iofunc.c

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            /* Enter SEH for allocations */
            _SEH_TRY
            {
                /* Select the right Buffer Length */
                BufferLength = (InputBufferLength > OutputBufferLength) ?
                                InputBufferLength : OutputBufferLength;

                /* Make sure there is one */
                if (BufferLength)
                {
                    /* Allocate the System Buffer */
                    Irp->AssociatedIrp.SystemBuffer =
                        ExAllocatePoolWithTag(NonPagedPool,
                                              BufferLength,
                                              TAG_SYS_BUF);

                    /* Check if we got a buffer */
                    if (InputBuffer)
                    {
                        /* Copy into the System Buffer */
                        RtlCopyMemory(Irp->AssociatedIrp.SystemBuffer,
                                      InputBuffer,
                                      InputBufferLength);
                    }

                    /* Write the flags */
                    Irp->Flags = IRP_BUFFERED_IO | IRP_DEALLOCATE_BUFFER;
                    if (OutputBuffer) Irp->Flags |= IRP_INPUT_OPERATION;

                    /* Save the Buffer */
                    Irp->UserBuffer = OutputBuffer;
                }
                else
                {
                    /* Clear the Flags and Buffer */
                    Irp->UserBuffer = NULL;
                }
            }
            _SEH_HANDLE
            {
                /* Cleanup after exception */
                IopCleanupAfterException(FileObject, Irp, Event, NULL);
                Status = _SEH_GetExceptionCode();
            }
            _SEH_END;
            if (!NT_SUCCESS(Status)) return Status;
            break;

        /* Direct I/O */
        case METHOD_IN_DIRECT:
        case METHOD_OUT_DIRECT:

            /* Enter SEH */
            _SEH_TRY
            {
                /* Check if we got an input buffer */
                if ((InputBufferLength) && (InputBuffer))
                {
                    /* Allocate the System Buffer */
                    Irp->AssociatedIrp.SystemBuffer =
                        ExAllocatePoolWithTag(NonPagedPool,
                                              InputBufferLength,
                                              TAG_SYS_BUF);

                    /* Copy into the System Buffer */
                    RtlCopyMemory(Irp->AssociatedIrp.SystemBuffer,
                                  InputBuffer,
                                  InputBufferLength);

                    /* Write the flags */
                    Irp->Flags = IRP_BUFFERED_IO | IRP_DEALLOCATE_BUFFER;
                }

                /* Check if we got an output buffer */
                if (OutputBuffer)
                {
                    /* Allocate the System Buffer */
                    Irp->MdlAddress = IoAllocateMdl(OutputBuffer,
                                                    OutputBufferLength,
                                                    FALSE,
                                                    FALSE,
                                                    Irp);
                    if (!Irp->MdlAddress)
                    {
                        /* Raise exception we'll catch */
                        ExRaiseStatus(STATUS_INSUFFICIENT_RESOURCES);
                    }

                    /* Do the probe */
                    MmProbeAndLockPages(Irp->MdlAddress,
                                        PreviousMode,
                                        (AccessType == METHOD_IN_DIRECT) ?
                                        IoReadAccess : IoWriteAccess);
                }
            }
            _SEH_HANDLE
            {
                /* Cleanup after exception */
                IopCleanupAfterException(FileObject, Irp, Event, NULL);
                Status = _SEH_GetExceptionCode();
            }
            _SEH_END;
            if (!NT_SUCCESS(Status)) return Status;
            break;

        case METHOD_NEITHER:

            /* Just save the Buffer */
            Irp->UserBuffer = OutputBuffer;
            StackPtr->Parameters.DeviceIoControl.Type3InputBuffer = InputBuffer;
    }

    /* Use deferred completion for FS I/O */
    Irp->Flags |= (!IsDevIoCtl) ? IRP_DEFER_IO_COMPLETION : 0;

    /* Perform the call */
    return IopPerformSynchronousRequest(DeviceObject,
                                        Irp,
                                        FileObject,
                                        !IsDevIoCtl,
                                        PreviousMode,
                                        LockedForSynch,
                                        IopOtherTransfer);
}

NTSTATUS
NTAPI
IopQueryDeviceInformation(IN PFILE_OBJECT FileObject,
                          IN ULONG InformationClass,
                          IN ULONG Length,
                          OUT PVOID Information,
                          OUT PULONG ReturnedLength,
                          IN BOOLEAN File)
{
    IO_STATUS_BLOCK IoStatusBlock;
    PIRP Irp;
    PDEVICE_OBJECT DeviceObject;
    PIO_STACK_LOCATION StackPtr;
    BOOLEAN LocalEvent = FALSE;
    KEVENT Event;
    NTSTATUS Status;
    PAGED_CODE();
    IOTRACE(IO_API_DEBUG, "Handle: %p. CTL: %lx. Type: %lx \n",
            FileObject, InformationClass, File);

    /* Reference the object */
    ObReferenceObject(FileObject);

    /* Check if this is a file that was opened for Synch I/O */
    if (FileObject->Flags & FO_SYNCHRONOUS_IO)
    {
        /* Lock it */
        IopLockFileObject(FileObject);

        /* Use File Object event */
        KeClearEvent(&FileObject->Event);
    }
    else
    {
        /* Use local event */
        KeInitializeEvent(&Event, SynchronizationEvent, FALSE);
        LocalEvent = TRUE;
    }

    /* Get the Device Object */
    DeviceObject = IoGetRelatedDeviceObject(FileObject);

    /* Allocate the IRP */
    Irp = IoAllocateIrp(DeviceObject->StackSize, FALSE);
    if (!Irp) return IopCleanupFailedIrp(FileObject, NULL, NULL);

    /* Set the IRP */
    Irp->Tail.Overlay.OriginalFileObject = FileObject;
    Irp->RequestorMode = KernelMode;
    Irp->Overlay.AsynchronousParameters.UserApcRoutine = NULL;
    Irp->UserIosb = &IoStatusBlock;
    Irp->UserEvent = (LocalEvent) ? &Event : NULL;
    Irp->Flags = (LocalEvent) ? IRP_SYNCHRONOUS_API : 0;
    Irp->Flags |= IRP_BUFFERED_IO;
    Irp->AssociatedIrp.SystemBuffer = Information;
    Irp->Tail.Overlay.Thread = PsGetCurrentThread();

    /* Set the Stack Data */
    StackPtr = IoGetNextIrpStackLocation(Irp);
    StackPtr->MajorFunction = File ? IRP_MJ_QUERY_INFORMATION:
                                     IRP_MJ_QUERY_VOLUME_INFORMATION;
    StackPtr->FileObject = FileObject;

    /* Check which type this is */
    if (File)
    {
        /* Set Parameters */
        StackPtr->Parameters.QueryFile.FileInformationClass = InformationClass;
        StackPtr->Parameters.QueryFile.Length = Length;
    }
    else
    {
        /* Set Parameters */
        StackPtr->Parameters.QueryVolume.FsInformationClass = InformationClass;
        StackPtr->Parameters.QueryVolume.Length = Length;
    }

    /* Queue the IRP */
    IopQueueIrpToThread(Irp);

    /* Call the Driver */
    Status = IoCallDriver(DeviceObject, Irp);

    /* Check if this was synch I/O */
    if (!LocalEvent)
    {
        /* Check if the requet is pending */
        if (Status == STATUS_PENDING)
        {
            /* Wait on the file object */
            Status = KeWaitForSingleObject(&FileObject->Event,
                                           Executive,
                                           KernelMode,
                                           FileObject->Flags & FO_ALERTABLE_IO,
                                           NULL);
            if (Status == STATUS_ALERTED)
            {
                /* Abort the operation */
                IopAbortInterruptedIrp(&FileObject->Event, Irp);
            }

            /* Get the final status */
            Status = FileObject->FinalStatus;
        }

        /* Release the file lock */
        IopUnlockFileObject(FileObject);
    }
    else if (Status == STATUS_PENDING)
    {
        /* Wait on the local event and get the final status */
        KeWaitForSingleObject(&Event,
                              Executive,
                              KernelMode,
                              FALSE,
                              NULL);
        Status = IoStatusBlock.Status;
    }

    /* Return the Length and Status. ReturnedLength is NOT optional */
    *ReturnedLength = IoStatusBlock.Information;
    return Status;
}

/* PUBLIC FUNCTIONS **********************************************************/

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoSynchronousPageWrite(IN PFILE_OBJECT FileObject,
                       IN PMDL Mdl,
                       IN PLARGE_INTEGER Offset,
                       IN PKEVENT Event,
                       IN PIO_STATUS_BLOCK StatusBlock)
{
    PIRP Irp;
    PIO_STACK_LOCATION StackPtr;
    PDEVICE_OBJECT DeviceObject;
    IOTRACE(IO_API_DEBUG, "FileObject: %p. Mdl: %p. Offset: %p \n",
            FileObject, Mdl, Offset);

    /* Get the Device Object */
    DeviceObject = IoGetRelatedDeviceObject(FileObject);

    /* Allocate IRP */
    Irp = IoAllocateIrp(DeviceObject->StackSize, FALSE);
    if (!Irp) return STATUS_INSUFFICIENT_RESOURCES;

    /* Get the Stack */
    StackPtr = IoGetNextIrpStackLocation(Irp);

    /* Create the IRP Settings */
    Irp->MdlAddress = Mdl;
    Irp->UserBuffer = MmGetMdlVirtualAddress(Mdl);
    Irp->UserIosb = StatusBlock;
    Irp->UserEvent = Event;
    Irp->RequestorMode = KernelMode;
    Irp->Flags = IRP_PAGING_IO | IRP_NOCACHE | IRP_SYNCHRONOUS_PAGING_IO;
    Irp->Tail.Overlay.OriginalFileObject = FileObject;
    Irp->Tail.Overlay.Thread = PsGetCurrentThread();

    /* Set the Stack Settings */
    StackPtr->Parameters.Write.Length = MmGetMdlByteCount(Mdl);
    StackPtr->Parameters.Write.ByteOffset = *Offset;
    StackPtr->MajorFunction = IRP_MJ_WRITE;
    StackPtr->FileObject = FileObject;

    /* Call the Driver */
    return IofCallDriver(DeviceObject, Irp);
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoPageRead(IN PFILE_OBJECT FileObject,
           IN PMDL Mdl,
           IN PLARGE_INTEGER Offset,
           IN PKEVENT Event,
           IN PIO_STATUS_BLOCK StatusBlock)
{
    PIRP Irp;
    PIO_STACK_LOCATION StackPtr;
    PDEVICE_OBJECT DeviceObject;
    IOTRACE(IO_API_DEBUG, "FileObject: %p. Mdl: %p. Offset: %p \n",
            FileObject, Mdl, Offset);

    /* Get the Device Object */
    DeviceObject = IoGetRelatedDeviceObject(FileObject);

    /* Allocate IRP */
    Irp = IoAllocateIrp(DeviceObject->StackSize, FALSE);
    if (!Irp) return STATUS_INSUFFICIENT_RESOURCES;

    /* Get the Stack */
    StackPtr = IoGetNextIrpStackLocation(Irp);

    /* Create the IRP Settings */
    Irp->MdlAddress = Mdl;
    Irp->UserBuffer = MmGetMdlVirtualAddress(Mdl);
    Irp->UserIosb = StatusBlock;
    Irp->UserEvent = Event;
    Irp->RequestorMode = KernelMode;
    Irp->Flags = IRP_PAGING_IO |
                 IRP_NOCACHE |
                 IRP_SYNCHRONOUS_PAGING_IO |
                 IRP_INPUT_OPERATION;
    Irp->Tail.Overlay.OriginalFileObject = FileObject;
    Irp->Tail.Overlay.Thread = PsGetCurrentThread();

    /* Set the Stack Settings */
    StackPtr->Parameters.Read.Length = MmGetMdlByteCount(Mdl);
    StackPtr->Parameters.Read.ByteOffset = *Offset;
    StackPtr->MajorFunction = IRP_MJ_READ;
    StackPtr->FileObject = FileObject;

    /* Call the Driver */
    return IofCallDriver(DeviceObject, Irp);
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoQueryFileInformation(IN PFILE_OBJECT FileObject,
                       IN FILE_INFORMATION_CLASS FileInformationClass,
                       IN ULONG Length,
                       OUT PVOID FileInformation,
                       OUT PULONG ReturnedLength)
{
    /* Call the shared routine */
    return IopQueryDeviceInformation(FileObject,
                                     FileInformationClass,
                                     Length,
                                     FileInformation,
                                     ReturnedLength,
                                     TRUE);
}

/*
 * @implemented
 */
NTSTATUS
NTAPI
IoQueryVolumeInformation(IN PFILE_OBJECT FileObject,
                         IN FS_INFORMATION_CLASS FsInformationClass,
                         IN ULONG Length,
                         OUT PVOID FsInformation,
                         OUT PULONG ReturnedLength)
{
    /* Call the shared routine */
    return IopQueryDeviceInformation(FileObject,
                                     FsInformationClass,
                                     Length,
                                     FsInformation,
                                     ReturnedLength,
                                     FALSE);
}