punktfunk/packaging/windows/drivers/wdk-iddcx/src/lib.rs

//! Safe-ish typed wrappers over the wdk-sys IddCx DDIs, dispatched through the `IddFunctions` table
//! (indexed by `_IDDFUNCENUM::<Name>TableIndex`, with `IddDriverGlobals` as the implicit first arg) —
//! the same model wdk-sys uses for WDF. Graduates the proven dispatch from `wdk-probe/src/iddcx_rt.rs`
//! (M1 step 1) and adds the full DDI set the pf-vdisplay driver needs (M1 step 2 / §14).
//!
//! Each DDI pins its `(_IDDFUNCENUM index, PFN_* type)` pair in exactly ONE place (the macro invocation)
//! — a wrong pairing is the only way the table dispatch can be UB, so it must never be expressed twice
//! (port-plan unsafe_hotspot #1). All wrappers return the raw `NTSTATUS`; the caller classifies it with
//! [`nt_success`] (or, for the HRESULT-shaped SwapChain DDIs, treats a nonzero as the documented retry
//! code — handled at the call site in STEP 5).
#![no_std]
#![allow(non_snake_case, clippy::missing_safety_doc)]
// P0 lint (audit §8): require explicit `unsafe {}` blocks inside `unsafe fn`s.
#![deny(unsafe_op_in_unsafe_fn)]

pub use wdk_sys::iddcx;

use wdk_sys::{NTSTATUS, PWDFDEVICE_INIT, WDFDEVICE};

/// `NT_SUCCESS` — IddCx DDIs that return a true NTSTATUS are errors iff negative.
#[inline]
#[must_use]
pub const fn nt_success(status: NTSTATUS) -> bool {
    status >= 0
}

/// Read the IddCx DDI at `index` from the stub-provided `IddFunctions` table and reinterpret it as the
/// concrete `PFN_*` type. `IddFunctions` is a flexible array (`[PFN_IDD_CX; 0]`) populated by IddCxStub
/// once the driver is loaded.
///
/// # Safety
/// `index`/`T` must be the matching `_IDDFUNCENUM` index and `PFN_*` type for the same DDI, and the
/// table must be populated (true after the driver is loaded by the IddCx runtime).
#[inline]
unsafe fn ddi<T: Copy>(index: i32) -> T {
    let table = (&raw const iddcx::IddFunctions).cast::<iddcx::PFN_IDD_CX>();
    // SAFETY: `index` is a valid IddCx table slot; the slot holds a `PFN_*` whose layout is `T`.
    let slot = unsafe { table.add(index as usize) };
    unsafe { slot.cast::<T>().read() }
}

/// The IddCx driver globals (set by `IddCxStub`), passed as the implicit first arg to every DDI.
///
/// # Safety
/// Only valid once the driver is loaded by the IddCx runtime.
#[inline]
unsafe fn globals() -> iddcx::PIDD_DRIVER_GLOBALS {
    // SAFETY: we only read the pointer value of the stub-provided global.
    unsafe { (&raw const iddcx::IddDriverGlobals).read() }
}

/// Generate a typed outbound-DDI wrapper. Body is identical for every DDI (table lookup → call with the
/// globals); only the `(index, PFN_*, args)` triple varies, and it appears here exactly once.
macro_rules! iddcx_ddi {
    (
        $(#[$meta:meta])*
        $name:ident ( $( $arg:ident : $aty:ty ),* $(,)? ) @ $idx:ident as $pfn:ident
    ) => {
        $(#[$meta])*
        ///
        /// # Safety
        /// Call only after the driver is loaded by IddCx; pointers must satisfy the IddCx contract.
        #[inline]
        pub unsafe fn $name( $( $arg: $aty ),* ) -> NTSTATUS {
            let f: iddcx::$pfn = unsafe { ddi(iddcx::_IDDFUNCENUM::$idx) };
            let g = unsafe { globals() };
            // SAFETY: dispatching a populated DDI with the stub globals and caller-valid args.
            unsafe { (f.unwrap())(g, $( $arg ),* ) }
        }
    };
    // void-returning variant (e.g. IddCxAdapterSetRenderAdapter): the DDI's PFN returns `()`.
    (
        $(#[$meta:meta])*
        $name:ident ( $( $arg:ident : $aty:ty ),* $(,)? ) @ $idx:ident as $pfn:ident -> ()
    ) => {
        $(#[$meta])*
        ///
        /// # Safety
        /// Call only after the driver is loaded by IddCx; pointers must satisfy the IddCx contract.
        #[inline]
        pub unsafe fn $name( $( $arg: $aty ),* ) {
            let f: iddcx::$pfn = unsafe { ddi(iddcx::_IDDFUNCENUM::$idx) };
            let g = unsafe { globals() };
            // SAFETY: dispatching a populated DDI with the stub globals and caller-valid args.
            unsafe { (f.unwrap())(g, $( $arg ),* ) }
        }
    };
}

iddcx_ddi!(
    /// Configure a `WDFDEVICE_INIT` for IddCx (call before `WdfDeviceCreate`).
    IddCxDeviceInitConfig(device_init: PWDFDEVICE_INIT, config: *const iddcx::IDD_CX_CLIENT_CONFIG)
        @ IddCxDeviceInitConfigTableIndex as PFN_IDDCXDEVICEINITCONFIG
);
iddcx_ddi!(
    /// Finish IddCx device init (call after `WdfDeviceCreate`).
    IddCxDeviceInitialize(device: WDFDEVICE)
        @ IddCxDeviceInitializeTableIndex as PFN_IDDCXDEVICEINITIALIZE
);
iddcx_ddi!(
    /// Create the WDDM adapter asynchronously; `out.AdapterObject` is the `IDDCX_ADAPTER`.
    IddCxAdapterInitAsync(
        in_args: *const iddcx::IDARG_IN_ADAPTER_INIT,
        out_args: *mut iddcx::IDARG_OUT_ADAPTER_INIT,
    ) @ IddCxAdapterInitAsyncTableIndex as PFN_IDDCXADAPTERINITASYNC
);
iddcx_ddi!(
    /// Create a monitor on the adapter; `out.MonitorObject` is the `IDDCX_MONITOR`.
    IddCxMonitorCreate(
        adapter: iddcx::IDDCX_ADAPTER,
        in_args: *const iddcx::IDARG_IN_MONITORCREATE,
        out_args: *mut iddcx::IDARG_OUT_MONITORCREATE,
    ) @ IddCxMonitorCreateTableIndex as PFN_IDDCXMONITORCREATE
);
iddcx_ddi!(
    /// Announce monitor arrival; `out.OsTargetId`/`out.OsAdapterLuid` come back.
    IddCxMonitorArrival(
        monitor: iddcx::IDDCX_MONITOR,
        out_args: *mut iddcx::IDARG_OUT_MONITORARRIVAL,
    ) @ IddCxMonitorArrivalTableIndex as PFN_IDDCXMONITORARRIVAL
);
iddcx_ddi!(
    /// Depart a monitor (host disconnect / session teardown).
    IddCxMonitorDeparture(monitor: iddcx::IDDCX_MONITOR)
        @ IddCxMonitorDepartureTableIndex as PFN_IDDCXMONITORDEPARTURE
);
iddcx_ddi!(
    /// Set the preferred render adapter (LUID) for the virtual adapter.
    IddCxAdapterSetRenderAdapter(
        adapter: iddcx::IDDCX_ADAPTER,
        in_args: *const iddcx::IDARG_IN_ADAPTERSETRENDERADAPTER,
    ) @ IddCxAdapterSetRenderAdapterTableIndex as PFN_IDDCXADAPTERSETRENDERADAPTER -> ()
);
iddcx_ddi!(
    /// Bind a D3D device to an assigned swap-chain. HRESULT-shaped (0x887A0026 → retry on monitor flap).
    IddCxSwapChainSetDevice(
        swap_chain: iddcx::IDDCX_SWAPCHAIN,
        in_args: *const iddcx::IDARG_IN_SWAPCHAINSETDEVICE,
    ) @ IddCxSwapChainSetDeviceTableIndex as PFN_IDDCXSWAPCHAINSETDEVICE
);
iddcx_ddi!(
    /// Release the previous frame and acquire the next (HDR/FP16 variant). HRESULT-shaped; E_PENDING
    /// (0x8000000A) means wait on the surface-available event.
    IddCxSwapChainReleaseAndAcquireBuffer2(
        swap_chain: iddcx::IDDCX_SWAPCHAIN,
        in_args: *mut iddcx::IDARG_IN_RELEASEANDACQUIREBUFFER2,
        out_args: *mut iddcx::IDARG_OUT_RELEASEANDACQUIREBUFFER2,
    ) @ IddCxSwapChainReleaseAndAcquireBuffer2TableIndex as PFN_IDDCXSWAPCHAINRELEASEANDACQUIREBUFFER2
);
iddcx_ddi!(
    /// Signal that the acquired frame has been processed. HRESULT-shaped.
    IddCxSwapChainFinishedProcessingFrame(swap_chain: iddcx::IDDCX_SWAPCHAIN)
        @ IddCxSwapChainFinishedProcessingFrameTableIndex as PFN_IDDCXSWAPCHAINFINISHEDPROCESSINGFRAME
);