1 /*
2  * Copyright (C) 2015 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package com.android.voicemail.impl.mail;
17 
18 import java.io.IOException;
19 import java.io.InputStream;
20 
21 /**
22  * A filtering InputStream that stops allowing reads after the given length has been read. This is
23  * used to allow a client to read directly from an underlying protocol stream without reading past
24  * where the protocol handler intended the client to read.
25  */
26 public class FixedLengthInputStream extends InputStream {
27   private final InputStream mIn;
28   private final int mLength;
29   private int mCount;
30 
FixedLengthInputStream(InputStream in, int length)31   public FixedLengthInputStream(InputStream in, int length) {
32     this.mIn = in;
33     this.mLength = length;
34   }
35 
36   @Override
available()37   public int available() throws IOException {
38     return mLength - mCount;
39   }
40 
41   @Override
read()42   public int read() throws IOException {
43     if (mCount < mLength) {
44       mCount++;
45       return mIn.read();
46     } else {
47       return -1;
48     }
49   }
50 
51   @Override
read(byte[] b, int offset, int length)52   public int read(byte[] b, int offset, int length) throws IOException {
53     if (mCount < mLength) {
54       int d = mIn.read(b, offset, Math.min(mLength - mCount, length));
55       if (d == -1) {
56         return -1;
57       } else {
58         mCount += d;
59         return d;
60       }
61     } else {
62       return -1;
63     }
64   }
65 
66   @Override
read(byte[] b)67   public int read(byte[] b) throws IOException {
68     return read(b, 0, b.length);
69   }
70 
getLength()71   public int getLength() {
72     return mLength;
73   }
74 
75   @Override
toString()76   public String toString() {
77     return String.format("FixedLengthInputStream(in=%s, length=%d)", mIn.toString(), mLength);
78   }
79 }
80