OpenXR loader: add API layer discovery support.

[quic-dengkail]

Loader currently did not support API layer disconvery yet. This patch supports this feature.

Loader will try to get all implicit/explicit API layers from broker supported by chosen active runtime and populate virtual API layer manifests from returned cursor.
Here is authority and path used to find correct cursor:

• Loader ---> broker

  • authority:org.khronos.openxr.runtime_broker
  • path:/openxr/major_ver/abi/[abi]/api_layer/[implicit:explicit]

Corresponding patch of broker part can be found here: https://gitlab.freedesktop.org/monado/utilities/openxr-android-broker/-/merge_requests/18

[CLAassistant]

All committers have signed the CLA.

[quic-dengkail]

Hi @rpavlik, here is loader patch of API layer discovery, please help review, thanks!

[rpavlik-bot]

An issue (number 2045) has been filed to correspond to this pull request in the internal Khronos GitLab (Khronos members only: KHR:openxr/openxr#2045 ), to facilitate working group processes.

This GitHub pull request will continue to be the main site of discussion.

[rblenkinsopp]

I've taken an initial pass over this with a few minor pieces, I want to double check the layer ordering as I think runtime shipped layers should be the lowest in the stack (just above the runtime) which I believe this is currently doing correctly but I want to double check.

[rpavlik]

I did import this into OpenXR gitlab for internal discussion: https://gitlab.khronos.org/openxr/openxr/-/merge_requests/2888

If you can't access that you might need one of your colleagues to assist, since I know they don't let everyone there make a Khronos account.

[quic-dengkail]

I've taken an initial pass over this with a few minor pieces, I want to double check the layer ordering as I think runtime shipped layers should be the lowest in the stack (just above the runtime) which I believe this is currently doing correctly but I want to double check.

Yes, I can confirm this is exactly this patch will do. Runtime layers will be loaded above the chosen runtime, and thanks for the suggestions, I will modify patch accordingly.

[quic-dengkail]

Updates (9/27):

1. Functions/instance_extensions query pattern should be revised, better to use similar pattern as functions query in runtime discovery.(loader/broker/runtime side) ---> done

• Following paths will be used:

  • /openxr/[major_ver]/abi/[abi]/runtimes/active (existing)
  • /openxr/[major_ver]/abi/[abi]/runtimes/[package_name]/functions (existing)
  • /openxr/[major_ver]/abi/[abi]/api_layers/[implicit|explicit] (new in this MR - rename from api_layer )
  • /openxr/[major_ver]/abi/[abi]/api_layers/[package_name]/[layer_name]/functions (new in this MR)
  • /openxr/[major_ver]/abi/[abi]/api_layers/[package_name]/[layer_name]/instance_extensions (new in this MR)

• The proceedure for API layers would then be:

  • Query active implict/explict layers by the /openxr/[major_ver]/abi/[abi]/api_layers/[implicit|explicit] path.

  • For each layer get it's package_name and layer_name and check has_functions and has_instance_extensions columns.

  • If has_functions is true, then query function mappings with /openxr/[major_ver]/abi/[abi]/api_layers/[package_name]/[layer_name]/functions

  • If has_instance_extensions is true, then query extensions and versions with /openxr/[major_ver]/abi/[abi]/api_layers/[package_name]/[layer_name]/instance_extensions

2. Adapt the protocol so that the existing authorities for the brokers are used, and so that both the system broker and installable broker can report API layers.(loader/broker/runtime side) ---> done
3. Remove ‘enableEnvironment’/‘disableEnvironment’ in API layers as they can have no effect on Android as EnvVars are not supported.(loader/broker/runtime side) ---> done
4. Multiple cases (case A, B, D, E, F1/F2/F3) in runtime/API layer discovery are not needed or have potential security issues to achieve ‘same-origin’ policy. (mainly loader side) ---> WIP

[quic-dengkail]

12/7/2023: rebase code base to OpenXR SDK 1.0.32.1 hotfix: Fix CMake build of loader on Universal Windows Platform

[quic-dengkail]

Rebase to latest: 99256e9 (3/22)

[quic-dengkail]

Rebase to latest: 9e9d023ffcc67037ee244f6f0bc3785370814c96. (4/18/2024)

• Rebase to loader release 1.1.36.

• Add "disable_environment" and "enable_environment" back on Android platform.