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/session_tracker.cc b/sql/session_tracker.cc
index 03d4b150434..61680fb17f6 100644
--- a/sql/session_tracker.cc
+++ b/sql/session_tracker.cc
@@ -396,7 +396,7 @@ bool Session_sysvars_tracker::vars_list::parse_var_list(THD *thd,
     return false;
   }
 
-  if(!strcmp(var_list.str,(const char *)"*"))
+  if(!strcmp(var_list.str, "*"))
   {
     track_all= true;
     buffer_length= 2;
@@ -418,7 +418,7 @@ bool Session_sysvars_tracker::vars_list::parse_var_list(THD *thd,
   for (;;)
   {
     sys_var *svar;
-    LEX_STRING var;
+    LEX_CSTRING var;
     uint not_used;
 
     lasts= (char *) memchr(token, separator, rest);
@@ -435,7 +435,7 @@ bool Session_sysvars_tracker::vars_list::parse_var_list(THD *thd,
     /* Remove leading/trailing whitespace. */
     trim_whitespace(char_set, &var, &not_used);
 
-    if(!strcmp(var.str,(const char *)"*"))
+    if(!strcmp(var.str, "*"))
     {
       track_all= true;
     }
@@ -483,7 +483,7 @@ bool Session_sysvars_tracker::check_var_list(THD *thd,
   size_t rest= var_list.length;
 
   if (!var_list.str || var_list.length == 0 ||
-      !strcmp(var_list.str,(const char *)"*"))
+      !strcmp(var_list.str, "*"))
   {
     return false;
   }
@@ -500,7 +500,7 @@ bool Session_sysvars_tracker::check_var_list(THD *thd,
     mysql_mutex_lock(&LOCK_plugin);
   for (;;)
   {
-    LEX_STRING var;
+    LEX_CSTRING var;
     uint not_used;
 
     lasts= (char *) memchr(token, separator, rest);
@@ -517,7 +517,7 @@ bool Session_sysvars_tracker::check_var_list(THD *thd,
     /* Remove leading/trailing whitespace. */
     trim_whitespace(char_set, &var, &not_used);
 
-    if(!strcmp(var.str,(const char *)"*") &&
+    if(!strcmp(var.str, "*") &&
        !find_sys_var_ex(thd, var.str, var.length, throw_error, true))
     {
       if (throw_error && take_mutex && thd)