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, * 013 * software distributed under the License is distributed on an * 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * 015 * KIND, either express or implied. See the License for the * 016 * specific language governing permissions and limitations * 017 * under the License. * 018 ****************************************************************/ 019 020 package org.apache.james.mime4j.io; 021 022 import java.io.InputStream; 023 import java.io.IOException; 024 025 public class LimitedInputStream extends PositionInputStream { 026 027 private final long limit; 028 029 public LimitedInputStream(InputStream instream, long limit) { 030 super(instream); 031 if (limit < 0) { 032 throw new IllegalArgumentException("Limit may not be negative"); 033 } 034 this.limit = limit; 035 } 036 037 private void enforceLimit() throws IOException { 038 if (position >= limit) { 039 throw new IOException("Input stream limit exceeded"); 040 } 041 } 042 043 @Override 044 public int read() throws IOException { 045 enforceLimit(); 046 return super.read(); 047 } 048 049 @Override 050 public int read(byte b[], int off, int len) throws IOException { 051 enforceLimit(); 052 len = Math.min(len, getBytesLeft()); 053 return super.read(b, off, len); 054 } 055 056 @Override 057 public long skip(long n) throws IOException { 058 enforceLimit(); 059 n = Math.min(n, getBytesLeft()); 060 return super.skip(n); 061 } 062 063 private int getBytesLeft() { 064 return (int)Math.min(Integer.MAX_VALUE, limit - position); 065 } 066 067 }