Gio.FILE_ATTRIBUTE_STANDARD_ALLOCATED_SIZE
A key in the "standard" namespace for getting the amount of disk space that is consumed by the file (in bytes). This will generally be larger than the file size (due to block size overhead) but can occasionally be smaller (for example, for sparse files). Corresponding Gio.FileAttributeType is Gio.FileAttributeType.uint64.
Since 2.20