daniel-lynch--ovrplugin-openxr-shim/docs/research/RECON.md

RE4 VR (Quest 2) — Dump & Recon Checklist

Goal of this phase: non-destructively dump your own legally-owned copy of RE4 VR off the Quest 2 and answer the one question that decides the whole project — is the VR runtime OpenXR (shimmable) or VrApi (proprietary, must reimplement)?

Target app: com.Armature.VR4 (Armature Studio / Capcom / Oculus, UE 4.25.3)

Legal posture: dump-your-own only. We extract from hardware you own running a copy you own. Nothing here gets redistributed — only patches/shims you author, applied by people who dump their own copy. Same model as ReXGlue.

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0. Prereqs (do while the Quest charges)

• Install Android platform-tools (adb): sudo apt install android-tools-adb or grab Google's platform-tools zip.
• Verify: adb version
• Install analysis tooling:
  • Ghidra (native .so disassembly/patching)
  • patchelf, binutils (readelf, nm, objdump), file, unzip
  • Python 3 + pip install lief (scripted ELF inspection/patching)
  • FModel or umodel/UModel (UE 4.25 .pak browsing) — optional this phase
  • FluffyQuack's UnrealPak tools — optional this phase
• Enable Developer Mode on the Quest (Meta Quest mobile app → Devices → Developer Mode → on; requires a registered dev org — free).
• Plug Quest into PC via USB-C, put on headset, Allow USB debugging when prompted (and check "always allow from this computer").

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1. Confirm the device + app are visible

adb devices                 # should list one device, state "device" not "unauthorized"
adb shell pm list packages | grep -i armature   # expect: com.Armature.VR4
adb shell dumpsys package com.Armature.VR4 | grep -i versionName

• Device shows as device
• com.Armature.VR4 present
• Note the versionName here: ____________

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2. Locate and pull the APK(s)

Split APKs are common, so grab every path.

adb shell pm path com.Armature.VR4          # prints one or more base/split apk paths
mkdir -p ~/dev/re4vr-port/dump && cd ~/dev/re4vr-port/dump
# pull each path the command above printed, e.g.:
adb pull /data/app/~~xxxx/com.Armature.VR4-yyyy/base.apk .
# repeat for any split_*.apk lines

• base.apk pulled
• Any split_*.apk pulled
• Record sizes: ls -lh *.apk

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3. Pull the OBB (game data / .pak files)

adb shell ls -la /sdcard/Android/obb/com.Armature.VR4/
adb pull /sdcard/Android/obb/com.Armature.VR4/ .

• OBB pulled (e.g. main.NNN.com.Armature.VR4.obb)
• Note the version number NNN in the OBB filename: ______ (you'll need it if you ever repack)

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4. ⭐ THE DECISIVE CHECK — OpenXR vs VrApi

This is the whole reason we're here. Inspect the native libs in the APK.

cd ~/dev/re4vr-port/dump
unzip -l base.apk | grep -iE 'lib/arm64-v8a/.*\.so'        # list native libs
# the money grep:
unzip -l base.apk | grep -iE 'arm64.*(vrapi|openxr|ovrplatform|oculus|UE4)'

Interpret the result:

Lib found in lib/arm64-v8a/	Meaning	Difficulty
libopenxr_loader.so	✅ Standard OpenXR — Steam Frame provides a runtime; you translate vendor extensions.	Tractable
libvrapi.so	⚠️ Proprietary Meta VrApi — must reimplement/shim the runtime.	Hard
libovrplatformloader.so	Present either way — this is the entitlement check to NOP/stub.	Required patch
libUE4.so (or split into modules)	The Unreal runtime itself — the host you'll be hooking.	n/a

• RESULT — runtime is: ☑ VrApi (legacy OVRPlugin path). Confirmed 2026-06-23 on app v2.3 (versionCode 203). libvrapi.so present, libopenxr_loader.so ABSENT. libOVRPlugin.so NEEDs libvrapi.so and imports 114 vrapi_* symbols; 0 OpenXR symbols anywhere.
• libovrplatformloader.so present? ☑ yes (hard-NEEDED by libUE4.so)

REFINED WIRING (the seam that matters):

libUE4.so --(ovrp_* C API, 239 refs)--> libOVRPlugin.so --(114 vrapi_)--> libvrapi.so --> Horizon OS
libUE4.so --(NEEDED + ovr_* Platform SDK, 132 refs)--> libovrplatformloader.so  (entitlement)

• libUE4.so has 0 vrapi_ refs — game speaks OVRPlugin's ovrp_ C API*, not VrApi directly. libvrapi is just OVRPlugin's backend.
• => PORT SEAM = reimplement libOVRPlugin.so (ovrp_ on OpenXR), drop libvrapi.* ovrp_* is the documented Unity-shared API (OVR_Plugin.h); modern Meta OVRPlugin has an OpenXR backend = reference impl / prior art.
• => Stub the ovr_ Platform SDK* (libovrplatformloader.so) — entitlement/account, just return OK; don't reimplement.

Editor's note (2026-06): the entitlement-stub approach described here and elsewhere in this doc (the §4 table, the wiring summary above, the decision tree below) was not carried into the project. Entitlement handling is out of scope and the shim ships no circumvention code — see the README's scope section. These passages are kept as a record of the original recon, not as instructions.

If you want to double-check beyond filename presence, extract and inspect imports of libUE4.so (it may dynamically link the runtime):

unzip base.apk 'lib/arm64-v8a/*' -d apk_libs
readelf -d apk_libs/lib/arm64-v8a/libUE4.so | grep -i NEEDED
nm -D --defined-only apk_libs/lib/arm64-v8a/libopenxr_loader.so 2>/dev/null | grep -i xr | head
nm -D apk_libs/lib/arm64-v8a/libUE4.so | grep -iE 'xrCreate|vrapi_' | head

xrCreate*/xr* symbols → OpenXR codepath. vrapi_* symbols → VrApi codepath. A binary can ship both libs but only call one — the symbol check tells you which is actually wired up.

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5. Manifest & build recon

# Needs apktool (sudo apt install apktool) OR aapt from build-tools
aapt dump badging base.apk | grep -iE 'sdkVersion|native-code|package'
apktool d -s base.apk -o apk_decoded     # -s = don't decode .dex, faster
grep -iE 'oculus|vr|xr|entitlement|permission' apk_decoded/AndroidManifest.xml

• minSdk / targetSdk noted: ______
• native-code ABI (expect arm64-v8a): ______
• Any Oculus/entitlement metadata flags in manifest noted below.

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6. Confirm .pak accessibility (asset layer)

The community reports these are unencrypted — verify so you know the asset layer is open if you ever need it.

# unzip the OBB (it's a zip), find Content/Paks/*.pak, then:
# try opening in FModel/umodel as UE 4.25.3, no AES key

• .pak opens with no AES key (confirms community finding) ☑ yes Verified 2026-06-23: pakchunk9 footer bEncryptedIndex=0, EncryptionKeyGuid all-zero, pak version 9 (FrozenIndex / UE4.25-26). Plaintext index — 53 readable asset paths incl. /Game/Levels/BIO4/... Asset layer fully open.
• OBB layout: store (uncompressed) zip. main.203 (4.0GB) + patch.203 (4.0GB, the v2.3 update layer) + a stashed VR4-Android-Shipping-arm64.apk (== base.apk). Paks at VR4/Content/Paks/pakchunk{0..9}[optional]-Android_ETC2.pak (ETC2 = Android texture compression; 'optional' = hi-res texture chunks). Bink cutscenes at VR4/Content/Movies/*.bk2.

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7. Record findings → decide path

Fill this in, then we branch:

versionName:        2.3 (versionCode 203, minSdk 25, targetSdk 29)
runtime:            VrApi  (libvrapi via libOVRPlugin; NO openxr)  [CONFIRMED 2026-06-23]
ovrplatform loader: present (hard-NEEDED by libUE4.so)
UE version:         4.25.3 (engine = libUE4.so, stripped, arm64)
ABIs:               arm64-v8a (single base.apk, no splits)
paks encrypted:     NO — unencrypted, no AES key (CONFIRMED 2026-06-23, pak v9)
device:             Quest 2 serial <redacted-serial> (codename hollywood)

Decision tree:

• OpenXR → next phase: map which Meta OpenXR vendor extensions the binary requests, plan the OpenXR→Steam-Frame-runtime shim + entitlement stub. This is the "weekend-of-shimming" branch.

  Editor's note (2026-06): the "entitlement stub" floated here was later removed from the project. Entitlement handling is out of scope and the shim ships no circumvention code — see the README's scope section. This line is left as a record of the original plan.

• VrApi → next phase: scope a VrApi reimplementation/translation shim (much larger). Reassess whether the project is worth it vs. waiting/UEVR.
• Either way → libovrplatformloader.so entitlement bypass is a required Ghidra patch (legal for your own copy).

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Notes / scratch

(paste command output, symbol dumps, and decisions here as you go)