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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.io.input;

import static org.apache.commons.io.IOUtils.EOF;

import java.io.IOException;
import java.io.InputStream;

/**
 * This is a stream that will only supply bytes up to a certain length - if its
 * position goes above that, it will stop.
 * 

* This is useful to wrap ServletInputStreams. The ServletInputStream will block * if you try to read content from it that isn't there, because it doesn't know * whether the content hasn't arrived yet or whether the content has finished. * So, one of these, initialized with the Content-length sent in the * ServletInputStream's header, will stop it blocking, providing it's been sent * with a correct content length. * * @since 2.0 */ public class BoundedInputStream extends InputStream { /** the wrapped input stream */ private final InputStream in; /** the max length to provide */ private final long max; /** the number of bytes already returned */ private long pos = 0; /** the marked position */ private long mark = EOF; /** flag if close should be propagated */ private boolean propagateClose = true; /** * Creates a new BoundedInputStream that wraps the given input * stream and limits it to a certain size. * * @param in The wrapped input stream * @param size The maximum number of bytes to return */ public BoundedInputStream(final InputStream in, final long size) { // Some badly designed methods - eg the servlet API - overload length // such that "-1" means stream finished this.max = size; this.in = in; } /** * Creates a new BoundedInputStream that wraps the given input * stream and is unlimited. * * @param in The wrapped input stream */ public BoundedInputStream(final InputStream in) { this(in, EOF); } /** * Invokes the delegate's read() method if * the current position is less than the limit. * @return the byte read or -1 if the end of stream or * the limit has been reached. * @throws IOException if an I/O error occurs */ @Override public int read() throws IOException { if (max >= 0 && pos >= max) { return EOF; } final int result = in.read(); pos++; return result; } /** * Invokes the delegate's read(byte[]) method. * @param b the buffer to read the bytes into * @return the number of bytes read or -1 if the end of stream or * the limit has been reached. * @throws IOException if an I/O error occurs */ @Override public int read(final byte[] b) throws IOException { return this.read(b, 0, b.length); } /** * Invokes the delegate's read(byte[], int, int) method. * @param b the buffer to read the bytes into * @param off The start offset * @param len The number of bytes to read * @return the number of bytes read or -1 if the end of stream or * the limit has been reached. * @throws IOException if an I/O error occurs */ @Override public int read(final byte[] b, final int off, final int len) throws IOException { if (max>=0 && pos>=max) { return EOF; } final long maxRead = max>=0 ? Math.min(len, max-pos) : len; final int bytesRead = in.read(b, off, (int)maxRead); if (bytesRead==EOF) { return EOF; } pos+=bytesRead; return bytesRead; } /** * Invokes the delegate's skip(long) method. * @param n the number of bytes to skip * @return the actual number of bytes skipped * @throws IOException if an I/O error occurs */ @Override public long skip(final long n) throws IOException { final long toSkip = max>=0 ? Math.min(n, max-pos) : n; final long skippedBytes = in.skip(toSkip); pos+=skippedBytes; return skippedBytes; } /** * {@inheritDoc} */ @Override public int available() throws IOException { if (max>=0 && pos>=max) { return 0; } return in.available(); } /** * Invokes the delegate's toString() method. * @return the delegate's toString() */ @Override public String toString() { return in.toString(); } /** * Invokes the delegate's close() method * if {@link #isPropagateClose()} is {@code true}. * @throws IOException if an I/O error occurs */ @Override public void close() throws IOException { if (propagateClose) { in.close(); } } /** * Invokes the delegate's reset() method. * @throws IOException if an I/O error occurs */ @Override public synchronized void reset() throws IOException { in.reset(); pos = mark; } /** * Invokes the delegate's mark(int) method. * @param readlimit read ahead limit */ @Override public synchronized void mark(final int readlimit) { in.mark(readlimit); mark = pos; } /** * Invokes the delegate's markSupported() method. * @return true if mark is supported, otherwise false */ @Override public boolean markSupported() { return in.markSupported(); } /** * Indicates whether the {@link #close()} method * should propagate to the underling {@link InputStream}. * * @return {@code true} if calling {@link #close()} * propagates to the close() method of the * underlying stream or {@code false} if it does not. */ public boolean isPropagateClose() { return propagateClose; } /** * Set whether the {@link #close()} method * should propagate to the underling {@link InputStream}. * * @param propagateClose {@code true} if calling * {@link #close()} propagates to the close() * method of the underlying stream or * {@code false} if it does not. */ public void setPropagateClose(final boolean propagateClose) { this.propagateClose = propagateClose; } }





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