OpenPrestige/injector

Prestige injector (Rust)

PrestigeInjector loads the native loader library (prestige_native.dll / libprestige_native.so / libprestige_native.dylib) into a running Minecraft 1.21.11 Fabric JVM (64-bit, Fabric Loader 0.19.x, Fabric API installed). It uses the same overall method as the openvape bundle, written from scratch in Rust with no external crates.

Supported platforms

OS	Architectures	Injector binary	Loader library
Windows	x86_64	PrestigeInjector.exe	prestige_native.dll
Linux	x86_64	PrestigeInjector	libprestige_native.so
macOS	x86_64, arm64	PrestigeInjector	libprestige_native.dylib

The injector and library must be built for the same architecture as the target JVM.

How it works

1. Injector lists the running Minecraft JVMs, then loads the library into the chosen process.
   • Windows: lists visible java.exe/javaw.exe windows (refreshed every 750 ms), then runs LoadLibraryW in the chosen process through CreateRemoteThread and confirms the module is mapped.
   • Linux / macOS: uses the HotSpot attach protocol (the same mechanism as jcmd <pid> JVMTI.agent_load). The injector creates .attach_pid<pid> and sends SIGQUIT to the JVM, connects to its attach socket (/tmp/.java_pid<pid>, under $TMPDIR on macOS) and asks it to load the library. The JVM dlopens libprestige_native and calls its Agent_OnAttach entry point. No ptrace, no root, no per-architecture shellcode. Processes are found via /proc (Linux) or ps (macOS); there are no window titles, so the picker shows the pid and instance name.
2. The native library only spawns a worker thread from its entry point (DllMain on Windows, Agent_OnAttach on unix, which also hands over the JavaVM*). The worker:
   • waits for the JVM (Windows: jvm.dll, JNI_GetCreatedJavaVMs), attaches, acquires the JVMTI redefine/retransform capabilities;
   • writes the embedded payload jar (the remapped prestige-*.jar) to the temp directory under PrestigeLoader;
   • looks for Fabric through the render thread's context class loader, then the system and other thread loaders;
   • FabricLauncherBase.getLauncher().addToClassPath(jar) so payload and game classes share the launcher's game class loader;
   • registers NativeBridge.classBytes / NativeBridge.redefine and calls Bootstrap.start().
3. Bootstrap (Java) waits for the client window, then for every ClassTransform hook target gets the current class bytes (JVMTI retransform capture), runs the hooks through InPlaceTransformer and redefines the class. The bundled ClassTransform inlines hook handlers into the target methods, so normally nothing is added to the class and a plain redefine works. If a transformer ever does add methods (a running JVM cannot), they are moved into generated dev.zprestige.prestige.hooks.H* helper classes, call sites become invokestatic, and private member access goes through Access MethodHandles. Finally the Prestige and ClickGUI entrypoints run on the client thread.

Build

The payload jar is embedded with include_bytes!, so each target needs its own build. Both scripts below build for the host OS only and run gradlew remapJar, cargo build --release, and copy the results to dist/.

.\build-injector.ps1      # Windows: dist\PrestigeInjector.exe + dist\prestige_native.dll

./build-injector.sh       # Linux/macOS: dist/PrestigeInjector + dist/libprestige_native.{so,dylib}

To build release zips for every platform from Windows, run build-release.bat. It cross-compiles Linux (x86_64, glibc 2.17+, so one build covers every mainstream distro) and macOS (universal x86_64 + arm64) with cargo-zigbuild, installing zig and cargo-zigbuild on first run, and writes dist\release\prestige-<ver>-{windows-x86_64,linux-x86_64,macos-universal}.zip, the bare mod jar and SHA256SUMS.txt.

Set JAVA_HOME beforehand to choose the JDK for Gradle (build-injector.sh honours it). The GitHub Actions workflow .github/workflows/injector.yml builds and tests all four targets (Windows x86_64, Linux x86_64, macOS x86_64, macOS arm64) and uploads them as artifacts.

Use

Start a Fabric 1.21.11 instance, then run:

PrestigeInjector                      # interactive: pick the game from the list
PrestigeInjector <pid> [lib path]     # inject into a specific pid, optionally with an explicit library path

On Windows this is PrestigeInjector.exe. By default the library is looked up beside the injector.

Dawn and Lunar Client 1.21.11

Use a 1.21.11 Fabric profile in Dawn or enable Lunar Client's Fabric add-on for 1.21.11. The target profile needs Fabric Loader 0.19.x and Fabric API. Wait for the title screen before selecting the game in the injector. The default Prestige menu key is Right Shift, which may overlap with a launcher keybind.

For Lunar, the native log should identify GenesisClassLoader. Check the game log for hooks installed and client initialised. Hook counts refer to classes with changed bytecode. A skipped or failed hook can leave its feature unavailable even if the menu opens.

An offline JVM replay accepted all 42 changed classes from Lunar's installed 1.21.11 cache after recalculating stack and local limits on the cached classes. Live injection and Dawn's in-game profile still need smoke testing.

Install as a mod instead

The payload jar is also a normal Fabric mod. Put prestige-*.jar (from dist/ or the CI payload-jar artifact) in the mods/ folder of a Fabric Loader 0.19+ / Fabric API / Minecraft 1.21.11 instance; no injector is needed, on any OS. Do not use both: if the mod is already loaded, the injector's bootstrap logs "already loaded as a Fabric mod" and skips.

Requirements (Linux / macOS)

• Run the injector as the same user as the game.
• The attach mechanism must be enabled: the game must not be started with -XX:+DisableAttachMechanism.
• The JVM architecture must match the injector build. On Apple Silicon use an arm64 JVM, or use the x86_64 build for JVMs running under Rosetta.
• Sandboxed launchers (Flatpak, Snap) hide the attach socket and are not supported.

Known limits

• On Linux/macOS the library stays loaded after self-destruct: hooks are removed and natives unregistered, but the library is not dlclosed (unmapping code the thread is still returning into would crash the JVM). On Windows the library is freed.
• Linux and macOS support is compile-checked in CI; test on a real host before relying on it.

Log

prestige-native.log is written beside the loader library, plus [Prestige-Inject] lines in the game log.