integrated the source code of a openzim file format reader. These are

the raw format reader files with no integration in YaCy yet, which will
maybe follow as a next step. The zim file format is documented in
https://openzim.org and the reader code was taken from the archived,
non-maintained repository at https://github.com/openzim/zimreader-java

source/org/openzim/ArticleEntry.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2011 Arunesh Mathur
+ *
+ * This file is a part of zimreader-java.
+ *
+ * zimreader-java is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3.0 as
+ * published by the Free Software Foundation.
+ *
+ * zimreader-java is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with zimreader-java.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+package org.openzim;
+
+public class ArticleEntry extends DirectoryEntry {
+
+    int clusterNumber;
+
+    int blobnumber;
+
+    public ArticleEntry(final int mimeType, final char namespace, final int revision,
+            final int clusterNumber, final int blobNumber, final String url, final String title,
+            final int urlListindex) {
+
+        super(mimeType, namespace, revision, url, title, urlListindex);
+
+        this.clusterNumber = clusterNumber;
+        this.blobnumber = blobNumber;
+    }
+
+    public int getClusterNumber() {
+        return this.clusterNumber;
+    }
+
+    public int getBlobnumber() {
+        return this.blobnumber;
+    }
+
+}

source/org/openzim/DirectoryEntry.java

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2011 Arunesh Mathur
+ *
+ * This file is a part of zimreader-java.
+ *
+ * zimreader-java is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3.0 as
+ * published by the Free Software Foundation.
+ *
+ * zimreader-java is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with zimreader-java.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.openzim;
+
+public abstract class DirectoryEntry {
+
+    int mimeType;
+
+    char namespace;
+
+    int revision;
+
+    String url;
+
+    String title;
+
+    int urlListindex;
+
+    public DirectoryEntry(final int mimeType, final char namespace, final int revision,
+            final String url, final String title, final int index) {
+        this.mimeType = mimeType;
+        this.namespace = namespace;
+        this.revision = revision;
+        this.url = url;
+        this.title = title;
+        this.urlListindex = index;
+    }
+
+    public int getMimeType() {
+        return this.mimeType;
+    }
+
+    public char getNamespace() {
+        return this.namespace;
+    }
+
+    public int getRevision() {
+        return this.revision;
+    }
+
+    public String getUrl() {
+        return this.url;
+    }
+
+    public String getTitle() {
+        return this.title;
+    }
+
+    public int getUrlListindex() {
+        return this.urlListindex;
+    }
+
+}

source/org/openzim/RandomAcessFileZIMInputStream.java

@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2011 Arunesh Mathur
+ *
+ * This file is a part of zimreader-java.
+ *
+ * zimreader-java is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3.0 as
+ * published by the Free Software Foundation.
+ *
+ * zimreader-java is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with zimreader-java.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.openzim;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.RandomAccessFile;
+
+/**
+ * This is an implementation of RandomAccessFile to ensure that it is an
+ * InputStream as well, specifically designed for reading a ZIM file. Ad-Hoc
+ * implementation, can be improved.
+ *
+ * @author Arunesh Mathur <aruneshmathur1990 at gmail.com>
+ */
+
+public class RandomAcessFileZIMInputStream extends InputStream {
+
+    private final RandomAccessFile mRAFReader;
+
+    private long mMarked = -1;
+
+    public RandomAcessFileZIMInputStream(final RandomAccessFile reader) {
+        this.mRAFReader = reader;
+    }
+
+    // TODO: Remove the parameter buffer
+    public int readTwoLittleEndianBytesValue(final byte[] buffer) throws IOException {
+        if (buffer.length < 2) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            this.mRAFReader.read(buffer, 0, 2);
+            return Utilities.toTwoLittleEndianInteger(buffer);
+        }
+    }
+
+    // TODO: Remove the parameter buffer
+    public int readFourLittleEndianBytesValue(final byte[] buffer) throws IOException {
+        if (buffer.length < 4) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            this.mRAFReader.read(buffer, 0, 4);
+            return Utilities.toFourLittleEndianInteger(buffer);
+        }
+    }
+
+    // TODO: Remove the parameter buffer
+    public int readEightLittleEndianBytesValue(final byte[] buffer)
+            throws IOException {
+        if (buffer.length < 8) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            this.mRAFReader.read(buffer, 0, 8);
+            return Utilities.toEightLittleEndianInteger(buffer);
+        }
+    }
+
+    // TODO: Remove the parameter buffer
+    public int readSixteenLittleEndianBytesValue(final byte[] buffer)
+            throws IOException {
+        if (buffer.length < 16) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            this.mRAFReader.read(buffer, 0, 16);
+            return Utilities.toSixteenLittleEndianInteger(buffer);
+        }
+    }
+
+    // Reads characters from the current position into a String and stops when a
+    // '\0' is encountered
+    public String readString() throws IOException {
+        final StringBuffer sb = new StringBuffer();
+        /*
+         * int i; byte[] buffer = new byte[100]; while (true) {
+         * mRAFReader.read(buffer); for (i = 0; i < buffer.length; i++) { if
+         * (buffer[i] == '\0') { break; } sb.append((char) buffer[i]); } if (i
+         * != buffer.length) break; } return sb.toString();
+         */
+        int b;
+        b = this.mRAFReader.read();
+        while (b != '\0') {
+            sb.append((char) b);
+            b = this.mRAFReader.read();
+        }
+        return sb.toString();
+
+    }
+
+    @Override
+    public int read() throws IOException {
+        return this.mRAFReader.read();
+    }
+
+    public RandomAccessFile getRandomAccessFile() {
+        return this.mRAFReader;
+    }
+
+    public void seek(final long pos) throws IOException {
+        this.mRAFReader.seek(pos);
+    }
+
+    public long getFilePointer() throws IOException {
+        return this.mRAFReader.getFilePointer();
+    }
+
+    public void mark() throws IOException {
+        this.mMarked = this.mRAFReader.getFilePointer();
+    }
+
+    @Override
+    public void reset() throws IOException {
+        if (this.mMarked == -1) {
+            return;
+        } else {
+            this.mRAFReader.seek(this.mMarked);
+            this.mMarked = -1;
+        }
+    }
+}

source/org/openzim/RedirectEntry.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2011 Arunesh Mathur
+ *
+ * This file is a part of zimreader-java.
+ *
+ * zimreader-java is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3.0 as
+ * published by the Free Software Foundation.
+ *
+ * zimreader-java is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with zimreader-java.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package org.openzim;
+
+public class RedirectEntry extends DirectoryEntry {
+
+    int redirectIndex;
+
+    public RedirectEntry(final int mimeType, final char namespace, final int revision,
+            final int redirectIndex, final String url, final String title, final int urlListindex) {
+
+        super(mimeType, namespace, revision, url, title, urlListindex);
+
+        this.redirectIndex = redirectIndex;
+    }
+
+    public int getRedirectIndex() {
+        return this.redirectIndex;
+    }
+
+}

source/org/openzim/Utilities.java

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2011 Arunesh Mathur
+ *
+ * This file is a part of zimreader-java.
+ *
+ * zimreader-java is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 3.0 as
+ * published by the Free Software Foundation.
+ *
+ * zimreader-java is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with zimreader-java.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+package org.openzim;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+public class Utilities {
+
+    // TODO: Write a binary search algorithm
+    public static int binarySearch() {
+        return -1;
+    }
+
+    public static int toTwoLittleEndianInteger(final byte[] buffer) throws IOException {
+        if (buffer.length < 2) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            final int result = ((buffer[0] & 0xFF) | ((buffer[1] & 0xFF) << 8));
+            return result;
+        }
+    }
+
+    public static int toFourLittleEndianInteger(final byte[] buffer) throws IOException {
+        if (buffer.length < 4) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            final int result = ((buffer[0] & 0xFF) | ((buffer[1] & 0xFF) << 8)
+                    | ((buffer[2] & 0xFF) << 16) | ((buffer[3] & 0xFF) << 24));
+            return result;
+        }
+    }
+
+    public static int toEightLittleEndianInteger(final byte[] buffer) throws IOException {
+        if (buffer.length < 8) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            final int result = ((buffer[0] & 0xFF) | ((buffer[1] & 0xFF) << 8)
+                    | ((buffer[2] & 0xFF) << 16) | ((buffer[3] & 0xFF) << 24)
+                    | ((buffer[4] & 0xFF) << 32) | ((buffer[5] & 0xFF) << 40)
+                    | ((buffer[6] & 0xFF) << 48) | ((buffer[7] & 0xFF) << 56));
+            return result;
+        }
+    }
+
+    public static int toSixteenLittleEndianInteger(final byte[] buffer) throws IOException {
+        if (buffer.length < 16) {
+            throw new OutOfMemoryError("buffer too small");
+        } else {
+            final int result = ((buffer[0] & 0xFF) | ((buffer[1] & 0xFF) << 8)
+                    | ((buffer[2] & 0xFF) << 16) | ((buffer[3] & 0xFF) << 24)
+                    | ((buffer[4] & 0xFF) << 32) | ((buffer[5] & 0xFF) << 40)
+                    | ((buffer[6] & 0xFF) << 48) | ((buffer[7] & 0xFF) << 56)
+                    | ((buffer[8] & 0xFF) << 64) | ((buffer[9] & 0xFF) << 72)
+                    | ((buffer[10] & 0xFF) << 80) | ((buffer[11] & 0xFF) << 88)
+                    | ((buffer[12] & 0xFF) << 96)
+                    | ((buffer[13] & 0xFF) << 104)
+                    | ((buffer[14] & 0xFF) << 112) | ((buffer[15] & 0xFF) << 120));
+            return result;
+        }
+    }
+
+    public static void skipFully(final InputStream stream, final long bytes) throws IOException {
+            for (long i = stream.skip(bytes); i < bytes; i += stream.skip(bytes - i));
+         }
+
+}