1 /* 2 * Copyright (C) 2014 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.internal.util; 18 19 import java.io.IOException; 20 import java.io.InputStream; 21 22 /** 23 * Reads exact number of bytes from wrapped stream, returning EOF once those 24 * bytes have been read. 25 */ 26 @android.ravenwood.annotation.RavenwoodKeepWholeClass 27 public class SizedInputStream extends InputStream { 28 private final InputStream mWrapped; 29 private long mLength; 30 SizedInputStream(InputStream wrapped, long length)31 public SizedInputStream(InputStream wrapped, long length) { 32 mWrapped = wrapped; 33 mLength = length; 34 } 35 36 @Override close()37 public void close() throws IOException { 38 super.close(); 39 mWrapped.close(); 40 } 41 42 @Override read()43 public int read() throws IOException { 44 byte[] buffer = new byte[1]; 45 int result = read(buffer, 0, 1); 46 return (result != -1) ? buffer[0] & 0xff : -1; 47 } 48 49 @Override read(byte[] buffer, int byteOffset, int byteCount)50 public int read(byte[] buffer, int byteOffset, int byteCount) throws IOException { 51 if (mLength <= 0) { 52 return -1; 53 } else if (byteCount > mLength) { 54 byteCount = (int) mLength; 55 } 56 57 final int n = mWrapped.read(buffer, byteOffset, byteCount); 58 if (n == -1) { 59 if (mLength > 0) { 60 throw new IOException("Unexpected EOF; expected " + mLength + " more bytes"); 61 } 62 } else { 63 mLength -= n; 64 } 65 return n; 66 } 67 } 68