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, 5 insertions, 5 deletions

diff --git a/sql/create_options.cc b/sql/create_options.cc
index e6d86860afd..a56357db588 100644
--- a/sql/create_options.cc
+++ b/sql/create_options.cc
@@ -119,7 +119,7 @@ static bool report_unknown_option(THD *thd, engine_option_value *val,
 #define value_ptr(STRUCT,OPT)    ((char*)(STRUCT) + (OPT)->offset)
 
 static bool set_one_value(ha_create_table_option *opt,
-                          THD *thd, const LEX_STRING *value, void *base,
+                          THD *thd, const LEX_CSTRING *value, void *base,
                           bool suppress_warning,
                           MEM_ROOT *root)
 {
@@ -311,7 +311,7 @@ bool parse_option_list(THD* thd, handlerton *hton, void *option_struct_arg,
     }
     if (!seen || (opt->var && !last->value.str))
     {
-      LEX_STRING default_val= null_lex_str;
+      LEX_CSTRING default_val= null_clex_str;
 
       /*
         Okay, here's the logic for sysvar options:
@@ -348,9 +348,9 @@ bool parse_option_list(THD* thd, handlerton *hton, void *option_struct_arg,
         {
           char buf[256];
           String sbuf(buf, sizeof(buf), system_charset_info), *str;
-          if ((str= sysvar->val_str(&sbuf, thd, OPT_SESSION, &null_lex_str)))
+          if ((str= sysvar->val_str(&sbuf, thd, OPT_SESSION, &null_clex_str)))
           {
-            LEX_STRING name= { const_cast<char*>(opt->name), opt->name_length };
+            LEX_CSTRING name= { opt->name, opt->name_length };
             default_val.str= strmake_root(root, str->ptr(), str->length());
             default_val.length= str->length();
             val= new (root) engine_option_value(name, default_val,
@@ -688,7 +688,7 @@ uchar *engine_option_value::frm_read(const uchar *buff, const uchar *buff_end,
                                      engine_option_value **start,
                                      engine_option_value **end, MEM_ROOT *root)
 {
-  LEX_STRING name, value;
+  LEX_CSTRING name, value;
   uint len;
 #define need_buff(N)  if (buff + (N) >= buff_end) return NULL