Always send dbus method reply (#56)

Some method handlers were never sending a reply.
Even if the method returns no data, the service should acknowledge that the
method call has been processed and reply to the sender.

This was previously triggering the dbus invocation timeout (25s by default),
and synchronous calls would block for a long time.

Author: aleasto

configure.ac

@@ -17,7 +17,7 @@ PKG_CHECK_MODULES([CPDB],[cpdb >= 2])
 PKG_CHECK_MODULES([LIBCUPSFILTERS], [libcupsfilters >= 2])
 PKG_CHECK_MODULES([GIO],[gio-2.0])
 PKG_CHECK_MODULES([GIOUNIX],[gio-unix-2.0])
-PKG_CHECK_MODULES([GLIB],[glib-2.0])
+PKG_CHECK_MODULES([GLIB],[glib-2.0 >= 2.74])
 
 # Checks for header files.
 AC_CHECK_HEADERS([stdlib.h string.h cups/cups.h cupsfilters/catalog.h])

src/print_backend_cups.c

@@ -23,6 +23,7 @@ int send_printer_added(void *_dialog_name, unsigned flags, cups_dest_t *dest);
 void connect_to_signals();
 
 BackendObj *b;
+GMainLoop *loop;
 
 void update_printer_lists()
 {
@@ -130,7 +131,7 @@ int main()
                             G_CALLBACK(on_printer_added), NULL);
     }
 
-    GMainLoop *loop = g_main_loop_new(NULL, FALSE);
+    loop = g_main_loop_new(NULL, FALSE);
     g_main_loop_run(loop);
 
     /* Main loop exited */
@@ -342,7 +343,7 @@ int send_printer_added(void *_dialog_name, unsigned flags, cups_dest_t *dest)
     return 1; //continue enumeration
 }
 
-static void on_handle_do_listing(PrintBackend *interface,
+static gboolean on_handle_do_listing(PrintBackend *interface,
                                     GDBusMethodInvocation *invocation,
                                     gboolean is_listed,
                                     gpointer not_used)
@@ -352,19 +353,24 @@ static void on_handle_do_listing(PrintBackend *interface,
         const char *dialog_name = g_dbus_method_invocation_get_sender(invocation);
         Dialog *d = find_dialog(b, dialog_name);
         if (d && d->keep_alive)
-            return;
+            goto out;
 
         set_dialog_cancel(b, dialog_name);
         remove_frontend(b, dialog_name);
         if (no_frontends(b))
         {
+            // FIXME: this is racy against method calls already in-flight from dbus
             g_message("No frontends connected .. exiting backend.\n");
-            exit(EXIT_SUCCESS);
+            g_idle_add_once((GSourceOnceFunc)g_main_loop_quit, loop);
         }
     }
+
+out:
+    print_backend_complete_do_listing(interface, invocation);
+    return TRUE;
 }
 
-static void on_handle_show_remote_printers(PrintBackend *interface,
+static gboolean on_handle_show_remote_printers(PrintBackend *interface,
                                     GDBusMethodInvocation *invocation,
                                     gboolean is_visible,
                                     gpointer not_used)
@@ -386,10 +392,12 @@ static void on_handle_show_remote_printers(PrintBackend *interface,
             refresh_printer_list(b, dialog_name);
         }
     }
+    print_backend_complete_show_remote_printers(interface, invocation);
+    return TRUE;
 }
 
 
-static void on_handle_show_temporary_printers(PrintBackend *interface,
+static gboolean on_handle_show_temporary_printers(PrintBackend *interface,
                                     GDBusMethodInvocation *invocation,
                                     gboolean is_visible,
                                     gpointer not_used)
@@ -411,6 +419,8 @@ static void on_handle_show_temporary_printers(PrintBackend *interface,
             refresh_printer_list(b, dialog_name);
         }
     }
+    print_backend_complete_show_temporary_printers(interface, invocation);
+    return TRUE;
 }
 
 static gboolean on_handle_is_accepting_jobs(PrintBackend *interface,