Hello trid users,
some days weeks i must migrate to Windows 10. During that process i
lost some Virtual Box machines. So i look for file formats related to
Virtual Box. One format use filename extension ova.
So i run trid utility on my OVA examples. Some of my Virtualization
packages are described as correctly as "Open Virtualization Format
package" with generic mime type application/octet-stream by
ova.trid.xml. All of my OVA samples are described with low priority as
"TAR - Tape ARchive (POSIX)" with mime type application/x-ustar by
ark-tar-posix.trid.xml (See appended output/trid-v-old.txt).
For comparison reason i also run file command (version 5.44) on such
samples. Here all OVA samples are recognized. Most are described
generic as "POSIX tar archive" (see appended
output/file-5.44.txt). When excluding internal tar checks by "-e tar"
option i get same description with additional information (first
member name is like *.ovf See appended output/file-soft-5.44.txt). It
also shows a generic mime type application/x-tar (see appended
output/file-i-5.44.txt) and wrong file name suffix tar/ustar (see
appended output/file-ext-5.44.txt).
For comparison reason i also run the file format identification
utility DROID ( See
https://sourceforge.net/projects/droid/). Here
often the program freeze. The samples are described as "Tape Archive
Format" with mime type application/x-tar by by PUID x-fmt/265. The OVA
suffix is considered as bad.
The samples are just tar files. So a generic mime type
application/x-tar in principal is OK. On my Windows system OVA samples
are associated with user defined application/x-virtualbox-ova. That
information can also be found on extension.nirsoft.net. This correct
type is now expressed by line like:
<Mime>application/x-virtualbox-ova</Mime>
According to documentation OVA are just tar files with OVF descriptor
(a file with extension .ovf). That can be verified by unpacking
listing (see appended 7z-l.txt) like done by command like:
7z l -ttar *.ova
Unfortunately the specification are not so preciously. It is not
written if ovf file is already first archive member. I also found no
description if tar is always POSIX variant. Furthermore there exist no
official registration at iana.org for example. So there is no
guarantee that trid definition works with 100%. So computer companies
and organizations should do first such basic stuff instead of wasting
times and resources inside KI field. So windows still relies on stupid
system that file types based on file name suffix. That is bad!
Because there exist no duty to register file types, collisions can
happen like db suffix is used for dozen of different database systems.
In old Mac there exist such a system, but Apple do not use it any
more. And a better system is not introduced onthese systemss. That
this is worse can be seen by looking at first computer aids
virus. This just changes also the file name suffix. So the files can
not be opened any more on DOS/Windows and you can not work with
these systems any more. Also the politician like European union fail
to work and are not using priorities. So they are able to forbid or
restrict the usage of light bulbs and vacuum cleaners. But computer
companies can put and get data parts on every PC in the whole world
without specification and rules. That is ridiculous.
So i run tridscan on my unrecognized samples to update ova.trid.xml.
Now i look what has changed. In global strings a few lines vanish
like:
<String>SECTION OVF</String>
<String>TEM OVF</String>
With the updated trid definition now all my OVA examples are described
(see appended output/trid-v-new.txt). TrID definitions, and output are
stored in archive ova_.zip. I hope that my definition can be used in
future version of triddefs.
With best wishes
Jörg Jenderek
