Bug #40877: multi statement execution fails in 5.1.30

      
Implemented the server infrastructure for the fix:

1. Added a function LEX_STRING *thd_query_string(THD) to return
a LEX_STRING structure instead of char *.
This is the function that must be called in innodb instead of 
thd_query()

2. Did some encapsulation in THD : aggregated thd_query and 
thd_query_length into a LEX_STRING and made accessor and mutator 
methods for easy code updating. 

3. Updated the server code to use the new methods where applicable.

1 files changed, 33 insertions, 11 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index f75dc2cb88a..aa556810402 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -376,14 +376,14 @@ char *thd_security_context(THD *thd, char *buffer, unsigned int length,
     str.append(proc_info);
   }
 
-  if (thd->query)
+  if (thd->query())
   {
     if (max_query_len < 1)
-      len= thd->query_length;
+      len= thd->query_length();
     else
-      len= min(thd->query_length, max_query_len);
+      len= min(thd->query_length(), max_query_len);
     str.append('\n');
-    str.append(thd->query, len);
+    str.append(thd->query(), len);
   }
   if (str.c_ptr_safe() == buffer)
     return buffer;
@@ -2434,12 +2434,12 @@ Statement::Statement(LEX *lex_arg, MEM_ROOT *mem_root_arg,
   id(id_arg),
   mark_used_columns(MARK_COLUMNS_READ),
   lex(lex_arg),
-  query(0),
-  query_length(0),
   cursor(0),
   db(NULL),
   db_length(0)
 {
+  query_string.length= 0;
+  query_string.str= NULL;
   name.str= NULL;
 }
 
@@ -2455,8 +2455,7 @@ void Statement::set_statement(Statement *stmt)
   id=             stmt->id;
   mark_used_columns=   stmt->mark_used_columns;
   lex=            stmt->lex;
-  query=          stmt->query;
-  query_length=   stmt->query_length;
+  query_string=   stmt->query_string;
   cursor=         stmt->cursor;
 }
 
@@ -2480,6 +2479,15 @@ void Statement::restore_backup_statement(Statement *stmt, Statement *backup)
 }
 
 
+/** Assign a new value to thd->query.  */
+
+void Statement::set_query_inner(char *query_arg, uint32 query_length_arg)
+{
+  query_string.str= query_arg;
+  query_string.length= query_length_arg;
+}
+
+
 void THD::end_statement()
 {
   /* Cleanup SQL processing state to reuse this statement in next query. */
@@ -2993,9 +3001,24 @@ extern "C" struct charset_info_st *thd_charset(MYSQL_THD thd)
   return(thd->charset());
 }
 
+/**
+  OBSOLETE : there's no way to ensure the string is null terminated.
+  Use thd_query_string instead()
+*/
 extern "C" char **thd_query(MYSQL_THD thd)
 {
-  return(&thd->query);
+  return(&thd->query_string.str);
+}
+
+/**
+  Get the current query string for the thread.
+
+  @param The MySQL internal thread pointer
+  @return query string and length. May be non-null-terminated.
+*/
+extern "C" LEX_STRING * thd_query_string (MYSQL_THD thd)
+{
+  return(&thd->query_string);
 }
 
 extern "C" int thd_slave_thread(const MYSQL_THD thd)
@@ -3174,8 +3197,7 @@ void THD::set_statement(Statement *stmt)
 void THD::set_query(char *query_arg, uint32 query_length_arg)
 {
   pthread_mutex_lock(&LOCK_thd_data);
-  query= query_arg;
-  query_length= query_length_arg;
+  set_query_inner(query_arg, query_length_arg);
   pthread_mutex_unlock(&LOCK_thd_data);
 }