[libgda] vprovider-data-model: fixed random segfault

[Daniel Espinosa Ortiz <despinosa src gnome org>]

commit c1bf65aa1d8be5fb3d1caa15e3f4a09a7d65bfa5
Author: Daniel Espinosa Ortiz <esodan gmail com>
Date:   Mon Mar 11 18:49:05 2019 -0600

    vprovider-data-model: fixed random segfault

 libgda/sqlite/virtual/gda-vprovider-data-model.c | 88 +++++++++++++-----------
 1 file changed, 46 insertions(+), 42 deletions(-)
---
diff --git a/libgda/sqlite/virtual/gda-vprovider-data-model.c 
b/libgda/sqlite/virtual/gda-vprovider-data-model.c
index b2f23e814..6fd78e453 100644
--- a/libgda/sqlite/virtual/gda-vprovider-data-model.c
+++ b/libgda/sqlite/virtual/gda-vprovider-data-model.c
@@ -942,12 +942,14 @@ get_data_value (VirtualTable *vtable, VirtualCursor *cursor, gint row, gint64 ro
                g_assert (vtable->td->context.current_vcontext);
                guint i;
                GPtrArray *values_array = vtable->td->context.current_vcontext->context_data;
-               for (i = 0; i < values_array->len; i++) {
-                       VirtualFilteredData *vd;
-                       vd = g_ptr_array_index (values_array, i);
-                       if (vd->rowid_offset == (guint32) (rowid >> 32)) {
-                               data = vd;
-                               break;
+               if (values_array != NULL) {
+                       for (i = 0; i < values_array->len; i++) {
+                               VirtualFilteredData *vd;
+                               vd = g_ptr_array_index (values_array, i);
+                               if (vd->rowid_offset == (guint32) (rowid >> 32)) {
+                                       data = vd;
+                                       break;
+                               }
                        }
                }
        }
@@ -1182,53 +1184,55 @@ virtualFilter (sqlite3_vtab_cursor *pVtabCursor, int idxNum, const char *idxStr,
        VirtualFilteredData *data = NULL;
        g_assert (vtable->td->context.current_vcontext);
        GPtrArray *values_array = vtable->td->context.current_vcontext->context_data;
+       if (values_array != NULL) {
+               if (values_array->len > 0) {
+                       guint i;
+                       for (i = 0; i < values_array->len; i++) {
+                               VirtualFilteredData *vd;
+                               vd = g_ptr_array_index (values_array, i);
+                               if (vd->reuseable &&
+                                         (vd->idxNum == idxNum) &&
+                                         (vd->argc == argc) &&
+                                         ((!idxStr && !vd->idxStr) || (idxStr && vd->idxStr && !strcmp 
(idxStr, vd->idxStr)))) {
+                                       GValue **avalues;
+                                       gint i;
+                                       gboolean equal = TRUE;
+                                       avalues = create_gvalues_array_from_sqlite3_array (prov, argc, argv);
+                                       for (i = 0; i < argc; i++) {
+                                               GValue *v1, *v2;
+                                               v1 = vd->argv [i];
+                                               v2 = avalues [i];
+
+                                               if (! ((!v1 && !v2) ||
+                                                            (v1 && v2 && (G_VALUE_TYPE (v1) == G_VALUE_TYPE 
(v2)) &&
+                                                       !gda_value_differ (v1, v2)))) {
+                                                       equal = FALSE;
+                                                       break;
+                                               }
+                                       }
+                                       for (i = 0; i < argc; i++) {
+                                               GValue *v2;
+                                               v2 = avalues [i];
+                                               if (v2)
+                                                       gda_value_free (v2);
+                                       }
+                                       g_free (avalues);
 
-       if (values_array->len > 0) {
-               guint i;
-               for (i = 0; i < values_array->len; i++) {
-                       VirtualFilteredData *vd;
-                       vd = g_ptr_array_index (values_array, i);
-                       if (vd->reuseable &&
-                           (vd->idxNum == idxNum) &&
-                           (vd->argc == argc) &&
-                           ((!idxStr && !vd->idxStr) || (idxStr && vd->idxStr && !strcmp (idxStr, 
vd->idxStr)))) {
-                               GValue **avalues;
-                               gint i;
-                               gboolean equal = TRUE;
-                               avalues = create_gvalues_array_from_sqlite3_array (prov, argc, argv);
-                               for (i = 0; i < argc; i++) {
-                                       GValue *v1, *v2;
-                                       v1 = vd->argv [i];
-                                       v2 = avalues [i];
-
-                                       if (! ((!v1 && !v2) ||
-                                              (v1 && v2 && (G_VALUE_TYPE (v1) == G_VALUE_TYPE (v2)) &&
-                                               !gda_value_differ (v1, v2)))) {
-                                               equal = FALSE;
+                                       if (equal) {
+                                               data = vd;
                                                break;
                                        }
                                }
-                               for (i = 0; i < argc; i++) {
-                                       GValue *v2;
-                                       v2 = avalues [i];
-                                       if (v2)
-                                               gda_value_free (v2);
-                               }
-                               g_free (avalues);
-                               
-                               if (equal) {
-                                       data = vd;
-                                       break;
-                               }
                        }
                }
        }
+
 #ifdef DEBUG_VCONTEXT
        if (data)
                g_print ("REUSE VData %p\n", data);
 #endif
 
-       if (!data) {
+       if (!data && values_array != NULL) {
                virtual_table_manage_real_data_model (vtable, idxNum, idxStr, argc, argv);
                if (! vtable->td->real_model)
                        return SQLITE_ERROR;
@@ -1602,7 +1606,7 @@ virtualUpdate (sqlite3_vtab *tab, int nData, sqlite3_value **apData, sqlite_int6
 
        g_assert (vtable->td->context.current_vcontext);
        GPtrArray *values_array = vtable->td->context.current_vcontext->context_data;
-       if (values_array) {
+       if (values_array != NULL) {
                guint i;
                for (i = 0; i < values_array->len; i++) {
                        VirtualFilteredData *data;