Support --default-branch when updating the repository summary file

Add support for this flag in build-update-repo, so that we can define
a default branch in the server side, to be picked by the clients.

https://github.com/flatpak/flatpak/issues/221

app/flatpak-builtins-repo-update.c

@@ -33,6 +33,7 @@
 #include "flatpak-utils.h"
 
 static char *opt_title;
+static char *opt_default_branch;
 static char *opt_gpg_homedir;
 static char **opt_gpg_key_ids;
 static gboolean opt_prune;
@@ -41,6 +42,7 @@ static gint opt_prune_depth = -1;
 
 static GOptionEntry options[] = {
   { "title", 0, 0, G_OPTION_ARG_STRING, &opt_title, N_("A nice name to use for this repository"), N_("TITLE") },
+  { "default-branch", 0, 0, G_OPTION_ARG_STRING, &opt_default_branch, N_("Default branch to use for this repository"), N_("BRANCH") },
   { "gpg-sign", 0, 0, G_OPTION_ARG_STRING_ARRAY, &opt_gpg_key_ids, N_("GPG Key ID to sign the summary with"), N_("KEY-ID") },
   { "gpg-homedir", 0, 0, G_OPTION_ARG_STRING, &opt_gpg_homedir, N_("GPG Homedir to use when looking for keyrings"), N_("HOMEDIR") },
   { "generate-static-deltas", 0, 0, G_OPTION_ARG_NONE, &opt_generate_deltas, N_("Generate delta files"), NULL },
@@ -376,6 +378,10 @@ flatpak_builtin_build_update_repo (int argc, char **argv,
       !flatpak_repo_set_title (repo, opt_title, error))
     return FALSE;
 
+  if (opt_default_branch &&
+      !flatpak_repo_set_default_branch (repo, opt_default_branch, error))
+    return FALSE;
+
   g_print (_("Updating appstream branch\n"));
   if (!flatpak_repo_generate_appstream (repo, (const char **) opt_gpg_key_ids, opt_gpg_homedir, cancellable, error))
     return FALSE;

common/flatpak-utils.c

@@ -2179,6 +2179,27 @@ flatpak_repo_set_title (OstreeRepo *repo,
   return TRUE;
 }
 
+
+gboolean
+flatpak_repo_set_default_branch (OstreeRepo *repo,
+                                 const char *branch,
+                                 GError    **error)
+{
+  g_autoptr(GKeyFile) config = NULL;
+
+  config = ostree_repo_copy_config (repo);
+
+  if (branch)
+    g_key_file_set_string (config, "flatpak", "default-branch", branch);
+  else
+    g_key_file_remove_key (config, "flatpak", "default-branch", NULL);
+
+  if (!ostree_repo_write_config (repo, config, error))
+    return FALSE;
+
+  return TRUE;
+}
+
 #define OSTREE_GIO_FAST_QUERYINFO ("standard::name,standard::type,standard::size,standard::is-symlink,standard::symlink-target," \
                                    "unix::device,unix::inode,unix::mode,unix::uid,unix::gid,unix::rdev")
 
@@ -2299,6 +2320,7 @@ flatpak_repo_update (OstreeRepo   *repo,
   GVariantBuilder ref_data_builder;
   GKeyFile *config;
   g_autofree char *title = NULL;
+  g_autofree char *default_branch = NULL;
   g_autoptr(GVariant) old_summary = NULL;
   g_autoptr(GHashTable) refs = NULL;
   const char *prefixes[] = { "appstream", "app", "runtime", NULL };
@@ -2312,12 +2334,18 @@ flatpak_repo_update (OstreeRepo   *repo,
   config = ostree_repo_get_config (repo);
 
   if (config)
-    title = g_key_file_get_string (config, "flatpak", "title", NULL);
+    {
+      title = g_key_file_get_string (config, "flatpak", "title", NULL);
+      default_branch = g_key_file_get_string (config, "flatpak", "default-branch", NULL);
+    }
 
   if (title)
     g_variant_builder_add (&builder, "{sv}", "xa.title",
                            g_variant_new_string (title));
 
+  if (default_branch)
+    g_variant_builder_add (&builder, "{sv}", "xa.default-branch",
+                           g_variant_new_string (default_branch));
 
   g_variant_builder_init (&ref_data_builder, G_VARIANT_TYPE ("a{s(tts)}"));
 

common/flatpak-utils.h

@@ -229,6 +229,9 @@ void                flatpak_table_printer_print (FlatpakTablePrinter *printer);
 gboolean flatpak_repo_set_title (OstreeRepo *repo,
                                  const char *title,
                                  GError    **error);
+gboolean flatpak_repo_set_default_branch (OstreeRepo *repo,
+                                          const char *branch,
+                                          GError    **error);
 gboolean flatpak_repo_update (OstreeRepo   *repo,
                               const char  **gpg_key_ids,
                               const char   *gpg_homedir,