MDEV-29473 UBSAN: Signed integer overflow: X * Y cannot be represented in type 'int' in strings/dtoa.c

Fixing a few problems relealed by UBSAN in type_float.test

- multiplication overflow in dtoa.c

- uninitialized Field::geom_type (and Field::srid as well)

- Wrong call-back function types used in combination with SHOW_FUNC.
  Changes in the mysql_show_var_func data type definition were not
  properly addressed all around the code by the following commits:
    b4ff64568c88ab3ce559e7bd39853d9cbf86704a
    18feb62feeb833494d003615861b9c78ec008a90
    0ee879ff8ac1b80cd9a963015344f5698a81f309

  Adding a helper SHOW_FUNC_ENTRY() function and replacing
  all mysql_show_var_func declarations using SHOW_FUNC
  to SHOW_FUNC_ENTRY, to catch mysql_show_var_func in the future
  at compilation time.

1 files changed, 4 insertions, 2 deletions

diff --git a/plugin/handler_socket/handlersocket/handlersocket.cpp b/plugin/handler_socket/handlersocket/handlersocket.cpp
index 8133497044c..45c9e13b2ca 100644
--- a/plugin/handler_socket/handlersocket/handlersocket.cpp
+++ b/plugin/handler_socket/handlersocket/handlersocket.cpp
@@ -185,7 +185,9 @@ static SHOW_VAR hs_status_variables[] = {
   {NullS, NullS, SHOW_LONG}
 };
 
-static int show_hs_vars(THD *thd, SHOW_VAR *var, char *buff)
+static int show_hs_vars(THD *thd, SHOW_VAR *var, void *buff,
+                        struct system_status_var *status_var,
+                        enum enum_var_type var_type)
 {
   var->type= SHOW_ARRAY;
   var->value= (char *) &hs_status_variables;
@@ -193,7 +195,7 @@ static int show_hs_vars(THD *thd, SHOW_VAR *var, char *buff)
 }
 
 static SHOW_VAR daemon_handlersocket_status_variables[] = {
-  {"Hs", (char*) show_hs_vars, SHOW_FUNC},
+  SHOW_FUNC_ENTRY("Hs", &show_hs_vars),
   {NullS, NullS, SHOW_LONG}
 };