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      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 
     32     public FixedLengthInputStream(InputStream in, int length) {
     33         this.mIn = in;
     34         this.mLength = length;
     35     }
     36 
     37     @Override
     38     public int available() throws IOException {
     39         return mLength - mCount;
     40     }
     41 
     42     @Override
     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
     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
     68     public int read(byte[] b) throws IOException {
     69         return read(b, 0, b.length);
     70     }
     71 
     72     public int getLength() {
     73         return mLength;
     74     }
     75 
     76     @Override
     77     public String toString() {
     78         return String.format("FixedLengthInputStream(in=%s, length=%d)", mIn.toString(), mLength);
     79     }
     80 }
     81