Question about ByteChunk.substract implementation

[Arvind Srinivasan <ar...@Sun.COM>]

Why does the implementation of the substract() methods of
org.apache.tomcat.util.buf.ByteChunk.java
(http://cvs.apache.org/viewcvs.cgi/jakarta-tomcat-connectors/util/java/org/apache/tomcat/util/buf/ByteChunk.java?rev=1.24&view=markup)
assume that in.realReadBytes will manipulate the start and end pointers
of ByteChunk?

org.apache.coyote.http11.InternalInputBuffer.doRead [which gets invoked
along the realReadBytes codepath] calls ByteChunk.setBytes (which
initializes start, end etc) so the scenario below doesn't occur with the
coyote connector. Just wondering if this is a contract that other
buffering connector implementations must adhere to.

In the code below, when buff needs to be refilled (e.g. start = end =
buff.length = 8192), and if realReadBytes doesn't reset start to 0, then
buff[start++] results in an IndexOutOfBoundsException. The other
substract() variants have a similar issue.

    public int substract()
         throws IOException {

         if ((end - start) == 0) {
             if (in == null)
                 return -1;
             int n = in.realReadBytes( buff, 0, buff.length );
             if (n < 0)
                 return -1;
         }

         return (buff[start++] & 0xFF);

     }

I expected to see start, off and end rest in the substract() method itself.
    public int substract()
         throws IOException {

         if ((end - start) == 0) {
             if (in == null)
                 return -1;
             int n = in.realReadBytes( buff, 0, buff.length );
 >>>>        start = off = 0;
>>>>        end = n;
         }

         return (buff[start++] & 0xFF);

     }



Thanks,
  Arvind


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