Setup CD conversion support

[TheJJ]

Very related to the conversion targets (#79) and the version detection (#61) is the support of converting media and game files from setup disk images. The Python module openage.cabextract provides cab extraction features needed by the .cab files on the disc.

1. Pass mount point of the original CD (or ISO image)
2. Detect version of the disk image
3. Use fslike abstraction to mount all archives on disk.
4. Convert contents of mounted archives.

The invocation should originate from openage/convert/driver.py.

[hwmrocker]

Why do you need ISO support? It is so easy to mount an ISO in Linux and Windows (and I am pretty sure also on a Mac)

If you point just to the filesystem structure of the DVD content and export the data from there it is all a user want. If try to read the content of the iso you need more dependencies and bloat your software. The usability gain is minimal.

Those people who have an iso probably know how to mount it.

[mic-e]

@hwmrocker: right... I think ISO browsing is pretty low priority; we shouldn't spend time to implement an ISOFS reader, nor should we make an ISOFS library a dependency. But if the user happens to have an ISO-browsing Python library installed, why not use it.

[boombatower]

Additionally, it would seem CD-ROM drives are being phased out of machine builds. Would also be cool if we could verify legal steam copy or cdkey and just provide assets, but probably as tricky and messy as drm.

[caschulz88]

Did anyone already implemented something related to this issue in the past? Otherwise I would like to start doing so because I don't really want to install WINE just to extract the media files from the AoE2 installer.

Do we have CD file layouts from all editions that are available out there? I think they might differ from version to version. I only have the first release fullversion on CD-ROM available here. Would be great to get information on differences between this release and others like the Gold Edition or the extension pack.

[TheJJ]

We have a cab reader and filesystem abstraction so you can transparently access all the archives on the CD. Mounting the iso should be done through udisksctl or something.

You can find the cab reading in openage/cabextract/.
The version detection is in openage/convert/driver.py, you might wanna improve and extend it.

We require the 1.0c patch i think, as the data format of empires.dat might be different before that.

You basically just wanna mix together now-existing stuff:

• Mount the CD via udiskctl (or if the user mounted already, query the path).
• Assemble the file structure via util.fslike (mount the cab archives).
• Adjust the converter to do better version detection and extract whatever is needed (driver.py)

[azrdev]

@caschulz88 I collected some of the disk layouts here: https://gist.github.com/azrdev/e20c13f360840bc0157c. No guarantees about those without "verified original" in the title, though.
You can fork that gist as any other repo, maybe even to PRs. I'm happy to extend the list!

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w.r.t. Implementing disk support: We have to decide if GameVersion should be different for an install disk and its installed variant. Since an installation (say, AoK+TC) often maps to multiple different disks.

I tend to make GameVersion an abstract class, whose singleton subclasses know how to identify themselves on a given sourcedir, and that known where the files the conversion needs are (see e.g. the empires2_x1 being named EMIRE_1.DAT in AOE2_GOLD).
The Disks would then have separate subclasses, probably.

Things might get even more complicated if we need multiple disks: AOE2 disk on its own lacks the TC content, but does TC disk have everything we need, or do we require both disks (how would we handle that)? AFAIK 1.0c patch is a requirement, what would we do with a TC disk pre-1.0c (does such exist?)