001/****************************************************************
002 * Licensed to the Apache Software Foundation (ASF) under one   *
003 * or more contributor license agreements.  See the NOTICE file *
004 * distributed with this work for additional information        *
005 * regarding copyright ownership.  The ASF licenses this file   *
006 * to you under the Apache License, Version 2.0 (the            *
007 * "License"); you may not use this file except in compliance   *
008 * with the License.  You may obtain a copy of the License at   *
009 *                                                              *
010 *   http://www.apache.org/licenses/LICENSE-2.0                 *
011 *                                                              *
012 * Unless required by applicable law or agreed to in writing,   *
013 * software distributed under the License is distributed on an  *
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
015 * KIND, either express or implied.  See the License for the    *
016 * specific language governing permissions and limitations      *
017 * under the License.                                           *
018 ****************************************************************/
019
020package org.apache.james.mime4j.io;
021
022import org.apache.james.mime4j.util.ByteArrayBuffer;
023
024import java.io.IOException;
025import java.io.InputStream;
026
027/**
028 * Input buffer that can be used to search for patterns using Quick Search
029 * algorithm in data read from an {@link InputStream}.
030 */
031public class BufferedLineReaderInputStream extends LineReaderInputStream {
032
033    private boolean truncated;
034
035    boolean tempBuffer = false;
036
037    private byte[] origBuffer;
038    private int origBufpos;
039    private int origBuflen;
040
041    private byte[] buffer;
042    private int bufpos;
043    private int buflen;
044
045    private final int maxLineLen;
046
047    public BufferedLineReaderInputStream(
048            final InputStream instream,
049            int buffersize,
050            int maxLineLen) {
051        super(instream);
052        if (instream == null) {
053            throw new IllegalArgumentException("Input stream may not be null");
054        }
055        if (buffersize <= 0) {
056            throw new IllegalArgumentException("Buffer size may not be negative or zero");
057        }
058        this.buffer = new byte[buffersize];
059        this.bufpos = 0;
060        this.buflen = 0;
061        this.maxLineLen = maxLineLen;
062        this.truncated = false;
063    }
064
065    public BufferedLineReaderInputStream(
066            final InputStream instream,
067            int buffersize) {
068        this(instream, buffersize, -1);
069    }
070
071    private void expand(int newlen) {
072        byte newbuffer[] = new byte[newlen];
073        int len = bufferLen();
074        if (len > 0) {
075            System.arraycopy(this.buffer, this.bufpos, newbuffer, this.bufpos, len);
076        }
077        this.buffer = newbuffer;
078    }
079
080    public void ensureCapacity(int len) {
081        if (len > this.buffer.length) {
082            expand(len);
083        }
084    }
085
086    public int fillBuffer() throws IOException {
087        if (tempBuffer) {
088            // we was on tempBuffer.
089            // check that we completed the tempBuffer
090            if (bufpos != buflen) throw new IllegalStateException("unread only works when a buffer is fully read before the next refill is asked!");
091            // restore the original buffer
092            buffer = origBuffer;
093            buflen = origBuflen;
094            bufpos = origBufpos;
095            tempBuffer = false;
096            // return that we just read bufferLen data.
097            return bufferLen();
098        }
099        // compact the buffer if necessary
100        if (this.bufpos > 0) { // could swtich to (this.buffer.length / 2) but needs a 4*boundary capacity, then (instead of 2).
101            int len = bufferLen();
102            if (len > 0) {
103                System.arraycopy(this.buffer, this.bufpos, this.buffer, 0, len);
104            }
105            this.bufpos = 0;
106            this.buflen = len;
107        }
108        int l;
109        int off = this.buflen;
110        int len = this.buffer.length - off;
111        l = in.read(this.buffer, off, len);
112        if (l == -1) {
113            return -1;
114        } else {
115            this.buflen = off + l;
116            return l;
117        }
118    }
119
120    private int bufferLen() {
121        return this.buflen - this.bufpos;
122    }
123
124    public boolean hasBufferedData() {
125        return bufferLen() > 0;
126    }
127
128    public void truncate() {
129        clear();
130        this.truncated = true;
131    }
132
133    protected boolean readAllowed() {
134        return !this.truncated;
135    }
136
137    @Override
138    public int read() throws IOException {
139        if (!readAllowed()) return -1;
140        int noRead = 0;
141        while (!hasBufferedData()) {
142            noRead = fillBuffer();
143            if (noRead == -1) {
144                return -1;
145            }
146        }
147        return this.buffer[this.bufpos++] & 0xff;
148    }
149
150    @Override
151    public int read(final byte[] b, int off, int len) throws IOException {
152        if (!readAllowed()) return -1;
153        if (b == null) {
154            return 0;
155        }
156        int noRead = 0;
157        while (!hasBufferedData()) {
158            noRead = fillBuffer();
159            if (noRead == -1) {
160                return -1;
161            }
162        }
163        int chunk = bufferLen();
164        if (chunk > len) {
165            chunk = len;
166        }
167        System.arraycopy(this.buffer, this.bufpos, b, off, chunk);
168        this.bufpos += chunk;
169        return chunk;
170    }
171
172    @Override
173    public int read(final byte[] b) throws IOException {
174        if (!readAllowed()) return -1;
175        if (b == null) {
176            return 0;
177        }
178        return read(b, 0, b.length);
179    }
180
181    @Override
182    public boolean markSupported() {
183        return false;
184    }
185
186    @Override
187    public int readLine(final ByteArrayBuffer dst)
188            throws MaxLineLimitException, IOException {
189        if (dst == null) {
190            throw new IllegalArgumentException("Buffer may not be null");
191        }
192        if (!readAllowed()) return -1;
193
194        int total = 0;
195        boolean found = false;
196        int bytesRead = 0;
197        while (!found) {
198            if (!hasBufferedData()) {
199                bytesRead = fillBuffer();
200                if (bytesRead == -1) {
201                    break;
202                }
203            }
204            int i = indexOf((byte)'\n');
205            int chunk;
206            if (i != -1) {
207                found = true;
208                chunk = i + 1 - pos();
209            } else {
210                chunk = length();
211            }
212            if (chunk > 0) {
213                dst.append(buf(), pos(), chunk);
214                skip(chunk);
215                total += chunk;
216            }
217            if (this.maxLineLen > 0 && dst.length() >= this.maxLineLen) {
218                throw new MaxLineLimitException("Maximum line length limit exceeded");
219            }
220        }
221        if (total == 0 && bytesRead == -1) {
222            return -1;
223        } else {
224            return total;
225        }
226    }
227
228    /**
229     * Implements quick search algorithm as published by
230     * <p>
231     * SUNDAY D.M., 1990,
232     * A very fast substring search algorithm,
233     * Communications of the ACM . 33(8):132-142.
234     * </p>
235     */
236    public int indexOf(final byte[] pattern, int off, int len) {
237        if (pattern == null) {
238            throw new IllegalArgumentException("Pattern may not be null");
239        }
240        if (off < this.bufpos || len < 0 || off + len > this.buflen) {
241            throw new IndexOutOfBoundsException("looking for "+off+"("+len+")"+" in "+bufpos+"/"+buflen);
242        }
243        if (len < pattern.length) {
244            return -1;
245        }
246
247        int[] shiftTable = new int[256];
248        for (int i = 0; i < shiftTable.length; i++) {
249            shiftTable[i] = pattern.length + 1;
250        }
251        for (int i = 0; i < pattern.length; i++) {
252            int x = pattern[i] & 0xff;
253            shiftTable[x] = pattern.length - i;
254        }
255
256        int j = 0;
257        while (j <= len - pattern.length) {
258            int cur = off + j;
259            boolean match = true;
260            for (int i = 0; i < pattern.length; i++) {
261                if (this.buffer[cur + i] != pattern[i]) {
262                    match = false;
263                    break;
264                }
265            }
266            if (match) {
267                return cur;
268            }
269
270            int pos = cur + pattern.length;
271            if (pos >= this.buffer.length) {
272                break;
273            }
274            int x = this.buffer[pos] & 0xff;
275            j += shiftTable[x];
276        }
277        return -1;
278    }
279
280    /**
281     * Implements quick search algorithm as published by
282     * <p>
283     * SUNDAY D.M., 1990,
284     * A very fast substring search algorithm,
285     * Communications of the ACM . 33(8):132-142.
286     * </p>
287     */
288    public int indexOf(final byte[] pattern) {
289        return indexOf(pattern, this.bufpos, this.buflen - this.bufpos);
290    }
291
292    public int indexOf(byte b, int off, int len) {
293        if (off < this.bufpos || len < 0 || off + len > this.buflen) {
294            throw new IndexOutOfBoundsException();
295        }
296        for (int i = off; i < off + len; i++) {
297            if (this.buffer[i] == b) {
298                return i;
299            }
300        }
301        return -1;
302    }
303
304    public int indexOf(byte b) {
305        return indexOf(b, this.bufpos, bufferLen());
306    }
307
308    public int byteAt(int pos) {
309        if (pos < this.bufpos || pos > this.buflen) {
310            throw new IndexOutOfBoundsException("looking for "+pos+" in "+bufpos+"/"+buflen);
311        }
312        return this.buffer[pos] & 0xff;
313    }
314
315    protected byte[] buf() {
316        return this.buffer;
317    }
318
319    protected int pos() {
320        return this.bufpos;
321    }
322
323    protected int limit() {
324        return this.buflen;
325    }
326
327    protected int length() {
328        return bufferLen();
329    }
330
331    public int capacity() {
332        return this.buffer.length;
333    }
334
335    protected int skip(int n) {
336        int chunk = Math.min(n, bufferLen());
337        this.bufpos += chunk;
338        return chunk;
339    }
340
341    private void clear() {
342        this.bufpos = 0;
343        this.buflen = 0;
344    }
345
346    @Override
347    public String toString() {
348        StringBuilder buffer = new StringBuilder();
349        buffer.append("[pos: ");
350        buffer.append(this.bufpos);
351        buffer.append("]");
352        buffer.append("[limit: ");
353        buffer.append(this.buflen);
354        buffer.append("]");
355        buffer.append("[");
356        for (int i = this.bufpos; i < this.buflen; i++) {
357            buffer.append((char) this.buffer[i]);
358        }
359        buffer.append("]");
360        if (tempBuffer) {
361            buffer.append("-ORIG[pos: ");
362            buffer.append(this.origBufpos);
363            buffer.append("]");
364            buffer.append("[limit: ");
365            buffer.append(this.origBuflen);
366            buffer.append("]");
367            buffer.append("[");
368            for (int i = this.origBufpos; i < this.origBuflen; i++) {
369                buffer.append((char) this.origBuffer[i]);
370            }
371            buffer.append("]");
372        }
373        return buffer.toString();
374    }
375
376    @Override
377    public boolean unread(ByteArrayBuffer buf) {
378        if (tempBuffer) return false;
379        origBuffer = buffer;
380        origBuflen = buflen;
381        origBufpos = bufpos;
382        bufpos = 0;
383        buflen = buf.length();
384        buffer = buf.buffer();
385        tempBuffer = true;
386        return true;
387    }
388
389}