--- a/src/common/buffer.cc	Wed Apr 23 08:35:59 2008 -0700
+++ b/src/common/buffer.cc	Wed Apr 23 08:54:29 2008 -0700
@@ -333,9 +333,10 @@
   return m_end - (m_zeroAreaEnd - m_zeroAreaStart);
 }
 
-void 
+int32_t
 Buffer::AddAtStart (uint32_t start)
 {
+  int32_t delta;
   NS_ASSERT (CheckInternalState ());
   bool isDirty = m_data->m_count > 1 && m_start > m_data->m_dirtyStart;
   if (m_start >= start && !isDirty)
@@ -347,6 +348,7 @@
        */
       NS_ASSERT (m_data->m_count == 1 || m_start == m_data->m_dirtyStart);
       m_start -= start;
+      delta = 0;
       HEURISTICS (g_nAddNoRealloc++);
     } 
   else
@@ -361,12 +363,14 @@
         }
       m_data = newData;
 
-      int32_t delta = start - m_start;
-      m_start = 0;
+      delta = start - m_start;
+      m_start += delta;
       m_zeroAreaStart += delta;
       m_zeroAreaEnd += delta;
       m_end += delta;
 
+      m_start -= start;
+
       HEURISTICS (g_nAddRealloc++);
     }
   HEURISTICS (m_maxZeroAreaStart = std::max (m_maxZeroAreaStart, m_zeroAreaStart));
@@ -375,10 +379,12 @@
   m_data->m_dirtyEnd = m_end;
   LOG_INTERNAL_STATE ("add start=" << start << ", ");
   NS_ASSERT (CheckInternalState ());
+  return delta;
 }
-void 
+int32_t
 Buffer::AddAtEnd (uint32_t end)
 {
+  int32_t delta;
   NS_ASSERT (CheckInternalState ());
   bool isDirty = m_data->m_count > 1 && m_end < m_data->m_dirtyEnd;
   if (GetInternalEnd () + end <= m_data->m_size && !isDirty)
@@ -391,6 +397,8 @@
       NS_ASSERT (m_data->m_count == 1 || m_end == m_data->m_dirtyEnd);
       m_end += end;
 
+      delta = 0;
+
       HEURISTICS (g_nAddNoRealloc++);
     } 
   else
@@ -405,10 +413,11 @@
         }
       m_data = newData;
 
+      delta = -m_start;
 
-      m_zeroAreaStart -= m_start;
-      m_zeroAreaEnd -= m_start;
-      m_end -= m_start;
+      m_zeroAreaStart += delta;
+      m_zeroAreaEnd += delta;
+      m_end += delta;
       m_start = 0;
 
       m_end += end;
@@ -421,6 +430,8 @@
   m_data->m_dirtyEnd = m_end;
   LOG_INTERNAL_STATE ("add end=" << end << ", ");
   NS_ASSERT (CheckInternalState ());
+
+  return delta;
 }
 
 void 

--- a/src/common/buffer.h	Wed Apr 23 08:35:59 2008 -0700
+++ b/src/common/buffer.h	Wed Apr 23 08:54:29 2008 -0700
@@ -392,24 +392,36 @@
 
   /**
    * \param start size to reserve
+   * \returns the adjustment delta.
    *
    * Add bytes at the start of the Buffer. The
    * content of these bytes is undefined but debugging
    * builds initialize them to 0x33.
    * Any call to this method invalidates any Iterator
    * pointing to this Buffer.
+   *
+   * The value returned by this method indicates how the internal
+   * buffer was modified to handle the user request to reserve space.
+   * If that value is zero, the buffer was not modified: the user
+   * request was completed without further memory allocation.
    */
-  void AddAtStart (uint32_t start);
+  int32_t AddAtStart (uint32_t start);
   /**
    * \param end size to reserve
+   * \returns the adjustment delta.
    *
    * Add bytes at the end of the Buffer. The
    * content of these bytes is undefined but debugging
    * builds initialize them to 0x33.
    * Any call to this method invalidates any Iterator
    * pointing to this Buffer.
+   *
+   * The value returned by this method indicates how the internal
+   * buffer was modified to handle the user request to reserve space.
+   * If that value is zero, the buffer was not modified: the user
+   * request was completed without further memory allocation.
    */
-  void AddAtEnd (uint32_t end);
+  int32_t AddAtEnd (uint32_t end);
 
   void AddAtEnd (const Buffer &o);
   /**