session-android/src/org/thoughtcrime/securesms/util/LimitedInputStream.java
2017-03-29 18:17:34 -07:00

120 lines
3.9 KiB
Java

package org.thoughtcrime.securesms.util;
/*
* 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.
*/
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* An input stream, which limits its data size. This stream is
* used, if the content length is unknown.
*/
public class LimitedInputStream extends FilterInputStream {
/**
* The maximum size of an item, in bytes.
*/
private long sizeMax;
/**
* The current number of bytes.
*/
private long count;
/**
* Whether this stream is already closed.
*/
private boolean closed;
/**
* Creates a new instance.
* @param pIn The input stream, which shall be limited.
* @param pSizeMax The limit; no more than this number of bytes
* shall be returned by the source stream.
*/
public LimitedInputStream(InputStream pIn, long pSizeMax) {
super(pIn);
sizeMax = pSizeMax;
}
/**
* Reads the next byte of data from this input stream. The value
* byte is returned as an <code>int</code> in the range
* <code>0</code> to <code>255</code>. If no byte is available
* because the end of the stream has been reached, the value
* <code>-1</code> is returned. This method blocks until input data
* is available, the end of the stream is detected, or an exception
* is thrown.
*
* This method
* simply performs <code>in.read()</code> and returns the result.
*
* @return the next byte of data, or <code>-1</code> if the end of the
* stream is reached.
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public int read() throws IOException {
if (count >= sizeMax) return -1;
int res = super.read();
if (res != -1) {
count++;
}
return res;
}
/**
* Reads up to <code>len</code> bytes of data from this input stream
* into an array of bytes. If <code>len</code> is not zero, the method
* blocks until some input is available; otherwise, no
* bytes are read and <code>0</code> is returned.
*
* This method simply performs <code>in.read(b, off, len)</code>
* and returns the result.
*
* @param b the buffer into which the data is read.
* @param off The start offset in the destination array
* <code>b</code>.
* @param len the maximum number of bytes read.
* @return the total number of bytes read into the buffer, or
* <code>-1</code> if there is no more data because the end of
* the stream has been reached.
* @exception NullPointerException If <code>b</code> is <code>null</code>.
* @exception IndexOutOfBoundsException If <code>off</code> is negative,
* <code>len</code> is negative, or <code>len</code> is greater than
* <code>b.length - off</code>
* @exception IOException if an I/O error occurs.
* @see java.io.FilterInputStream#in
*/
public int read(byte[] b, int off, int len) throws IOException {
if (count >= sizeMax) return -1;
long correctLength = Math.min(len, sizeMax - count);
int res = super.read(b, off, Util.toIntExact(correctLength));
if (res > 0) {
count += res;
}
return res;
}
}