rw.c

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/*
* COPYRIGHT:  See COPYING in the top level directory
* PROJECT:    ReactOS kernel
* FILE:       drivers/fs/np/rw.c
* PURPOSE:    Named pipe filesystem
* PROGRAMMER: David Welch <welch@cwcom.net>
*             Michael Martin
*/

/* INCLUDES ******************************************************************/

#include "npfs.h"

#define NDEBUG
#include <debug.h>

/* FUNCTIONS *****************************************************************/

VOID HexDump(PUCHAR Buffer, ULONG Length)
{
    CHAR Line[65];
    UCHAR ch;
    const char Hex[] = "0123456789ABCDEF";
    ULONG i, j;

    DbgPrint("---------------\n");

    for (i = 0; i < Length; i+= 16)
    {
        memset(Line, ' ', 64);
        Line[64] = 0;

        for (j = 0; j < 16 && j + i < Length; j++)
        {
            ch = Buffer[i + j];
            Line[3*j + 0] = Hex[ch >> 4];
            Line[3*j + 1] = Hex[ch & 0x0f];
            Line[48 + j] = isprint(ch) ? ch : '.';
        }
        DbgPrint("%s\n", Line);
    }
    DbgPrint("---------------\n");
}

static DRIVER_CANCEL NpfsReadWriteCancelRoutine;
static VOID NTAPI
NpfsReadWriteCancelRoutine(IN PDEVICE_OBJECT DeviceObject,
                           IN PIRP Irp)
{
    PNPFS_CONTEXT Context;
    PIO_STACK_LOCATION IoStack;
    PNPFS_VCB Vcb;
    PNPFS_CCB Ccb;
    PLIST_ENTRY ListEntry;
    PNPFS_THREAD_CONTEXT ThreadContext;
    ULONG i;

    DPRINT("NpfsReadWriteCancelRoutine(DeviceObject %p, Irp %p)\n", DeviceObject, Irp);

    IoReleaseCancelSpinLock(Irp->CancelIrql);

    Context = (PNPFS_CONTEXT)&Irp->Tail.Overlay.DriverContext;
    Vcb = (PNPFS_VCB)DeviceObject->DeviceExtension;
    IoStack = IoGetCurrentIrpStackLocation(Irp);
    Ccb = IoStack->FileObject->FsContext2;

    KeLockMutex(&Vcb->PipeListLock);
    ExAcquireFastMutex(&Ccb->DataListLock);
    switch(IoStack->MajorFunction)
    {
    case IRP_MJ_READ:
        ListEntry = Vcb->ThreadListHead.Flink;
        while (ListEntry != &Vcb->ThreadListHead)
        {
            ThreadContext = CONTAINING_RECORD(ListEntry, NPFS_THREAD_CONTEXT, ListEntry);
            /* Real events start at index 1 */
            for (i = 1; i < ThreadContext->Count; i++)
            {
                if (ThreadContext->WaitIrpArray[i] == Irp)
                {
                    ASSERT(ThreadContext->WaitObjectArray[i] == Context->WaitEvent);

                    ThreadContext->WaitIrpArray[i] = NULL;

                    RemoveEntryList(&Context->ListEntry);

                    Irp->IoStatus.Status = STATUS_CANCELLED;
                    Irp->IoStatus.Information = 0;

                    IoCompleteRequest(Irp, IO_NO_INCREMENT);

                    KeSetEvent(&ThreadContext->Event, IO_NO_INCREMENT, FALSE);

                    ExReleaseFastMutex(&Ccb->DataListLock);
                    KeUnlockMutex(&Vcb->PipeListLock);

                    return;
                }
            }
            ListEntry = ListEntry->Flink;
        }

        RemoveEntryList(&Context->ListEntry);

        ExReleaseFastMutex(&Ccb->DataListLock);
        KeUnlockMutex(&Vcb->PipeListLock);

        Irp->IoStatus.Status = STATUS_CANCELLED;
        Irp->IoStatus.Information = 0;

        IoCompleteRequest(Irp, IO_NO_INCREMENT);
        break;
    default:
        ASSERT(FALSE);
    }
}

static VOID NTAPI
NpfsWaiterThread(PVOID InitContext)
{
    PNPFS_THREAD_CONTEXT ThreadContext = (PNPFS_THREAD_CONTEXT) InitContext;
    ULONG CurrentCount;
    ULONG Count = 0, i;
    PIRP Irp = NULL;
    NTSTATUS Status;
    PIO_STACK_LOCATION IoStack = NULL;
    KIRQL OldIrql;

    KeLockMutex(&ThreadContext->Vcb->PipeListLock);

    while (1)
    {
        CurrentCount = ThreadContext->Count;
        KeUnlockMutex(&ThreadContext->Vcb->PipeListLock);
        IoAcquireCancelSpinLock(&OldIrql);
        if (Irp && IoSetCancelRoutine(Irp, NULL) != NULL)
        {
            IoReleaseCancelSpinLock(OldIrql);
            IoStack = IoGetCurrentIrpStackLocation(Irp);
            switch (IoStack->MajorFunction)
            {
                case IRP_MJ_READ:
                    NpfsRead(IoStack->DeviceObject, Irp);
                    break;
                default:
                    ASSERT(FALSE);
            }
        }
        else
        {
            IoReleaseCancelSpinLock(OldIrql);
        }
        Status = KeWaitForMultipleObjects(CurrentCount,
            ThreadContext->WaitObjectArray,
            WaitAny,
            Executive,
            KernelMode,
            FALSE,
            NULL,
            ThreadContext->WaitBlockArray);
        if (!NT_SUCCESS(Status))
        {
            ASSERT(FALSE);
        }
        KeLockMutex(&ThreadContext->Vcb->PipeListLock);
        Count = Status - STATUS_WAIT_0;
        ASSERT (Count < CurrentCount);
        if (Count > 0)
        {
            Irp = ThreadContext->WaitIrpArray[Count];
            ThreadContext->Count--;
            ThreadContext->Vcb->EmptyWaiterCount++;
            ThreadContext->WaitObjectArray[Count] = ThreadContext->WaitObjectArray[ThreadContext->Count];
            ThreadContext->WaitIrpArray[Count] = ThreadContext->WaitIrpArray[ThreadContext->Count];
        }
        else
        {
            /* someone has add a new wait request or cancelled an old one */
            Irp = NULL;

            /* Look for cancelled requests */
            for (i = 1; i < ThreadContext->Count; i++)
            {
                if (ThreadContext->WaitIrpArray[i] == NULL)
                {
                   ThreadContext->Count--;
                   ThreadContext->Vcb->EmptyWaiterCount++;
                   ThreadContext->WaitObjectArray[i] = ThreadContext->WaitObjectArray[ThreadContext->Count];
                   ThreadContext->WaitIrpArray[i] = ThreadContext->WaitIrpArray[ThreadContext->Count];
                }
            }
        }
        if (ThreadContext->Count == 1 && ThreadContext->Vcb->EmptyWaiterCount >= MAXIMUM_WAIT_OBJECTS)
        {
            /* it exist an other thread with empty wait slots, we can remove our thread from the list */
            RemoveEntryList(&ThreadContext->ListEntry);
            ExFreePoolWithTag(ThreadContext, TAG_NPFS_THREAD_CONTEXT);
            KeUnlockMutex(&ThreadContext->Vcb->PipeListLock);
            break;
        }
    }
}

static NTSTATUS
NpfsAddWaitingReadWriteRequest(IN PDEVICE_OBJECT DeviceObject,
                               IN PIRP Irp)
{
    PLIST_ENTRY ListEntry;
    PNPFS_THREAD_CONTEXT ThreadContext = NULL;
    PNPFS_CONTEXT Context;
    HANDLE hThread;
    PNPFS_VCB Vcb;
    KIRQL oldIrql;
    NTSTATUS Status;

    Context = (PNPFS_CONTEXT)&Irp->Tail.Overlay.DriverContext;
    Vcb = (PNPFS_VCB)DeviceObject->DeviceExtension;

    DPRINT("NpfsAddWaitingReadWriteRequest(DeviceObject %p, Irp %p)\n", DeviceObject, Irp);

    KeLockMutex(&Vcb->PipeListLock);

    ListEntry = Vcb->ThreadListHead.Flink;
    while (ListEntry != &Vcb->ThreadListHead)
    {
        ThreadContext = CONTAINING_RECORD(ListEntry, NPFS_THREAD_CONTEXT, ListEntry);
        if (ThreadContext->Count < MAXIMUM_WAIT_OBJECTS)
        {
            break;
        }
        ListEntry = ListEntry->Flink;
    }

    if (ListEntry == &Vcb->ThreadListHead)
    {
        ThreadContext = ExAllocatePoolWithTag(NonPagedPool,
                                              sizeof(NPFS_THREAD_CONTEXT),
                                              TAG_NPFS_THREAD_CONTEXT);
        if (ThreadContext == NULL)
        {
            KeUnlockMutex(&Vcb->PipeListLock);
            return STATUS_NO_MEMORY;
        }

        ThreadContext->Vcb = Vcb;
        KeInitializeEvent(&ThreadContext->Event, SynchronizationEvent, FALSE);
        ThreadContext->Count = 1;
        ThreadContext->WaitObjectArray[0] = &ThreadContext->Event;

        DPRINT("Creating a new system thread for waiting read/write requests\n");

        Status = PsCreateSystemThread(&hThread,
            THREAD_ALL_ACCESS,
            NULL,
            NULL,
            NULL,
            NpfsWaiterThread,
            (PVOID)ThreadContext);
        if (!NT_SUCCESS(Status))
        {
            ExFreePoolWithTag(ThreadContext, TAG_NPFS_THREAD_CONTEXT);
            KeUnlockMutex(&Vcb->PipeListLock);
            return Status;
        }

        InsertHeadList(&Vcb->ThreadListHead, &ThreadContext->ListEntry);
        Vcb->EmptyWaiterCount += MAXIMUM_WAIT_OBJECTS - 1;
    }
    IoMarkIrpPending(Irp);

    IoAcquireCancelSpinLock(&oldIrql);
    if (Irp->Cancel)
    {
        IoReleaseCancelSpinLock(oldIrql);
        Status = STATUS_CANCELLED;
    }
    else
    {
        (void)IoSetCancelRoutine(Irp, NpfsReadWriteCancelRoutine);
        IoReleaseCancelSpinLock(oldIrql);
        ThreadContext->WaitObjectArray[ThreadContext->Count] = Context->WaitEvent;
        ThreadContext->WaitIrpArray[ThreadContext->Count] = Irp;
        ThreadContext->Count++;
        Vcb->EmptyWaiterCount--;
        KeSetEvent(&ThreadContext->Event, IO_NO_INCREMENT, FALSE);
        Status = STATUS_SUCCESS;
    }
    KeUnlockMutex(&Vcb->PipeListLock);
    return Status;
}

NTSTATUS NTAPI
NpfsRead(IN PDEVICE_OBJECT DeviceObject,
         IN PIRP Irp)
{
    PFILE_OBJECT FileObject;
    NTSTATUS Status;
    NTSTATUS OriginalStatus = STATUS_SUCCESS;
    PNPFS_CCB Ccb;
    PNPFS_CONTEXT Context;
    KEVENT Event;
    ULONG Length;
    ULONG Information = 0;
    ULONG CopyLength = 0;
    ULONG TempLength;
    BOOLEAN IsOriginalRequest = TRUE;
    PVOID Buffer;

    DPRINT("NpfsRead(DeviceObject %p, Irp %p)\n", DeviceObject, Irp);

    FileObject = IoGetCurrentIrpStackLocation(Irp)->FileObject;
    DPRINT("FileObject %p\n", FileObject);
    DPRINT("Pipe name %wZ\n", &FileObject->FileName);
    Ccb = FileObject->FsContext2;

    /* Fail, if the CCB is not a pipe CCB */
    if (Ccb->Type != CCB_PIPE)
    {
        DPRINT("Not a pipe!\n");
        Status = STATUS_INVALID_PARAMETER;
        Irp->IoStatus.Information = 0;
        goto done;
    }

    if (Irp->MdlAddress == NULL)
    {
        DPRINT("Irp->MdlAddress == NULL\n");
        Status = STATUS_UNSUCCESSFUL;
        Irp->IoStatus.Information = 0;
        goto done;
    }

    Context = (PNPFS_CONTEXT)&Irp->Tail.Overlay.DriverContext;

    if ((Ccb->OtherSide) && (Ccb->OtherSide->PipeState == FILE_PIPE_DISCONNECTED_STATE) && (Ccb->PipeState == FILE_PIPE_DISCONNECTED_STATE))
    {
        DPRINT("Both Client and Server are disconnected!\n");
        Status = STATUS_PIPE_DISCONNECTED;
        Irp->IoStatus.Information = 0;
        goto done;

    }

    if ((Ccb->OtherSide == NULL) && (Ccb->ReadDataAvailable == 0))
    {
        if (Ccb->PipeState == FILE_PIPE_CONNECTED_STATE)
            Status = STATUS_PIPE_BROKEN;
        else if (Ccb->PipeState == FILE_PIPE_LISTENING_STATE)
            Status = STATUS_PIPE_LISTENING;
        else if (Ccb->PipeState == FILE_PIPE_DISCONNECTED_STATE)
            Status = STATUS_PIPE_DISCONNECTED;
        else
            Status = STATUS_UNSUCCESSFUL;
        Irp->IoStatus.Information = 0;
        goto done;
    }

    if (Ccb->Data == NULL)
    {
        DPRINT("Pipe is NOT readable!\n");
        Status = STATUS_UNSUCCESSFUL;
        Irp->IoStatus.Information = 0;
        goto done;
    }

    ExAcquireFastMutex(&Ccb->DataListLock);

    if (IoIsOperationSynchronous(Irp))
    {
        InsertTailList(&Ccb->ReadRequestListHead, &Context->ListEntry);
        if (Ccb->ReadRequestListHead.Flink != &Context->ListEntry)
        {
            KeInitializeEvent(&Event, SynchronizationEvent, FALSE);
            Context->WaitEvent = &Event;
            ExReleaseFastMutex(&Ccb->DataListLock);
            KeWaitForSingleObject(&Event,
                Executive,
                KernelMode,
                FALSE,
                NULL);
            ExAcquireFastMutex(&Ccb->DataListLock);
        }
        Irp->IoStatus.Information = 0;
    }
    else
    {
        KIRQL oldIrql;
        if (IsListEmpty(&Ccb->ReadRequestListHead) ||
            Ccb->ReadRequestListHead.Flink != &Context->ListEntry)
        {
            /* this is a new request */
            Irp->IoStatus.Information = 0;
            Context->WaitEvent = &Ccb->ReadEvent;
            InsertTailList(&Ccb->ReadRequestListHead, &Context->ListEntry);
            if (Ccb->ReadRequestListHead.Flink != &Context->ListEntry)
            {
                /* there was already a request on the list */
                IoAcquireCancelSpinLock(&oldIrql);
                if (Irp->Cancel)
                {
                    IoReleaseCancelSpinLock(oldIrql);
                    RemoveEntryList(&Context->ListEntry);
                    ExReleaseFastMutex(&Ccb->DataListLock);
                    Status = STATUS_CANCELLED;
                    goto done;
                }
                (void)IoSetCancelRoutine(Irp, NpfsReadWriteCancelRoutine);
                IoReleaseCancelSpinLock(oldIrql);
                ExReleaseFastMutex(&Ccb->DataListLock);
                IoMarkIrpPending(Irp);
                Status = STATUS_PENDING;
                goto done;
            }
        }
    }

    while (1)
    {
        Buffer = MmGetSystemAddressForMdl(Irp->MdlAddress);
        Information = Irp->IoStatus.Information;
        Length = IoGetCurrentIrpStackLocation(Irp)->Parameters.Read.Length;
        ASSERT (Information <= Length);
        Buffer = (PVOID)((ULONG_PTR)Buffer + Information);
        Length -= Information;
        Status = STATUS_SUCCESS;

        while (1)
        {
            if (Ccb->ReadDataAvailable == 0)
            {
                ULONG ConnectionSideReadMode;

                if (Ccb->PipeEnd == FILE_PIPE_CLIENT_END) ConnectionSideReadMode=Ccb->Fcb->ClientReadMode;
                else ConnectionSideReadMode = Ccb->Fcb->ServerReadMode;

                if ((Ccb->PipeState == FILE_PIPE_CONNECTED_STATE) && (Ccb->OtherSide))
                {
                    KeSetEvent(&Ccb->OtherSide->WriteEvent, IO_NO_INCREMENT, FALSE);
                }
                if (Information > 0 &&
                    (ConnectionSideReadMode != FILE_PIPE_BYTE_STREAM_MODE ||
                    Ccb->PipeState != FILE_PIPE_CONNECTED_STATE))
                {
                    break;
                }
                if (((Ccb->PipeState != FILE_PIPE_CONNECTED_STATE) || (!Ccb->OtherSide)) && (Ccb->ReadDataAvailable == 0))
                {
                    DPRINT("PipeState: %x\n", Ccb->PipeState);
                    Status = STATUS_PIPE_BROKEN;
                    break;
                }
                ExReleaseFastMutex(&Ccb->DataListLock);

                if (IoIsOperationSynchronous(Irp))
                {
                    /* Wait for ReadEvent to become signaled */

                    DPRINT("Waiting for readable data (%wZ)\n", &Ccb->Fcb->PipeName);
                    Status = KeWaitForSingleObject(&Ccb->ReadEvent,
                        UserRequest,
                        Irp->RequestorMode,
                        (FileObject->Flags & FO_ALERTABLE_IO),
                        NULL);
                    DPRINT("Finished waiting (%wZ)! Status: %x\n", &Ccb->Fcb->PipeName, Status);

                    ExAcquireFastMutex(&Ccb->DataListLock);

                    if ((Status == STATUS_USER_APC) || (Status == STATUS_KERNEL_APC) || (Status == STATUS_ALERTED))
                    {
                        Status = STATUS_CANCELLED;
                        break;
                    }
                    if (!NT_SUCCESS(Status))
                    {
                        ASSERT(FALSE);
                    }
                }
                else
                {
                    Context = (PNPFS_CONTEXT)&Irp->Tail.Overlay.DriverContext;

                    Context->WaitEvent = &Ccb->ReadEvent;
                    Status = NpfsAddWaitingReadWriteRequest(DeviceObject, Irp);

                    if (NT_SUCCESS(Status))
                    {
                        Status = STATUS_PENDING;
                        goto done;
                    }
                    ExAcquireFastMutex(&Ccb->DataListLock);
                    break;
                }
            }
            ASSERT(IoGetCurrentIrpStackLocation(Irp)->FileObject != NULL);

            /* If the pipe type and read mode are both byte stream */
            if (Ccb->Fcb->PipeType == FILE_PIPE_BYTE_STREAM_TYPE)
            {
                DPRINT("Byte stream mode: Ccb->Data %x\n", Ccb->Data);
                /* Byte stream mode */
                while (Length > 0 && Ccb->ReadDataAvailable > 0)
                {
                    CopyLength = min(Ccb->ReadDataAvailable, Length);
                    if ((ULONG_PTR)Ccb->ReadPtr + CopyLength <= (ULONG_PTR)Ccb->Data + Ccb->MaxDataLength)
                    {
                        memcpy(Buffer, Ccb->ReadPtr, CopyLength);
                        Ccb->ReadPtr = (PVOID)((ULONG_PTR)Ccb->ReadPtr + CopyLength);
                        if (Ccb->ReadPtr == (PVOID)((ULONG_PTR)Ccb->Data + Ccb->MaxDataLength))
                        {
                            Ccb->ReadPtr = Ccb->Data;
                        }
                    }
                    else
                    {
                        TempLength = (ULONG)((ULONG_PTR)Ccb->Data + Ccb->MaxDataLength - (ULONG_PTR)Ccb->ReadPtr);
                        memcpy(Buffer, Ccb->ReadPtr, TempLength);
                        memcpy((PVOID)((ULONG_PTR)Buffer + TempLength), Ccb->Data, CopyLength - TempLength);
                        Ccb->ReadPtr = (PVOID)((ULONG_PTR)Ccb->Data + CopyLength - TempLength);
                    }

                    Buffer = (PVOID)((ULONG_PTR)Buffer + CopyLength);
                    Length -= CopyLength;
                    Information += CopyLength;

                    Ccb->ReadDataAvailable -= CopyLength;
                    Ccb->WriteQuotaAvailable += CopyLength;
                }

                if ((Length == 0) || (Ccb->ReadDataAvailable == 0))
                {
                    if ((Ccb->PipeState == FILE_PIPE_CONNECTED_STATE) && (Ccb->OtherSide))
                    {
                        KeSetEvent(&Ccb->OtherSide->WriteEvent, IO_NO_INCREMENT, FALSE);
                    }
                    KeResetEvent(&Ccb->ReadEvent);
                    break;
                }
            }
            else if (Ccb->Fcb->PipeType == FILE_PIPE_MESSAGE_TYPE)
            {
                DPRINT("Message mode: Ccb>Data %x\n", Ccb->Data);

                /* Check if buffer is full and the read pointer is not at the start of the buffer */
                if ((Ccb->WriteQuotaAvailable == 0) && (Ccb->ReadPtr > Ccb->Data))
                {
                    Ccb->WriteQuotaAvailable += (ULONG_PTR)Ccb->ReadPtr - (ULONG_PTR)Ccb->Data;
                    memcpy(Ccb->Data, Ccb->ReadPtr, (ULONG_PTR)Ccb->WritePtr - (ULONG_PTR)Ccb->ReadPtr);
                    Ccb->WritePtr = (PVOID)((ULONG_PTR)Ccb->WritePtr - ((ULONG_PTR)Ccb->ReadPtr - (ULONG_PTR)Ccb->Data));
                    Ccb->ReadPtr = Ccb->Data;
                    ASSERT((ULONG_PTR)Ccb->WritePtr < ((ULONG_PTR)Ccb->Data + Ccb->MaxDataLength));
                    ASSERT(Ccb->WritePtr >= Ccb->Data);
                }

                /* For Message mode, the Message length is stored in the buffer preceeding the Message. */
                if (Ccb->ReadDataAvailable)
                {
                    ULONG NextMessageLength = 0;

                    /*First get the size of the message */
                    memcpy(&NextMessageLength, Ccb->ReadPtr, sizeof(NextMessageLength));

                    if ((NextMessageLength == 0) || (NextMessageLength > Ccb->ReadDataAvailable))
                    {
                        DPRINT1("Possible memory corruption.\n");
                        HexDump(Ccb->Data, (ULONG_PTR)Ccb->WritePtr - (ULONG_PTR)Ccb->Data);
                        ASSERT(FALSE);
                    }

                    /* Use the smaller value */
                    CopyLength = min(NextMessageLength, Length);
                    ASSERT(CopyLength > 0);
                    ASSERT(CopyLength <= Ccb->ReadDataAvailable);
                    /* retrieve the message from the buffer */
                    memcpy(Buffer, (PVOID)((ULONG_PTR)Ccb->ReadPtr + sizeof(NextMessageLength)), CopyLength);

                    if (Ccb->ReadDataAvailable > CopyLength)
                    {
                        if (CopyLength < NextMessageLength)
                        /* Client only requested part of the message */
                        {
                            /* Calculate the remaining message new size */
                            ULONG NewMessageSize = NextMessageLength-CopyLength;

                            /* Update ReadPtr to point to new Message size location */
                            Ccb->ReadPtr = (PVOID)((ULONG_PTR)Ccb->ReadPtr + CopyLength);

                            /* Write a new Message size to buffer for the part of the message still there */
                            memcpy(Ccb->ReadPtr, &NewMessageSize, sizeof(NewMessageSize));
                        }
                        else
                        /* Client wanted the entire message */
                        {
                            /* Update ReadPtr to point to next message size */
                            Ccb->ReadPtr = (PVOID)((ULONG_PTR)Ccb->ReadPtr + CopyLength + sizeof(CopyLength));
                        }
                    }
                    else
                    {
                        /* This was the last Message, so just zero start of buffer for safety sake */
                        memset(Ccb->Data, 0, NextMessageLength + sizeof(NextMessageLength));

                        /* Reset to MaxDataLength as partial message retrievals dont
                           give the length back to Quota */
                        Ccb->WriteQuotaAvailable = Ccb->MaxDataLength;

                        /* reset read and write pointer to beginning of buffer */
                        Ccb->WritePtr = Ccb->Data;
                        Ccb->ReadPtr = Ccb->Data;
                    }
#ifndef NDEBUG
                    DPRINT("Length %d Buffer %x\n",CopyLength,Buffer);
                    HexDump((PUCHAR)Buffer, CopyLength);
#endif

                    Information += CopyLength;

                    Ccb->ReadDataAvailable -= CopyLength;

                    if ((ULONG)Ccb->WriteQuotaAvailable > (ULONG)Ccb->MaxDataLength) ASSERT(FALSE);
                }

                if (Information > 0)
                {
                    ULONG ConnectionSideReadMode;

                    if (Ccb->PipeEnd == FILE_PIPE_CLIENT_END) ConnectionSideReadMode=Ccb->Fcb->ClientReadMode;
                    else ConnectionSideReadMode = Ccb->Fcb->ServerReadMode;

                    if ((ConnectionSideReadMode == FILE_PIPE_BYTE_STREAM_MODE) && (Ccb->ReadDataAvailable) && (Length > CopyLength))
                    {
                        Buffer = (PVOID)((ULONG_PTR)Buffer + CopyLength);
                        Length -= CopyLength;
                    }
                    else
                    {
                        KeResetEvent(&Ccb->ReadEvent);

                        if ((Ccb->PipeState == FILE_PIPE_CONNECTED_STATE) && (Ccb->WriteQuotaAvailable > 0) && (Ccb->OtherSide))
                        {
                            KeSetEvent(&Ccb->OtherSide->WriteEvent, IO_NO_INCREMENT, FALSE);
                        }
                        break;
                    }
                }
            }
            else
            {
                DPRINT1("Unhandled Pipe Mode!\n");
                ASSERT(FALSE);
            }
        }
        Irp->IoStatus.Information = Information;
        Irp->IoStatus.Status = Status;

        ASSERT(IoGetCurrentIrpStackLocation(Irp)->FileObject != NULL);

        if (IoIsOperationSynchronous(Irp))
        {
            RemoveEntryList(&Context->ListEntry);
            if (!IsListEmpty(&Ccb->ReadRequestListHead))
            {
                Context = CONTAINING_RECORD(Ccb->ReadRequestListHead.Flink, NPFS_CONTEXT, ListEntry);
                KeSetEvent(Context->WaitEvent, IO_NO_INCREMENT, FALSE);
            }
            ExReleaseFastMutex(&Ccb->DataListLock);
            IoCompleteRequest(Irp, IO_NO_INCREMENT);

            DPRINT("NpfsRead done (Status %lx)\n", Status);
            return Status;
        }
        else
        {
            KIRQL oldIrql;

            if (IsOriginalRequest)
            {
                IsOriginalRequest = FALSE;
                OriginalStatus = Status;
            }
            if (Status == STATUS_PENDING)
            {
                ExReleaseFastMutex(&Ccb->DataListLock);
                DPRINT("NpfsRead done (Status %lx)\n", OriginalStatus);
                return OriginalStatus;
            }
            RemoveEntryList(&Context->ListEntry);
            IoCompleteRequest(Irp, IO_NO_INCREMENT);
            if (IsListEmpty(&Ccb->ReadRequestListHead))
            {
                ExReleaseFastMutex(&Ccb->DataListLock);
                DPRINT("NpfsRead done (Status %lx)\n", OriginalStatus);
                return OriginalStatus;
            }

            IoAcquireCancelSpinLock(&oldIrql);
            Context = CONTAINING_RECORD(Ccb->ReadRequestListHead.Flink, NPFS_CONTEXT, ListEntry);

            Irp = CONTAINING_RECORD(Context, IRP, Tail.Overlay.DriverContext);
            /* Verify the Irp wasnt cancelled */
            if (Irp->Cancel)
            {
                IoReleaseCancelSpinLock(oldIrql);
                RemoveEntryList(&Context->ListEntry);
                ExReleaseFastMutex(&Ccb->DataListLock);
                Status = STATUS_CANCELLED;
                goto done;
            }
            /* The Irp will now be handled, so remove the CancelRoutine */
            (void)IoSetCancelRoutine(Irp, NULL);
            IoReleaseCancelSpinLock(oldIrql);
        }
    }

done:
    Irp->IoStatus.Status = Status;

    if (Status != STATUS_PENDING)
    {
        IoCompleteRequest(Irp, IO_NO_INCREMENT);
    }
    DPRINT("NpfsRead done (Status %lx)\n", Status);

    return Status;
}

NTSTATUS NTAPI
NpfsWrite(PDEVICE_OBJECT DeviceObject,
          PIRP Irp)
{
    PIO_STACK_LOCATION IoStack;
    PFILE_OBJECT FileObject;
    PNPFS_FCB Fcb = NULL;
    PNPFS_CCB Ccb = NULL;
    PNPFS_CCB ReaderCcb;
    PUCHAR Buffer;
    NTSTATUS Status = STATUS_SUCCESS;
    ULONG Length;
    ULONG Offset;
    ULONG Information = 0;
    ULONG CopyLength;
    ULONG TempLength;

    DPRINT("NpfsWrite()\n");

    IoStack = IoGetCurrentIrpStackLocation(Irp);
    FileObject = IoStack->FileObject;
    DPRINT("FileObject %p\n", FileObject);
    DPRINT("Pipe name %wZ\n", &FileObject->FileName);

    Ccb = FileObject->FsContext2;

    /* Fail, if the CCB is not a pipe CCB */
    if (Ccb->Type != CCB_PIPE)
    {
        DPRINT("Not a pipe!\n");
        Status = STATUS_INVALID_PARAMETER;
        Length = 0;
        goto done;
    }

    ReaderCcb = Ccb->OtherSide;
    Fcb = Ccb->Fcb;

    Length = IoStack->Parameters.Write.Length;
    Offset = IoStack->Parameters.Write.ByteOffset.u.LowPart;

    if (Irp->MdlAddress == NULL)
    {
        DPRINT("Irp->MdlAddress == NULL\n");
        Status = STATUS_UNSUCCESSFUL;
        Length = 0;
        goto done;
    }

    if ((ReaderCcb == NULL) || (Ccb->PipeState != FILE_PIPE_CONNECTED_STATE))
    {
        DPRINT("Pipe is NOT connected!\n");
        if (Ccb->PipeState == FILE_PIPE_LISTENING_STATE)
            Status = STATUS_PIPE_LISTENING;
        else if (Ccb->PipeState == FILE_PIPE_DISCONNECTED_STATE)
            Status = STATUS_PIPE_DISCONNECTED;
        else
            Status = STATUS_UNSUCCESSFUL;
        Length = 0;
        goto done;
    }

    if (ReaderCcb->Data == NULL)
    {
        DPRINT("Pipe is NOT writable!\n");
        Status = STATUS_UNSUCCESSFUL;
        Length = 0;
        goto done;
    }

    Status = STATUS_SUCCESS;
    Buffer = MmGetSystemAddressForMdlSafe (Irp->MdlAddress, NormalPagePriority);

    if (!Buffer)
    {
        DPRINT("MmGetSystemAddressForMdlSafe failed\n");
        Status = STATUS_INSUFFICIENT_RESOURCES;
        Length = 0;
        goto done;

    }

    ExAcquireFastMutex(&ReaderCcb->DataListLock);

    DPRINT("Length %d Buffer %x Offset %x\n",Length,Buffer,Offset);

#ifndef NDEBUG
    HexDump(Buffer, Length);
#endif

    while(1)
    {
        if ((ReaderCcb->WriteQuotaAvailable == 0))
        {
            if (Ccb->PipeState != FILE_PIPE_CONNECTED_STATE || !Ccb->OtherSide)
            {
                Status = STATUS_PIPE_BROKEN;
                ExReleaseFastMutex(&ReaderCcb->DataListLock);
                goto done;
            }
            KeSetEvent(&ReaderCcb->ReadEvent, IO_NO_INCREMENT, FALSE);
            ExReleaseFastMutex(&ReaderCcb->DataListLock);

            DPRINT("Write Waiting for buffer space (%S)\n", Fcb->PipeName.Buffer);
            Status = KeWaitForSingleObject(&Ccb->WriteEvent,
                UserRequest,
                Irp->RequestorMode,
                (FileObject->Flags & FO_ALERTABLE_IO),
                NULL);
            DPRINT("Write Finished waiting (%S)! Status: %x\n", Fcb->PipeName.Buffer, Status);

            if ((Status == STATUS_USER_APC) || (Status == STATUS_KERNEL_APC) || (Status == STATUS_ALERTED))
            {
                Status = STATUS_CANCELLED;
                goto done;
            }
            if (!NT_SUCCESS(Status))
            {
                ASSERT(FALSE);
            }
            /*
            * It's possible that the event was signaled because the
            * other side of pipe was closed.
            */
            if (Ccb->PipeState != FILE_PIPE_CONNECTED_STATE || !Ccb->OtherSide)
            {
                DPRINT("PipeState: %x\n", Ccb->PipeState);
                Status = STATUS_PIPE_BROKEN;
                goto done;
            }
            /* Check that the pipe has not been closed */
            if (ReaderCcb->PipeState != FILE_PIPE_CONNECTED_STATE || !ReaderCcb->OtherSide)
            {
                Status = STATUS_PIPE_BROKEN;
                goto done;
            }
            ExAcquireFastMutex(&ReaderCcb->DataListLock);
        }

        if (Ccb->Fcb->PipeType == FILE_PIPE_BYTE_STREAM_TYPE)
        {
            DPRINT("Byte stream mode: Ccb->Data %x, Ccb->WritePtr %x\n", ReaderCcb->Data, ReaderCcb->WritePtr);

            while (Length > 0 && ReaderCcb->WriteQuotaAvailable > 0)
            {
                CopyLength = min(Length, ReaderCcb->WriteQuotaAvailable);

                if ((ULONG_PTR)ReaderCcb->WritePtr + CopyLength <= (ULONG_PTR)ReaderCcb->Data + ReaderCcb->MaxDataLength)
                {
                    memcpy(ReaderCcb->WritePtr, Buffer, CopyLength);
                    ReaderCcb->WritePtr = (PVOID)((ULONG_PTR)ReaderCcb->WritePtr + CopyLength);
                    if ((ULONG_PTR)ReaderCcb->WritePtr == (ULONG_PTR)ReaderCcb->Data + ReaderCcb->MaxDataLength)
                    {
                        ReaderCcb->WritePtr = ReaderCcb->Data;
                    }
                }
                else
                {

                    TempLength = (ULONG)((ULONG_PTR)ReaderCcb->Data + ReaderCcb->MaxDataLength -
                            (ULONG_PTR)ReaderCcb->WritePtr);

                    memcpy(ReaderCcb->WritePtr, Buffer, TempLength);
                    memcpy(ReaderCcb->Data, Buffer + TempLength, CopyLength - TempLength);
                    ReaderCcb->WritePtr = (PVOID)((ULONG_PTR)ReaderCcb->Data + CopyLength - TempLength);
                }

                Buffer += CopyLength;
                Length -= CopyLength;
                Information += CopyLength;

                ReaderCcb->ReadDataAvailable += CopyLength;
                ReaderCcb->WriteQuotaAvailable -= CopyLength;
            }

            if (Length == 0)
            {
                KeSetEvent(&ReaderCcb->ReadEvent, IO_NO_INCREMENT, FALSE);
                KeResetEvent(&Ccb->WriteEvent);
                break;
            }
        }
        else if (Ccb->Fcb->PipeType == FILE_PIPE_MESSAGE_TYPE)
        {
            /* For Message Type Pipe, the Pipes memory will be used to store the size of each message */
            DPRINT("Message mode: Ccb->Data %x, Ccb->WritePtr %x\n",ReaderCcb->Data, ReaderCcb->WritePtr);
            if (Length > 0)
            {
                /* Verify the WritePtr is still inside the buffer */
                if (((ULONG_PTR)ReaderCcb->WritePtr > ((ULONG_PTR)ReaderCcb->Data + (ULONG_PTR)ReaderCcb->MaxDataLength)) ||
                ((ULONG_PTR)ReaderCcb->WritePtr < (ULONG_PTR)ReaderCcb->Data))
                {
                    DPRINT1("NPFS is writing out of its buffer. Report to developer!\n");
                    DPRINT1("ReaderCcb->WritePtr %x, ReaderCcb->Data %x, ReaderCcb->MaxDataLength %lu\n",
                        ReaderCcb->WritePtr, ReaderCcb->Data, ReaderCcb->MaxDataLength);
                    ASSERT(FALSE);
                }

                CopyLength = min(Length, ReaderCcb->WriteQuotaAvailable - sizeof(ULONG));
                if (CopyLength > ReaderCcb->WriteQuotaAvailable)
                {
                    DPRINT1("Writing %lu byte to pipe would overflow as only %lu bytes are available\n",
                        CopyLength, ReaderCcb->WriteQuotaAvailable);
                    ASSERT(FALSE);
                }

                /* First Copy the Length of the message into the pipes buffer */
                memcpy(ReaderCcb->WritePtr, &CopyLength, sizeof(CopyLength));

                /* Now the user buffer itself */
                memcpy((PVOID)((ULONG_PTR)ReaderCcb->WritePtr + sizeof(CopyLength)), Buffer, CopyLength);

                /* Update the write pointer */
                ReaderCcb->WritePtr = (PVOID)((ULONG_PTR)ReaderCcb->WritePtr + sizeof(CopyLength) + CopyLength);

                Information += CopyLength;

                ReaderCcb->ReadDataAvailable += CopyLength;

                ReaderCcb->WriteQuotaAvailable -= (CopyLength + sizeof(ULONG));

                if ((ULONG_PTR)ReaderCcb->WriteQuotaAvailable > (ULONG)ReaderCcb->MaxDataLength)
                {
                    DPRINT1("QuotaAvailable is greater than buffer size!\n");
                    ASSERT(FALSE);
                }
            }

            if (Information > 0)
            {
                KeSetEvent(&ReaderCcb->ReadEvent, IO_NO_INCREMENT, FALSE);
                KeResetEvent(&Ccb->WriteEvent);
                break;
            }
        }
        else
        {
            DPRINT1("Unhandled Pipe Type Mode and Read Write Mode!\n");
            ASSERT(FALSE);
        }
    }

    ExReleaseFastMutex(&ReaderCcb->DataListLock);

done:
    Irp->IoStatus.Status = Status;
    Irp->IoStatus.Information = Information;

    IoCompleteRequest(Irp, IO_NO_INCREMENT);

    DPRINT("NpfsWrite done (Status %lx)\n", Status);

    return Status;
}

/* EOF */