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, 7 insertions, 6 deletions

diff --git a/sql/sql_db.h b/sql/sql_db.h
index 7b3417dde1b..a4ada7de6a2 100644
--- a/sql/sql_db.h
+++ b/sql/sql_db.h
@@ -20,18 +20,18 @@
 
 class THD;
 
-int mysql_create_db(THD *thd, char *db,
+int mysql_create_db(THD *thd, const char *db,
                     const DDL_options_st &options,
                     const Schema_specification_st *create);
 bool mysql_alter_db(THD *thd, const char *db,
                     const Schema_specification_st *create);
-bool mysql_rm_db(THD *thd, char *db, bool if_exists);
-bool mysql_upgrade_db(THD *thd, LEX_STRING *old_db);
-bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name,
+bool mysql_rm_db(THD *thd, const char *db, bool if_exists);
+bool mysql_upgrade_db(THD *thd, LEX_CSTRING *old_db);
+bool mysql_change_db(THD *thd, const LEX_CSTRING *new_db_name,
                      bool force_switch);
 
 bool mysql_opt_change_db(THD *thd,
-                         const LEX_STRING *new_db_name,
+                         const LEX_CSTRING *new_db_name,
                          LEX_STRING *saved_db_name,
                          bool force_switch,
                          bool *cur_db_changed);
@@ -45,7 +45,8 @@ CHARSET_INFO *get_default_db_collation(THD *thd, const char *db_name);
 bool my_dbopt_init(void);
 void my_dbopt_cleanup(void);
 
-char *normalize_db_name(char *db, char *buffer, size_t buffer_size);
+const char *normalize_db_name(const char *db, char *buffer,
+                              size_t buffer_size);
 
 #define MY_DB_OPT_FILE "db.opt"