[tracker/tracker-1.2] libtracker-data: Guard against invalid statements in public API

[Debarshi Ray <debarshir src gnome org>]

commit 33d11ac7f2de221104d223139e5e40e3f8f8b4ec
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Oct 13 14:27:07 2014 +0200

    libtracker-data: Guard against invalid statements in public API
    
    https://bugzilla.gnome.org/show_bug.cgi?id=738450

 src/libtracker-data/tracker-db-interface-sqlite.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/src/libtracker-data/tracker-db-interface-sqlite.c 
b/src/libtracker-data/tracker-db-interface-sqlite.c
index ee531c9..749a8d5 100644
--- a/src/libtracker-data/tracker-db-interface-sqlite.c
+++ b/src/libtracker-data/tracker-db-interface-sqlite.c
@@ -2339,6 +2339,7 @@ void
 tracker_db_statement_execute (TrackerDBStatement  *stmt,
                               GError             **error)
 {
+       g_return_if_fail (TRACKER_IS_DB_STATEMENT (stmt));
        g_return_if_fail (!stmt->stmt_is_sunk);
 
        execute_stmt (stmt->db_interface, stmt->stmt, NULL, error);
@@ -2348,6 +2349,7 @@ TrackerDBCursor *
 tracker_db_statement_start_cursor (TrackerDBStatement  *stmt,
                                    GError             **error)
 {
+       g_return_val_if_fail (TRACKER_IS_DB_STATEMENT (stmt), NULL);
        g_return_val_if_fail (!stmt->stmt_is_sunk, NULL);
 
        return tracker_db_cursor_sqlite_new (stmt->stmt, stmt, NULL, 0, NULL, 0, FALSE);
@@ -2362,6 +2364,7 @@ tracker_db_statement_start_sparql_cursor (TrackerDBStatement   *stmt,
                                           gboolean              threadsafe,
                                           GError              **error)
 {
+       g_return_val_if_fail (TRACKER_IS_DB_STATEMENT (stmt), NULL);
        g_return_val_if_fail (!stmt->stmt_is_sunk, NULL);
 
        return tracker_db_cursor_sqlite_new (stmt->stmt, stmt, types, n_types, variable_names, 
n_variable_names, threadsafe);