Changing field::field_name and Item::name to LEX_CSTRING

Benefits of this patch:
- Removed a lot of calls to strlen(), especially for field_string
- Strings generated by parser are now const strings, less chance of
  accidently changing a string
- Removed a lot of calls with LEX_STRING as parameter (changed to pointer)
- More uniform code
- Item::name_length was not kept up to date. Now fixed
- Several bugs found and fixed (Access to null pointers,
  access of freed memory, wrong arguments to printf like functions)
- Removed a lot of casts from (const char*) to (char*)

Changes:
- This caused some ABI changes
  - lex_string_set now uses LEX_CSTRING
  - Some fucntions are now taking const char* instead of char*
- Create_field::change and after changed to LEX_CSTRING
- handler::connect_string, comment and engine_name() changed to LEX_CSTRING
- Checked printf() related calls to find bugs. Found and fixed several
  errors in old code.
- A lot of changes from LEX_STRING to LEX_CSTRING, especially related to
  parsing and events.
- Some changes from LEX_STRING and LEX_STRING & to LEX_CSTRING*
- Some changes for char* to const char*
- Added printf argument checking for my_snprintf()
- Introduced null_clex_str, star_clex_string, temp_lex_str to simplify
  code
- Added item_empty_name and item_used_name to be able to distingush between
  items that was given an empty name and items that was not given a name
  This is used in sql_yacc.yy to know when to give an item a name.
- select table_name."*' is not anymore same as table_name.*
- removed not used function Item::rename()
- Added comparision of item->name_length before some calls to
  my_strcasecmp() to speed up comparison
- Moved Item_sp_variable::make_field() from item.h to item.cc
- Some minimal code changes to avoid copying to const char *
- Fixed wrong error message in wsrep_mysql_parse()
- Fixed wrong code in find_field_in_natural_join() where real_item() was
  set when it shouldn't
- ER_ERROR_ON_RENAME was used with extra arguments.
- Removed some (wrong) ER_OUTOFMEMORY, as alloc_root will already
  give the error.

TODO:
- Check possible unsafe casts in plugin/auth_examples/qa_auth_interface.c
- Change code to not modify LEX_CSTRING for database name
  (as part of lower_case_table_names)

1 files changed, 6 insertions, 6 deletions

diff --git a/sql/log_event.h b/sql/log_event.h
index 57692803b5b..e79c88c28f1 100644
--- a/sql/log_event.h
+++ b/sql/log_event.h
@@ -2013,8 +2013,8 @@ protected:
 */
 class Query_log_event: public Log_event
 {
-  LEX_STRING user;
-  LEX_STRING host;
+  LEX_CSTRING user;
+  LEX_CSTRING host;
 protected:
   Log_event::Byte* data_buf;
 public:
@@ -3041,9 +3041,9 @@ public:
     UNDEF_F= 0,
     UNSIGNED_F= 1
   };
-  char *name;
+  const char *name;
   uint name_len;
-  char *val;
+  const char *val;
   ulong val_len;
   Item_result type;
   uint charset_number;
@@ -3052,8 +3052,8 @@ public:
 #ifdef MYSQL_SERVER
   bool deferred;
   query_id_t query_id;
-  User_var_log_event(THD* thd_arg, char *name_arg, uint name_len_arg,
-                     char *val_arg, ulong val_len_arg, Item_result type_arg,
+  User_var_log_event(THD* thd_arg, const char *name_arg, uint name_len_arg,
+                     const char *val_arg, ulong val_len_arg, Item_result type_arg,
 		     uint charset_number_arg, uchar flags_arg,
                      bool using_trans, bool direct)
     :Log_event(thd_arg, 0, using_trans),