[glib] g_variant_get_data_as_bytes: return a sub-bytes if necessary

[Ryan Lortie <ryanl src gnome org>]

commit ac1379e22cc6d97f1336eee0f846900950e978b5
Author: Lars Uebernickel <lars uebernickel canonical com>
Date:   Sat Apr 20 11:44:21 2013 -0400

    g_variant_get_data_as_bytes: return a sub-bytes if necessary
    
    https://bugzilla.gnome.org/show_bug.cgi?id=698457

 glib/gvariant-core.c  | 15 ++++++++++++++-
 glib/tests/gvariant.c | 11 +++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
---
diff --git a/glib/gvariant-core.c b/glib/gvariant-core.c
index f823e01..dc20c32 100644
--- a/glib/gvariant-core.c
+++ b/glib/gvariant-core.c
@@ -882,11 +882,24 @@ g_variant_get_data (GVariant *value)
 GBytes *
 g_variant_get_data_as_bytes (GVariant *value)
 {
+  const gchar *bytes_data;
+  const gchar *data;
+  gsize bytes_size;
+  gsize size;
+
   g_variant_lock (value);
   g_variant_ensure_serialised (value);
   g_variant_unlock (value);
 
-  return g_bytes_ref (value->contents.serialised.bytes);
+  bytes_data = g_bytes_get_data (value->contents.serialised.bytes, &bytes_size);
+  data = value->contents.serialised.data;
+  size = value->size;
+
+  if (data == bytes_data && size == bytes_size)
+    return g_bytes_ref (value->contents.serialised.bytes);
+  else
+    return g_bytes_new_from_bytes (value->contents.serialised.bytes,
+                                   data - bytes_data, size);
 }
 
 
diff --git a/glib/tests/gvariant.c b/glib/tests/gvariant.c
index d2d09d9..4e531c8 100644
--- a/glib/tests/gvariant.c
+++ b/glib/tests/gvariant.c
@@ -4258,6 +4258,7 @@ static void
 test_gbytes (void)
 {
   GVariant *a;
+  GVariant *tuple;
   GBytes *bytes;
   GBytes *bytes2;
   const guint8 values[5] = { 1, 2, 3, 4, 5 };
@@ -4279,9 +4280,19 @@ test_gbytes (void)
 
   bytes = g_bytes_new (&values, 5);
   g_assert (g_bytes_equal (bytes, bytes2));
+  g_bytes_unref (bytes);
+  g_bytes_unref (bytes2);
+
+  tuple = g_variant_new_parsed ("['foo', 'bar']");
+  bytes = g_variant_get_data_as_bytes (tuple); /* force serialisation */
+  a = g_variant_get_child_value (tuple, 1);
+  bytes2 = g_variant_get_data_as_bytes (a);
+  g_assert (!g_bytes_equal (bytes, bytes2));
 
   g_bytes_unref (bytes);
   g_bytes_unref (bytes2);
+  g_variant_unref (a);
+  g_variant_unref (tuple);
 }
 
 int