MDEV-5067: Valgrind warnings (Invalid read) in QPF_table_access::print_explain

- Query plan footprint (in new terms, "EXPLAIN structure") should always keep 
  a copy of key_name.  This is because the table might be a temporary table which
  may be already freed by the time we use query plan footprint.

1 files changed, 15 insertions, 17 deletions

diff --git a/sql/opt_range.cc b/sql/opt_range.cc
index c216a035794..97cbe73dcb4 100644
--- a/sql/opt_range.cc
+++ b/sql/opt_range.cc
@@ -11940,23 +11940,21 @@ void QUICK_SELECT_I::add_key_name(String *str, bool *first)
 }
  
 
-void QUICK_RANGE_SELECT::save_info(QPF_quick_select *qpf)
+void QUICK_RANGE_SELECT::save_info(MEM_ROOT *alloc, QPF_quick_select *qpf)
 {
   qpf->quick_type= QS_TYPE_RANGE;
-  qpf->range.key_name= head->key_info[index].name;
-  qpf->range.key_len= max_used_key_length;
+  qpf->range.set(alloc, head->key_info[index].name, max_used_key_length);
 }
 
 
-void QUICK_GROUP_MIN_MAX_SELECT::save_info(QPF_quick_select *qpf)
+void QUICK_GROUP_MIN_MAX_SELECT::save_info(MEM_ROOT *alloc, QPF_quick_select *qpf)
 {
   qpf->quick_type= QS_TYPE_GROUP_MIN_MAX;
-  qpf->range.key_name= head->key_info[index].name;
-  qpf->range.key_len= max_used_key_length;
+  qpf->range.set(alloc, head->key_info[index].name, max_used_key_length);
 }
 
 
-void QUICK_INDEX_SORT_SELECT::save_info(QPF_quick_select *qpf)
+void QUICK_INDEX_SORT_SELECT::save_info(MEM_ROOT *alloc, QPF_quick_select *qpf)
 {
   qpf->quick_type= get_type();
 
@@ -11967,14 +11965,14 @@ void QUICK_INDEX_SORT_SELECT::save_info(QPF_quick_select *qpf)
   {
     child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    quick->save_info(child_qpf);
+    quick->save_info(alloc, child_qpf);
   }
 
   if (pk_quick_select)
   {
     child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    pk_quick_select->save_info(child_qpf);
+    pk_quick_select->save_info(alloc, child_qpf);
   }
 }
 
@@ -11982,7 +11980,7 @@ void QUICK_INDEX_SORT_SELECT::save_info(QPF_quick_select *qpf)
   Same as QUICK_INDEX_SORT_SELECT::save_info(), but primary key is printed
   first
 */
-void QUICK_INDEX_INTERSECT_SELECT::save_info(QPF_quick_select *qpf)
+void QUICK_INDEX_INTERSECT_SELECT::save_info(MEM_ROOT *alloc, QPF_quick_select *qpf)
 {
   qpf->quick_type= get_type();
   QPF_quick_select *child_qpf;
@@ -11991,7 +11989,7 @@ void QUICK_INDEX_INTERSECT_SELECT::save_info(QPF_quick_select *qpf)
   {
     child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    pk_quick_select->save_info(child_qpf);
+    pk_quick_select->save_info(alloc, child_qpf);
   }
 
   QUICK_RANGE_SELECT *quick;
@@ -12000,13 +11998,13 @@ void QUICK_INDEX_INTERSECT_SELECT::save_info(QPF_quick_select *qpf)
   {
     child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    quick->save_info(child_qpf);
+    quick->save_info(alloc, child_qpf);
   }
 
 }
 
 
-void QUICK_ROR_INTERSECT_SELECT::save_info(QPF_quick_select *qpf)
+void QUICK_ROR_INTERSECT_SELECT::save_info(MEM_ROOT *alloc, QPF_quick_select *qpf)
 {
   qpf->quick_type= get_type();
 
@@ -12016,19 +12014,19 @@ void QUICK_ROR_INTERSECT_SELECT::save_info(QPF_quick_select *qpf)
   {
     QPF_quick_select *child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    qr->quick->save_info(child_qpf);
+    qr->quick->save_info(alloc, child_qpf);
   }
 
   if (cpk_quick)
   {
     QPF_quick_select *child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    cpk_quick->save_info(child_qpf);
+    cpk_quick->save_info(alloc, child_qpf);
   }
 }
 
 
-void QUICK_ROR_UNION_SELECT::save_info(QPF_quick_select *qpf)
+void QUICK_ROR_UNION_SELECT::save_info(MEM_ROOT *alloc, QPF_quick_select *qpf)
 {
   qpf->quick_type= get_type();
 
@@ -12038,7 +12036,7 @@ void QUICK_ROR_UNION_SELECT::save_info(QPF_quick_select *qpf)
   {
     QPF_quick_select *child_qpf= new QPF_quick_select;
     qpf->children.push_back(child_qpf);
-    quick->save_info(child_qpf);
+    quick->save_info(alloc, child_qpf);
   }
 }