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      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.phone.common.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
     23  * is used to allow a client to read directly from an underlying protocol stream without reading
     24  * past 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 
     31     public FixedLengthInputStream(InputStream in, int length) {
     32         this.mIn = in;
     33         this.mLength = length;
     34     }
     35 
     36     @Override
     37     public int available() throws IOException {
     38         return mLength - mCount;
     39     }
     40 
     41     @Override
     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
     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
     67     public int read(byte[] b) throws IOException {
     68         return read(b, 0, b.length);
     69     }
     70 
     71     public int getLength() {
     72         return mLength;
     73     }
     74 
     75     @Override
     76     public String toString() {
     77         return String.format("FixedLengthInputStream(in=%s, length=%d)", mIn.toString(), mLength);
     78     }
     79 }