Static deltas support

https://bugzilla.gnome.org/show_bug.cgi?id=721799

src/libostree/ostree-core.c

@@ -1321,11 +1321,31 @@ _ostree_get_relative_object_path (const char         *checksum,
   return g_string_free (path, FALSE);
 }
 
+static char *
+get_delta_path (const char *from,
+                const char *to,
+                const char *target)
+{
+  char prefix[3];
+  prefix[0] = from[0];
+  prefix[1] = from[1];
+  prefix[2] = '\0';
+  from += 2;
+  return g_strconcat ("deltas/", prefix, "/", from, "-", to, "/", target, NULL);
+}
+
 char *
 _ostree_get_relative_static_delta_path (const char        *from,
                                         const char        *to)
 {
-  return g_strdup_printf ("deltas/%s-%s/meta", from, to);
+  return get_delta_path (from, to, "superblock");
+}
+
+char *
+_ostree_get_relative_static_delta_detachedmeta_path (const char        *from,
+                                                     const char        *to)
+{
+  return get_delta_path (from, to, "meta");
 }
 
 char *
@@ -1333,7 +1353,8 @@ _ostree_get_relative_static_delta_part_path (const char        *from,
                                              const char        *to,
                                              guint              i)
 {
-  return g_strdup_printf ("deltas/%s-%s/%u", from, to, i);
+  gs_free char *partstr = g_strdup_printf ("%u", i);
+  return get_delta_path (from, to, partstr);
 }
 
 /*
@@ -1763,3 +1784,31 @@ ostree_commit_get_timestamp (GVariant  *commit_variant)
   g_variant_get_child (commit_variant, 5, "t", &ret);
   return GUINT64_FROM_BE (ret);
 }
+
+GVariant *
+_ostree_detached_metadata_append_gpg_sig (GVariant   *existing_metadata,
+                                          GBytes     *signature_bytes)
+{
+  GVariantBuilder *builder = NULL;
+  gs_unref_variant GVariant *signaturedata = NULL;
+  gs_unref_variant_builder GVariantBuilder *signature_builder = NULL;
+
+  if (existing_metadata)
+    {
+      builder = ot_util_variant_builder_from_variant (existing_metadata, G_VARIANT_TYPE ("a{sv}"));
+      signaturedata = g_variant_lookup_value (existing_metadata, "ostree.gpgsigs", G_VARIANT_TYPE ("aay"));
+      if (signaturedata)
+        signature_builder = ot_util_variant_builder_from_variant (signaturedata, G_VARIANT_TYPE ("aay"));
+    }
+  if (!builder)
+    builder = g_variant_builder_new (G_VARIANT_TYPE ("a{sv}"));
+  if (!signature_builder)
+    signature_builder = g_variant_builder_new (G_VARIANT_TYPE ("aay"));
+
+  g_variant_builder_add (signature_builder, "@ay", ot_gvariant_new_ay_bytes (signature_bytes));
+
+  g_variant_builder_add (builder, "{sv}", "ostree.gpgsigs", g_variant_builder_end (signature_builder));
+  
+  return g_variant_ref_sink (g_variant_builder_end (builder));
+}
+