[glib] measure_disk_usage: skip progress on NULL callback

[Ryan Lortie <desrt src gnome org>]

commit dbf95a5ae94441dc235d8dcf003f05cb5c6bd84b
Author: Ryan Lortie <desrt desrt ca>
Date:   Tue Sep 17 09:40:04 2013 -0400

    measure_disk_usage: skip progress on NULL callback
    
    In the real_..._async wrapper for GFile.measure_disk_usage, skip the
    wrapping of the progress callback in the case that the user gave a NULL
    callback to the async function.  This is a performance improvement
    because the sync version won't have to do continuous sampling of the
    clock to issue a call to the wrapper which will then do nothing.
    
    Unfortunately, I made this simplifying assumption when writing the
    wrapper, but forgot to actually implement it when making the sync call.
    As a result, the wrapper is still called, and invokes the NULL callback,
    causing a segfault.
    
    Make sure we pass NULL if the user's callback was NULL.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=707787

 gio/gfile.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gio/gfile.c b/gio/gfile.c
index 0c95942..d321c24 100644
--- a/gio/gfile.c
+++ b/gio/gfile.c
@@ -7453,7 +7453,7 @@ measure_disk_usage_thread (GTask        *task,
   MeasureResult result;
 
   if (g_file_measure_disk_usage (source_object, data->flags, cancellable,
-                                 measure_disk_usage_progress, task,
+                                 data->progress_callback ? measure_disk_usage_progress : NULL, task,
                                  &result.disk_usage, &result.num_dirs, &result.num_files,
                                  &error))
     g_task_return_pointer (task, g_memdup (&result, sizeof result), g_free);