1 /*
2  * Copyright (C) 2008 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 
17 package com.android.email;
18 
19 import java.io.IOException;
20 import java.io.InputStream;
21 
22 /**
23  * A filtering InputStream that stops allowing reads after the given length has been read. This
24  * is used to allow a client to read directly from an underlying protocol stream without reading
25  * past where the protocol handler intended the client to read.
26  */
27 public class FixedLengthInputStream extends InputStream {
28     private final InputStream mIn;
29     private final int mLength;
30     private int mCount;
31 
FixedLengthInputStream(InputStream in, int length)32     public FixedLengthInputStream(InputStream in, int length) {
33         this.mIn = in;
34         this.mLength = length;
35     }
36 
37     @Override
available()38     public int available() throws IOException {
39         return mLength - mCount;
40     }
41 
42     @Override
read()43     public int read() throws IOException {
44         if (mCount < mLength) {
45             mCount++;
46             return mIn.read();
47         } else {
48             return -1;
49         }
50     }
51 
52     @Override
read(byte[] b, int offset, int length)53     public int read(byte[] b, int offset, int length) throws IOException {
54         if (mCount < mLength) {
55             int d = mIn.read(b, offset, Math.min(mLength - mCount, length));
56             if (d == -1) {
57                 return -1;
58             } else {
59                 mCount += d;
60                 return d;
61             }
62         } else {
63             return -1;
64         }
65     }
66 
67     @Override
read(byte[] b)68     public int read(byte[] b) throws IOException {
69         return read(b, 0, b.length);
70     }
71 
getLength()72     public int getLength() {
73         return mLength;
74     }
75 
76     @Override
toString()77     public String toString() {
78         return String.format("FixedLengthInputStream(in=%s, length=%d)", mIn.toString(), mLength);
79     }
80 }
81