hooks.c

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#include <dttr_pcdogs.h>
 
#include <stdlib.h>
#include <windows.h>
 
#include <dttr_config.h>
 
#include "graphics_com_private.h"
#include "graphics_private.h"
#include "hooks_private.h"
#include "sidecar_private.h"
#include <dttr_log.h>
 
static DTTR_Graphics_COM_DirectDraw7 *graphics_hook_ddraw7;
static HWND graphics_hook_hwnd;
 
static const DTTR_PCDOGS_T_Patch_Spec graphics_byte_patches[] = {
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "83 F8 ?? 7C ?? D9 43 ?? D8 1D ?? ?? ?? ?? DF E0 F6 C4 41 0F ?? ?? ?? ??",
        19,
        0xE9,
        0xBA,
        0x00,
        0x00,
        0x00,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "8B 08 EB ?? A1 ?? ?? ?? ?? 8B 0D ?? ?? ?? ?? 3B C1",
        17,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "83 C1 14 4E 75 ?? A1 ?? ?? ?? ?? 8B 0D ?? ?? ?? ?? 3B C1",
        19,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "DB 44 24 30 D9 1F",
        -15,
        0xD9,
        0x1F,
        0x90,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "DB 44 24 30 D9 1F",
        -10,
        0x90,
        0x90,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "8D AE ?? ?? ?? ?? DB 44 24 30 D9 1F",
        10,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "8D AE ?? ?? ?? ?? DB 44 24 30",
        6,
        0x90,
        0x90,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "8B 54 24 18 89 44 24 30",
        -5,
        0xD9,
        0x5D,
        0x00,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(
        true,
        "8B 54 24 18 89 44 24 30",
        4,
        0x90,
        0x90,
        0x90,
        0x90
    ),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(true, "83 C0 14 50 55 D9 5D 00", 5, 0x90, 0x90, 0x90),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(true, "52 DB 44 24 34", 1, 0x90, 0x90, 0x90, 0x90),
    DTTR_PCDOGS_PATCH_SPEC_AOB_BYTES(false, "53 8B 5C 24 14 55 33 C9 56 57 85 DB", 0, 0xC3),
};
 
static DTTR_Core_PatchGroup *graphics_import_thunk_patch_group;
static DTTR_Core_PatchGroup *graphics_byte_patch_group;
 
// Lazily creates the DirectDraw 7 facade that satisfies the game's renderer bootstrap.
static DTTR_Graphics_COM_DirectDraw7 *get_or_create_ddraw7() {
    if (!graphics_hook_ddraw7) {
        graphics_hook_ddraw7 = dttr_graphics_com_create_directdraw7();
    }
 
    return graphics_hook_ddraw7;
}
 
// Temporarily relaxes page protection so the DirectDraw callback can publish the facade
// pointer through the game-provided slot.
static void store_pointer(void **slot, void *value) {
    DWORD old = 0;
    const SIZE_T slot_size = sizeof(*slot);
 
    if (!VirtualProtect(slot, slot_size, PAGE_READWRITE, &old)) {
        DTTR_LOG_ERROR(
            "VirtualProtect failed for slot=%p error=%lu",
            slot,
            GetLastError()
        );
        return;
    }
 
    *slot = value;
    VirtualProtect(slot, slot_size, old, &old);
}
 
// Replaces DirectDrawCreateEx with the sidecar facade so the game renders through the
// selected backend.
HRESULT __stdcall dttr_hook_directdraw_create_ex_callback(
    DTTR_PCDOGS_T_Win32_GUID *guid,
    void **ddraw_out,
    DTTR_PCDOGS_T_Win32_GUID *iid,
    DTTR_PCDOGS_T_COM_IUnknown *outer
) {
    DTTR_Graphics_COM_DirectDraw7 *const ddraw7 = get_or_create_ddraw7();
 
    if (!ddraw7) {
        return E_OUTOFMEMORY;
    }
 
    DTTR_Result result = DTTR_PCDOGS_D_D3D_CreateTextureSurface_DDrawObject->Write(
        (DTTR_PCDOGS_T_DDraw_IDirectDraw7 *)ddraw7
    );
    if (!DTTR_ResultOK(result)) {
        DTTR_LOG_ERROR(
            "Failed to publish DirectDraw object: %s",
            dttr_sidecar_result_detail(result)
        );
        return E_FAIL;
    }
 
    if (ddraw_out) {
        store_pointer(ddraw_out, ddraw7);
    }
 
    DTTR_LOG_DEBUG("DirectDrawCreateEx returning S_OK, vtbl=%p", ddraw7->vtbl);
    return S_OK;
}
 
// Reports a single compatible DirectDraw device to keep the game enumeration path on
// the sidecar renderer.
HRESULT __stdcall dttr_hook_directdraw_enumerate_ex_a_callback(
    DDraw_EnumCallbackExA lpCallback,
    LPVOID lpContext,
    DWORD dwFlags
) {
    DTTR_LOG_DEBUG(
        "DirectDrawEnumerateExA intercepted - callback=%p context=%p flags=0x%x",
        lpCallback,
        lpContext,
        dwFlags
    );
 
    if (!lpCallback) {
        return S_OK;
    }
 
    lpCallback(NULL, "DTTR Virtual Display", "display", lpContext, NULL);
 
    return S_OK;
}
 
// Initializes the sidecar renderer before DirectDraw callbacks hand it to the game.
bool dttr_graphics_hooks_init(const DTTR_Mods_Context *ctx) {
    graphics_hook_hwnd = dttr_graphics_init();
 
    if (!graphics_hook_hwnd) {
        DTTR_LOG_ERROR("Failed to initialize backend");
        return false;
    }
 
    if (!get_or_create_ddraw7()) {
        DTTR_LOG_ERROR("Failed to create DirectDraw translator");
        return false;
    }
 
    const DTTR_PCDOGS_T_Patch_Spec graphics_import_thunk_patches[] = {
        DTTR_PCDOGS_F_DDraw_CreateEx
            ->PatchSpec(true, dttr_hook_directdraw_create_ex_callback, NULL),
        DTTR_PCDOGS_F_DDraw_EnumerateExA
            ->PatchSpec(true, dttr_hook_directdraw_enumerate_ex_a_callback, NULL),
    };
 
    if (!dttr_sidecar_install_pcdogs_patch_group(
            ctx,
            "sidecar/graphics-import-thunk",
            graphics_import_thunk_patches,
            DTTR_ARRAY_COUNT(graphics_import_thunk_patches),
            &graphics_import_thunk_patch_group
        )) {
        return false;
    }
 
    if (dttr_config.vertex_precision == DTTR_VERTEX_PRECISION_SUBPIXEL) {
        if (!dttr_sidecar_install_pcdogs_patch_group(
                ctx,
                "sidecar/graphics-byte-patch",
                graphics_byte_patches,
                DTTR_ARRAY_COUNT(graphics_byte_patches),
                &graphics_byte_patch_group
            )) {
            return false;
        }
    }
 
    return true;
}
 
// Releases DirectDraw facade state after graphics patches are removed.
void dttr_graphics_hooks_cleanup(const DTTR_Mods_Context *ctx) {
    DTTR_Core_PatchGroupRelease(&graphics_byte_patch_group);
    DTTR_Core_PatchGroupRelease(&graphics_import_thunk_patch_group);
 
    if (!graphics_hook_ddraw7) {
        return;
    }
 
    free(graphics_hook_ddraw7);
    graphics_hook_ddraw7 = NULL;
}