bk commit into 5.1 tree (cbell:1.2570) BUG#30790

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ChangeSet@stripped, 2007-09-07 13:31:38-04:00, cbell@mysql_cab_desk. +2 -0
  BUG#30790 : Suspicious code in rpl_utility.cc
  
  This patch clarifies some of the coding choices with documentationa and
  removes a limitation in the code for future expansion of the CHAR and
  BINARY fields to length > 255.

  sql/log_event.cc@stripped, 2007-09-07 13:31:26-04:00, cbell@mysql_cab_desk. +10 -0
    BUG#30790 : Suspicious code in rpl_utility.cc
    
    This patch adds comments to help explain the choice of variable types.

  sql/rpl_utility.cc@stripped, 2007-09-07 13:31:26-04:00, cbell@mysql_cab_desk. +5 -1
    BUG#30790 : Suspicious code in rpl_utility.cc
    
    This patch removes the mask to allow length to be > 255. This is a 
    future expansion measure since CHAR fields are limited to 255 characters.
    The code mirrors that of the packing methods in field.cc that are written
    to permit > 255 characters for CHAR -type fields should that change be
    made in the future.

diff -Nrup a/sql/log_event.cc b/sql/log_event.cc
--- a/sql/log_event.cc	2007-08-27 14:27:42 -04:00
+++ b/sql/log_event.cc	2007-09-07 13:31:26 -04:00
@@ -6469,6 +6469,16 @@ void Rows_log_event::print_helper(FILE *
   data) in the table map are initialized as zero (0). The array size is the 
   same as the columns for the table on the slave.
 
+  Additionally, values saved for field metadata on the master are saved as a 
+  string of bytes (uchar) in the binlog. A field may require 1 or more bytes
+  to store the information. In cases where values require multiple bytes 
+  (e.g. values > 255), the endian-safe methods are used to properly encode 
+  the values on the master and decode them on the slave. When the field
+  metadata values are captured on the slave, they are stored in an array of
+  type uint16. This allows the least number of casts to prevent casting bugs
+  when the field metadata is used in comparisons of field attributes. When
+  the field metadata is used for calculating addresses in pointer math, the
+  type used is uint32. 
 */
 
 /**
diff -Nrup a/sql/rpl_utility.cc b/sql/rpl_utility.cc
--- a/sql/rpl_utility.cc	2007-08-27 07:43:58 -04:00
+++ b/sql/rpl_utility.cc	2007-09-07 13:31:26 -04:00
@@ -47,7 +47,11 @@ uint32 table_def::calc_field_size(uint c
       length= m_field_metadata[col] & 0x00ff;
     else
     {
-      length= m_field_metadata[col] & 0x00ff;
+      /*
+        Currently, MYSQL_TYPE_STRING is limited to 255 characters. The 
+        following code is implemented to allow the expansion of that
+        restriction.
+      */
       DBUG_ASSERT(length > 0);
       if (length > 255)
       {