Support for multipacket statements

Remove double free in cloned DCB's

server/core/buffer.c

@@ -31,6 +31,7 @@
  * 10/06/13	Mark Riddoch		Initial implementation
  * 11/07/13	Mark Riddoch		Add reference count mechanism
  * 16/07/2013	Massimiliano Pinto	Added command type to gwbuf struct
+ * 24/06/2014	Mark Riddoch		Addition of gwbuf_trim
  *
  * @endverbatim
  */
@@ -297,6 +298,26 @@ int	rval = 0;
 	return rval;
 }
 
+/**
+ * Trim bytes form the end of a GWBUF structure
+ *
+ * @param buf		The buffer to trim
+ * @param nbytes	The number of bytes to trim off
+ * @return 		The buffer chain
+ */
+GWBUF *
+gwbuf_trim(GWBUF *buf, unsigned int n_bytes)
+{
+	if (GWBUF_LENGTH(buf) <= n_bytes)
+	{
+		gwbuf_consume(buf, GWBUF_LENGTH(buf));
+		return NULL;
+	}
+	buf->end -= n_bytes;
+
+	return buf;
+}
+
 bool gwbuf_set_type(
         GWBUF*       buf,
         gwbuf_type_t type)

server/core/dcb.c

@@ -347,7 +347,7 @@ DCB_CALLBACK		*cb;
 		}
 	}
 
-	if (dcb->protocol != NULL)
+	if (dcb->protocol && ((dcb->flags & DCBF_CLONE) ==0))
 		free(dcb->protocol);
 	if (dcb->data && ((dcb->flags & DCBF_CLONE) ==0))
 		free(dcb->data);

server/core/modutil.c

@@ -57,9 +57,12 @@ unsigned char	*ptr;
  * This routine is very simplistic and does not deal with SQL text
  * that spans multiple buffers.
  *
+ * The length returned is the complete length of the SQL, which may
+ * be larger than the amount of data in this packet.
+ *
  * @param	buf	The packet buffer
  * @param	sql	Pointer that is set to point at the SQL data
- * @param	length	Length of the SQL data
+ * @param	length	Length of the SQL query data
  * @return	True if the packet is a COM_QUERY packet
  */
 int
@@ -79,7 +82,54 @@ char	*ptr;
 	return 1;
 }
 
+/**
+ * Extract the SQL portion of a COM_QUERY packet
+ *
+ * NB This sets *sql to point into the packet and does not
+ * allocate any new storage. The string pointed to by *sql is
+ * not NULL terminated.
+ *
+ * The number of bytes pointed to *sql is returned in *length
+ *
+ * The remaining number of bytes required for the complete query string
+ * are returned in *residual
+ *
+ * @param	buf		The packet buffer
+ * @param	sql		Pointer that is set to point at the SQL data
+ * @param	length		Length of the SQL query data pointed to by sql
+ * @param	residual	Any remain part of the query in future packets
+ * @return	True if the packet is a COM_QUERY packet
+ */
+int
+modutil_MySQL_Query(GWBUF *buf, char **sql, int *length, int *residual)
+{
+char	*ptr;
 
+	if (!modutil_is_SQL(buf))
+		return 0;
+	ptr = GWBUF_DATA(buf);
+	*residual = *ptr++;
+	*residual += (*ptr++ << 8);
+	*residual += (*ptr++ << 8);
+        ptr += 2;  // Skip sequence id	and COM_QUERY byte
+	*residual = *residual - 1;
+	*length = GWBUF_LENGTH(buf) - 5;
+	*residual -= *length;
+	*sql = ptr;
+	return 1;
+}
+
+
+
+/**
+ * Replace the contents of a GWBUF with the new SQL statement passed as a text string.
+ * The routine takes care of the modification needed to the MySQL packet,
+ * returning a GWBUF chian that cna be used to send the data to a MySQL server
+ *
+ * @param orig	The original request in a GWBUF
+ * @param sql	The SQL text to replace in the packet
+ * @return A newly formed GWBUF containing the MySQL packet.
+ */
 GWBUF *
 modutil_replace_SQL(GWBUF *orig, char *sql)
 {