gdi/eng/ldevobj.c

/*
 * COPYRIGHT:        See COPYING in the top level directory
 * PROJECT:          ReactOS Win32k subsystem
 * PURPOSE:          Support for logical devices
 * FILE:             win32ss/gdi/eng/ldevobj.c
 * PROGRAMER:        Timo Kreuzer (timo.kreuzer@reactos.org)
 */

#include <win32k.h>
#define NDEBUG
#include <debug.h>
DBG_DEFAULT_CHANNEL(EngLDev);

#ifndef RVA_TO_ADDR
#define RVA_TO_ADDR(Base,Rva) ((PVOID)(((ULONG_PTR)(Base)) + (Rva)))
#endif

/** Globals *******************************************************************/

static HSEMAPHORE ghsemLDEVList;
static LIST_ENTRY gleLdevListHead;
static LDEVOBJ *gpldevWin32k = NULL;


/** Private functions *********************************************************/

CODE_SEG("INIT")
NTSTATUS
NTAPI
InitLDEVImpl(VOID)
{
    ULONG cbSize;

    /* Initialize the LDEV list head */
    InitializeListHead(&gleLdevListHead);

    /* Initialize the loader lock */
    ghsemLDEVList = EngCreateSemaphore();
    if (!ghsemLDEVList)
    {
        ERR("Failed to create ghsemLDEVList\n");
        return STATUS_INSUFFICIENT_RESOURCES;
    }

    /* Allocate a LDEVOBJ for win32k */
    gpldevWin32k = ExAllocatePoolWithTag(PagedPool,
                                         sizeof(LDEVOBJ) +
                                         sizeof(SYSTEM_GDI_DRIVER_INFORMATION),
                                         GDITAG_LDEV);
    if (!gpldevWin32k)
    {
        return STATUS_NO_MEMORY;
    }

    /* Initialize the LDEVOBJ for win32k */
    gpldevWin32k->leLink.Flink = NULL;
    gpldevWin32k->leLink.Blink = NULL;
    gpldevWin32k->ldevtype = LDEV_DEVICE_DISPLAY;
    gpldevWin32k->cRefs = 1;
    gpldevWin32k->ulDriverVersion = GDI_ENGINE_VERSION;
    gpldevWin32k->pGdiDriverInfo = (PVOID)(gpldevWin32k + 1);
    RtlInitUnicodeString(&gpldevWin32k->pGdiDriverInfo->DriverName,
                         L"\\SystemRoot\\System32\\win32k.sys");
    gpldevWin32k->pGdiDriverInfo->ImageAddress = &__ImageBase;
    gpldevWin32k->pGdiDriverInfo->SectionPointer = NULL;
    gpldevWin32k->pGdiDriverInfo->EntryPoint = (PVOID)DriverEntry;
    gpldevWin32k->pGdiDriverInfo->ExportSectionPointer =
        RtlImageDirectoryEntryToData(&__ImageBase,
                                     TRUE,
                                     IMAGE_DIRECTORY_ENTRY_EXPORT,
                                     &cbSize);
    gpldevWin32k->pGdiDriverInfo->ImageLength = 0; // FIXME

    return STATUS_SUCCESS;
}

static
PLDEVOBJ
LDEVOBJ_AllocLDEV(
    _In_ LDEVTYPE ldevtype)
{
    PLDEVOBJ pldev;

    /* Allocate the structure from paged pool */
    pldev = ExAllocatePoolWithTag(PagedPool, sizeof(LDEVOBJ), GDITAG_LDEV);
    if (!pldev)
    {
        ERR("Failed to allocate LDEVOBJ.\n");
        return NULL;
    }

    /* Zero out the structure */
    RtlZeroMemory(pldev, sizeof(LDEVOBJ));

    /* Set the ldevtype */
    pldev->ldevtype = ldevtype;

    return pldev;
}

static
VOID
LDEVOBJ_vFreeLDEV(
    _In_ _Post_ptr_invalid_ PLDEVOBJ pldev)
{
    /* Make sure we don't have a driver loaded */
    ASSERT(pldev && pldev->pGdiDriverInfo == NULL);
    ASSERT(pldev->cRefs == 0);

    /* Free the memory */
    ExFreePoolWithTag(pldev, GDITAG_LDEV);
}

static
BOOL
LDEVOBJ_bLoadImage(
    _Inout_ PLDEVOBJ pldev,
    _In_ PUNICODE_STRING pustrPathName)
{
    PSYSTEM_GDI_DRIVER_INFORMATION pDriverInfo;
    NTSTATUS Status;
    ULONG cbSize;

    /* Make sure no image is loaded yet */
    ASSERT(pldev && pldev->pGdiDriverInfo == NULL);

    /* Allocate a SYSTEM_GDI_DRIVER_INFORMATION structure */
    cbSize = sizeof(SYSTEM_GDI_DRIVER_INFORMATION) + pustrPathName->Length;
    pDriverInfo = ExAllocatePoolWithTag(PagedPool, cbSize, GDITAG_LDEV);
    if (!pDriverInfo)
    {
        ERR("Failed to allocate SYSTEM_GDI_DRIVER_INFORMATION\n");
        return FALSE;
    }

    /* Initialize the UNICODE_STRING and copy the driver name */
    RtlInitEmptyUnicodeString(&pDriverInfo->DriverName,
                              (PWSTR)(pDriverInfo + 1),
                              pustrPathName->Length);
    RtlCopyUnicodeString(&pDriverInfo->DriverName, pustrPathName);

    /* Try to load the driver */
    Status = ZwSetSystemInformation(SystemLoadGdiDriverInformation,
                                    pDriverInfo,
                                    sizeof(SYSTEM_GDI_DRIVER_INFORMATION));
    if (!NT_SUCCESS(Status))
    {
        ERR("Failed to load a GDI driver: '%wZ', Status = 0x%lx\n",
            pustrPathName, Status);

        /* Free the allocated memory */
        ExFreePoolWithTag(pDriverInfo, GDITAG_LDEV);
        return FALSE;
    }

    /* Set the driver info */
    pldev->pGdiDriverInfo = pDriverInfo;

    /* Return success. */
    return TRUE;
}

static
BOOL
LDEVOBJ_bEnableDriver(
    _Inout_ PLDEVOBJ pldev,
    _In_ PFN_DrvEnableDriver pfnEnableDriver)
{
    DRVENABLEDATA ded;
    ULONG i;

    TRACE("LDEVOBJ_bEnableDriver('%wZ')\n", &pldev->pGdiDriverInfo->DriverName);

    ASSERT(pldev);
    ASSERT(pldev->cRefs == 0);

    if (pldev->ldevtype == LDEV_IMAGE)
        return TRUE;

    /* Call the drivers DrvEnableDriver function */
    RtlZeroMemory(&ded, sizeof(ded));
    if (!pfnEnableDriver(GDI_ENGINE_VERSION, sizeof(ded), &ded))
    {
        ERR("DrvEnableDriver failed\n");
        return FALSE;
    }

    /* Copy the returned driver version */
    pldev->ulDriverVersion = ded.iDriverVersion;

    /* Fill the driver function array */
    for (i = 0; i < ded.c; i++)
    {
        pldev->apfn[ded.pdrvfn[i].iFunc] = ded.pdrvfn[i].pfn;
    }

    /* Return success. */
    return TRUE;
}

static
VOID
LDEVOBJ_vDisableDriver(
    _Inout_ PLDEVOBJ pldev)
{
    ASSERT(pldev);
    ASSERT(pldev->cRefs == 0);

    TRACE("LDEVOBJ_vDisableDriver('%wZ')\n", &pldev->pGdiDriverInfo->DriverName);

    if (pldev->ldevtype == LDEV_IMAGE)
        return;

    if (pldev->pfn.DisableDriver)
    {
        /* Call the unload function */
        pldev->pfn.DisableDriver();
    }
}

static
PVOID
LDEVOBJ_pvFindImageProcAddress(
    _In_ PLDEVOBJ pldev,
    _In_z_ LPSTR pszProcName)
{
    PVOID pvImageBase;
    PIMAGE_EXPORT_DIRECTORY pExportDir;
    PVOID pvProcAdress = NULL;
    PUSHORT pOrdinals;
    PULONG pNames, pAddresses;
    ULONG i;

    /* Make sure we have a driver info */
    ASSERT(pldev && pldev->pGdiDriverInfo != NULL);

    /* Get the pointer to the export directory */
    pvImageBase = pldev->pGdiDriverInfo->ImageAddress;
    pExportDir = pldev->pGdiDriverInfo->ExportSectionPointer;
    if (!pExportDir)
    {
        ERR("LDEVOBJ_pvFindImageProcAddress: no export section found\n");
        return NULL;
    }

    /* Get pointers to some tables */
    pNames = RVA_TO_ADDR(pvImageBase, pExportDir->AddressOfNames);
    pOrdinals = RVA_TO_ADDR(pvImageBase, pExportDir->AddressOfNameOrdinals);
    pAddresses = RVA_TO_ADDR(pvImageBase, pExportDir->AddressOfFunctions);

    /* Loop the export table */
    for (i = 0; i < pExportDir->NumberOfNames; i++)
    {
        /* Compare the name */
        if (_stricmp(pszProcName, RVA_TO_ADDR(pvImageBase, pNames[i])) == 0)
        {
            /* Found! Calculate the procedure address */
            pvProcAdress = RVA_TO_ADDR(pvImageBase, pAddresses[pOrdinals[i]]);
            break;
        }
    }

    /* Return the address */
    return pvProcAdress;
}

static
BOOL
LDEVOBJ_bUnloadImage(
    _Inout_ PLDEVOBJ pldev)
{
    NTSTATUS Status;

    /* Make sure we have a driver info */
    ASSERT(pldev && pldev->pGdiDriverInfo != NULL);
    ASSERT(pldev->cRefs == 0);

    TRACE("LDEVOBJ_bUnloadImage('%wZ')\n", &pldev->pGdiDriverInfo->DriverName);

    /* Unload the driver */
#if 0
    Status = ZwSetSystemInformation(SystemUnloadGdiDriverInformation,
                                    &pldev->pGdiDriverInfo->SectionPointer,
                                    sizeof(HANDLE));
#else
    /* Unfortunately, ntoskrnl allows unloading a driver, but fails loading
     * it again with STATUS_IMAGE_ALREADY_LOADED. Prevent this problem by
     * never unloading any driver.
     */
    UNIMPLEMENTED;
    Status = STATUS_NOT_IMPLEMENTED;
#endif
    if (!NT_SUCCESS(Status))
        return FALSE;

    ExFreePoolWithTag(pldev->pGdiDriverInfo, GDITAG_LDEV);
    pldev->pGdiDriverInfo = NULL;

    return TRUE;
}

PLDEVOBJ
LDEVOBJ_pLoadInternal(
    _In_ PFN_DrvEnableDriver pfnEnableDriver,
    _In_ ULONG ldevtype)
{
    PLDEVOBJ pldev;

    TRACE("LDEVOBJ_pLoadInternal(%lu)\n", ldevtype);

    /* Lock loader */
    EngAcquireSemaphore(ghsemLDEVList);

    /* Allocate a new LDEVOBJ */
    pldev = LDEVOBJ_AllocLDEV(ldevtype);
    if (!pldev)
    {
        ERR("Could not allocate LDEV\n");
        goto leave;
    }

    /* Load the driver */
    if (!LDEVOBJ_bEnableDriver(pldev, pfnEnableDriver))
    {
        ERR("LDEVOBJ_bEnableDriver failed\n");
        LDEVOBJ_vFreeLDEV(pldev);
        pldev = NULL;
        goto leave;
    }

    /* Insert the LDEV into the global list */
    InsertHeadList(&gleLdevListHead, &pldev->leLink);

    /* Increase ref count */
    pldev->cRefs++;

leave:
    /* Unlock loader */
    EngReleaseSemaphore(ghsemLDEVList);

    TRACE("LDEVOBJ_pLoadInternal returning %p\n", pldev);
    return pldev;
}

PLDEVOBJ
NTAPI
LDEVOBJ_pLoadDriver(
    _In_z_ LPWSTR pwszDriverName,
    _In_ ULONG ldevtype)
{
    WCHAR acwBuffer[MAX_PATH];
    PLIST_ENTRY pleLink;
    PLDEVOBJ pldev;
    UNICODE_STRING strDriverName;
    SIZE_T cwcLength;
    LPWSTR pwsz;

    TRACE("LDEVOBJ_pLoadDriver(%ls, %lu)\n", pwszDriverName, ldevtype);
    ASSERT(pwszDriverName);

    /* Initialize buffer for the the driver name */
    RtlInitEmptyUnicodeString(&strDriverName, acwBuffer, sizeof(acwBuffer));

    /* Start path with systemroot */
    RtlAppendUnicodeToString(&strDriverName, L"\\SystemRoot\\System32\\");

    /* Get Length of given string */
    cwcLength = wcslen(pwszDriverName);

    /* Check if we have a system32 path given */
    pwsz = pwszDriverName + cwcLength;
    while (pwsz > pwszDriverName)
    {
        if ((*pwsz == L'\\') && (_wcsnicmp(pwsz, L"\\system32\\", 10) == 0))
        {
            /* Driver name starts after system32 */
            pwsz += 10;
            break;
        }
        pwsz--;
    }

    /* Append the driver name */
    RtlAppendUnicodeToString(&strDriverName, pwsz);

    /* MSDN says "The driver must include this suffix in the pwszDriver string."
       But in fact it's optional. The function can also load .sys files without
       appending the .dll extension. */
    if ((cwcLength < 4) ||
        ((_wcsnicmp(pwszDriverName + cwcLength - 4, L".dll", 4) != 0) &&
         (_wcsnicmp(pwszDriverName + cwcLength - 4, L".sys", 4) != 0)) )
    {
        /* Append the .dll suffix */
        RtlAppendUnicodeToString(&strDriverName, L".dll");
    }

    /* Lock loader */
    EngAcquireSemaphore(ghsemLDEVList);

    /* Search the List of LDEVS for the driver name */
    for (pleLink = gleLdevListHead.Flink;
         pleLink != &gleLdevListHead;
         pleLink = pleLink->Flink)
    {
        pldev = CONTAINING_RECORD(pleLink, LDEVOBJ, leLink);

        /* Check if the ldev is associated with a file */
        if (pldev->pGdiDriverInfo)
        {
            /* Check for match (case insensative) */
            if (RtlEqualUnicodeString(&pldev->pGdiDriverInfo->DriverName, &strDriverName, TRUE))
            {
                /* Image found in LDEV list */
                break;
            }
        }
    }

    /* Did we find one? */
    if (pleLink == &gleLdevListHead)
    {
        /* No, allocate a new LDEVOBJ */
        pldev = LDEVOBJ_AllocLDEV(ldevtype);
        if (!pldev)
        {
            ERR("Could not allocate LDEV\n");
            goto leave;
        }

        /* Load the image */
        if (!LDEVOBJ_bLoadImage(pldev, &strDriverName))
        {
            LDEVOBJ_vFreeLDEV(pldev);
            pldev = NULL;
            ERR("LDEVOBJ_bLoadImage failed\n");
            goto leave;
        }

        /* Load the driver */
        if (!LDEVOBJ_bEnableDriver(pldev, pldev->pGdiDriverInfo->EntryPoint))
        {
            ERR("LDEVOBJ_bEnableDriver failed\n");

            /* Unload the image. */
            LDEVOBJ_bUnloadImage(pldev);
            LDEVOBJ_vFreeLDEV(pldev);
            pldev = NULL;
            goto leave;
        }

        /* Insert the LDEV into the global list */
        InsertHeadList(&gleLdevListHead, &pldev->leLink);
    }

    /* Increase ref count */
    pldev->cRefs++;

leave:
    /* Unlock loader */
    EngReleaseSemaphore(ghsemLDEVList);

    TRACE("LDEVOBJ_pLoadDriver returning %p\n", pldev);
    return pldev;
}

static
VOID
LDEVOBJ_vDereference(
    _Inout_ PLDEVOBJ pldev)
{
    /* Lock loader */
    EngAcquireSemaphore(ghsemLDEVList);

    /* Decrement reference count */
    ASSERT(pldev->cRefs > 0);
    pldev->cRefs--;

    /* More references left? */
    if (pldev->cRefs > 0)
    {
        EngReleaseSemaphore(ghsemLDEVList);
        return;
    }

    LDEVOBJ_vDisableDriver(pldev);

    if (LDEVOBJ_bUnloadImage(pldev))
    {
        /* Remove ldev from the list */
        RemoveEntryList(&pldev->leLink);

        /* Free the driver info structure */
        LDEVOBJ_vFreeLDEV(pldev);
    }
    else
    {
        WARN("Failed to unload driver '%wZ', trying to re-enable it.\n", &pldev->pGdiDriverInfo->DriverName);
        LDEVOBJ_bEnableDriver(pldev, pldev->pGdiDriverInfo->EntryPoint);

        /* Increment again reference count */
        pldev->cRefs++;
    }

    /* Unlock loader */
    EngReleaseSemaphore(ghsemLDEVList);
}

ULONG
LDEVOBJ_ulGetDriverModes(
    _In_ LPWSTR pwszDriverName,
    _In_ HANDLE hDriver,
    _Out_ PDEVMODEW *ppdm)
{
    PLDEVOBJ pldev = NULL;
    ULONG cbSize = 0;
    PDEVMODEW pdm = NULL;

    TRACE("LDEVOBJ_ulGetDriverModes('%ls', %p)\n", pwszDriverName, hDriver);

    pldev = LDEVOBJ_pLoadDriver(pwszDriverName, LDEV_DEVICE_DISPLAY);
    if (!pldev)
        goto cleanup;

    /* Mirror drivers may omit this function */
    if (!pldev->pfn.GetModes)
        goto cleanup;

    /* Call the driver to get the required size */
    cbSize = pldev->pfn.GetModes(hDriver, 0, NULL);
    if (!cbSize)
    {
        ERR("DrvGetModes returned 0\n");
        goto cleanup;
    }

    /* Allocate a buffer for the DEVMODE array */
    pdm = ExAllocatePoolWithTag(PagedPool, cbSize, GDITAG_DEVMODE);
    if (!pdm)
    {
        ERR("Could not allocate devmodeinfo\n");
        goto cleanup;
    }

    /* Call the driver again to fill the buffer */
    cbSize = pldev->pfn.GetModes(hDriver, cbSize, pdm);
    if (!cbSize)
    {
        /* Could not get modes */
        ERR("DrvrGetModes returned 0 on second call\n");
        ExFreePoolWithTag(pdm, GDITAG_DEVMODE);
        pdm = NULL;
    }

cleanup:
    if (pldev)
        LDEVOBJ_vDereference(pldev);

    *ppdm = pdm;
    return cbSize;
}

BOOL
LDEVOBJ_bBuildDevmodeList(
    _Inout_ PGRAPHICS_DEVICE pGraphicsDevice)
{
    PWSTR pwsz;
    PDEVMODEINFO pdminfo;
    PDEVMODEW pdm, pdmEnd;
    ULONG i, cModes = 0;
    ULONG cbSize, cbFull;

    if (pGraphicsDevice->pdevmodeInfo)
        return TRUE;
    ASSERT(pGraphicsDevice->pDevModeList == NULL);

    pwsz = pGraphicsDevice->pDiplayDrivers;

    /* Loop through the driver names
     * This is a REG_MULTI_SZ string */
    for (; *pwsz; pwsz += wcslen(pwsz) + 1)
    {
        /* Get the mode list from the driver */
        TRACE("Trying driver: %ls\n", pwsz);
        cbSize = LDEVOBJ_ulGetDriverModes(pwsz, pGraphicsDevice->DeviceObject, &pdm);
        if (!cbSize)
        {
            WARN("Driver %ls returned no valid mode\n", pwsz);
            continue;
        }

        /* Add space for the header */
        cbFull = cbSize + FIELD_OFFSET(DEVMODEINFO, adevmode);

        /* Allocate a buffer for the DEVMODE array */
        pdminfo = ExAllocatePoolWithTag(PagedPool, cbFull, GDITAG_DEVMODE);
        if (!pdminfo)
        {
            ERR("Could not allocate devmodeinfo\n");
            ExFreePoolWithTag(pdm, GDITAG_DEVMODE);
            continue;
        }

        pdminfo->cbdevmode = cbSize;
        RtlCopyMemory(pdminfo->adevmode, pdm, cbSize);
        ExFreePoolWithTag(pdm, GDITAG_DEVMODE);

        /* Attach the mode info to the device */
        pdminfo->pdmiNext = pGraphicsDevice->pdevmodeInfo;
        pGraphicsDevice->pdevmodeInfo = pdminfo;

        /* Loop all DEVMODEs */
        pdmEnd = (DEVMODEW*)((PCHAR)pdminfo->adevmode + pdminfo->cbdevmode);
        for (pdm = pdminfo->adevmode;
             (pdm + 1 <= pdmEnd) && (pdm->dmSize != 0);
             pdm = (DEVMODEW*)((PCHAR)pdm + pdm->dmSize + pdm->dmDriverExtra))
        {
            /* Count this DEVMODE */
            cModes++;

            /* Some drivers like the VBox driver don't fill the dmDeviceName
               with the name of the display driver. So fix that here. */
            RtlStringCbCopyW(pdm->dmDeviceName, sizeof(pdm->dmDeviceName), pwsz);
        }
    }

    if (!pGraphicsDevice->pdevmodeInfo || cModes == 0)
    {
        ERR("No devmodes\n");
        return FALSE;
    }

    /* Allocate an index buffer */
    pGraphicsDevice->cDevModes = cModes;
    pGraphicsDevice->pDevModeList = ExAllocatePoolWithTag(PagedPool,
                                                          cModes * sizeof(DEVMODEENTRY),
                                                          GDITAG_GDEVICE);
    if (!pGraphicsDevice->pDevModeList)
    {
        ERR("No devmode list\n");
        return FALSE;
    }

    /* Loop through all DEVMODEINFOs */
    for (pdminfo = pGraphicsDevice->pdevmodeInfo, i = 0;
         pdminfo;
         pdminfo = pdminfo->pdmiNext)
    {
        /* Calculate End of the DEVMODEs */
        pdmEnd = (DEVMODEW*)((PCHAR)pdminfo->adevmode + pdminfo->cbdevmode);

        /* Loop through the DEVMODEs */
        for (pdm = pdminfo->adevmode;
             (pdm + 1 <= pdmEnd) && (pdm->dmSize != 0);
             pdm = (PDEVMODEW)((PCHAR)pdm + pdm->dmSize + pdm->dmDriverExtra))
        {
            TRACE("    %S has mode %lux%lux%lu(%lu Hz)\n",
                  pdm->dmDeviceName,
                  pdm->dmPelsWidth,
                  pdm->dmPelsHeight,
                  pdm->dmBitsPerPel,
                  pdm->dmDisplayFrequency);

            /* Initialize the entry */
            pGraphicsDevice->pDevModeList[i].dwFlags = 0;
            pGraphicsDevice->pDevModeList[i].pdm = pdm;
            i++;
        }
    }
    return TRUE;
}

/* Search the closest display mode according to some settings.
 * Note that we don't care about the DM_* flags in dmFields, but check if value != 0 instead */
static
BOOL
LDEVOBJ_bGetClosestMode(
    _Inout_ PGRAPHICS_DEVICE pGraphicsDevice,
    _In_ PDEVMODEW RequestedMode,
    _Out_ PDEVMODEW *pSelectedMode)
{
    DEVMODEW dmDiff;
    PDEVMODEW pdmCurrent, pdmBest = NULL;
    ULONG i;

    /* Use a DEVMODE to keep the differences between best mode found and expected mode.
     * Initialize fields to max value so we can find better modes. */
    dmDiff.dmPelsWidth = 0xffffffff;
    dmDiff.dmPelsHeight = 0xffffffff;
    dmDiff.dmBitsPerPel = 0xffffffff;
    dmDiff.dmDisplayFrequency = 0xffffffff;

    /* Search the closest mode */
#define DM_DIFF(field) (RequestedMode->field > pdmCurrent->field ? (RequestedMode->field - pdmCurrent->field) : (pdmCurrent->field - RequestedMode->field))
    for (i = 0; i < pGraphicsDevice->cDevModes; i++)
    {
        pdmCurrent = pGraphicsDevice->pDevModeList[i].pdm;

        /* Skip current mode if it is worse than best mode found */
        if (RequestedMode->dmPelsWidth != 0 && DM_DIFF(dmPelsWidth) > dmDiff.dmPelsWidth)
            continue;
        if (RequestedMode->dmPelsHeight != 0 && DM_DIFF(dmPelsHeight) > dmDiff.dmPelsHeight)
            continue;
        if (RequestedMode->dmBitsPerPel != 0 && DM_DIFF(dmBitsPerPel) > dmDiff.dmBitsPerPel)
            continue;
        if (RequestedMode->dmDisplayFrequency != 0 && DM_DIFF(dmDisplayFrequency) > dmDiff.dmDisplayFrequency)
            continue;

        /* Better (or equivalent) mode found. Update differences */
        dmDiff.dmPelsWidth = DM_DIFF(dmPelsWidth);
        dmDiff.dmPelsHeight = DM_DIFF(dmPelsHeight);
        dmDiff.dmBitsPerPel = DM_DIFF(dmBitsPerPel);
        dmDiff.dmDisplayFrequency = DM_DIFF(dmDisplayFrequency);
        pdmBest = pdmCurrent;
    }
#undef DM_DIFF

    if (pdmBest)
    {
        TRACE("Closest display mode to '%dx%dx%d %d Hz' is '%dx%dx%d %d Hz'\n",
              RequestedMode->dmPelsWidth,
              RequestedMode->dmPelsHeight,
              RequestedMode->dmBitsPerPel,
              RequestedMode->dmDisplayFrequency,
              pdmBest->dmPelsWidth,
              pdmBest->dmPelsHeight,
              pdmBest->dmBitsPerPel,
              pdmBest->dmDisplayFrequency);
    }

    *pSelectedMode = pdmBest;
    return pdmBest != NULL;
}

BOOL
LDEVOBJ_bProbeAndCaptureDevmode(
    _Inout_ PGRAPHICS_DEVICE pGraphicsDevice,
    _In_ PDEVMODEW RequestedMode,
    _Out_ PDEVMODEW *pSelectedMode,
    _In_ BOOL bSearchClosestMode)
{
    DEVMODEW dmSearch;
    PDEVMODEW pdmCurrent, pdm, pdmSelected = NULL;
    ULONG i;
    ULONG ulVirtualWidth = 0, ulVirtualHeight = 0;
    BOOL bResult = TRUE;
    NTSTATUS Status;

    if (!LDEVOBJ_bBuildDevmodeList(pGraphicsDevice))
        return FALSE;

    /* At first, load information from registry */
    RtlZeroMemory(&dmSearch, sizeof(dmSearch));
    Status = EngpGetDisplayDriverParameters(pGraphicsDevice, &dmSearch);
    if (!NT_SUCCESS(Status))
    {
        ERR("EngpGetDisplayDriverParameters() failed with status 0x%08x\n", Status);
        return FALSE;
    }

    /* Override values with the new ones provided */

    _SEH2_TRY
    {
        bSearchClosestMode |= RequestedMode->dmFields == 0;

        /* Copy standard fields (if provided) */
        if (RequestedMode->dmFields & DM_BITSPERPEL && RequestedMode->dmBitsPerPel != 0)
            dmSearch.dmBitsPerPel = RequestedMode->dmBitsPerPel;
        if (RequestedMode->dmFields & DM_PELSWIDTH && RequestedMode->dmPelsWidth != 0)
            dmSearch.dmPelsWidth = RequestedMode->dmPelsWidth;
        if (RequestedMode->dmFields & DM_PELSHEIGHT && RequestedMode->dmPelsHeight != 0)
            dmSearch.dmPelsHeight = RequestedMode->dmPelsHeight;
        if (RequestedMode->dmFields & DM_DISPLAYFREQUENCY && RequestedMode->dmDisplayFrequency != 0)
            dmSearch.dmDisplayFrequency = RequestedMode->dmDisplayFrequency;

        if ((RequestedMode->dmFields & (DM_PANNINGWIDTH | DM_PANNINGHEIGHT)) == (DM_PANNINGWIDTH | DM_PANNINGHEIGHT) &&
            RequestedMode->dmPanningWidth != 0 && RequestedMode->dmPanningHeight != 0 &&
            RequestedMode->dmPanningWidth < dmSearch.dmPelsWidth &&
            RequestedMode->dmPanningHeight < dmSearch.dmPelsHeight)
        {
            /* Get new panning values */
            ulVirtualWidth = RequestedMode->dmPelsWidth;
            ulVirtualHeight = RequestedMode->dmPelsHeight;
            dmSearch.dmPelsWidth = RequestedMode->dmPanningWidth;
            dmSearch.dmPelsHeight = RequestedMode->dmPanningHeight;
        }
        else if (dmSearch.dmPanningWidth != 0 && dmSearch.dmPanningHeight != 0 &&
                 dmSearch.dmPanningWidth < dmSearch.dmPelsWidth &&
                 dmSearch.dmPanningHeight < dmSearch.dmPelsHeight)
        {
            /* Keep existing panning values */
            ulVirtualWidth = dmSearch.dmPelsWidth;
            ulVirtualHeight = dmSearch.dmPelsHeight;
            dmSearch.dmPelsWidth = dmSearch.dmPanningWidth;
            dmSearch.dmPelsHeight = dmSearch.dmPanningHeight;
        }
    }
    _SEH2_EXCEPT(EXCEPTION_EXECUTE_HANDLER)
    {
        bResult = FALSE;
    }
    _SEH2_END;

    if (!bResult)
        return FALSE;

    if (bSearchClosestMode)
    {
        if (LDEVOBJ_bGetClosestMode(pGraphicsDevice, &dmSearch, &pdmSelected))
        {
            /* Ok, found a closest mode. Update search */
            dmSearch.dmBitsPerPel = pdmSelected->dmBitsPerPel;
            dmSearch.dmPelsWidth = pdmSelected->dmPelsWidth;
            dmSearch.dmPelsHeight = pdmSelected->dmPelsHeight;
            dmSearch.dmDisplayFrequency = pdmSelected->dmDisplayFrequency;
        }
    }

    /* Now, search the exact mode to return to caller */
    for (i = 0; i < pGraphicsDevice->cDevModes; i++)
    {
        pdmCurrent = pGraphicsDevice->pDevModeList[i].pdm;

        /* For now, we only need those */
        if (pdmCurrent->dmBitsPerPel != dmSearch.dmBitsPerPel)
            continue;
        if (pdmCurrent->dmPelsWidth != dmSearch.dmPelsWidth)
            continue;
        if (pdmCurrent->dmPelsHeight != dmSearch.dmPelsHeight)
            continue;
        if (pdmCurrent->dmDisplayFrequency != dmSearch.dmDisplayFrequency)
            continue;

        pdmSelected = pdmCurrent;
        break;
    }

    if (!pdmSelected)
    {
        ERR("Requested mode not found (%dx%dx%d %d Hz)\n",
            dmSearch.dmPelsWidth,
            dmSearch.dmPelsHeight,
            dmSearch.dmBitsPerPel,
            dmSearch.dmDisplayFrequency);
        return FALSE;
    }

    /* Allocate memory for output */
    pdm = ExAllocatePoolZero(PagedPool, pdmSelected->dmSize + pdmSelected->dmDriverExtra, GDITAG_DEVMODE);
    if (!pdm)
        return FALSE;

    /* Copy selected mode */
    RtlCopyMemory(pdm, pdmSelected, pdmSelected->dmSize);
    RtlCopyMemory((PVOID)((ULONG_PTR)pdm + pdm->dmSize),
                  (PVOID)((ULONG_PTR)pdmSelected + pdmSelected->dmSize),
                  pdmSelected->dmDriverExtra);

    /* Add back panning */
    if (ulVirtualWidth != 0 && ulVirtualHeight != 0 &&
        pdm->dmPelsWidth < ulVirtualWidth &&
        pdm->dmPelsHeight < ulVirtualHeight)
    {
        pdm->dmFields |= DM_PANNINGWIDTH | DM_PANNINGHEIGHT;
        pdm->dmPanningWidth = pdm->dmPelsWidth;
        pdm->dmPanningHeight = pdm->dmPelsHeight;
        pdm->dmPelsWidth = ulVirtualWidth;
        pdm->dmPelsHeight = ulVirtualHeight;
    }

    *pSelectedMode = pdm;
    return TRUE;
}

/** Exported functions ********************************************************/

HANDLE
APIENTRY
EngLoadImage(
    _In_ LPWSTR pwszDriverName)
{
    return (HANDLE)LDEVOBJ_pLoadDriver(pwszDriverName, LDEV_IMAGE);
}


VOID
APIENTRY
EngUnloadImage(
    _In_ HANDLE hModule)
{
    PLDEVOBJ pldev = (PLDEVOBJ)hModule;

    /* Make sure the LDEV is in the list */
    ASSERT((pldev->leLink.Flink != NULL) &&  (pldev->leLink.Blink != NULL));

    LDEVOBJ_vDereference(pldev);
}


PVOID
APIENTRY
EngFindImageProcAddress(
    _In_ HANDLE hModule,
    _In_ LPSTR  lpProcName)
{
    PLDEVOBJ pldev = (PLDEVOBJ)hModule;

    ASSERT(gpldevWin32k != NULL);

    /* Check if win32k is requested */
    if (!pldev)
    {
        pldev = gpldevWin32k;
    }

    /* Check if the drivers entry point is requested */
    if (_strnicmp(lpProcName, "DrvEnableDriver", 15) == 0)
    {
        return pldev->pGdiDriverInfo->EntryPoint;
    }

    /* Try to find the address */
    return LDEVOBJ_pvFindImageProcAddress(pldev, lpProcName);
}

/* EOF */