Tally usage based on apparent file
sizes. Normally, the block-size is used, if available, as this is a
more accurate representation of disk space used.
Compare with du --apparent-size.
No flags set.
Do not cross mount point boundaries.
Compare with du -x.
Report any error encountered while traversing the directory tree. Normally errors are only reported for the toplevel file.
Flags that can be used with g_file_measure_disk_usage().