Fix for bug#21416 SP: Recursion level higher than zero needed for non-recursive call

The following procedure was not possible if max_sp_recursion_depth is 0
create procedure show_proc() show create procedure show_proc;
  
Actually there is no recursive call but the limit is checked.
  
Solved by temporarily increasing the thread's limit just before the fetch from cache
and decreasing after that.

1 files changed, 15 insertions, 6 deletions

diff --git a/sql/sp.cc b/sql/sp.cc
index b7bf049cb1d..fc72822c15e 100644
--- a/sql/sp.cc
+++ b/sql/sp.cc
@@ -1006,6 +1006,12 @@ sp_find_routine(THD *thd, int type, sp_name *name, sp_cache **cp,
       }
       DBUG_RETURN(sp->m_first_free_instance);
     }
+    /*
+      Actually depth could be +1 than the actual value in case a SP calls
+      SHOW CREATE PROCEDURE. Hence, the linked list could hold up to one more
+      instance.
+    */
+
     level= sp->m_last_cached_sp->m_recursion_level + 1;
     if (level > depth)
     {
@@ -1175,19 +1181,22 @@ sp_update_procedure(THD *thd, sp_name *name, st_sp_chistics *chistics)
 int
 sp_show_create_procedure(THD *thd, sp_name *name)
 {
+  int ret= SP_KEY_NOT_FOUND;
   sp_head *sp;
   DBUG_ENTER("sp_show_create_procedure");
   DBUG_PRINT("enter", ("name: %.*s", name->m_name.length, name->m_name.str));
 
+  /*
+    Increase the recursion limit for this statement. SHOW CREATE PROCEDURE
+    does not do actual recursion.  
+  */
+  thd->variables.max_sp_recursion_depth++;
   if ((sp= sp_find_routine(thd, TYPE_ENUM_PROCEDURE, name,
                            &thd->sp_proc_cache, FALSE)))
-  {
-    int ret= sp->show_create_procedure(thd);
+    ret= sp->show_create_procedure(thd);
 
-    DBUG_RETURN(ret);
-  }
-
-  DBUG_RETURN(SP_KEY_NOT_FOUND);
+  thd->variables.max_sp_recursion_depth--;
+  DBUG_RETURN(ret);
 }