reset position/limit after encoding page

git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@630 f203690c-595d-4dc9-a70b-905162fa7fd2

src/java/com/healthmarketscience/jackcess/PageChannel.java

 
       // re-encode page
       encodedPage = _codecHandler.encodePage(page, pageNumber, pageOffset);
+
+      // reset position/limit in case they were affected by encoding
+      encodedPage.position(pageOffset).limit(pageOffset + writeLen);
     }
 
     try {
-      encodedPage.position(pageOffset);
       _channel.write(encodedPage, (getPageOffset(pageNumber) + pageOffset));
       if(_autoSync) {
         flush();

test/src/java/com/healthmarketscience/jackcess/CodecHandlerTest.java

       throws IOException
     {
       ByteBuffer bb = _bufH.getPageBuffer(_channel);
+      bb.clear();
       simpleEncode(page.array(), bb.array(), pageNumber, pageOffset, 
                    page.limit());
       return bb;
       assertEquals(_channel.getFormat().PAGE_SIZE, page.limit());
 
       ByteBuffer bb = _bufH.getPageBuffer(_channel);
+      bb.clear();
       fullEncode(page.array(), bb.array(), pageNumber);
       return bb;
     }