deviosup.c

windows 2000中的UDF文件系统的驱动程序.只有读的功能,不支持未关闭的盘片.只支持UDF2.0以下版本,不支持VAT格式的UDF.

        //  Setup the next IRP stack location in the associated Irp for the disk
        //  driver beneath us.
        //

        IrpSp = IoGetNextIrpStackLocation( Irp );

        //
        //  Setup the Stack location to do a read from the disk driver.
        //

        IrpSp->MajorFunction = IRP_MJ_READ;
        IrpSp->Parameters.Read.Length = IoRuns[UnwindRunCount].DiskByteCount;
        IrpSp->Parameters.Read.ByteOffset.QuadPart = IoRuns[UnwindRunCount].DiskOffset;
    }

    //
    //  We only need to set the associated IRP count in the master irp to
    //  make it a master IRP.  But we set the count to one more than our
    //  caller requested, because we do not want the I/O system to complete
    //  the I/O.  We also set our own count.
    //

    IrpContext->IoContext->IrpCount = RunCount;
    IrpContext->IoContext->MasterIrp = MasterIrp;

    //
    //  We set the count in the master Irp to 1 since typically we
    //  will clean up the associated irps ourselves.  Setting this to one
    //  means completing the last associated Irp with SUCCESS (in the async
    //  case) will complete the master irp.
    //

    MasterIrp->AssociatedIrp.IrpCount = 1;

    //
    //  Now that all the dangerous work is done, issue the Io requests
    //

    for (UnwindRunCount = 0;
         UnwindRunCount < RunCount;
         UnwindRunCount++) {

        Irp = IoRuns[UnwindRunCount].SavedIrp;
        IoRuns[UnwindRunCount].SavedIrp = NULL;

        //
        //  If IoCallDriver returns an error, it has completed the Irp
        //  and the error will be caught by our completion routines
        //  and dealt with as a normal IO error.
        //

        (VOID) IoCallDriver( IrpContext->Vcb->TargetDeviceObject, Irp );
    }

    return;
}


//
//  Local support routine
//

VOID
UdfSingleAsync (
    IN PIRP_CONTEXT IrpContext,
    IN LONGLONG ByteOffset,
    IN ULONG ByteCount
    )

/*++

Routine Description:

    This routine reads one or more contiguous sectors from a device
    asynchronously, and is used if there is only one read necessary to
    complete the IRP.  It implements the read by simply filling
    in the next stack frame in the Irp, and passing it on.  The transfer
    occurs to the single buffer originally specified in the user request.

Arguments:

    ByteOffset - Supplies the starting Logical Byte Offset to begin reading from

    ByteCount - Supplies the number of bytes to read from the device

Return Value:

    None.

--*/

{
    PIO_STACK_LOCATION IrpSp;
    PIO_COMPLETION_ROUTINE CompletionRoutine;

    PAGED_CODE();

    //
    //  Set up things according to whether this is truely async.
    //

    if (FlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT )) {

        CompletionRoutine = UdfSingleSyncCompletionRoutine;

    } else {

        CompletionRoutine = UdfSingleAsyncCompletionRoutine;
    }

    //
    // Set up the completion routine address in our stack frame.
    //

    IoSetCompletionRoutine( IrpContext->Irp,
                            CompletionRoutine,
                            IrpContext->IoContext,
                            TRUE,
                            TRUE,
                            TRUE );

    //
    //  Setup the next IRP stack location in the associated Irp for the disk
    //  driver beneath us.
    //

    IrpSp = IoGetNextIrpStackLocation( IrpContext->Irp );

    //
    //  Setup the Stack location to do a read from the disk driver.
    //

    IrpSp->MajorFunction = IRP_MJ_READ;
    IrpSp->Parameters.Read.Length = ByteCount;
    IrpSp->Parameters.Read.ByteOffset.QuadPart = ByteOffset;

    //
    //  Issue the Io request
    //

    //
    //  If IoCallDriver returns an error, it has completed the Irp
    //  and the error will be caught by our completion routines
    //  and dealt with as a normal IO error.
    //

    (VOID)IoCallDriver( IrpContext->Vcb->TargetDeviceObject, IrpContext->Irp );

    //
    //  And return to our caller
    //

    return;
}


//
//  Local support routine
//

VOID
UdfWaitSync (
    IN PIRP_CONTEXT IrpContext
    )

/*++

Routine Description:

    This routine waits for one or more previously started I/O requests
    from the above routines, by simply waiting on the event.

Arguments:

Return Value:

    None

--*/

{
    PAGED_CODE();

    KeWaitForSingleObject( &IrpContext->IoContext->SyncEvent,
                           Executive,
                           KernelMode,
                           FALSE,
                           NULL );

    KeClearEvent( &IrpContext->IoContext->SyncEvent );

    return;
}


//
//  Local support routine
//

NTSTATUS
UdfMultiSyncCompletionRoutine (
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context
    )

/*++

Routine Description:

    This is the completion routine for all synchronous reads
    started via UdfMultipleAsync.

    The completion routine has has the following responsibilities:

        If the individual request was completed with an error, then
        this completion routine must see if this is the first error
        and remember the error status in the Context.

        If the IrpCount goes to 1, then it sets the event in the Context
        parameter to signal the caller that all of the asynch requests
        are done.

Arguments:

    DeviceObject - Pointer to the file system device object.

    Irp - Pointer to the associated Irp which is being completed.  (This
        Irp will no longer be accessible after this routine returns.)

    Context - The context parameter which was specified for all of
        the multiple asynch I/O requests for this MasterIrp.

Return Value:

    The routine returns STATUS_MORE_PROCESSING_REQUIRED so that we can
    immediately complete the Master Irp without being in a race condition
    with the IoCompleteRequest thread trying to decrement the IrpCount in
    the Master Irp.

--*/

{
    PUDF_IO_CONTEXT IoContext = Context;

    //
    //  If we got an error (or verify required), remember it in the Irp
    //

    if (!NT_SUCCESS( Irp->IoStatus.Status )) {

        InterlockedExchange( &IoContext->Status, Irp->IoStatus.Status );
        IoContext->MasterIrp->IoStatus.Information = 0;
    }

    //
    //  We must do this here since IoCompleteRequest won't get a chance
    //  on this associated Irp.
    //

    IoFreeMdl( Irp->MdlAddress );
    IoFreeIrp( Irp );

    if (InterlockedDecrement( &IoContext->IrpCount ) == 0) {

        //
        //  Update the Master Irp with any error status from the associated Irps.
        //

        IoContext->MasterIrp->IoStatus.Status = IoContext->Status;
        KeSetEvent( &IoContext->SyncEvent, 0, FALSE );
    }

    UNREFERENCED_PARAMETER( DeviceObject );

    return STATUS_MORE_PROCESSING_REQUIRED;
}


//
//  Local support routine
//

NTSTATUS
UdfMultiAsyncCompletionRoutine (
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context
    )

/*++

Routine Description:

    This is the completion routine for all asynchronous reads
    started via UdfMultipleAsync.

    The completion routine has has the following responsibilities:

        If the individual request was completed with an error, then
        this completion routine must see if this is the first error
        and remember the error status in the Context.

Arguments:

    DeviceObject - Pointer to the file system device object.

    Irp - Pointer to the associated Irp which is being completed.  (This
        Irp will no longer be accessible after this routine returns.)

    Context - The context parameter which was specified for all of
             the multiple asynch I/O requests for this MasterIrp.

Return Value:

    Currently always returns STATUS_SUCCESS.

--*/

{
    PUDF_IO_CONTEXT IoContext = Context;
    PIO_STACK_LOCATION IrpSp = IoGetCurrentIrpStackLocation( Irp );

    //
    //  If we got an error (or verify required), remember it in the Irp
    //

    if (!NT_SUCCESS( Irp->IoStatus.Status )) {

        InterlockedExchange( &IoContext->Status, Irp->IoStatus.Status );
    }

    //
    //  Decrement IrpCount and see if it goes to zero.
    //

    if (InterlockedDecrement( &IoContext->IrpCount ) == 0) {

        //
        //  Mark the master Irp pending
        //

        IoMarkIrpPending( IoContext->MasterIrp );

        //
        //  Update the Master Irp with any error status from the associated Irps.
        //

        IoContext->MasterIrp->IoStatus.Status = IoContext->Status;

        //
        //  Update the information field with the correct value.
        //

        IoContext->MasterIrp->IoStatus.Information = 0;

        if (NT_SUCCESS( IoContext->MasterIrp->IoStatus.Status )) {

            IoContext->MasterIrp->IoStatus.Information = IoContext->RequestedByteCount;
        }

        //
        //  Now release the resource
        //

        ExReleaseResourceForThread( IoContext->Resource,
                                    IoContext->ResourceThreadId );

        //
        //  and finally, free the context record.
        //

        UdfFreeIoContext( IoContext );

        //
        //  Return success in this case.
        //

        return STATUS_SUCCESS;

    } else {

        //
        //  We need to cleanup the associated Irp and its Mdl.
        //

        IoFreeMdl( Irp->MdlAddress );
        IoFreeIrp( Irp );

        return STATUS_MORE_PROCESSING_REQUIRED;
    }

    UNREFERENCED_PARAMETER( DeviceObject );
}


//
//  Local support routine
//

NTSTATUS
UdfSingleSyncCompletionRoutine (
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context
    )

/*++

Routine Description:

    This is the completion routine for all reads started via UdfSingleAsync.

    The completion routine has has the following responsibilities:

        It sets the event in the Context parameter to signal the caller
        that all of the asynch requests are done.

Arguments:

    DeviceObject - Pointer to the file system device object.

    Irp - Pointer to the Irp for this request.  (This Irp will no longer
        be accessible after this routine returns.)

    Context - The context parameter which was specified in the call to
        UdfSingleAsynch.

Return Value:

    The routine returns STATUS_MORE_PROCESSING_REQUIRED so that we can
    immediately complete the Master Irp without being in a race condition
    with the IoCompleteRequest thread trying to decrement the IrpCount in
    the Master Irp.

--*/

{
    //
    //  Store the correct information field into the Irp.
    //

    if (!NT_SUCCESS( Irp->IoStatus.Status )) {

        Irp->IoStatus.Information = 0;
    }

    KeSetEvent( &((PUDF_IO_CONTEXT)Context)->SyncEvent, 0, FALSE );

    return STATUS_MORE_PROCESSING_REQUIRED;

    UNREFERENCED_PARAMETER( DeviceObject );
}


//
//  Local support routine
//

NTSTATUS
UdfSingleAsyncCompletionRoutine (
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context
    )

/*++

Routine Description:

    This is the completion routine for all asynchronous reads
    started via UdfSingleAsynch.

Arguments:

    DeviceObject - Pointer to the file system device object.

    Irp - Pointer to the Irp for this request.  (This Irp will no longer
        be accessible after this routine returns.)

    Context - The context parameter which was specified in the call to
        UdfSingleAsynch.

Return Value:

    Currently always returns STATUS_SUCCESS.

--*/

{
    //
    //  Update the information field with the correct value for bytes read.
    //

    Irp->IoStatus.Information = 0;

    if (NT_SUCCESS( Irp->IoStatus.Status )) {

        Irp->IoStatus.Information = ((PUDF_IO_CONTEXT) Context)->RequestedByteCount;
    }

    //
    //  Mark the Irp pending
    //

    IoMarkIrpPending( Irp );

    //
    //  Now release the resource
    //

    ExReleaseResourceForThread( ((PUDF_IO_CONTEXT) Context)->Resource,
                                ((PUDF_IO_CONTEXT) Context)->ResourceThreadId );

    //
    //  and finally, free the context record.
    //

    UdfFreeIoContext( (PUDF_IO_CONTEXT) Context );
    return STATUS_SUCCESS;

    UNREFERENCED_PARAMETER( DeviceObject );
}