BCR as LSPosed module

[Mino260806]

I am always cautious with installing magisk modules because they may bootloop the phone and are very hard to debug.

So I prefer doing it with LSPosed because everything is possible with it.

I don't know if we can make the existing BCR app compatible with LSPosed too, so can you answer these few questions for me :

• How does BCR intercept the incoming and ongoing voice ?
• What are all the ways in which it communicates with the system (storage, notifications, ...)

By hooking a system app like Calling App, we can make use of each privileges without having to make BCR a system app.

If you think it's better we made a seperate apk for BCR LSPosed module, can you still tell me where the call interception occurs exactly and what code parts I can reuse (example encoding and saving audio etc) ?

[chenxiaolong]

If you were to rewrite this as an LSPosed module, you'd have to hook into some system app that has the CONTROL_INCALL_EXPERIENCE and CAPTURE_AUDIO_OUTPUT permissions. These are the only things that require system app permissions. Root permissions are not used during runtime.

CONTROL_INCALL_EXPERIENCE is implicitly used by Android to invoke BCR's RecorderInCallService. InCallService is the API that smartwatch apps, Android Auto, etc. detect phone calls, but the permission allows it to work without an associated companion device.

CAPTURE_AUDIO_OUTPUT is used by the normal AudioRecord API to allow access to the VOICE_CALL audio source. This is used in RecorderThread.

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If your only goal is to avoid bootloops, I'd recommend just deleting service.sh and post-fs-data.sh hooks from BCR's module. They're used for 2 reasons:

• For broken devices where the system time is incorrect during boot, post-fs-data.sh will clear Android's package manager cache entry for BCR to prevent certain crashes. This is not needed for most devices.
• service.sh allows BCR to prompt for the READ_CALL_LOG permission (which apps aren't allowed to even ask for by default on Android). If you have no use for this functionality, this script isn't needed either.

Without those, the only thing left in the module is mounting BCR's /system/priv-app/ and /system/etc/ files, which have an extremely low chance of causing a bootloop.