GVariant: add preconditions to ref. counting functions

These prevent GVariants from accidentally being brought back to life after
being freed, and should make it easier to track down ref. counting issues.

Closes: bgo#665184

diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
index 436d4bf..fdbe034 100644 (file)
--- a/glib/gvariant-core.c
+++ b/glib/gvariant-core.c
@@ -619,6 +619,9 @@ g_variant_is_trusted (GVariant *value)
 void
 g_variant_unref (GVariant *value)
 {
+  g_return_if_fail (value != NULL);
+  g_return_if_fail (value->ref_count > 0);
+
   if (g_atomic_int_dec_and_test (&value->ref_count))
     {
       if G_UNLIKELY (value->state & STATE_LOCKED)
@@ -652,6 +655,9 @@ g_variant_unref (GVariant *value)
 GVariant *
 g_variant_ref (GVariant *value)
 {
+  g_return_val_if_fail (value != NULL, NULL);
+  g_return_val_if_fail (value->ref_count > 0, NULL);
+
   g_atomic_int_inc (&value->ref_count);
 
   return value;
@@ -691,6 +697,9 @@ g_variant_ref (GVariant *value)
 GVariant *
 g_variant_ref_sink (GVariant *value)
 {
+  g_return_val_if_fail (value != NULL, NULL);
+  g_return_val_if_fail (value->ref_count > 0, NULL);
+
   g_variant_lock (value);
 
   if (~value->state & STATE_FLOATING)
@@ -746,6 +755,7 @@ GVariant *
 g_variant_take_ref (GVariant *value)
 {
   g_return_val_if_fail (value != NULL, NULL);
+  g_return_val_if_fail (value->ref_count > 0, NULL);
 
   g_atomic_int_and (&value->state, ~STATE_FLOATING);