A fix and test case for Bug#5315 "mysql_change_user() doesn't free

prepared statements."


include/hash.h:
  New declaration for hash_reset() function. The old version was not used.
libmysql/client_settings.h:
  Declaration for mysql_detach_stmt_list().
libmysql/libmysql.c:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  add call to mysql_detach_stmt_list(prepared statements) to
  mysql_change_user(): all statements are freed by server, so client
  counterparts need to be marked as not usable.
mysys/hash.c:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  implementation of hash_reset(), which frees all hash elements
  and prepares the hash for reuse.
sql-common/client.c:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  implementation of mysql_detach_stmt_list(): zero connection pointer
  in given statement list, thus marking given statements as not usable.
sql/sql_class.cc:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  reset prepared statements map in THD::change_user().
sql/sql_class.h:
  Fix for bug#5315 "mysql_change_user() doesn't free prepared statements":
  implementation of Statement_map::reset().
  A little cleanup of ~Statement_map(): first empty names_hash, as st_hash
  has a free function, which will delete statements.
tests/client_test.c:
  A test case for bug #5315 "mysql_change_user() doesn't free prepared
  statements".

1 files changed, 10 insertions, 3 deletions

diff --git a/sql/sql_class.h b/sql/sql_class.h
index 387bba43cad..09b44568f90 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -566,7 +566,7 @@ public:
   assignment in Statement::Statement)
   Non-empty statement names are unique too: attempt to insert a new statement
   with duplicate name causes older statement to be deleted
-  
+
   Statements are auto-deleted when they are removed from the map and when the
   map is deleted.
 */
@@ -575,7 +575,7 @@ class Statement_map
 {
 public:
   Statement_map();
-  
+
   int insert(Statement *statement);
 
   Statement *find_by_name(LEX_STRING *name)
@@ -608,11 +608,18 @@ public:
     }
     hash_delete(&st_hash, (byte *) statement);
   }
+  /* Erase all statements (calls Statement destructor) */
+  void reset()
+  {
+    hash_reset(&names_hash);
+    hash_reset(&st_hash);
+    last_found_statement= 0;
+  }
 
   ~Statement_map()
   {
-    hash_free(&st_hash);
     hash_free(&names_hash);
+    hash_free(&st_hash);
   }
 private:
   HASH st_hash;