interrupted
         * FileUpload I/O operations.
         *
         * This exception wraps a {@link FileUploadException}.
         */
        public static class FileUploadIOException extends IOException {

            /**
             * The exceptions UID, for serializing an instance.
             */
            private static final long serialVersionUID = -7047616958165584154L;

            /**
             * Creates a {@code FileUploadIOException} with the given cause.
             *
             * @param cause The exceptions cause, if any, or null.
             */
            public FileUploadIOException(final FileUploadException cause) {
                super(cause);
            }
        }

        /**
         * Thrown to indicate that the request is not a multipart request.
         */
        public static class InvalidContentTypeException
                extends FileUploadException {

            /**
             * The exceptions UID, for serializing an instance.
             */
            private static final long serialVersionUID = -9073026332015646668L;

            /**
             * Constructs a {@code InvalidContentTypeException} with no
             * detail message.
             */
            public InvalidContentTypeException() {
            }

            /**
             * Constructs an {@code InvalidContentTypeException} with
             * the specified detail message.
             *
             * @param message The detail message.
             */
            public InvalidContentTypeException(final String message) {
                super(message);
            }

            /**
             * Constructs an {@code InvalidContentTypeException} with
             * the specified detail message and cause.
             *
             * @param message The detail message.
             * @param cause the original cause
             * @since 1.3.1
             */
            public InvalidContentTypeException(final String message, final Throwable cause) {
                super(message, cause);
            }
        }

        /**
         * Thrown to indicate an IOException.
         */
        public static class IOFileUploadException extends FileUploadException {

            /**
             * The exceptions UID, for serializing an instance.
             */
            private static final long serialVersionUID = 1749796615868477269L;

            /**
             * Creates a new instance with the given cause.
             *
             * @param message The detail message.
             * @param cause The exceptions cause.
             */
            public IOFileUploadException(final String message, final IOException cause) {
                super(message, cause);
            }

        }

        /**
         * This exception is thrown, if a requests permitted size
         * is exceeded.
         */
        protected abstract static class SizeException extends FileUploadException {

            /**
             * Serial version UID, being used, if serialized.
             */
            private static final long serialVersionUID = -8776225574705254126L;

            /**
             * The actual size of the request.
             */
            private final long actual;

            /**
             * The maximum permitted size of the request.
             */
            private final long permitted;

            /**
             * Creates a new instance.
             *
             * @param message The detail message.
             * @param actual The actual number of bytes in the request.
             * @param permitted The requests size limit, in bytes.
             */
            protected SizeException(final String message, final long actual, final long permitted) {
                super(message);
                this.actual = actual;
                this.permitted = permitted;
            }

            /**
             * Gets the actual size of the request.
             *
             * @return The actual size of the request.
             * @since 1.3
             */
            public long getActualSize() {
                return actual;
            }

            /**
             * Gets the permitted size of the request.
             *
             * @return The permitted size of the request.
             * @since 1.3
             */
            public long getPermittedSize() {
                return permitted;
            }

        }

        /**
         * Thrown to indicate that the request size exceeds the configured maximum.
         */
        public static class SizeLimitExceededException
                extends SizeException {

            /**
             * The exceptions UID, for serializing an instance.
             */
            private static final long serialVersionUID = -2474893167098052828L;

            /**
             * @deprecated 1.2 Replaced by
             * {@link #SizeLimitExceededException(String, long, long)}
             */
            @Deprecated
            public SizeLimitExceededException() {
                this(null, 0, 0);
            }

            /**
             * @deprecated 1.2 Replaced by
             * {@link #SizeLimitExceededException(String, long, long)}
             * @param message The exceptions detail message.
             */
            @Deprecated
            public SizeLimitExceededException(final String message) {
                this(message, 0, 0);
            }

            /**
             * Constructs a {@code SizeExceededException} with
             * the specified detail message, and actual and permitted sizes.
             *
             * @param message   The detail message.
             * @param actual    The actual request size.
             * @param permitted The maximum permitted request size.
             */
            public SizeLimitExceededException(final String message, final long actual,
                    final long permitted) {
                super(message, actual, permitted);
            }

        }

        /**
         * Thrown to indicate that the request size is not specified. In other
         * words, it is thrown, if the content-length header is missing or
         * contains the value -1.
         *
         * @deprecated 1.2 As of commons-fileupload 1.2, the presence of a
         *   content-length header is no longer required.
         */
        @Deprecated
        public static class UnknownSizeException extends FileUploadException {

            /**
             * The exceptions UID, for serializing an instance.
             */
            private static final long serialVersionUID = 7062279004812015273L;

            /**
             * Constructs a {@code UnknownSizeException} with no
             * detail message.
             */
            public UnknownSizeException() {
            }

            /**
             * Constructs an {@code UnknownSizeException} with
             * the specified detail message.
             *
             * @param message The detail message.
             */
            public UnknownSizeException(final String message) {
                super(message);
            }

        }

        /**
         * Line feed.
         */
        private static final char LF = '\n';

        /**
         * Carriage return.
         */
        private static final char CR = '\r';

        /**
         * HTTP content type header name.
         */
        public static final String CONTENT_TYPE = "Content-type";

        /**
         * HTTP content disposition header name.
         */
        public static final String CONTENT_DISPOSITION = "Content-disposition";

        /**
         * HTTP content length header name.
         */
        public static final String CONTENT_LENGTH = "Content-length";

        /**
         * Content-disposition value for form data.
         */
        public static final String FORM_DATA = "form-data";

        /**
         * Content-disposition value for file attachment.
         */
        public static final String ATTACHMENT = "attachment";

        /**
         * Part of HTTP content type header.
         */
        public static final String MULTIPART = "multipart/";

        /**
         * HTTP content type header for multipart forms.
         */
        public static final String MULTIPART_FORM_DATA = "multipart/form-data";

        /**
         * HTTP content type header for multiple uploads.
         */
        public static final String MULTIPART_MIXED = "multipart/mixed";

        /**
         * HTTP content type header for multiple related data.
         *
         * @since 1.6.0
         */
        public static final String MULTIPART_RELATED = "multipart/related";

        /**
         * The maximum length of a single header line that will be parsed
         * (1024 bytes).
         * @deprecated This constant is no longer used. As of commons-fileupload
         *   1.6, the applicable limit is the total size of a single part's headers,
         *   {@link #getPartHeaderSizeMax()} in bytes.
         */
        @Deprecated
        public static final int MAX_HEADER_SIZE = 1024;

        /**
         * Default per part header size limit in bytes.
         *
         * @since 1.6.0
         */
        public static final int DEFAULT_PART_HEADER_SIZE_MAX = 512;

        /**
         * Utility method that determines whether the request contains multipart
         * content.
         *
         * @param req The servlet request to be evaluated. Must be non-null.
         * @return {@code true} if the request is multipart;
         *         {@code false} otherwise.
         *
         * @deprecated 1.1 Use the method on {@code ServletFileUpload} instead.
         */
        @Deprecated
        public static boolean isMultipartContent(final HttpServletRequest req) {
            return ServletFileUpload.isMultipartContent(req);
        }

        /**
         * <p>Utility method that determines whether the request contains multipart
         * content.</p>
         *
         * <p><strong>NOTE:</strong>This method will be moved to the
         * {@code ServletFileUpload} class after the FileUpload 1.1 release.
         * Unfortunately, since this method is static, it is not possible to
         * provide its replacement until this method is removed.</p>
         *
         * @param ctx The request context to be evaluated. Must be non-null.
         * @return {@code true} if the request is multipart;
         *         {@code false} otherwise.
         */
        public static final boolean isMultipartContent(final RequestContext ctx) {
            final String contentType = ctx.getContentType();
            if (contentType == null) {
                return false;
            }
            return contentType.toLowerCase(Locale.ROOT).startsWith(MULTIPART);
        }

        /**
         * The maximum size permitted for the complete request, as opposed to
         * {@link #fileSizeMax}. A value of -1 indicates no maximum.
         */
        private long sizeMax = -1;

        /**
         * The maximum size permitted for a single uploaded file, as opposed
         * to {@link #sizeMax}. A value of -1 indicates no maximum.
         */
        private long fileSizeMax = -1;

        /**
         * The maximum permitted number of files that may be uploaded in a single
         * request. A value of -1 indicates no maximum.
         */
        private long fileCountMax = -1;

        /**
         * The maximum permitted size of the headers provided with a single part in bytes.
         */
        private int partHeaderSizeMax = DEFAULT_PART_HEADER_SIZE_MAX;

        /**
         * The content encoding to use when reading part headers.
         */
        private String headerEncoding;

        /**
         * The progress listener.
         */
        private ProgressListener listener;

        /**
         * Constructs a new instance.
         */
        public FileUploadBase() {
            // empty
        }

        /**
         * Creates a new {@link FileItem} instance.
         *
         * @param headers       A {@code Map} containing the HTTP request
         *                      headers.
         * @param isFormField   Whether or not this item is a form field, as
         *                      opposed to a file.
         *
         * @return A newly created {@code FileItem} instance.
         * @deprecated 1.2 This method is no longer used in favor of
         *   internally created instances of {@link FileItem}.
         */
        @Deprecated
        protected FileItem createItem(final Map<String, String> headers, final boolean isFormField) {
            return getFileItemFactory().createItem(getFieldName(headers), getHeader(headers, CONTENT_TYPE), isFormField, getFileName(headers));
        }

        /**
         * Gets the boundary from the {@code Content-type} header.
         *
         * @param contentType The value of the content type header from which to
         *                    extract the boundary value.
         *
         * @return The boundary, as a byte array.
         */
        protected byte[] getBoundary(final String contentType) {
            final ParameterParser parser = new ParameterParser();
            parser.setLowerCaseNames(true);
            // Parameter parser can handle null input
            final Map<String, String> params = parser.parse(contentType, new char[] { ';', ',' });
            final String boundaryStr = params.get("boundary");
            if (boundaryStr == null) {
                return null; // NOPMD
            }
            return boundaryStr.getBytes(StandardCharsets.ISO_8859_1);
        }

        /**
         * Gets the field name from the {@code Content-disposition}
         * header.
         *
         * @param headers A {@code Map} containing the HTTP request headers.
         * @return The field name for the current {@code encapsulation}.
         */
        protected String getFieldName(final FileItemHeaders headers) {
            return getFieldName(headers.getHeader(CONTENT_DISPOSITION));
        }

        /**
         * Gets the field name from the {@code Content-disposition}
         * header.
         *
         * @param headers A {@code Map} containing the HTTP request headers.
         * @return The field name for the current {@code encapsulation}.
         * @deprecated 1.2.1 Use {@link #getFieldName(FileItemHeaders)}.
         */
        @Deprecated
        protected String getFieldName(final Map<String, String> headers) {
            return getFieldName(getHeader(headers, CONTENT_DISPOSITION));
        }

        /**
         * Returns the field name, which is given by the content-disposition
         * header.
         * @param contentDisposition The content-dispositions header value.
         * @return The field name.
         */
        private String getFieldName(final String contentDisposition) {
            String fieldName = null;
            if (contentDisposition != null && contentDisposition.toLowerCase(Locale.ROOT).startsWith(FORM_DATA)) {
                final ParameterParser parser = new ParameterParser();
                parser.setLowerCaseNames(true);
                // Parameter parser can handle null input
                final Map<String, String> params = parser.parse(contentDisposition, ';');
                fieldName = params.get("name");
                if (fieldName != null) {
                    fieldName = fieldName.trim();
                }
            }
            return fieldName;
        }

        /**
         * Returns the maximum number of files allowed in a single request.
         *
         * @return The maximum number of files allowed in a single request.
         */
        public long getFileCountMax() {
            return fileCountMax;
        }

        /**
         * Returns the factory class used when creating file items.
         *
         * @return The factory class for new file items.
         */
        public abstract FileItemFactory getFileItemFactory();

        /**
         * Gets the file name from the {@code Content-disposition}
         * header.
         *
         * @param headers The HTTP headers object.
         * @return The file name for the current {@code encapsulation}.
         */
        protected String getFileName(final FileItemHeaders headers) {
            return getFileName(headers.getHeader(CONTENT_DISPOSITION));
        }

        /**
         * Gets the file name from the {@code Content-disposition}
         * header.
         *
         * @param headers A {@code Map} containing the HTTP request headers.
         * @return The file name for the current {@code encapsulation}.
         * @deprecated 1.2.1 Use {@link #getFileName(FileItemHeaders)}.
         */
        @Deprecated
        protected String getFileName(final Map<String, String> headers) {
            return getFileName(getHeader(headers, CONTENT_DISPOSITION));
        }

        /**
         * Returns the given content-disposition headers file name.
         * @param contentDisposition The content-disposition headers value.
         * @return The file name
         */
        private String getFileName(final String contentDisposition) {
            String fileName = null;
            if (contentDisposition != null) {
                final String cdl = contentDisposition.toLowerCase(Locale.ROOT);
                if (cdl.startsWith(FORM_DATA) || cdl.startsWith(ATTACHMENT)) {
                    final ParameterParser parser = new ParameterParser();
                    parser.setLowerCaseNames(true);
                    // Parameter parser can handle null input
                    final Map<String, String> params = parser.parse(contentDisposition, ';');
                    if (params.containsKey("filename")) {
                        fileName = params.get("filename");
                        if (fileName != null) {
                            fileName = fileName.trim();
                        } else {
                            // Even if there is no value, the parameter is present,
                            // so we return an empty file name rather than no file
                            // name.
                            fileName = "";
                        }
                    }
                }
            }
            return fileName;
        }

        /**
         * Returns the maximum allowed size of a single uploaded file,
         * as opposed to {@link #getSizeMax()}.
         *
         * @see #setFileSizeMax(long)
         * @return Maximum size of a single uploaded file.
         */
        public long getFileSizeMax() {
            return fileSizeMax;
        }

        /**
         * Returns the header with the specified name from the supplied map. The
         * header lookup is case-insensitive.
         *
         * @param headers A {@code Map} containing the HTTP request headers.
         * @param name    The name of the header to return.
         * @return The value of specified header, or a comma-separated list if
         *         there were multiple headers of that name.
         * @deprecated 1.2.1 Use {@link FileItemHeaders#getHeader(String)}.
         */
        @Deprecated
        protected final String getHeader(final Map<String, String> headers,
                final String name) {
            return headers.get(name.toLowerCase(Locale.ROOT));
        }

        /**
         * Gets the character encoding used when reading the headers of an
         * individual part. When not specified, or {@code null}, the request
         * encoding is used. If that is also not specified, or {@code null},
         * the platform default encoding is used.
         *
         * @return The encoding used to read part headers.
         */
        public String getHeaderEncoding() {
            return headerEncoding;
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param ctx The context for the request to be parsed.
         * @return An iterator to instances of {@code FileItemStream}
         *         parsed from the request, in the order that they were
         *         transmitted.
         *
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         * @throws IOException An I/O error occurred. This may be a network
         *   error while communicating with the client or a problem while
         *   storing the uploaded content.
         */
        public FileItemIterator getItemIterator(final RequestContext ctx)
        throws FileUploadException, IOException {
            try {
                return new FileItemIteratorImpl(ctx);
            } catch (final FileUploadIOException e) {
                // unwrap encapsulated SizeException
                throw (FileUploadException) e.getCause();
            }
        }

        /**
         * <p> Parses the {@code header-part} and returns as key/value
         * pairs.
         *
         * <p> If there are multiple headers of the same names, the name
         * will map to a comma-separated list containing the values.
         *
         * @param headerPart The {@code header-part} of the current
         *                   {@code encapsulation}.
         *
         * @return A {@code Map} containing the parsed HTTP request headers.
         */
        protected FileItemHeaders getParsedHeaders(final String headerPart) {
            final int len = headerPart.length();
            final FileItemHeadersImpl headers = newFileItemHeaders();
            int start = 0;
            for (;;) {
                int end = parseEndOfLine(headerPart, start);
                if (start == end) {
                    break;
                }
                final StringBuilder header = new StringBuilder(headerPart.substring(start, end));
                start = end + 2;
                while (start < len) {
                    int nonWs = start;
                    while (nonWs < len) {
                        final char c = headerPart.charAt(nonWs);
                        if (c != ' '  &&  c != '\t') {
                            break;
                        }
                        ++nonWs;
                    }
                    if (nonWs == start) {
                        break;
                    }
                    // Continuation line found
                    end = parseEndOfLine(headerPart, nonWs);
                    header.append(' ').append(headerPart, nonWs, end);
                    start = end + 2;
                }
                parseHeaderLine(headers, header.toString());
            }
            return headers;
        }

        /**
         * Obtain the per part size limit for headers.
         *
         * @return The maximum size of the headers for a single part in bytes.
         *
         * @since 1.6.0
         */
        public int getPartHeaderSizeMax() {
            return partHeaderSizeMax;
        }

        /**
         * Returns the progress listener.
         *
         * @return The progress listener, if any, or null.
         */
        public ProgressListener getProgressListener() {
            return listener;
        }

        /**
         * Returns the maximum allowed size of a complete request, as opposed
         * to {@link #getFileSizeMax()}.
         *
         * @return The maximum allowed size, in bytes. The default value of
         *   -1 indicates, that there is no limit.
         *
         * @see #setSizeMax(long)
         *
         */
        public long getSizeMax() {
            return sizeMax;
        }

        /**
         * Creates a new instance of {@link FileItemHeaders}.
         * @return The new instance.
         */
        protected FileItemHeadersImpl newFileItemHeaders() {
            return new FileItemHeadersImpl();
        }

        /**
         * Skips bytes until the end of the current line.
         * @param headerPart The headers, which are being parsed.
         * @param end Index of the last byte, which has yet been
         *   processed.
         * @return Index of the \r\n sequence, which indicates
         *   end of line.
         */
        private int parseEndOfLine(final String headerPart, final int end) {
            int index = end;
            for (;;) {
                final int offset = headerPart.indexOf(CR, index);
                if (offset == -1  ||  offset + 1 >= headerPart.length()) {
                    throw new IllegalStateException(
                        "Expected headers to be terminated by an empty line.");
                }
                if (headerPart.charAt(offset + 1) == LF) {
                    return offset;
                }
                index = offset + 1;
            }
        }

        /**
         * Reads the next header line.
         * @param headers String with all headers.
         * @param header Map where to store the current header.
         */
        private void parseHeaderLine(final FileItemHeadersImpl headers, final String header) {
            final int colonOffset = header.indexOf(':');
            if (colonOffset == -1) {
                // This header line is malformed, skip it.
                return;
            }
            final String headerName = header.substring(0, colonOffset).trim();
            final String headerValue = header.substring(colonOffset + 1).trim();
            headers.addHeader(headerName, headerValue);
        }

        /**
         * <p> Parses the {@code header-part} and returns as key/value
         * pairs.
         *
         * <p> If there are multiple headers of the same names, the name
         * will map to a comma-separated list containing the values.
         *
         * @param headerPart The {@code header-part} of the current
         *                   {@code encapsulation}.
         *
         * @return A {@code Map} containing the parsed HTTP request headers.
         * @deprecated 1.2.1 Use {@link #getParsedHeaders(String)}
         */
        @Deprecated
        protected Map<String, String> parseHeaders(final String headerPart) {
            final FileItemHeaders headers = getParsedHeaders(headerPart);
            final Map<String, String> result = new HashMap<>();
            for (final Iterator<String> iter = headers.getHeaderNames();  iter.hasNext();) {
                final String headerName = iter.next();
                final Iterator<String> iter2 = headers.getHeaders(headerName);
                final StringBuilder headerValue = new StringBuilder(iter2.next());
                while (iter2.hasNext()) {
                    headerValue.append(",").append(iter2.next());
                }
                result.put(headerName, headerValue.toString());
            }
            return result;
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param ctx The context for the request to be parsed.
         * @return A map of {@code FileItem} instances parsed from the request.
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         *
         * @since 1.3
         */
        public Map<String, List<FileItem>> parseParameterMap(final RequestContext ctx) throws FileUploadException {
            final List<FileItem> items = parseRequest(ctx);
            final Map<String, List<FileItem>> itemsMap = new HashMap<>(items.size());
            for (final FileItem fileItem : items) {
                final String fieldName = fileItem.getFieldName();
                List<FileItem> mappedItems = itemsMap.get(fieldName);
                if (mappedItems == null) {
                    mappedItems = new ArrayList<>();
                    itemsMap.put(fieldName, mappedItems);
                }
                mappedItems.add(fileItem);
            }
            return itemsMap;
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param req The servlet request to be parsed.
         * @return A list of {@code FileItem} instances parsed from the
         *         request, in the order that they were transmitted.
         *
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         *
         * @deprecated 1.1 Use {@link ServletFileUpload#parseRequest(HttpServletRequest)} instead.
         */
        @Deprecated
        public List<FileItem> parseRequest(final HttpServletRequest req)
        throws FileUploadException {
            return parseRequest(new ServletRequestContext(req));
        }

        /**
         * Processes an <a href="http://www.ietf.org/rfc/rfc1867.txt">RFC 1867</a>
         * compliant {@code multipart/form-data} stream.
         *
         * @param ctx The context for the request to be parsed.
         * @return A list of {@code FileItem} instances parsed from the
         *         request, in the order that they were transmitted.
         *
         * @throws FileUploadException if there are problems reading/parsing
         *                             the request or storing files.
         */
        public List<FileItem> parseRequest(final RequestContext ctx) throws FileUploadException {
            final List<FileItem> items = new ArrayList<>();
            boolean successful = false;
            try {
                final FileItemIterator iter = getItemIterator(ctx);
                final FileItemFactory fileItemFactory = getFileItemFactory();
                Objects.requireNonNull(fileItemFactory, "getFileItemFactory()");
                final byte[] buffer = new byte[Streams.DEFAULT_BUFFER_SIZE];
                while (iter.hasNext()) {
                    if (items.size() == fileCountMax) {
                        // The next item will exceed the limit.
                        throw new FileCountLimitExceededException(ATTACHMENT, getFileCountMax());
                    }
                    final FileItemStream item = iter.next();
                    // Don't use getName() here to prevent an InvalidFileNameException.
                    final String fileName = ((FileItemIteratorImpl.FileItemStreamImpl) item).name;
                    final FileItem fileItem = fileItemFactory.createItem(item.getFieldName(), item.getContentType(), item.isFormField(), fileName);
                    items.add(fileItem);
                    try {
                        Streams.copy(item.openStream(), fileItem.getOutputStream(), true, buffer);
                    } catch (final FileUploadIOException e) {
                        throw (FileUploadException) e.getCause();
                    } catch (final IOException e) {
                        throw new IOFileUploadException(format("Processing of %s request failed. %s", MULTIPART_FORM_DATA, e.getMessage()), e);
                    }
                    final FileItemHeaders fih = item.getHeaders();
                    fileItem.setHeaders(fih);
                }
                successful = true;
                return items;
            } catch (final FileUploadIOException e) {
                throw (FileUploadException) e.getCause();
            } catch (final IOException e) {
                throw new FileUploadException(e.getMessage(), e);
            } finally {
                if (!successful) {
                    for (final FileItem fileItem : items) {
                        try {
                            fileItem.delete();
                        } catch (final Exception ignored) {
                            // ignored TODO perhaps add to tracker delete failure list somehow?
                        }
                    }
                }
            }
        }

        /**
         * Sets the maximum number of files allowed per request.
         *
         * @param fileCountMax The new limit. {@code -1} means no limit.
         */
        public void setFileCountMax(final long fileCountMax) {
            this.fileCountMax = fileCountMax;
        }

        /**
         * Sets the factory class to use when creating file items.
         *
         * @param factory The factory class for new file items.
         */
        public abstract void setFileItemFactory(FileItemFactory factory);

        /**
         * Sets the maximum allowed size of a single uploaded file,
         * as opposed to {@link #getSizeMax()}.
         *
         * @see #getFileSizeMax()
         * @param fileSizeMax Maximum size of a single uploaded file.
         */
        public void setFileSizeMax(final long fileSizeMax) {
            this.fileSizeMax = fileSizeMax;
        }

        /**
         * Specifies the character encoding to be used when reading the headers of
         * individual part. When not specified, or {@code null}, the request
         * encoding is used. If that is also not specified, or {@code null},
         * the platform default encoding is used.
         *
         * @param encoding The encoding used to read part headers.
         */
        public void setHeaderEncoding(final String encoding) {
            headerEncoding = encoding;
        }

        /**
         * Sets the per part size limit for headers.
         *
         * @param partHeaderSizeMax The maximum size of the headers in bytes.
         *
         * @since 1.6.0
         */
        public void setPartHeaderSizeMax(final int partHeaderSizeMax) {
            this.partHeaderSizeMax = partHeaderSizeMax;
        }

        /**
         * Sets the progress listener.
         *
         * @param listener The progress listener, if any. Defaults to null.
         */
        public void setProgressListener(final ProgressListener listener) {
            this.listener = listener;
        }

        /**
         * Sets the maximum allowed size of a complete request, as opposed
         * to {@link #setFileSizeMax(long)}.
         *
         * @param sizeMax The maximum allowed size, in bytes. The default value of
         *   -1 indicates, that there is no limit.
         *
         * @see #getSizeMax()
         *
         */
        public void setSizeMax(final long sizeMax) {
            this.sizeMax = sizeMax;
        }

    }