/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package frame.upload.util;
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import java.io.FilterInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import frame.upload.util.Closeable;
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/**
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* An input stream, which limits its data size. This stream is
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* used, if the content length is unknown.
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*/
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public abstract class LimitedInputStream
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extends FilterInputStream implements Closeable {
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/**
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* The maximum size of an item, in bytes.
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*/
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private long sizeMax;
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/**
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* The current number of bytes.
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*/
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private long count;
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/**
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* Whether this stream is already closed.
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*/
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private boolean closed;
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/**
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* Creates a new instance.
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* @param pIn The input stream, which shall be limited.
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* @param pSizeMax The limit; no more than this number of bytes
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* shall be returned by the source stream.
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*/
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public LimitedInputStream(InputStream pIn, long pSizeMax) {
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super(pIn);
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sizeMax = pSizeMax;
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}
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/**
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* Called to indicate, that the input streams limit has
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* been exceeded.
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* @param pSizeMax The input streams limit, in bytes.
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* @param pCount The actual number of bytes.
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* @throws IOException The called method is expected
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* to raise an IOException.
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*/
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protected abstract void raiseError(long pSizeMax, long pCount)
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throws IOException;
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/** Called to check, whether the input streams
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* limit is reached.
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* @throws IOException The given limit is exceeded.
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*/
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private void checkLimit() throws IOException {
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if (count > sizeMax) {
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raiseError(sizeMax, count);
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}
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}
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/**
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* Reads the next byte of data from this input stream. The value
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* byte is returned as an <code>int</code> in the range
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* <code>0</code> to <code>255</code>. If no byte is available
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* because the end of the stream has been reached, the value
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* <code>-1</code> is returned. This method blocks until input data
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* is available, the end of the stream is detected, or an exception
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* is thrown.
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* <p>
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* This method
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* simply performs <code>in.read()</code> and returns the result.
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*
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* @return the next byte of data, or <code>-1</code> if the end of the
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* stream is reached.
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* @exception IOException if an I/O error occurs.
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* @see java.io.FilterInputStream#in
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*/
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public int read() throws IOException {
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int res = super.read();
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if (res != -1) {
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count++;
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checkLimit();
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}
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return res;
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}
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/**
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* Reads up to <code>len</code> bytes of data from this input stream
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* into an array of bytes. If <code>len</code> is not zero, the method
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* blocks until some input is available; otherwise, no
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* bytes are read and <code>0</code> is returned.
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* <p>
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* This method simply performs <code>in.read(b, off, len)</code>
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* and returns the result.
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*
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* @param b the buffer into which the data is read.
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* @param off The start offset in the destination array
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* <code>b</code>.
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* @param len the maximum number of bytes read.
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* @return the total number of bytes read into the buffer, or
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* <code>-1</code> if there is no more data because the end of
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* the stream has been reached.
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* @exception NullPointerException If <code>b</code> is <code>null</code>.
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* @exception IndexOutOfBoundsException If <code>off</code> is negative,
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* <code>len</code> is negative, or <code>len</code> is greater than
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* <code>b.length - off</code>
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* @exception IOException if an I/O error occurs.
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* @see java.io.FilterInputStream#in
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*/
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public int read(byte[] b, int off, int len) throws IOException {
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int res = super.read(b, off, len);
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if (res > 0) {
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count += res;
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checkLimit();
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}
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return res;
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}
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/**
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* Returns, whether this stream is already closed.
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* @return True, if the stream is closed, otherwise false.
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* @throws IOException An I/O error occurred.
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*/
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public boolean isClosed() throws IOException {
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return closed;
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}
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/**
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* Closes this input stream and releases any system resources
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* associated with the stream.
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* This
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* method simply performs <code>in.close()</code>.
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*
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* @exception IOException if an I/O error occurs.
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* @see java.io.FilterInputStream#in
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*/
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public void close() throws IOException {
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closed = true;
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super.close();
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}
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}
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