Merge branch '1865-variant-get-child-serialisation' into 'master'

gvariant: Handle empty serialisations in get_child_value()

Closes #1865

See merge request GNOME/glib!1043

2 files changed, 48 insertions, 0 deletions

diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
index 123220c1d..9397573a3 100644
--- a/glib/gvariant-core.c
+++ b/glib/gvariant-core.c
@@ -949,6 +949,12 @@ g_variant_get_data_as_bytes (GVariant *value)
   data = value->contents.serialised.data;
   size = value->size;
 
+  if (data == NULL)
+    {
+      g_assert (size == 0);
+      data = bytes_data;
+    }
+
   if (data == bytes_data && size == bytes_size)
     return g_bytes_ref (value->contents.serialised.bytes);
   else
diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
index ce413bedf..927ae4e12 100644
--- a/glib/tests/gvariant.c
+++ b/glib/tests/gvariant.c
@@ -2304,6 +2304,46 @@ test_byteswaps (void)
 }
 
 static void
+test_serialiser_children (void)
+{
+  GBytes *data1, *data2;
+  GVariant *child1, *child2;
+  GVariantType *mv_type = g_variant_type_new_maybe (G_VARIANT_TYPE_VARIANT);
+  GVariant *variant, *child;
+
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/issues/1865");
+  g_test_summary ("Test that getting a child variant before and after "
+                  "serialisation of the parent works");
+
+  /* Construct a variable sized array containing a child which serialises to a
+   * zero-length bytestring. */
+  child = g_variant_new_maybe (G_VARIANT_TYPE_VARIANT, NULL);
+  variant = g_variant_new_array (mv_type, &child, 1);
+
+  /* Get the child before serialising. */
+  child1 = g_variant_get_child_value (variant, 0);
+  data1 = g_variant_get_data_as_bytes (child1);
+
+  /* Serialise the parent variant. */
+  g_variant_get_data (variant);
+
+  /* Get the child again after serialising — this uses a different code path. */
+  child2 = g_variant_get_child_value (variant, 0);
+  data2 = g_variant_get_data_as_bytes (child2);
+
+  /* Check things are equal. */
+  g_assert_cmpvariant (child1, child2);
+  g_assert_true (g_bytes_equal (data1, data2));
+
+  g_variant_unref (child2);
+  g_variant_unref (child1);
+  g_variant_unref (variant);
+  g_bytes_unref (data2);
+  g_bytes_unref (data1);
+  g_variant_type_free (mv_type);
+}
+
+static void
 test_fuzz (gdouble *fuzziness)
 {
   GVariantSerialised serialised;
@@ -5075,6 +5115,7 @@ main (int argc, char **argv)
   guint i;
 
   g_test_init (&argc, &argv, NULL);
+  g_test_bug_base ("");
 
   g_test_add_func ("/gvariant/type", test_gvarianttype);
   g_test_add_func ("/gvariant/type/string-scan/recursion/tuple",
@@ -5088,6 +5129,7 @@ main (int argc, char **argv)
   g_test_add_func ("/gvariant/serialiser/variant", test_variants);
   g_test_add_func ("/gvariant/serialiser/strings", test_strings);
   g_test_add_func ("/gvariant/serialiser/byteswap", test_byteswaps);
+  g_test_add_func ("/gvariant/serialiser/children", test_serialiser_children);
 
   for (i = 1; i <= 20; i += 4)
     {