Fix for bug #24117 "server crash on a FETCH with a cursor on a table which is not in the table cache"

Problem:
When creating a temporary field for a temporary table in create_tmp_field_from_field(), a resulting field is created as an exact copy of an original one (in Field::new_field()). However, Field_enum and Field_set contain a pointer (typelib) to memory allocated in the parent table's MEM_ROOT, which under some circumstances may be deallocated later by the time a temporary table is used.

Solution:
Override the new_field() method for Field_enum and Field_set and create a separate copy of the typelib structure in there.


include/typelib.h:
  Added copy_typelib() declaration
mysql-test/r/sp.result:
  Added a testcase for bug #24117 "server crash on a FETCH with a cursor on a table which is not in the table cache"
mysql-test/t/sp.test:
  Added a testcase for bug #24117 "server crash on a FETCH with a cursor on a table which is not in the table cache"
mysys/typelib.c:
  Added copy_typelib() definition
sql/field.cc:
  Create a copy of the internal 'typelib' structure when copying Field_enum of Field_set objects.
sql/field.h:
  Override new_field method in Field_enum (and Field_set) to copy the typelib structure.

1 files changed, 3 insertions, 0 deletions

diff --git a/include/typelib.h b/include/typelib.h
index 4d6a90ad51e..fe19f1001d4 100644
--- a/include/typelib.h
+++ b/include/typelib.h
@@ -18,6 +18,8 @@
 #ifndef _typelib_h
 #define _typelib_h
 
+#include "my_alloc.h"
+
 typedef struct st_typelib {	/* Different types saved here */
   unsigned int count;		/* How many types */
   const char *name;		/* Name of typelib */
@@ -28,6 +30,7 @@ typedef struct st_typelib {	/* Different types saved here */
 extern int find_type(char *x,TYPELIB *typelib,unsigned int full_name);
 extern void make_type(char *to,unsigned int nr,TYPELIB *typelib);
 extern const char *get_type(TYPELIB *typelib,unsigned int nr);
+extern TYPELIB *copy_typelib(MEM_ROOT *root, TYPELIB *from);
 
 extern TYPELIB sql_protocol_typelib;