fcb.c

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/*
* FILE:             drivers/fs/vfat/fcb.c
* PURPOSE:          Routines to manipulate FCBs.
* COPYRIGHT:        See COPYING in the top level directory
* PROJECT:          ReactOS kernel
* PROGRAMMER:       Jason Filby (jasonfilby@yahoo.com)
*                   Rex Jolliff (rex@lvcablemodem.com)
*                   Herve Poussineau (reactos@poussine.freesurf.fr)
*/

/*  -------------------------------------------------------  INCLUDES  */

#ifdef __GNUC__
#include <wctype.h> /* towlower prototype */
#endif

#define NDEBUG
#include "vfat.h"

/*  --------------------------------------------------------  DEFINES  */

#define TAG_FCB 'BCFV'

/*  --------------------------------------------------------  PUBLICS  */

static ULONG vfatNameHash(ULONG hash, PUNICODE_STRING NameU)
{
    PWCHAR last;
    PWCHAR curr;
    register WCHAR c;

    // LFN could start from "."
    //ASSERT(NameU->Buffer[0] != L'.');
    curr = NameU->Buffer;
    last = NameU->Buffer + NameU->Length / sizeof(WCHAR);

    while(curr < last)
    {
        c = towlower(*curr++);
        hash = (hash + (c << 4) + (c >> 4)) * 11;
    }
    return hash;
}

VOID
vfatSplitPathName(PUNICODE_STRING PathNameU, PUNICODE_STRING DirNameU, PUNICODE_STRING FileNameU)
{
    PWCHAR pName;
    USHORT Length = 0;
    pName = PathNameU->Buffer + PathNameU->Length / sizeof(WCHAR) - 1;
    while (*pName != L'\\' && pName >= PathNameU->Buffer)
    {
        pName--;
        Length++;
    }
    ASSERT(*pName == L'\\' || pName < PathNameU->Buffer);
    if (FileNameU)
    {
        FileNameU->Buffer = pName + 1;
        FileNameU->Length = FileNameU->MaximumLength = Length * sizeof(WCHAR);
    }
    if (DirNameU)
    {
        DirNameU->Buffer = PathNameU->Buffer;
        DirNameU->Length = (pName + 1 - PathNameU->Buffer) * sizeof(WCHAR);
        DirNameU->MaximumLength = DirNameU->Length;
    }
}

static VOID
vfatInitFcb(PVFATFCB Fcb, PUNICODE_STRING NameU)
{
    USHORT PathNameBufferLength;

    if (NameU)
        PathNameBufferLength = NameU->Length + sizeof(WCHAR);
    else
        PathNameBufferLength = 0;

    Fcb->PathNameBuffer = ExAllocatePoolWithTag(NonPagedPool, PathNameBufferLength, TAG_FCB);
    if (!Fcb->PathNameBuffer)
    {
        /* FIXME: what to do if no more memory? */
        DPRINT1("Unable to initialize FCB for filename '%wZ'\n", NameU);
        KeBugCheckEx(FAT_FILE_SYSTEM, (ULONG_PTR)Fcb, (ULONG_PTR)NameU, 0, 0);
    }

    Fcb->PathNameU.Length = 0;
    Fcb->PathNameU.Buffer = Fcb->PathNameBuffer;
    Fcb->PathNameU.MaximumLength = PathNameBufferLength;
    Fcb->ShortNameU.Length = 0;
    Fcb->ShortNameU.Buffer = Fcb->ShortNameBuffer;
    Fcb->ShortNameU.MaximumLength = sizeof(Fcb->ShortNameBuffer);
    Fcb->DirNameU.Buffer = Fcb->PathNameU.Buffer;
    if (NameU && NameU->Length)
    {
        RtlCopyUnicodeString(&Fcb->PathNameU, NameU);
        vfatSplitPathName(&Fcb->PathNameU, &Fcb->DirNameU, &Fcb->LongNameU);
    }
    else
    {
        Fcb->DirNameU.Buffer = Fcb->LongNameU.Buffer = NULL;
        Fcb->DirNameU.MaximumLength = Fcb->DirNameU.Length = 0;
        Fcb->LongNameU.MaximumLength = Fcb->LongNameU.Length = 0;
    }
    RtlZeroMemory(&Fcb->FCBShareAccess, sizeof(SHARE_ACCESS));
    Fcb->OpenHandleCount = 0;
}

PVFATFCB
vfatNewFCB(PDEVICE_EXTENSION  pVCB, PUNICODE_STRING pFileNameU)
{
    PVFATFCB  rcFCB;

    DPRINT("'%wZ'\n", pFileNameU);

    rcFCB = ExAllocateFromNPagedLookasideList(&VfatGlobalData->FcbLookasideList);
    if (rcFCB == NULL)
    {
        return NULL;
    }
    RtlZeroMemory(rcFCB, sizeof(VFATFCB));
    vfatInitFcb(rcFCB, pFileNameU);
    if (pVCB->Flags & VCB_IS_FATX)
    {
        rcFCB->Flags |= FCB_IS_FATX_ENTRY;
        rcFCB->Attributes = &rcFCB->entry.FatX.Attrib;
    }
    else
        rcFCB->Attributes = &rcFCB->entry.Fat.Attrib;
    rcFCB->Hash.Hash = vfatNameHash(0, &rcFCB->PathNameU);
    rcFCB->Hash.self = rcFCB;
    rcFCB->ShortHash.self = rcFCB;
    ExInitializeResourceLite(&rcFCB->PagingIoResource);
    ExInitializeResourceLite(&rcFCB->MainResource);
    FsRtlInitializeFileLock(&rcFCB->FileLock, NULL, NULL);
    ExInitializeFastMutex(&rcFCB->LastMutex);
    rcFCB->RFCB.PagingIoResource = &rcFCB->PagingIoResource;
    rcFCB->RFCB.Resource = &rcFCB->MainResource;
    rcFCB->RFCB.IsFastIoPossible = FastIoIsNotPossible;

    return  rcFCB;
}

VOID
vfatDestroyCCB(PVFATCCB pCcb)
{
    if (pCcb->SearchPattern.Buffer)
    {
        ExFreePool(pCcb->SearchPattern.Buffer);
    }
    ExFreeToNPagedLookasideList(&VfatGlobalData->CcbLookasideList, pCcb);
}

VOID
vfatDestroyFCB(PVFATFCB pFCB)
{
    FsRtlUninitializeFileLock(&pFCB->FileLock);
    ExFreePool(pFCB->PathNameBuffer);
    ExDeleteResourceLite(&pFCB->PagingIoResource);
    ExDeleteResourceLite(&pFCB->MainResource);
    ExFreeToNPagedLookasideList(&VfatGlobalData->FcbLookasideList, pFCB);
}

BOOLEAN
vfatFCBIsDirectory(PVFATFCB FCB)
{
    return  *FCB->Attributes & FILE_ATTRIBUTE_DIRECTORY;
}

BOOLEAN
vfatFCBIsRoot(PVFATFCB FCB)
{
    return  FCB->PathNameU.Length == sizeof(WCHAR) && FCB->PathNameU.Buffer[0] == L'\\' ? TRUE : FALSE;
}

VOID
vfatReleaseFCB(PDEVICE_EXTENSION  pVCB,  PVFATFCB  pFCB)
{
    HASHENTRY* entry;
    ULONG Index;
    ULONG ShortIndex;
    PVFATFCB tmpFcb;

    DPRINT ("releasing FCB at %p: %wZ, refCount:%d\n",
        pFCB,
        &pFCB->PathNameU,
        pFCB->RefCount);

    while (pFCB)
    {
        Index = pFCB->Hash.Hash % pVCB->HashTableSize;
        ShortIndex = pFCB->ShortHash.Hash % pVCB->HashTableSize;
        pFCB->RefCount--;
        if (pFCB->RefCount == 0)
        {
            tmpFcb = pFCB->parentFcb;
            RemoveEntryList (&pFCB->FcbListEntry);
            if (pFCB->Hash.Hash != pFCB->ShortHash.Hash)
            {
                entry = pVCB->FcbHashTable[ShortIndex];
                if (entry->self == pFCB)
                {
                    pVCB->FcbHashTable[ShortIndex] = entry->next;
                }
                else
                {
                    while (entry->next->self != pFCB)
                    {
                        entry = entry->next;
                    }
                    entry->next = pFCB->ShortHash.next;
                }
            }
            entry = pVCB->FcbHashTable[Index];
            if (entry->self == pFCB)
            {
                pVCB->FcbHashTable[Index] = entry->next;
            }
            else
            {
                while (entry->next->self != pFCB)
                {
                    entry = entry->next;
                }
                entry->next = pFCB->Hash.next;
            }
            vfatDestroyFCB (pFCB);
        }
        else
        {
            tmpFcb = NULL;
        }
        pFCB = tmpFcb;
    }
}

VOID
vfatAddFCBToTable(PDEVICE_EXTENSION  pVCB,  PVFATFCB  pFCB)
{
    ULONG Index;
    ULONG ShortIndex;

    Index = pFCB->Hash.Hash % pVCB->HashTableSize;
    ShortIndex = pFCB->ShortHash.Hash % pVCB->HashTableSize;

    InsertTailList (&pVCB->FcbListHead, &pFCB->FcbListEntry);

    pFCB->Hash.next = pVCB->FcbHashTable[Index];
    pVCB->FcbHashTable[Index] = &pFCB->Hash;
    if (pFCB->Hash.Hash != pFCB->ShortHash.Hash)
    {
        pFCB->ShortHash.next = pVCB->FcbHashTable[ShortIndex];
        pVCB->FcbHashTable[ShortIndex] = &pFCB->ShortHash;
    }
    if (pFCB->parentFcb)
    {
        pFCB->parentFcb->RefCount++;
    }
}

PVFATFCB
vfatGrabFCBFromTable(PDEVICE_EXTENSION  pVCB, PUNICODE_STRING  PathNameU)
{
    PVFATFCB  rcFCB;
    ULONG Hash;
    UNICODE_STRING DirNameU;
    UNICODE_STRING FileNameU;
    PUNICODE_STRING FcbNameU;

    HASHENTRY* entry;

    DPRINT("'%wZ'\n", PathNameU);

    Hash = vfatNameHash(0, PathNameU);

    entry = pVCB->FcbHashTable[Hash % pVCB->HashTableSize];
    if (entry)
    {
        vfatSplitPathName(PathNameU, &DirNameU, &FileNameU);
    }

    while (entry)
    {
        if (entry->Hash == Hash)
        {
            rcFCB = entry->self;
            DPRINT("'%wZ' '%wZ'\n", &DirNameU, &rcFCB->DirNameU);
            if (RtlEqualUnicodeString(&DirNameU, &rcFCB->DirNameU, TRUE))
            {
                if (rcFCB->Hash.Hash == Hash)
                {
                    FcbNameU = &rcFCB->LongNameU;
                }
                else
                {
                    FcbNameU = &rcFCB->ShortNameU;
                }
                /* compare the file name */
                DPRINT("'%wZ' '%wZ'\n", &FileNameU, FcbNameU);
                if (RtlEqualUnicodeString(&FileNameU, FcbNameU, TRUE))
                {
                    rcFCB->RefCount++;
                    return rcFCB;
                }
            }
        }
        entry = entry->next;
    }
    return  NULL;
}

static NTSTATUS
vfatFCBInitializeCacheFromVolume (PVCB  vcb, PVFATFCB  fcb)
{
    PFILE_OBJECT  fileObject;
    PVFATCCB  newCCB;

    fileObject = IoCreateStreamFileObject (NULL, vcb->StorageDevice);

    newCCB = ExAllocateFromNPagedLookasideList(&VfatGlobalData->CcbLookasideList);
    if (newCCB == NULL)
    {
        return  STATUS_INSUFFICIENT_RESOURCES;
    }
    RtlZeroMemory(newCCB, sizeof (VFATCCB));

    fileObject->SectionObjectPointer = &fcb->SectionObjectPointers;
    fileObject->FsContext = fcb;
    fileObject->FsContext2 = newCCB;
    fcb->FileObject = fileObject;
    fcb->RefCount++;

    CcInitializeCacheMap(fileObject,
        (PCC_FILE_SIZES)(&fcb->RFCB.AllocationSize),
        TRUE,
        &VfatGlobalData->CacheMgrCallbacks,
        fcb);

    fcb->Flags |= FCB_CACHE_INITIALIZED;
    return STATUS_SUCCESS;
}

PVFATFCB
vfatMakeRootFCB(PDEVICE_EXTENSION  pVCB)
{
    PVFATFCB  FCB;
    ULONG FirstCluster, CurrentCluster, Size = 0;
    NTSTATUS Status = STATUS_SUCCESS;
    UNICODE_STRING NameU = RTL_CONSTANT_STRING(L"\\");

    FCB = vfatNewFCB(pVCB, &NameU);
    if (FCB->Flags & FCB_IS_FATX_ENTRY)
    {
        memset(FCB->entry.FatX.Filename, ' ', 42);
        FCB->entry.FatX.FileSize = pVCB->FatInfo.rootDirectorySectors * pVCB->FatInfo.BytesPerSector;
        FCB->entry.FatX.Attrib = FILE_ATTRIBUTE_DIRECTORY;
        FCB->entry.FatX.FirstCluster = 1;
        Size = pVCB->FatInfo.rootDirectorySectors * pVCB->FatInfo.BytesPerSector;
    }
    else
    {
        memset(FCB->entry.Fat.ShortName, ' ', 11);
        FCB->entry.Fat.FileSize = pVCB->FatInfo.rootDirectorySectors * pVCB->FatInfo.BytesPerSector;
        FCB->entry.Fat.Attrib = FILE_ATTRIBUTE_DIRECTORY;
        if (pVCB->FatInfo.FatType == FAT32)
        {
            CurrentCluster = FirstCluster = pVCB->FatInfo.RootCluster;
            FCB->entry.Fat.FirstCluster = (unsigned short)(FirstCluster & 0xffff);
            FCB->entry.Fat.FirstClusterHigh = (unsigned short)(FirstCluster >> 16);

            while (CurrentCluster != 0xffffffff && NT_SUCCESS(Status))
            {
                Size += pVCB->FatInfo.BytesPerCluster;
                Status = NextCluster (pVCB, FirstCluster, &CurrentCluster, FALSE);
            }
        }
        else
        {
            FCB->entry.Fat.FirstCluster = 1;
            Size = pVCB->FatInfo.rootDirectorySectors * pVCB->FatInfo.BytesPerSector;
        }
    }
    FCB->ShortHash.Hash = FCB->Hash.Hash;
    FCB->RefCount = 2;
    FCB->dirIndex = 0;
    FCB->RFCB.FileSize.QuadPart = Size;
    FCB->RFCB.ValidDataLength.QuadPart = Size;
    FCB->RFCB.AllocationSize.QuadPart = Size;
    FCB->RFCB.IsFastIoPossible = FastIoIsNotPossible;

    vfatFCBInitializeCacheFromVolume(pVCB, FCB);
    vfatAddFCBToTable(pVCB, FCB);

    return(FCB);
}

PVFATFCB
vfatOpenRootFCB(PDEVICE_EXTENSION  pVCB)
{
    PVFATFCB  FCB;
    UNICODE_STRING NameU = RTL_CONSTANT_STRING(L"\\");

    FCB = vfatGrabFCBFromTable (pVCB, &NameU);
    if (FCB == NULL)
    {
        FCB = vfatMakeRootFCB (pVCB);
    }

    return  FCB;
}

NTSTATUS
vfatMakeFCBFromDirEntry(
    PVCB  vcb,
    PVFATFCB  directoryFCB,
    PVFAT_DIRENTRY_CONTEXT DirContext,
    PVFATFCB* fileFCB)
{
    PVFATFCB  rcFCB;
    PWCHAR PathNameBuffer;
    USHORT PathNameLength;
    ULONG Size;
    ULONG hash;

    UNICODE_STRING NameU;

    PathNameLength = directoryFCB->PathNameU.Length + max(DirContext->LongNameU.Length, DirContext->ShortNameU.Length);
    if (!vfatFCBIsRoot (directoryFCB))
    {
        PathNameLength += sizeof(WCHAR);
    }

    if (PathNameLength > LONGNAME_MAX_LENGTH * sizeof(WCHAR))
    {
        return  STATUS_OBJECT_NAME_INVALID;
    }
    PathNameBuffer = ExAllocatePoolWithTag(NonPagedPool, PathNameLength + sizeof(WCHAR), TAG_FCB);
    if (!PathNameBuffer)
    {
        return STATUS_INSUFFICIENT_RESOURCES;
    }
    NameU.Buffer = PathNameBuffer;
    NameU.Length = 0;
    NameU.MaximumLength = PathNameLength;

    RtlCopyUnicodeString(&NameU, &directoryFCB->PathNameU);
    if (!vfatFCBIsRoot (directoryFCB))
    {
        RtlAppendUnicodeToString(&NameU, L"\\");
    }
    hash = vfatNameHash(0, &NameU);
    if (DirContext->LongNameU.Length > 0)
    {
        RtlAppendUnicodeStringToString(&NameU, &DirContext->LongNameU);
    }
    else
    {
        RtlAppendUnicodeStringToString(&NameU, &DirContext->ShortNameU);
    }
    NameU.Buffer[NameU.Length / sizeof(WCHAR)] = 0;

    rcFCB = vfatNewFCB (vcb, &NameU);
    RtlCopyMemory (&rcFCB->entry, &DirContext->DirEntry, sizeof (DIR_ENTRY));
    RtlCopyUnicodeString(&rcFCB->ShortNameU, &DirContext->ShortNameU);
    if (vcb->Flags & VCB_IS_FATX)
    {
        rcFCB->ShortHash.Hash = rcFCB->Hash.Hash;
    }
    else
    {
        rcFCB->ShortHash.Hash = vfatNameHash(hash, &rcFCB->ShortNameU);
    }

    if (vfatFCBIsDirectory(rcFCB))
    {
        ULONG FirstCluster, CurrentCluster;
        NTSTATUS Status = STATUS_SUCCESS;
        Size = 0;
        FirstCluster = vfatDirEntryGetFirstCluster (vcb, &rcFCB->entry);
        if (FirstCluster == 1)
        {
            Size = vcb->FatInfo.rootDirectorySectors * vcb->FatInfo.BytesPerSector;
        }
        else if (FirstCluster != 0)
        {
            CurrentCluster = FirstCluster;
            while (CurrentCluster != 0xffffffff && NT_SUCCESS(Status))
            {
                Size += vcb->FatInfo.BytesPerCluster;
                Status = NextCluster (vcb, FirstCluster, &CurrentCluster, FALSE);
            }
        }
    }
    else if (rcFCB->Flags & FCB_IS_FATX_ENTRY)
    {
        Size = rcFCB->entry.FatX.FileSize;
    }
    else
    {
        Size = rcFCB->entry.Fat.FileSize;
    }
    rcFCB->dirIndex = DirContext->DirIndex;
    rcFCB->startIndex = DirContext->StartIndex;
    if ((rcFCB->Flags & FCB_IS_FATX_ENTRY) && !vfatFCBIsRoot (directoryFCB))
    {
        ASSERT(DirContext->DirIndex >= 2 && DirContext->StartIndex >= 2);
        rcFCB->dirIndex = DirContext->DirIndex-2;
        rcFCB->startIndex = DirContext->StartIndex-2;
    }
    rcFCB->RFCB.FileSize.QuadPart = Size;
    rcFCB->RFCB.ValidDataLength.QuadPart = Size;
    rcFCB->RFCB.AllocationSize.QuadPart = ROUND_UP(Size, vcb->FatInfo.BytesPerCluster);
    rcFCB->RefCount++;
    if (vfatFCBIsDirectory(rcFCB))
    {
        vfatFCBInitializeCacheFromVolume(vcb, rcFCB);
    }
    rcFCB->parentFcb = directoryFCB;
    vfatAddFCBToTable (vcb, rcFCB);
    *fileFCB = rcFCB;

    ExFreePool(PathNameBuffer);
    return  STATUS_SUCCESS;
}

NTSTATUS
vfatAttachFCBToFileObject (
    PDEVICE_EXTENSION  vcb,
    PVFATFCB  fcb,
    PFILE_OBJECT  fileObject)
{
    PVFATCCB  newCCB;

    newCCB = ExAllocateFromNPagedLookasideList(&VfatGlobalData->CcbLookasideList);
    if (newCCB == NULL)
    {
        return  STATUS_INSUFFICIENT_RESOURCES;
    }
    RtlZeroMemory (newCCB, sizeof (VFATCCB));

    fileObject->SectionObjectPointer = &fcb->SectionObjectPointers;
    fileObject->FsContext = fcb;
    fileObject->FsContext2 = newCCB;
    DPRINT ("file open: fcb:%p PathName:%wZ\n", fcb, &fcb->PathNameU);

    return  STATUS_SUCCESS;
}

NTSTATUS
vfatDirFindFile (
    PDEVICE_EXTENSION  pDeviceExt,
    PVFATFCB  pDirectoryFCB,
    PUNICODE_STRING FileToFindU,
    PVFATFCB * pFoundFCB)
{
    NTSTATUS  status;
    PVOID Context = NULL;
    PVOID Page = NULL;
    BOOLEAN First = TRUE;
    VFAT_DIRENTRY_CONTEXT DirContext;
    /* This buffer must have a size of 260 characters, because
    vfatMakeFCBFromDirEntry can copy 20 name entries with 13 characters. */
    WCHAR LongNameBuffer[260];
    WCHAR ShortNameBuffer[13];
    BOOLEAN FoundLong = FALSE;
    BOOLEAN FoundShort = FALSE;

    ASSERT(pDeviceExt);
    ASSERT(pDirectoryFCB);
    ASSERT(FileToFindU);

    DPRINT ("vfatDirFindFile(VCB:%p, dirFCB:%p, File:%wZ)\n",
        pDeviceExt,
        pDirectoryFCB,
        FileToFindU);
    DPRINT ("Dir Path:%wZ\n", &pDirectoryFCB->PathNameU);

    DirContext.DirIndex = 0;
    DirContext.LongNameU.Buffer = LongNameBuffer;
    DirContext.LongNameU.Length = 0;
    DirContext.LongNameU.MaximumLength = sizeof(LongNameBuffer);
    DirContext.ShortNameU.Buffer = ShortNameBuffer;
    DirContext.ShortNameU.Length = 0;
    DirContext.ShortNameU.MaximumLength = sizeof(ShortNameBuffer);

    while (TRUE)
    {
        status = pDeviceExt->GetNextDirEntry(&Context,
            &Page,
            pDirectoryFCB,
            &DirContext,
            First);
        First = FALSE;
        if (status == STATUS_NO_MORE_ENTRIES)
        {
            return STATUS_OBJECT_NAME_NOT_FOUND;
        }
        if (!NT_SUCCESS(status))
        {
            return status;
        }

        DPRINT ("  Index:%d  longName:%wZ\n",
            DirContext.DirIndex,
            &DirContext.LongNameU);

        if (!ENTRY_VOLUME(pDeviceExt, &DirContext.DirEntry))
        {
            FoundLong = RtlEqualUnicodeString(FileToFindU, &DirContext.LongNameU, TRUE);
            if (FoundLong == FALSE)
            {
                FoundShort = RtlEqualUnicodeString(FileToFindU, &DirContext.ShortNameU, TRUE);
            }
            if (FoundLong || FoundShort)
            {
                status = vfatMakeFCBFromDirEntry (pDeviceExt,
                    pDirectoryFCB,
                    &DirContext,
                    pFoundFCB);
                CcUnpinData(Context);
                return  status;
            }
        }
        DirContext.DirIndex++;
    }

    return  STATUS_OBJECT_NAME_NOT_FOUND;
}

NTSTATUS
vfatGetFCBForFile (
    PDEVICE_EXTENSION  pVCB,
    PVFATFCB  *pParentFCB,
    PVFATFCB  *pFCB,
    PUNICODE_STRING pFileNameU)
{
    NTSTATUS  status;
    PVFATFCB  FCB = NULL;
    PVFATFCB  parentFCB;
    UNICODE_STRING NameU;
    UNICODE_STRING RootNameU = RTL_CONSTANT_STRING(L"\\");
        UNICODE_STRING FileNameU;
        WCHAR NameBuffer[260];
    PWCHAR curr, prev, last;
    ULONG Length;

    DPRINT ("vfatGetFCBForFile (%p,%p,%p,%wZ)\n",
        pVCB,
        pParentFCB,
        pFCB,
        pFileNameU);

        FileNameU.Buffer = NameBuffer;
        FileNameU.MaximumLength = sizeof(NameBuffer);
        RtlCopyUnicodeString(&FileNameU, pFileNameU);

    parentFCB = *pParentFCB;

    if (parentFCB == NULL)
    {
        //  Trivial case, open of the root directory on volume
        if (RtlEqualUnicodeString(&FileNameU, &RootNameU, FALSE))
        {
            DPRINT ("returning root FCB\n");

            FCB = vfatOpenRootFCB (pVCB);
            *pFCB = FCB;
            *pParentFCB = NULL;

            return  (FCB != NULL) ? STATUS_SUCCESS : STATUS_OBJECT_PATH_NOT_FOUND;
        }

        /* Check for an existing FCB */
        FCB = vfatGrabFCBFromTable (pVCB, &FileNameU);
        if (FCB)
        {
            *pFCB = FCB;
            *pParentFCB = FCB->parentFcb;
            (*pParentFCB)->RefCount++;
            return STATUS_SUCCESS;
        }

        last = curr = FileNameU.Buffer + FileNameU.Length / sizeof(WCHAR) - 1;
        while (*curr != L'\\' && curr > FileNameU.Buffer)
        {
            curr--;
        }

        if (curr > FileNameU.Buffer)
        {
            NameU.Buffer = FileNameU.Buffer;
            NameU.MaximumLength = NameU.Length = (curr - FileNameU.Buffer) * sizeof(WCHAR);
            FCB = vfatGrabFCBFromTable(pVCB, &NameU);
            if (FCB)
            {
                Length = (curr - FileNameU.Buffer) * sizeof(WCHAR);
                if (Length != FCB->PathNameU.Length)
                {
                    if (FileNameU.Length + FCB->PathNameU.Length - Length > FileNameU.MaximumLength)
                    {
                        vfatReleaseFCB (pVCB, FCB);
                        return STATUS_OBJECT_NAME_INVALID;
                    }
                    RtlMoveMemory(FileNameU.Buffer + FCB->PathNameU.Length / sizeof(WCHAR),
                        curr, FileNameU.Length - Length);
                    FileNameU.Length += (USHORT)(FCB->PathNameU.Length - Length);
                    curr = FileNameU.Buffer + FCB->PathNameU.Length / sizeof(WCHAR);
                    last = FileNameU.Buffer + FileNameU.Length / sizeof(WCHAR) - 1;
                }
                RtlCopyMemory(FileNameU.Buffer, FCB->PathNameU.Buffer, FCB->PathNameU.Length);
            }
        }
        else
        {
            FCB = NULL;
        }

        if (FCB == NULL)
        {
            FCB = vfatOpenRootFCB(pVCB);
            curr = FileNameU.Buffer;
        }

        parentFCB = NULL;
        prev = curr;
    }
    else
    {
        FCB = parentFCB;
        parentFCB = NULL;
        prev = curr = FileNameU.Buffer - 1;
        last = FileNameU.Buffer + FileNameU.Length / sizeof(WCHAR) - 1;
    }

    while (curr <= last)
    {
        if (parentFCB)
        {
            vfatReleaseFCB (pVCB, parentFCB);
            parentFCB = 0;
        }
        //  fail if element in FCB is not a directory
        if (!vfatFCBIsDirectory (FCB))
        {
            DPRINT ("Element in requested path is not a directory\n");

            vfatReleaseFCB (pVCB, FCB);
            FCB = NULL;
            *pParentFCB = NULL;
            *pFCB = NULL;

            return  STATUS_OBJECT_PATH_NOT_FOUND;
        }
        parentFCB = FCB;
        if (prev < curr)
        {
            Length = (curr - prev) * sizeof(WCHAR);
            if (Length != parentFCB->LongNameU.Length)
            {
                if (FileNameU.Length + parentFCB->LongNameU.Length - Length > FileNameU.MaximumLength)
                {
                    vfatReleaseFCB (pVCB, parentFCB);
                    return STATUS_OBJECT_NAME_INVALID;
                }
                RtlMoveMemory(prev + parentFCB->LongNameU.Length / sizeof(WCHAR), curr,
                    FileNameU.Length - (curr - FileNameU.Buffer) * sizeof(WCHAR));
                FileNameU.Length += (USHORT)(parentFCB->LongNameU.Length - Length);
                curr = prev + parentFCB->LongNameU.Length / sizeof(WCHAR);
                last = FileNameU.Buffer + FileNameU.Length / sizeof(WCHAR) - 1;
            }
            RtlCopyMemory(prev, parentFCB->LongNameU.Buffer, parentFCB->LongNameU.Length);
        }
        curr++;
        prev = curr;
        while (*curr != L'\\' && curr <= last)
        {
            curr++;
        }
        NameU.Buffer = FileNameU.Buffer;
        NameU.Length = (curr - NameU.Buffer) * sizeof(WCHAR);
        NameU.MaximumLength = FileNameU.MaximumLength;
        DPRINT("%wZ\n", &NameU);
        FCB = vfatGrabFCBFromTable(pVCB, &NameU);
        if (FCB == NULL)
        {
            NameU.Buffer = prev;
            NameU.MaximumLength = NameU.Length = (curr - prev) * sizeof(WCHAR);
            status = vfatDirFindFile(pVCB, parentFCB, &NameU, &FCB);
            if (status == STATUS_OBJECT_NAME_NOT_FOUND)
            {
                *pFCB = NULL;
                if (curr > last)
                {
                    *pParentFCB = parentFCB;
                    return  STATUS_OBJECT_NAME_NOT_FOUND;
                }
                else
                {
                    vfatReleaseFCB (pVCB, parentFCB);
                    *pParentFCB = NULL;
                    return  STATUS_OBJECT_PATH_NOT_FOUND;
                }
            }
            else if (!NT_SUCCESS (status))
            {
                vfatReleaseFCB (pVCB, parentFCB);
                *pParentFCB = NULL;
                *pFCB = NULL;

                return  status;
            }
        }
    }

    *pParentFCB = parentFCB;
    *pFCB = FCB;

    return  STATUS_SUCCESS;
}