| /* |
| * Copyright (C) 2020 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.server.integrity.parser; |
| |
| import java.io.FilterInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** An {@link InputStream} that basically truncates another {@link InputStream} */ |
| public class LimitInputStream extends FilterInputStream { |
| private int mReadBytes; |
| private final int mLimit; |
| |
| public LimitInputStream(InputStream in, int limit) { |
| super(in); |
| if (limit < 0) { |
| throw new IllegalArgumentException("limit " + limit + " cannot be negative"); |
| } |
| mReadBytes = 0; |
| mLimit = limit; |
| } |
| |
| @Override |
| public int available() throws IOException { |
| return Math.min(super.available(), mLimit - mReadBytes); |
| } |
| |
| @Override |
| public int read() throws IOException { |
| if (mReadBytes == mLimit) { |
| return -1; |
| } |
| mReadBytes++; |
| return super.read(); |
| } |
| |
| @Override |
| public int read(byte[] b) throws IOException { |
| return read(b, 0, b.length); |
| } |
| |
| @Override |
| public int read(byte[] b, int off, int len) throws IOException { |
| if (len <= 0) { |
| return 0; |
| } |
| int available = available(); |
| if (available <= 0) { |
| return -1; |
| } |
| int result = super.read(b, off, Math.min(len, available)); |
| mReadBytes += result; |
| return result; |
| } |
| |
| @Override |
| public long skip(long n) throws IOException { |
| if (n <= 0) { |
| return 0; |
| } |
| int available = available(); |
| if (available <= 0) { |
| return 0; |
| } |
| int bytesToSkip = (int) Math.min(available, n); |
| long bytesSkipped = super.skip(bytesToSkip); |
| mReadBytes += (int) bytesSkipped; |
| return bytesSkipped; |
| } |
| } |