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, 27 insertions, 14 deletions

diff --git a/sql-common/client.c b/sql-common/client.c
index 930388d2459..43e116eb0b6 100644
--- a/sql-common/client.c
+++ b/sql-common/client.c
@@ -2239,6 +2239,32 @@ static void mysql_close_free(MYSQL *mysql)
 }
 
 
+/*
+  Clear connection pointer of every statement: this is necessary
+  to give error on attempt to use a prepared statement of closed
+  connection.
+
+  SYNOPSYS
+    mysql_detach_stmt_list()
+      stmt_list  pointer to mysql->stmts
+*/
+
+void mysql_detach_stmt_list(LIST **stmt_list)
+{
+#ifdef MYSQL_CLIENT
+  /* Reset connection handle in all prepared statements. */
+  LIST *element= *stmt_list;
+  for (; element; element= element->next)
+  {
+    MYSQL_STMT *stmt= (MYSQL_STMT *) element->data;
+    stmt->mysql= 0;
+    /* No need to call list_delete for statement here */
+  }
+  *stmt_list= 0;
+#endif /* MYSQL_CLIENT */
+}
+
+
 void STDCALL mysql_close(MYSQL *mysql)
 {
   DBUG_ENTER("mysql_close");
@@ -2255,20 +2281,7 @@ void STDCALL mysql_close(MYSQL *mysql)
     }
     mysql_close_free_options(mysql);
     mysql_close_free(mysql);
-#ifdef MYSQL_CLIENT
-    if (mysql->stmts)
-    {
-      /* Reset connection handle in all prepared statements. */
-      LIST *element;
-      for (element= mysql->stmts; element; element= element->next)
-      {
-        MYSQL_STMT *stmt= (MYSQL_STMT *) element->data;
-        stmt->mysql= 0;
-        /* No need to call list_delete for statement here */
-      }
-      mysql->stmts= 0;
-    }
-#endif /*MYSQL_CLIENT*/
+    mysql_detach_stmt_list(&mysql->stmts);
 #ifndef TO_BE_DELETED
     /* free/close slave list */
     if (mysql->rpl_pivot)