libgcj java.io.ObjectInputStream patches

[Dave Carnal <dave at netfuel dot com>]

All,
   I'm looking for some advise on how to formally submit these patches, 
or better yet, let one of you all who are maintaining java.io review and 
apply these simple changes on my behalf.   Both patches apply to the 
java.io.ObjectInputStream.java.  I'm sorry to say, it's nearly 
impossible to for me to publish the code that encountered these problems.

Patch 1
   Stream corruption problems when reading an object that implements 
java.io.Externalizable.

   The issue here is that readObject() was not properly looking for and 
reading TC_ENDBLOCK when the SC_BLOCK_DATA flag is set.  This caused 
subsequent reads to fail because TC_ENDBLOCK was left unread on the stream.

   According to the serialization standard, the TC_ENDBLOCK is used to 
signal the end of the object (when SC_BLOCK_DATA is set in the header), 
thus allowing extra data members that are present in the stream but left 
unread to be discarded.  This allows the version of the object to change 
without breaking anything.  My patch DOES NOT correctly handle the case 
where extra data needs to be discarded, but it does handle the simple 
case where the objects read exactly what they write without breaking.


Patch 2
   The implementation of  "public int read(byte[] data, int offset, int 
length) throws IOException" did not properly change to the next block 
nor did it always return the correct number of bytes that had been read.


The patch below and updated .java file (the one I've tested) can be 
found at: http://www.carnals.com/gcj.

Regards,
dave

--
Dave Carnal
Director of Engineering,
NetFuel, Inc.
+1-847.708.1560
dave@netfuel.com





> cvs diff -u ObjectInputStream.java
Index: ObjectInputStream.java
===================================================================
RCS file: /cvsroot/gcc/gcc/libjava/java/io/ObjectInputStream.java,v
retrieving revision 1.38
diff -u -r1.38 ObjectInputStream.java
--- ObjectInputStream.java      25 Nov 2004 03:47:01 -0000      1.38
+++ ObjectInputStream.java      8 Feb 2005 19:34:35 -0000
@@ -292,6 +292,7 @@

                 int handle = assignNewHandle(obj);

+                 boolean has_write_method = osc.hasWriteMethod();
                 boolean read_from_blocks = ((osc.getFlags() & 
SC_BLOCK_DATA) != 0);

                 boolean oldmode = this.readDataFromBlock;
@@ -300,9 +301,13 @@

                 obj.readExternal(this);

+                 if (read_from_blocks)
+                     // Read TC_ENDBLOCKDATA !
+                     this.realInputStream.readByte()
+
                 if (read_from_blocks)
                   setBlockDataMode(oldmode);
-
+
                 ret_val = processResolution(osc, obj, handle);
                 break;
               } // end if (osc.realClassIsExternalizable)
@@ -905,7 +910,9 @@
  {
    if (this.readDataFromBlock)
      {
-       if (this.blockDataPosition + length > this.blockDataBytes)
+        int total = 0;
+
+       while (this.blockDataPosition + length > this.blockDataBytes)
         {
           int remain = this.blockDataBytes - this.blockDataPosition;
           if (remain != 0)
@@ -914,6 +921,7 @@
                                data, offset, remain);
               offset += remain;
               length -= remain;
+               total += remain;
             }
           readNextBlock ();
         }
@@ -922,7 +930,9 @@
                        data, offset, length);
       this.blockDataPosition += length;

-       return length;
+       total += length;
+
+       return total;
      }
    else
      return this.realInputStream.read(data, offset, length);

-

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