001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.imaging.common.bytesource;
018
019import java.io.BufferedInputStream;
020import java.io.ByteArrayOutputStream;
021import java.io.IOException;
022import java.io.InputStream;
023import java.util.Objects;
024
025import org.apache.commons.imaging.common.BinaryFunctions;
026
027public class ByteSourceInputStream extends ByteSource {
028    private static final int BLOCK_SIZE = 1024;
029
030    private final InputStream is;
031    private CacheBlock cacheHead;
032    private byte[] readBuffer;
033    private long streamLength = -1;
034
035    public ByteSourceInputStream(final InputStream is, final String fileName) {
036        super(fileName);
037        this.is = new BufferedInputStream(is);
038    }
039
040    private class CacheBlock {
041        public final byte[] bytes;
042        private CacheBlock next;
043        private boolean triedNext;
044
045        CacheBlock(final byte[] bytes) {
046            this.bytes = bytes;
047        }
048
049        public CacheBlock getNext() throws IOException {
050            if (null != next) {
051                return next;
052            }
053            if (triedNext) {
054                return null;
055            }
056            triedNext = true;
057            next = readBlock();
058            return next;
059        }
060
061    }
062
063    private CacheBlock readBlock() throws IOException {
064        if (null == readBuffer) {
065            readBuffer = new byte[BLOCK_SIZE];
066        }
067
068        final int read = is.read(readBuffer);
069        if (read < 1) {
070            return null;
071        } else if (read < BLOCK_SIZE) {
072            // return a copy.
073            final byte[] result = new byte[read];
074            System.arraycopy(readBuffer, 0, result, 0, read);
075            return new CacheBlock(result);
076        } else {
077            // return current buffer.
078            final byte[] result = readBuffer;
079            readBuffer = null;
080            return new CacheBlock(result);
081        }
082    }
083
084    private CacheBlock getFirstBlock() throws IOException {
085        if (null == cacheHead) {
086            cacheHead = readBlock();
087        }
088        return cacheHead;
089    }
090
091    private class CacheReadingInputStream extends InputStream {
092        private CacheBlock block;
093        private boolean readFirst;
094        private int blockIndex;
095
096        @Override
097        public int read() throws IOException {
098            if (null == block) {
099                if (readFirst) {
100                    return -1;
101                }
102                block = getFirstBlock();
103                readFirst = true;
104            }
105
106            if (block != null && blockIndex >= block.bytes.length) {
107                block = block.getNext();
108                blockIndex = 0;
109            }
110
111            if (null == block) {
112                return -1;
113            }
114
115            if (blockIndex >= block.bytes.length) {
116                return -1;
117            }
118
119            return 0xff & block.bytes[blockIndex++];
120        }
121
122        @Override
123        public int read(final byte[] array, final int off, final int len) throws IOException {
124            // first section copied verbatim from InputStream
125            Objects.requireNonNull(array, "array");
126            if ((off < 0) || (off > array.length) || (len < 0)
127                    || ((off + len) > array.length) || ((off + len) < 0)) {
128                throw new IndexOutOfBoundsException();
129            } else if (len == 0) {
130                return 0;
131            }
132
133            // optimized block read
134
135            if (null == block) {
136                if (readFirst) {
137                    return -1;
138                }
139                block = getFirstBlock();
140                readFirst = true;
141            }
142
143            if (block != null && blockIndex >= block.bytes.length) {
144                block = block.getNext();
145                blockIndex = 0;
146            }
147
148            if (null == block) {
149                return -1;
150            }
151
152            if (blockIndex >= block.bytes.length) {
153                return -1;
154            }
155
156            final int readSize = Math.min(len, block.bytes.length - blockIndex);
157            System.arraycopy(block.bytes, blockIndex, array, off, readSize);
158            blockIndex += readSize;
159            return readSize;
160        }
161
162        @Override
163        public long skip(final long n) throws IOException {
164
165            long remaining = n;
166
167            if (n <= 0) {
168                return 0;
169            }
170
171            while (remaining > 0) {
172                // read the first block
173                if (null == block) {
174                    if (readFirst) {
175                        return -1;
176                    }
177                    block = getFirstBlock();
178                    readFirst = true;
179                }
180
181                // get next block
182                if (block != null && blockIndex >= block.bytes.length) {
183                    block = block.getNext();
184                    blockIndex = 0;
185                }
186
187                if (null == block) {
188                    break;
189                }
190
191                if (blockIndex >= block.bytes.length) {
192                    break;
193                }
194
195                final int readSize = Math.min((int) Math.min(BLOCK_SIZE, remaining), block.bytes.length - blockIndex);
196
197                blockIndex += readSize;
198                remaining -= readSize;
199            }
200
201            return n - remaining;
202        }
203
204    }
205
206    @Override
207    public InputStream getInputStream() throws IOException {
208        return new CacheReadingInputStream();
209    }
210
211    @Override
212    public byte[] getBlock(final long blockStart, final int blockLength) throws IOException {
213        // We include a separate check for int overflow.
214        if ((blockStart < 0) || (blockLength < 0)
215                || (blockStart + blockLength < 0)
216                || (blockStart + blockLength > getLength())) {
217            throw new IOException("Could not read block (block start: "
218                    + blockStart + ", block length: " + blockLength
219                    + ", data length: " + streamLength + ").");
220        }
221
222        final InputStream cis = getInputStream();
223        BinaryFunctions.skipBytes(cis, blockStart);
224
225        final byte[] bytes = new byte[blockLength];
226        int total = 0;
227        while (true) {
228            final int read = cis.read(bytes, total, bytes.length - total);
229            if (read < 1) {
230                throw new IOException("Could not read block.");
231            }
232            total += read;
233            if (total >= blockLength) {
234                return bytes;
235            }
236        }
237    }
238
239    @Override
240    public long getLength() throws IOException {
241        if (streamLength >= 0) {
242            return streamLength;
243        }
244
245        final InputStream cis = getInputStream();
246        long result = 0;
247        long skipped;
248        while ((skipped = cis.skip(1024)) > 0) {
249            result += skipped;
250        }
251        streamLength = result;
252        return result;
253    }
254
255    @Override
256    public byte[] getAll() throws IOException {
257        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
258
259        CacheBlock block = getFirstBlock();
260        while (block != null) {
261            baos.write(block.bytes);
262            block = block.getNext();
263        }
264        return baos.toByteArray();
265    }
266
267    @Override
268    public String getDescription() {
269        return "Inputstream: '" + getFileName() + "'";
270    }
271
272}