[tracker/wip/carlosg/cli-improvements: 1/8] tracker: Add --list argument to "tracker3 endpoint" command

[Carlos Garnacho <carlosg src gnome org>]

commit f198a7cd711299ad109c0536ef4819f4d576db6d
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Aug 18 15:36:41 2020 +0200

    tracker: Add --list argument to "tracker3 endpoint" command
    
    This lists all SPARQL endpoints that are visible on DBus.

 docs/manpages/tracker-endpoint.1.txt |   2 +
 src/tracker/tracker-endpoint.c       | 101 ++++++++++++++++++++++++++++++++++-
 2 files changed, 102 insertions(+), 1 deletion(-)
---
diff --git a/docs/manpages/tracker-endpoint.1.txt b/docs/manpages/tracker-endpoint.1.txt
index 96ed80b88..c791cdd80 100644
--- a/docs/manpages/tracker-endpoint.1.txt
+++ b/docs/manpages/tracker-endpoint.1.txt
@@ -46,6 +46,8 @@ The database itself will be stored according to _database_path_.
   Use the session bus. This is the default.
 *--system*::
   Use the system bus.
+*-l, --list*::
+  List all SPARQL endpoints available in DBus
 
 == EXAMPLES
 
diff --git a/src/tracker/tracker-endpoint.c b/src/tracker/tracker-endpoint.c
index f41719901..b58609719 100644
--- a/src/tracker/tracker-endpoint.c
+++ b/src/tracker/tracker-endpoint.c
@@ -41,6 +41,7 @@ static gchar *ontology_path = NULL;
 static gboolean session_bus = FALSE;
 static gboolean system_bus = FALSE;
 static gboolean name_owned = FALSE;
+static gboolean list = FALSE;
 
 static GOptionEntry entries[] = {
        { "database", 'd', 0, G_OPTION_ARG_FILENAME, &database_path,
@@ -67,6 +68,10 @@ static GOptionEntry entries[] = {
          N_("Use system bus"),
          NULL
        },
+       { "list", 'l', 0, G_OPTION_ARG_NONE, &list,
+         N_("List SPARQL endpoints available in DBus"),
+         NULL
+       },
        { NULL }
 };
 
@@ -82,7 +87,14 @@ typedef enum _TrackerEndpointError {
 static gboolean
 sanity_check (void)
 {
-       if (!!ontology_path == !!ontology_name) {
+       if (list &&
+           (ontology_path || ontology_name || dbus_service || database_path)) {
+               /* TRANSLATORS: these are commandline arguments */
+               g_printerr ("%s\n", _("--list can only be used with --session or --system"));
+               return FALSE;
+       }
+
+       if (!list && !!ontology_path == !!ontology_name) {
                /* TRANSLATORS: those are commandline arguments */
                g_printerr ("%s\n", _("One “ontology” or “ontology-path” option should be provided"));
                return FALSE;
@@ -187,6 +199,89 @@ run_endpoint (TrackerSparqlConnection  *connection,
        return TRUE;
 }
 
+static int
+run_list_endpoints (void)
+{
+       GDBusConnection *connection;
+       GDBusMessage *message, *reply;
+       GVariant *variant;
+       GStrv names;
+       guint i;
+
+       if (system_bus) {
+               connection = g_bus_get_sync (G_BUS_TYPE_SYSTEM, NULL, NULL);
+       } else {
+               connection = g_bus_get_sync (G_BUS_TYPE_SESSION, NULL, NULL);
+       }
+
+       message = g_dbus_message_new_method_call ("org.freedesktop.DBus",
+                                                 "/org/freedesktop/DBus",
+                                                 "org.freedesktop.DBus",
+                                                 "ListNames");
+       reply = g_dbus_connection_send_message_with_reply_sync (connection,
+                                                               message,
+                                                               G_DBUS_SEND_MESSAGE_FLAGS_NONE,
+                                                               -1,
+                                                               NULL,
+                                                               NULL,
+                                                               NULL);
+       g_object_unref (message);
+
+       if (!reply)
+               return EXIT_FAILURE;
+
+       if (g_dbus_message_get_error_name (reply)) {
+               g_object_unref (reply);
+               return EXIT_FAILURE;
+       }
+
+       variant = g_dbus_message_get_body (reply);
+       g_variant_get (variant, "(^a&s)", &names);
+
+       for (i = 0; names[i]; i++) {
+               GDBusMessage *check;
+               GError *error = NULL;
+
+               if (names[i][0] == ':')
+                       continue;
+
+               /* Do a 'Query' method call, we don't mind the wrong message arguments,
+                * and even look for that specific error to detect at least the interface
+                * is implemented by this DBus service.
+                */
+               message = g_dbus_message_new_method_call (names[i],
+                                                         "/org/freedesktop/Tracker3/Endpoint",
+                                                         "org.freedesktop.Tracker3.Endpoint",
+                                                         "Query");
+               check = g_dbus_connection_send_message_with_reply_sync (connection,
+                                                                      message,
+                                                                      G_DBUS_SEND_MESSAGE_FLAGS_NONE,
+                                                                      -1,
+                                                                      NULL,
+                                                                      NULL,
+                                                                      NULL);
+               g_object_unref (message);
+
+               if (!check)
+                       continue;
+
+               if (!g_dbus_message_to_gerror (check, &error)) {
+                       g_object_unref (check);
+                       continue;
+               }
+
+               if (g_error_matches (error, G_DBUS_ERROR, G_DBUS_ERROR_INVALID_ARGS))
+                       g_print ("%s\n", names[i]);
+
+               g_clear_error (&error);
+               g_object_unref (check);
+       }
+
+       g_object_unref (reply);
+
+       return EXIT_SUCCESS;
+}
+
 int
 tracker_endpoint (int argc, const char **argv)
 {
@@ -217,6 +312,10 @@ tracker_endpoint (int argc, const char **argv)
                return EXIT_FAILURE;
        }
 
+       if (list) {
+               return run_list_endpoints ();
+       }
+
        if (database_path)
                database = g_file_new_for_commandline_arg (database_path);