Include Rar3 volume number

[Safihre]

We (me and @sanderjo) were very happy to see your activity here again!
And now you also added a way to actually retrieve the volume number from Rar5 files.
Could you implement the same for Rar3? It would be very useful for our application where we have to deal with obfuscated Rar files and detect which ones belong together.

We now have our own custom code, but would be great if we could use Rarfile for everything! We already use it in a number of different locations in our application.
sabnzbd/sabnzbd@a5c8318

[markokr]

Unfortunately RAR3 does not contain such info, so cannot implement it.

[sanderjo]

Unfortunately RAR3 does not contain such info, so cannot implement it.

Did you see sabnzbd/sabnzbd@a5c8318#diff-13c4161154ee8c590e1c06c8cbc3da8dR20-R24 ?

The volume number is at the end of each rar3 file, like this:

            if rar_ver == 3:
                # At the end of the file, we need about 20 bytes
                fh.seek(-20, os.SEEK_END)
                mybuf = fh.read()
                volumenumber = 1 + mybuf[-9] + 256 * mybuf[-8]

We use it like that in the Sabnzbd code. Which works.

[markokr]

Aha, I missed it then. Its problably endarc-volnr, which we dont parse yet. But indeed we should.

[markokr]

Please see if it works for you now.