Disk image object needs some file object fixity fields

[ajnelson-nist]

The diskimageobject would benefit from a few fileobject fields.

• filesize - would help with reporting when a disk image is incomplete, when used in conjunction with byte_runs. (E.g. a discontinuous byte_run list could show some sectors weren't captured, like from intentionally partial disk imaging or from read errors.)
• hashdigest - frequently reported for disk image provenance.

[ajnelson-nist]

A development branch of the DFXML code repository has implemented these features for testing:

https://github.com/ajnelson-nist/dfxml/tree/add_disk_image_object_fixity_fields

[ajnelson-nist]

A test implementation, using the DFXML development branch add_disk_image_object_fixity_fields, is available at gddrescue_mapfile_to_dfxml.

[ajnelson-nist]

Instead of using filesize, mediumsize may be better: A record of the size of the original storage medium.

There may be one more round of name-picking on this. I recall there was something in the Carrier File Systems Forensic Analysis book on some nuance in storage medium size interpretation.