1 files changed, 23 insertions, 3 deletions

diff --git a/src/membuf.cpp b/src/membuf.cpp
index 6d850bf..e7c7ac8 100644
--- a/src/membuf.cpp
+++ b/src/membuf.cpp
@@ -41,9 +41,29 @@ size_t Bu::MemBuf::read( void *pBuf, size_t nBytes )
         
 size_t Bu::MemBuf::write( const void *pBuf, size_t nBytes )
 {
-        sBuf.append( (const char *)pBuf, nBytes );
-        nPos += nBytes;
-        return nBytes;
+        if( nPos == sBuf.getSize() )
+        {
+                // Easiest, just append the data.
+                sBuf.append( (const char *)pBuf, nBytes );
+                nPos += nBytes;
+                return nBytes;
+        }
+        else
+        {
+                // Trickier, we must do this in two parts, overwrite, then append
+                // Frist, overwrite.
+                int iOver = sBuf.getSize() - nPos;
+                if( iOver > nBytes )
+                        iOver = nBytes;
+                memcpy( sBuf.getStr()+nPos, pBuf, iOver );
+                // Then append
+                if( iOver < nBytes )
+                {
+                        sBuf.append( ((const char *)pBuf)+iOver, nBytes-iOver );
+                }
+                nPos += nBytes;
+                return nBytes;
+        }
 }
 
 long Bu::MemBuf::tell()