Merge from 5.1.

1 files changed, 4 insertions, 3 deletions

diff --git a/sql/set_var.cc b/sql/set_var.cc
index f31fe6a351d..8e48e0213f0 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -117,7 +117,8 @@ void sys_var_end()
   sys_var constructor
 
   @param chain     variables are linked into chain for mysql_add_sys_var_chain()
-  @param name_arg  the name of the variable. @sa my_option::name
+  @param name_arg  the name of the variable. Must be 0-terminated and exist
+                   for the liftime of the sys_var object. @sa my_option::name
   @param comment   shown in mysqld --help, @sa my_option::comment
   @param flags_arg or'ed flag_enum values
   @param off       offset of the global variable value from the
@@ -164,8 +165,8 @@ sys_var::sys_var(sys_var_chain *chain, const char *name_arg,
   */
   DBUG_ASSERT(parse_flag == PARSE_NORMAL || getopt_id <= 0 || getopt_id >= 255);
 
-  name.str= name_arg;
-  name.length= strlen(name_arg);
+  name.str= name_arg;     // ER_NO_DEFAULT relies on 0-termination of name_arg
+  name.length= strlen(name_arg);                // and so does this.
   DBUG_ASSERT(name.length <= NAME_CHAR_LEN);
 
   bzero(&option, sizeof(option));