001/*
002 * Copyright (C) 2007 The Guava Authors
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 * http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package com.google.common.io;
018
019import com.google.common.annotations.Beta;
020import com.google.common.base.Preconditions;
021
022import java.io.FilterInputStream;
023import java.io.IOException;
024import java.io.InputStream;
025
026/**
027 * An InputStream that limits the number of bytes which can be read.
028 *
029 * @author Charles Fry
030 * @since 1.0
031 * @deprecated Use {@link ByteStreams#limit} instead. This class is scheduled
032 *     to be removed in Guava release 15.0.
033 */
034@Beta
035@Deprecated
036public final class LimitInputStream extends FilterInputStream {
037
038  private long left;
039  private long mark = -1;
040
041  /**
042   * Wraps another input stream, limiting the number of bytes which can be read.
043   *
044   * @param in the input stream to be wrapped
045   * @param limit the maximum number of bytes to be read
046   */
047  public LimitInputStream(InputStream in, long limit) {
048    super(in);
049    Preconditions.checkNotNull(in);
050    Preconditions.checkArgument(limit >= 0, "limit must be non-negative");
051    left = limit;
052  }
053
054  @Override public int available() throws IOException {
055    return (int) Math.min(in.available(), left);
056  }
057
058  @Override public synchronized void mark(int readlimit) {
059    in.mark(readlimit);
060    mark = left;
061    // it's okay to mark even if mark isn't supported, as reset won't work
062  }
063
064  @Override public int read() throws IOException {
065    if (left == 0) {
066      return -1;
067    }
068
069    int result = in.read();
070    if (result != -1) {
071      --left;
072    }
073    return result;
074  }
075
076  @Override public int read(byte[] b, int off, int len) throws IOException {
077    if (left == 0) {
078      return -1;
079    }
080
081    len = (int) Math.min(len, left);
082    int result = in.read(b, off, len);
083    if (result != -1) {
084      left -= result;
085    }
086    return result;
087  }
088
089  @Override public synchronized void reset() throws IOException {
090    if (!in.markSupported()) {
091      throw new IOException("Mark not supported");
092    }
093    if (mark == -1) {
094      throw new IOException("Mark not set");
095    }
096
097    in.reset();
098    left = mark;
099  }
100
101  @Override public long skip(long n) throws IOException {
102    n = Math.min(n, left);
103    long skipped = in.skip(n);
104    left -= skipped;
105    return skipped;
106  }
107}