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, 12 insertions, 9 deletions

diff --git a/sql/structs.h b/sql/structs.h
index 1b3c0b7a7f2..1a143602eea 100644
--- a/sql/structs.h
+++ b/sql/structs.h
@@ -124,10 +124,10 @@ typedef struct st_key {
   union
   {
     plugin_ref parser;                  /* Fulltext [pre]parser */
-    LEX_STRING *parser_name;            /* Fulltext [pre]parser name */
+    LEX_CSTRING *parser_name;           /* Fulltext [pre]parser name */
   };
   KEY_PART_INFO *key_part;
-  char	*name;				/* Name of key */
+  const char *name;				/* Name of key */
   /* Unique name for cache;  db + \0 + table_name + \0 + key_name + \0 */
   uchar *cache_name;
   /*
@@ -152,7 +152,7 @@ typedef struct st_key {
     int  bdb_return_if_eq;
   } handler;
   TABLE *table;
-  LEX_STRING comment;
+  LEX_CSTRING comment;
   /** reference to the list of options or NULL */
   engine_option_value *option_list;
   ha_index_option_struct *option_struct;                  /* structure with parsed options */
@@ -204,21 +204,24 @@ extern const char *show_comp_option_name[];
 typedef int *(*update_var)(THD *, struct st_mysql_show_var *);
 
 typedef struct	st_lex_user {
-  LEX_STRING user, host, plugin, auth;
-  LEX_STRING pwtext, pwhash;
+  LEX_CSTRING user, host, plugin, auth;
+  LEX_CSTRING pwtext, pwhash;
   bool is_role() const { return user.str[0] && !host.str[0]; }
-  void set_lex_string(LEX_STRING *l, char *buf)
+  void set_lex_string(LEX_CSTRING *l, char *buf)
   {
     if (is_role())
       *l= user;
     else
-      l->length= strxmov(l->str= buf, user.str, "@", host.str, NullS) - buf;
+    {
+      l->str= buf;
+      l->length= strxmov(buf, user.str, "@", host.str, NullS) - buf;
+    }
   }
   void reset_auth()
   {
     pwtext.length= pwhash.length= plugin.length= auth.length= 0;
     pwtext.str= pwhash.str= 0;
-    plugin.str= auth.str= const_cast<char*>("");
+    plugin.str= auth.str= "";
   }
 } LEX_USER;
 
@@ -708,7 +711,7 @@ public:
 };
 
 
-struct Lex_string_with_pos_st: public LEX_STRING
+struct Lex_string_with_pos_st: public LEX_CSTRING
 {
   const char *m_pos;
 };