DotStuffingInputStream


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17  
18  package org.apache.james.util;
19  
20  import java.io.FilterInputStream  ;
21  import java.io.IOException  ;
22  import java.io.InputStream  ;
23  
24  /**
25   * Removes the dot-stuffing happening during the NNTP and SMTP message
26   * transfer
27   */
28  public class DotStuffingInputStream extends FilterInputStream   {
29      /**
30       * An array to hold the last two bytes read off the stream.
31       * This allows the stream to detect '\r\n' sequences even
32       * when they occur across read boundaries.
33       */
34      protected int last[] = new int[2];
35  
36      public DotStuffingInputStream(InputStream   in) {
37          super(in);
38          last[0] = -1;
39          last[1] = -1;
40      }
41  
42      /**
43       * Read through the stream, checking for '\r\n.'
44       *
45       * @return the byte read from the stream
46       */
47      public int read() throws IOException   {
48          int b = in.read();
49          if (b == '.' && last[0] == '\r' && last[1] == '\n') {
50              //skip this '.' because it should have been stuffed
51              b = in.read();
52          }
53          last[0] = last[1];
54          last[1] = b;
55          return b;
56      }
57  
58      /**
59       * Read through the stream, checking for '\r\n.'
60       *
61       * @param b the byte array into which the bytes will be read
62       * @param off the offset into the byte array where the bytes will be inserted
63       * @param len the maximum number of bytes to be read off the stream
64       * @return the number of bytes read
65       */
66      public int read(byte[] b, int off, int len) throws IOException   {
67          if (b == null) {
68              throw new NullPointerException  ();
69          } else if ((off < 0) || (off > b.length) || (len < 0) ||
70                 ((off + len) > b.length) || ((off + len) < 0)) {
71              throw new IndexOutOfBoundsException  ();
72          } else if (len == 0) {
73              return 0;
74          }
75  
76          int c = read();
77          if (c == -1) {
78              return -1;
79          }
80          b[off] = (byte)c;
81  
82          int i = 1;
83  
84          for (; i < len ; i++) {
85              c = read();
86              if (c == -1) {
87                  break;
88              }
89              if (b != null) {
90                  b[off + i] = (byte)c;
91              }
92          }
93  
94          return i;
95      }
96  }
97
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