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, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.commons.crypto.stream.input;
019
020import java.io.IOException;
021import java.io.InputStream;
022import java.nio.ByteBuffer;
023
024/**
025 * The StreamInput class takes a {@code InputStream} object and wraps it as
026 * {@code Input} object acceptable by {@code CryptoInputStream}.
027 */
028public class StreamInput implements Input {
029    private final byte[] buf;
030    private final int bufferSize;
031    final InputStream in;
032
033    /**
034     * Constructs a {@link org.apache.commons.crypto.stream.input.StreamInput}.
035     *
036     * @param inputStream the inputstream object.
037     * @param bufferSize the buffersize.
038     */
039    public StreamInput(final InputStream inputStream, final int bufferSize) {
040        this.in = inputStream;
041        this.bufferSize = bufferSize;
042        buf = new byte[bufferSize];
043    }
044
045    /**
046     * Overrides the
047     * {@link org.apache.commons.crypto.stream.input.Input#read(ByteBuffer)}.
048     * Reads a sequence of bytes from input into the given buffer.
049     *
050     * @param dst The buffer into which bytes are to be transferred.
051     *
052     * @return the total number of bytes read into the buffer, or
053     *         {@code -1} if there is no more data because the end of the
054     *         stream has been reached.
055     * @throws IOException if an I/O error occurs.
056     */
057    @Override
058    public int read(final ByteBuffer dst) throws IOException {
059        int remaining = dst.remaining();
060        int read = 0;
061        while (remaining > 0) {
062            final int n = in.read(buf, 0, Math.min(remaining, bufferSize));
063            if (n == -1) {
064                if (read == 0) {
065                    read = -1;
066                }
067                break;
068            } else if (n > 0) {
069                dst.put(buf, 0, n);
070                read += n;
071                remaining -= n;
072            }
073        }
074        return read;
075    }
076
077    /**
078     * Overrides the
079     * {@link org.apache.commons.crypto.stream.input.Input#skip(long)}. Skips
080     * over and discards {@code n} bytes of data from this input stream.
081     *
082     * @param n the number of bytes to be skipped.
083     * @return the actual number of bytes skipped.
084     * @throws IOException if an I/O error occurs.
085     */
086    @Override
087    public long skip(final long n) throws IOException {
088        return in.skip(n);
089    }
090
091    /**
092     * Overrides the {@link Input#available()}. Returns an estimate of the
093     * number of bytes that can be read (or skipped over) from this input stream
094     * without blocking by the next invocation of a method for this input
095     * stream. The next invocation might be the same thread or another thread. A
096     * single read or skip of this many bytes will not block, but may read or
097     * skip fewer bytes.
098     *
099     * @return an estimate of the number of bytes that can be read (or skipped
100     *         over) from this input stream without blocking or {@code 0} when
101     *         it reaches the end of the input stream.
102     * @throws IOException if an I/O error occurs.
103     */
104    @Override
105    public int available() throws IOException {
106        return in.available();
107    }
108
109    /**
110     * Overrides the
111     * {@link org.apache.commons.crypto.stream.input.Input#read(long, byte[], int, int)}
112     * . Reads up to {@code len} bytes of data from the input stream into
113     * an array of bytes. An attempt is made to read as many as {@code len}
114     * bytes, but a smaller number may be read. The number of bytes actually
115     * read is returned as an integer.
116     *
117     * @param position the given position within a stream.
118     * @param buffer the buffer into which the data is read.
119     * @param offset the start offset in array buffer.
120     * @param length the maximum number of bytes to read.
121     * @return the total number of bytes read into the buffer, or
122     *         {@code -1} if there is no more data because the end of the
123     *         stream has been reached.
124     * @throws IOException if an I/O error occurs.
125     */
126    @Override
127    public int read(final long position, final byte[] buffer, final int offset, final int length)
128            throws IOException {
129        throw new UnsupportedOperationException(
130                "Positioned read is not supported by this implementation");
131    }
132
133    /**
134     * Overrides the
135     * {@link org.apache.commons.crypto.stream.input.Input#seek(long)}. Seeks to
136     * the given offset from the start of the stream. The next read() will be
137     * from that location.
138     *
139     * @param position the offset from the start of the stream.
140     * @throws IOException if an I/O error occurs.
141     */
142    @Override
143    public void seek(final long position) throws IOException {
144        throw new UnsupportedOperationException(
145                "Seek is not supported by this implementation");
146    }
147
148    /**
149     * Overrides the
150     * {@link org.apache.commons.crypto.stream.input.Input#seek(long)}. Closes
151     * this input and releases any system resources associated with the under
152     * layer input.
153     *
154     * @throws IOException if an I/O error occurs.
155     */
156    @Override
157    public void close() throws IOException {
158        in.close();
159    }
160}