Post-review fixes of BUG#9937: Crash on call to stored procedure.

sql/item_cmpfunc.cc:
  Put the buff parameter back in check_stack_overrun().
sql/item_func.cc:
  Put the buff parameter back in check_stack_overrun().
sql/item_subselect.cc:
  Put the buff parameter back in check_stack_overrun().
sql/mysql_priv.h:
  Put the buff parameter back in check_stack_overrun().
sql/mysqld.cc:
  Style fixes.
sql/sp_head.cc:
  Put the buff parameter back in check_stack_overrun().
sql/sql_parse.cc:
  Put the buff parameter back in check_stack_overrun(), and added comment explaining the purpose.
sql/table.cc:
  Put the buff parameter back in check_stack_overrun().

sql/item_cmpfunc.cc

@@ -2321,7 +2321,7 @@ Item_cond::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
   */
   and_tables_cache= ~(table_map) 0;
 
-  if (check_stack_overrun(thd, STACK_MIN_SIZE))
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, buff))
     return TRUE;				// Fatal error flag is set!
   /*
     The following optimization reduces the depth of an AND-OR tree.

sql/item_func.cc

@@ -293,11 +293,14 @@ Item_func::fix_fields(THD *thd, TABLE_LIST *tables, Item **ref)
 {
   DBUG_ASSERT(fixed == 0);
   Item **arg,**arg_end;
+#ifndef EMBEDDED_LIBRARY			// Avoid compiler warning
+  char buff[STACK_BUFF_ALLOC];			// Max argument in function
+#endif
 
   used_tables_cache= not_null_tables_cache= 0;
   const_item_cache=1;
 
-  if (check_stack_overrun(thd, STACK_MIN_SIZE+STACK_BUFF_ALLOC))
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, buff))
     return TRUE;				// Fatal error if flag is set!
   if (arg_count)
   {						// Print purify happy
@@ -2564,9 +2567,12 @@ bool
 udf_handler::fix_fields(THD *thd, TABLE_LIST *tables, Item_result_field *func,
 			uint arg_count, Item **arguments)
 {
+#ifndef EMBEDDED_LIBRARY			// Avoid compiler warning
+  char buff[STACK_BUFF_ALLOC];			// Max argument in function
+#endif
   DBUG_ENTER("Item_udf_func::fix_fields");
 
-  if (check_stack_overrun(thd, STACK_MIN_SIZE+STACK_BUFF_ALLOC))
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, buff))
     DBUG_RETURN(TRUE);				// Fatal error flag is set!
 
   udf_func *tmp_udf=find_udf(u_d->name.str,(uint) u_d->name.length,1);

sql/item_subselect.cc

@@ -138,7 +138,7 @@ bool Item_subselect::fix_fields(THD *thd_param, TABLE_LIST *tables, Item **ref)
   DBUG_ASSERT(fixed == 0);
   engine->set_thd((thd= thd_param));
 
-  if (check_stack_overrun(thd, STACK_MIN_SIZE))
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, (gptr)&res))
     return TRUE;
 
   res= engine->prepare();

sql/mysql_priv.h

@@ -1429,11 +1429,11 @@ inline int hexchar_to_int(char c)
 #ifndef EMBEDDED_LIBRARY
 extern "C" void unireg_abort(int exit_code);
 void kill_delayed_threads(void);
-bool check_stack_overrun(THD *thd, long margin);
+bool check_stack_overrun(THD *thd, long margin, char *dummy);
 #else
 #define unireg_abort(exit_code) DBUG_RETURN(exit_code)
 inline void kill_delayed_threads(void) {}
-#define check_stack_overrun(A, B) 0
+#define check_stack_overrun(A, B, C) 0
 #endif
 
 #endif /* MYSQL_CLIENT */

sql/mysqld.cc

@@ -2091,8 +2091,10 @@ static void start_signal_handler(void)
   if (!(opt_specialflag & SPECIAL_NO_PRIOR))
     my_pthread_attr_setprio(&thr_attr,INTERRUPT_PRIOR);
 #if defined(__ia64__) || defined(__ia64)
-  /* Peculiar things with ia64 platforms - it seems we only have half the
+  /*
-     stack size in reality, so we have to double it here */
+    Peculiar things with ia64 platforms - it seems we only have half the
+    stack size in reality, so we have to double it here
+  */
   pthread_attr_setstacksize(&thr_attr,thread_stack*2);
 #else
   pthread_attr_setstacksize(&thr_attr,thread_stack);
@@ -3018,8 +3020,10 @@ int main(int argc, char **argv)
   if (!(opt_specialflag & SPECIAL_NO_PRIOR))
     my_pthread_setprio(pthread_self(),CONNECT_PRIOR);
 #if defined(__ia64__) || defined(__ia64)
-  /* Peculiar things with ia64 platforms - it seems we only have half the
+  /*
-     stack size in reality, so we have to double it here */
+    Peculiar things with ia64 platforms - it seems we only have half the
+    stack size in reality, so we have to double it here
+  */
   pthread_attr_setstacksize(&connection_attrib,thread_stack*2);
 #else
   pthread_attr_setstacksize(&connection_attrib,thread_stack);

sql/sp_head.cc

@@ -565,7 +565,7 @@ sp_head::execute(THD *thd)
   String old_packet;
 
   /* Use some extra margin for possible SP recursion and functions */
-  if (check_stack_overrun(thd, 4*STACK_MIN_SIZE))
+  if (check_stack_overrun(thd, 4*STACK_MIN_SIZE, olddb))
   {
     DBUG_RETURN(-1);
   }

sql/sql_parse.cc

@@ -4986,7 +4986,14 @@ long max_stack_used;
 #endif
 
 #ifndef EMBEDDED_LIBRARY
-bool check_stack_overrun(THD *thd, long margin)
+/*
+  Note: The 'buf' parameter is necessary, even if it is unused here.
+  - fix_fields functions has a "dummy" buffer large enough for the
+    corresponding exec. (Thus we only have to check in fix_fields.)
+  - Passing to check_stack_overrun() prevents the compiler from removing it.
+ */
+bool check_stack_overrun(THD *thd, long margin,
+			 char *buf __attribute__((unused)))
 {
   long stack_used;
   if ((stack_used=used_stack(thd->thread_stack,(char*) &stack_used)) >=

sql/table.cc

@@ -1815,7 +1815,7 @@ bool st_table_list::setup_ancestor(THD *thd, Item **conds,
   bool res= FALSE;
   DBUG_ENTER("st_table_list::setup_ancestor");
 
-  if (check_stack_overrun(thd, STACK_MIN_SIZE))
+  if (check_stack_overrun(thd, STACK_MIN_SIZE, (char *)&res))
     return TRUE;
 
   for (tbl= ancestor; tbl; tbl= tbl->next_local)