1 | /**************************************************************** |
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2 | * Licensed to the Apache Software Foundation (ASF) under one * |
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3 | * or more contributor license agreements. See the NOTICE file * |
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4 | * distributed with this work for additional information * |
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5 | * regarding copyright ownership. The ASF licenses this file * |
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6 | * to you under the Apache License, Version 2.0 (the * |
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7 | * "License"); you may not use this file except in compliance * |
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8 | * with the License. You may obtain a copy of the License at * |
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9 | * * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
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11 | * * |
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12 | * Unless required by applicable law or agreed to in writing, * |
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13 | * software distributed under the License is distributed on an * |
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14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
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15 | * KIND, either express or implied. See the License for the * |
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16 | * specific language governing permissions and limitations * |
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17 | * under the License. * |
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18 | ****************************************************************/ |
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19 | |
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20 | package org.apache.james.mime4j.io; |
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21 | |
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22 | import java.io.InputStream; |
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23 | import java.io.IOException; |
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24 | |
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25 | public class LimitedInputStream extends PositionInputStream { |
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26 | |
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27 | private final long limit; |
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28 | |
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29 | public LimitedInputStream(InputStream instream, long limit) { |
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30 | super(instream); |
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31 | if (limit < 0) { |
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32 | throw new IllegalArgumentException("Limit may not be negative"); |
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33 | } |
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34 | this.limit = limit; |
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35 | } |
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36 | |
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37 | private void enforceLimit() throws IOException { |
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38 | if (position >= limit) { |
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39 | throw new IOException("Input stream limit exceeded"); |
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40 | } |
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41 | } |
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42 | |
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43 | @Override |
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44 | public int read() throws IOException { |
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45 | enforceLimit(); |
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46 | return super.read(); |
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47 | } |
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48 | |
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49 | @Override |
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50 | public int read(byte b[], int off, int len) throws IOException { |
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51 | enforceLimit(); |
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52 | len = Math.min(len, getBytesLeft()); |
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53 | return super.read(b, off, len); |
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54 | } |
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55 | |
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56 | @Override |
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57 | public long skip(long n) throws IOException { |
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58 | enforceLimit(); |
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59 | n = Math.min(n, getBytesLeft()); |
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60 | return super.skip(n); |
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61 | } |
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62 | |
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63 | private int getBytesLeft() { |
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64 | return (int)Math.min(Integer.MAX_VALUE, limit - position); |
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65 | } |
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66 | |
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67 | } |
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