Feature/multiple automount

[aaronclarke]

Implementation for #30 :

The virtualization framework supports having multiple automounted volumes with different readonly vs readwrite statuses, as can be seen described in Apple's documentation for VZVirtioFileSystemDeviceConfiguration

But the current support for --vol only allows for one automounted volume. If two are specified, an error is thrown due to reusing the same VZVirtioFileSystemDeviceConfiguration.macOSGuestAutomountTag tag.

There is a method already in macosvm called addAutomountDirectoryShares:readOnly: which does know how to share describe multiple automounted directories, but it forces them all to have the same value for readOnly, and the code is currently unreachable.

Motivating example:

I want to start my VM with two automounted directories, one that is readonly so that the guest VM can't ruin it, and one that has readwrite capabilities so that the guest VM can write some data back to the host.

~/Desktop/macosvm -g \
--vol ~/Desktop/sharedWithVM/fromHost,ro,automount \
--vol ~/Desktop/sharedWithVM/fromGuest,automount \
macos_14.1/vm.json

Implementation:

I've hacked this together by making macosvm loop over the shares twice:

1. Loop one: Loop over all shares
   • if share is an automount share and automounting is available, add it to a list of automount shares and continue
   • otherwise do normal share specifications
2. Loop two:
   • Loop over all discovered automount shares. Batch each directory together into a single VZMultipleDirectoryShare and set that as the share for VZVirtioFileSystemDeviceConfiguration with the VZVirtioFileSystemDeviceConfiguration.macOSGuestAutomountTag tag.

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Additionally, while editing this months ago, I had found myself getting lost multiple times when trying to follow the code's conditions and ifdefs because several blocks of the code were indented inconsistently across those boundaries and would look like they were different code blocks in my IDE. So I spent some time re-indenting the blocks that were giving me trouble. I can undo that if you prefer.

[s-u]

@aaronclarke thanks, this is a good idea, but, unfortunately, the PR completely messed up the sources. I had a look at your fork before, but couldn't use it for that reason. Please see if you can provide a clean PR, i.e., with only the changes that are necessary to add the feature, that would be highly appreciated. Thanks.