support for writing car files

[dvc94ch]

to upload an app to the appstore you need to add your icons to an asset bundle with .car extension. I'm currently using xcode to construct the Assets.car file, but this is only a temporary workaround.

[indygreg]

https://blog.timac.org/2018/1018-reverse-engineering-the-car-file-format/ seems like a useful reference. The author produced code at https://github.com/Timac/CARParser/.

I then did a search for various magic values in that post. I stumbled across https://github.com/facebookarchive/xcbuild/tree/dbaee552d2f13640773eb1ad3c79c0d2aca7229c/Libraries/libcar and https://github.com/Reflejo/pycar, and https://github.com/iineva/bom/blob/b998a3aac1c0e863cfc92fdfca74adf8931b831e/pkg/asset/decode.go as other implementations.

Haven't looked at them at all and don't know if they are comprehensive enough to do what we need.

I do know Facebook invested heavily in Linux based tooling for Apple platform development. It would not surprise me if Facebook was able to do application building + packaging purely from Linux. So I suspect that this archived Facebook repo is a trove of information that can bypass a lot of reversing work.