    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 *      https://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
    018package org.apache.commons.net.ftp;
    019
    020import java.io.BufferedReader;
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.io.InputStreamReader;
    024import java.util.LinkedList;
    025import java.util.List;
    026import java.util.ListIterator;
    027import java.util.stream.Collectors;
    028
    029import org.apache.commons.io.Charsets;
    030
    031
    032/**
    033 * This class handles the entire process of parsing a listing of file entries from the server.
    034 * <p>
    035 * This object defines a two-part parsing mechanism.
    036 * </p>
    037 * <p>
    038 * The first part consists of reading the raw input into an internal list of strings. Every item in this list corresponds to an actual file. All extraneous
    039 * matter emitted by the server will have been removed by the end of this phase. This is accomplished in conjunction with the FTPFileEntryParser associated with
    040 * this engine, by calling its methods {@code readNextEntry()} - which handles the issue of what delimits one entry from another, usually but not always a line
    041 * feed and {@code preParse()} - which handles removal of extraneous matter such as the preliminary lines of a listing, removal of duplicates on versioning
    042 * systems, etc.
    043 * </p>
    044 * <p>
    045 * The second part is composed of the actual parsing, again in conjunction with the particular parser used by this engine. This is controlled by an iterator
    046 * over the internal list of strings. This may be done either in block mode, by calling the {@code getNext()} and {@code getPrevious()} methods to provide
    047 * "paged" output of less than the whole list at one time, or by calling the {@code getFiles()} method to return the entire list.
    048 * </p>
    049 * <p>
    050 * Examples:
    051 * </p>
    052 * <p>
    053 * Paged access:
    054 * </p>
    055 * <pre>
    056 * FTPClient f = FTPClient();
    057 * f.connect(server);
    058 * f.login(user, password);
    059 * FTPListParseEngine engine = f.initiateListParsing(directory);
    060 *
    061 * while (engine.hasNext()) {
    062 *     FTPFile[] files = engine.getNext(25); // "page size" you want
    063 *     // do whatever you want with these files, display them, etc.
    064 *     // expensive FTPFile objects not created until needed.
    065 * }
    066 * </pre>
    067 * <p>
    068 * For unpaged access, simply use FTPClient.listFiles(). That method uses this class transparently.
    069 * </p>
    070 */
    071public class FTPListParseEngine {
    072    /**
    073     * An empty immutable {@code FTPFile} array.
    074     */
    075    private static final FTPFile[] EMPTY_FTP_FILE_ARRAY = {};
    076    private List<String> entries = new LinkedList<>();
    077
    078    private ListIterator<String> internalIterator = entries.listIterator();
    079    private final FTPFileEntryParser parser;
    080
    081    // Should invalid files (parse failures) be allowed?
    082    private final boolean saveUnparseableEntries;
    083
    084    /**
    085     * Constructs a new instance.
    086     *
    087     * @param parser How to parse file entries.
    088     */
    089    public FTPListParseEngine(final FTPFileEntryParser parser) {
    090        this(parser, null);
    091    }
    092
    093    /**
    094     * Intended for use by FTPClient only
    095     *
    096     * @since 3.4
    097     */
    098    FTPListParseEngine(final FTPFileEntryParser parser, final FTPClientConfig configuration) {
    099        this.parser = parser;
    100        this.saveUnparseableEntries = configuration != null && configuration.getUnparseableEntries();
    101    }
    102
    103    /**
    104     * Gets a list of FTPFile objects containing the whole list of files returned by the server as read by this object's parser. The files are filtered
    105     * before being added to the array.
    106     *
    107     * @param filter FTPFileFilter, must not be {@code null}.
    108     * @return a list of FTPFile objects containing the whole list of files returned by the server as read by this object's parser.
    109     *         <p>
    110     *         <strong> NOTE:</strong> This array may contain null members if any of the individual file listings failed to parse. The caller should check each
    111     *         entry for null before referencing it, or use a filter such as {@link FTPFileFilters#NON_NULL} which does not allow null entries.
    112     * @since 3.9.0
    113     */
    114    public List<FTPFile> getFileList(final FTPFileFilter filter) {
    115        return entries.stream().map(e -> {
    116            final FTPFile file = parser.parseFTPEntry(e);
    117            return file == null && saveUnparseableEntries ? new FTPFile(e) : file;
    118        }).filter(filter::accept).collect(Collectors.toList());
    119    }
    120
    121    /**
    122     * Gets an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser.
    123     *
    124     * @return an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser. None of the entries will
    125     *         be null
    126     * @throws IOException - not ever thrown, may be removed in a later release
    127     */
    128    // TODO remove; not actually thrown
    129    public FTPFile[] getFiles() throws IOException {
    130        return getFiles(FTPFileFilters.NON_NULL);
    131    }
    132
    133    /**
    134     * Gets an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser. The files are filtered
    135     * before being added to the array.
    136     *
    137     * @param filter FTPFileFilter, must not be {@code null}.
    138     * @return an array of FTPFile objects containing the whole list of files returned by the server as read by this object's parser.
    139     *         <p>
    140     *         <strong> NOTE:</strong> This array may contain null members if any of the individual file listings failed to parse. The caller should check each
    141     *         entry for null before referencing it, or use a filter such as {@link FTPFileFilters#NON_NULL} which does not allow null entries.
    142     * @throws IOException - not ever thrown, may be removed in a later release
    143     * @since 2.2
    144     */
    145    // TODO remove; not actually thrown
    146    public FTPFile[] getFiles(final FTPFileFilter filter) throws IOException {
    147        return getFileList(filter).toArray(EMPTY_FTP_FILE_ARRAY);
    148    }
    149
    150    /**
    151     * Gets an array of at most {@code quantityRequested} FTPFile objects starting at this object's internal iterator's current position. If fewer than
    152     * {@code quantityRequested} such elements are available, the returned array will have a length equal to the number of entries at and after the current
    153     * position. If no such entries are found, this array will have a length of 0.
    154     *
    155     * After this method is called this object's internal iterator is advanced by a number of positions equal to the size of the array returned.
    156     *
    157     * @param quantityRequested the maximum number of entries we want to get.
    158     * @return an array of at most {@code quantityRequested} FTPFile objects starting at the current position of this iterator within its list and at least the
    159     *         number of elements which exist in the list at and after its current position.
    160     *         <p>
    161     *         <strong> NOTE:</strong> This array may contain null members if any of the individual file listings failed to parse. The caller should check each
    162     *         entry for null before referencing it.
    163     */
    164    public FTPFile[] getNext(final int quantityRequested) {
    165        final List<FTPFile> tmpResults = new LinkedList<>();
    166        int count = quantityRequested;
    167        while (count > 0 && internalIterator.hasNext()) {
    168            final String entry = internalIterator.next();
    169            FTPFile temp = parser.parseFTPEntry(entry);
    170            if (temp == null && saveUnparseableEntries) {
    171                temp = new FTPFile(entry);
    172            }
    173            tmpResults.add(temp);
    174            count--;
    175        }
    176        return tmpResults.toArray(EMPTY_FTP_FILE_ARRAY);
    177
    178    }
    179
    180    /**
    181     * Gets an array of at most {@code quantityRequested} FTPFile objects starting at this object's internal iterator's current position, and working back
    182     * toward the beginning.
    183     *
    184     * If fewer than {@code quantityRequested} such elements are available, the returned array will have a length equal to the number of entries at and after
    185     * the current position. If no such entries are found, this array will have a length of 0.
    186     *
    187     * After this method is called this object's internal iterator is moved back by a number of positions equal to the size of the array returned.
    188     *
    189     * @param quantityRequested the maximum number of entries we want to get.
    190     * @return an array of at most {@code quantityRequested} FTPFile objects starting at the current position of this iterator within its list and at least the
    191     *         number of elements which exist in the list at and after its current position. This array will be in the same order as the underlying list (not
    192     *         reversed).
    193     *         <p>
    194     *         <strong> NOTE:</strong> This array may contain null members if any of the individual file listings failed to parse. The caller should check each
    195     *         entry for null before referencing it.
    196     */
    197    public FTPFile[] getPrevious(final int quantityRequested) {
    198        final List<FTPFile> tmpResults = new LinkedList<>();
    199        int count = quantityRequested;
    200        while (count > 0 && internalIterator.hasPrevious()) {
    201            final String entry = internalIterator.previous();
    202            FTPFile temp = parser.parseFTPEntry(entry);
    203            if (temp == null && saveUnparseableEntries) {
    204                temp = new FTPFile(entry);
    205            }
    206            tmpResults.add(0, temp);
    207            count--;
    208        }
    209        return tmpResults.toArray(EMPTY_FTP_FILE_ARRAY);
    210    }
    211
    212    /**
    213     * convenience method to allow clients to know whether this object's internal iterator's current position is at the end of the list.
    214     *
    215     * @return true if internal iterator is not at end of list, false otherwise.
    216     */
    217    public boolean hasNext() {
    218        return internalIterator.hasNext();
    219    }
    220
    221    /**
    222     * convenience method to allow clients to know whether this object's internal iterator's current position is at the beginning of the list.
    223     *
    224     * @return true if internal iterator is not at beginning of list, false otherwise.
    225     */
    226    public boolean hasPrevious() {
    227        return internalIterator.hasPrevious();
    228    }
    229
    230    /**
    231     * Internal method for reading (and closing) the input into the {@code entries} list. After this method has completed, {@code entries} will contain a
    232     * collection of entries (as defined by {@code FTPFileEntryParser.readNextEntry()}), but this may contain various non-entry preliminary lines from the
    233     * server output, duplicates, and other data that will not be part of the final listing.
    234     *
    235     * @param inputStream The socket stream on which the input will be read.
    236     * @param charsetName The encoding to use.
    237     * @throws IOException thrown on any failure to read the stream
    238     */
    239    private void read(final InputStream inputStream, final String charsetName) throws IOException {
    240        try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, Charsets.toCharset(charsetName)))) {
    241            String line = parser.readNextEntry(reader);
    242            while (line != null) {
    243                entries.add(line);
    244                line = parser.readNextEntry(reader);
    245            }
    246        }
    247    }
    248
    249    /**
    250     * Do not use.
    251     *
    252     * @param inputStream the stream from which to read
    253     * @throws IOException on error
    254     * @deprecated use {@link #readServerList(InputStream, String)} instead
    255     */
    256    @Deprecated
    257    public void readServerList(final InputStream inputStream) throws IOException {
    258        readServerList(inputStream, null);
    259    }
    260
    261    /**
    262     * Reads (and closes) the initial reading and preparsing of the list returned by the server. After this method has completed, this object will contain a
    263     * list of unparsed entries (Strings) each referring to a unique file on the server.
    264     *
    265     * @param inputStream input stream provided by the server socket.
    266     * @param charsetName the encoding to be used for reading the stream
    267     * @throws IOException thrown on any failure to read from the sever.
    268     */
    269    public void readServerList(final InputStream inputStream, final String charsetName) throws IOException {
    270        entries = new LinkedList<>();
    271        read(inputStream, charsetName);
    272        parser.preParse(entries);
    273        resetIterator();
    274    }
    275
    276    /**
    277     * resets this object's internal iterator to the beginning of the list.
    278     */
    279    public void resetIterator() {
    280        internalIterator = entries.listIterator();
    281    }
    282
    283}