MDEV-7113 difference between check_vcol_func_processor and check_partition_func_processor

MDEV-6789 segfault in Item_func_from_unixtime::get_date on updating table with virtual columns

* prohibit VALUES in partitioning expression
* prohibit user and system variables in virtual column expressions
* fix Item_func_date_format to cache locale (for %M/%W to return the same as MONTHNAME/DAYNAME)
* fix Item_func_from_unixtime to cache time_zone directly, not THD (and not to crash)
* added tests for other incorrectly allowed (in vcols) functions to see that they don't crash

4 files changed, 14 insertions, 15 deletions

diff --git a/sql/item.h b/sql/item.h
index f7ee860390f..57e91e5b3d8 100644
--- a/sql/item.h
+++ b/sql/item.h
@@ -3939,6 +3939,7 @@ public:
     return arg->walk(processor, walk_subquery, args) ||
 	    (this->*processor)(args);
   }
+  bool check_partition_func_processor(uchar *int_arg) {return TRUE;}
   bool check_vcol_func_processor(uchar *arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor("values");
diff --git a/sql/item_func.h b/sql/item_func.h
index 49966964fbb..ab0ae5f0bda 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -1696,6 +1696,7 @@ public:
   bool register_field_in_bitmap(uchar *arg);
   bool set_entry(THD *thd, bool create_if_not_exists);
   void cleanup();
+  bool check_vcol_func_processor(uchar *int_arg) {return TRUE;}
 };
 
 
@@ -1735,6 +1736,7 @@ public:
   {
     return this;
   }
+  bool check_vcol_func_processor(uchar *int_arg) { return TRUE;}
 };
 
 
@@ -1817,6 +1819,7 @@ public:
   bool eq(const Item *item, bool binary_cmp) const;
 
   void cleanup();
+  bool check_vcol_func_processor(uchar *int_arg) { return TRUE;}
 };
 
 
@@ -2090,7 +2093,6 @@ public:
   longlong val_int();
   void fix_length_and_dec()
   { max_length= 21; unsigned_flag=1; }
-  bool check_partition_func_processor(uchar *int_arg) {return FALSE;}
   bool check_vcol_func_processor(uchar *int_arg) 
   {
     return trace_unsupported_by_check_vcol_func_processor(func_name());
diff --git a/sql/item_timefunc.cc b/sql/item_timefunc.cc
index 15701658015..59a5f1849f8 100644
--- a/sql/item_timefunc.cc
+++ b/sql/item_timefunc.cc
@@ -450,16 +450,14 @@ err:
   Create a formated date/time value in a string.
 */
 
-bool make_date_time(DATE_TIME_FORMAT *format, MYSQL_TIME *l_time,
-		    timestamp_type type, String *str)
+static bool make_date_time(DATE_TIME_FORMAT *format, MYSQL_TIME *l_time,
+                           timestamp_type type, MY_LOCALE *locale, String *str)
 {
   char intbuff[15];
   uint hours_i;
   uint weekday;
   ulong length;
   const char *ptr, *end;
-  THD *thd= current_thd;
-  MY_LOCALE *locale= thd->variables.lc_time_names;
 
   str->length(0);
 
@@ -1726,6 +1724,8 @@ overflow:
 void Item_func_date_format::fix_length_and_dec()
 {
   THD* thd= current_thd;
+  locale= thd->variables.lc_time_names;
+
   /*
     Must use this_item() in case it's a local SP variable
     (for ->max_length and ->str_value)
@@ -1889,7 +1889,7 @@ String *Item_func_date_format::val_str(String *str)
   if (!make_date_time(&date_time_format, &l_time,
                       is_time_format ? MYSQL_TIMESTAMP_TIME :
                                        MYSQL_TIMESTAMP_DATE,
-                      str))
+                      locale, str))
     return str;
 
 null_date:
@@ -1900,8 +1900,9 @@ null_date:
 
 void Item_func_from_unixtime::fix_length_and_dec()
 { 
-  thd= current_thd;
+  THD *thd= current_thd;
   thd->time_zone_used= 1;
+  tz= thd->variables.time_zone;
   decimals= args[0]->decimals;
   Item_temporal_func::fix_length_and_dec();
 }
@@ -1922,7 +1923,7 @@ bool Item_func_from_unixtime::get_date(MYSQL_TIME *ltime,
   if (args[0]->null_value || sign || sec > TIMESTAMP_MAX_VALUE)
     return (null_value= 1);
 
-  thd->variables.time_zone->gmt_sec_to_TIME(ltime, (my_time_t)sec);
+  tz->gmt_sec_to_TIME(ltime, (my_time_t)sec);
 
   ltime->second_part= sec_part;
 
diff --git a/sql/item_timefunc.h b/sql/item_timefunc.h
index 455540c4b0d..3a03ee4b27a 100644
--- a/sql/item_timefunc.h
+++ b/sql/item_timefunc.h
@@ -688,6 +688,7 @@ public:
 
 class Item_func_date_format :public Item_str_func
 {
+  MY_LOCALE *locale;
   int fixed_length;
   const bool is_time_format;
   String value;
@@ -705,7 +706,7 @@ public:
 
 class Item_func_from_unixtime :public Item_temporal_func
 {
-  THD *thd;
+  Time_zone *tz;
  public:
   Item_func_from_unixtime(Item *a) :Item_temporal_func(a) {}
   const char *func_name() const { return "from_unixtime"; }
@@ -1046,10 +1047,4 @@ public:
   bool get_date(MYSQL_TIME *res, ulonglong fuzzy_date);
 };
 
-
-/* Function prototypes */
-
-bool make_date_time(DATE_TIME_FORMAT *format, MYSQL_TIME *l_time,
-                    timestamp_type type, String *str);
-
 #endif /* ITEM_TIMEFUNC_INCLUDED */