git.gag.com Git - debian/openrocket/blob - core/src/net/sf/openrocket/util/LimitedInputStream.java

   1 package net.sf.openrocket.util;
   2
   3 import java.io.FilterInputStream;
   4 import java.io.IOException;
   5 import java.io.InputStream;
   6
   7 /**
   8  * A filtering InputStream that limits the number of bytes that can be
   9  * read from a stream.   This can be used to enforce security, so that overlong
  10  * input is ignored.
  11  *
  12  * @author Sampo Niskanen <sampo.niskanen@iki.fi>
  13  */
  14 public class LimitedInputStream extends FilterInputStream {
  15
  16         private int remaining;
  17
  18         public LimitedInputStream(InputStream is, int limit) {
  19                 super(is);
  20                 this.remaining = limit;
  21         }
  22
  23
  24         @Override
  25         public int available() throws IOException {
  26                 int available = super.available();
  27                 return Math.min(available, remaining);
  28         }
  29
  30
  31         @Override
  32         public int read(byte[] b, int off, int len) throws IOException {
  33                 if (remaining <= 0)
  34                         return -1;
  35
  36                 int result = super.read(b, off, Math.min(len, remaining));
  37                 if (result >= 0)
  38                         remaining -= result;
  39                 return result;
  40         }
  41
  42
  43         @Override
  44         public long skip(long n) throws IOException {
  45                 if (n > remaining)
  46                         n = remaining;
  47                 long result = super.skip(n);
  48                 remaining -= result;
  49                 return result;
  50         }
  51
  52
  53         @Override
  54         public int read() throws IOException {
  55                 if (remaining <= 0)
  56                         return -1;
  57
  58                 int result = super.read();
  59                 if (result >= 0)
  60                         remaining--;
  61                 return result;
  62         }
  63
  64
  65
  66         //  Disable mark support
  67
  68         @Override
  69         public void mark(int readlimit) {
  70
  71         }
  72
  73         @Override
  74         public boolean markSupported() {
  75                 return false;
  76         }
  77
  78         @Override
  79         public synchronized void reset() throws IOException {
  80                 throw new IOException("mark/reset not supported");
  81         }
  82
  83 }