write.c File Reference

#include "cdprocs.h"

Include dependency graph for write.c:

Go to the source code of this file.

Macros
#define	BugCheckFileId   (CDFS_BUG_CHECK_WRITE)
#define	SafeZeroMemory(IC, AT, BYTE_COUNT)

Functions
	_Requires_lock_held_ (_Global_critical_region_)

Macro Definition Documentation

BugCheckFileId

#define BugCheckFileId   (CDFS_BUG_CHECK_WRITE)

Definition at line 23 of file write.c.

SafeZeroMemory

#define SafeZeroMemory	(		IC,
			AT,
			BYTE_COUNT
	)

Value:

{                  \
    _SEH2_TRY {                                             \
        RtlZeroMemory( (AT), (BYTE_COUNT) );                \
__pragma(warning(suppress: 6320))                           \
    } _SEH2_EXCEPT( EXCEPTION_EXECUTE_HANDLER ) {           \
         CdRaiseStatus( IC, STATUS_INVALID_USER_BUFFER );   \
    } _SEH2_END;                                            \
}

Definition at line 38 of file write.c.

Function Documentation

_Requires_lock_held_()

_Requires_lock_held_

(

_Global_critical_region_

)

Definition at line 61 of file write.c.

{
    NTSTATUS Status = STATUS_SUCCESS;
    PIO_STACK_LOCATION IrpSp = IoGetCurrentIrpStackLocation( Irp );

    TYPE_OF_OPEN TypeOfOpen;
    PFCB Fcb;
    PCCB Ccb;

    BOOLEAN Wait;
    ULONG SynchronousIo;
    PVOID UserBuffer;

    LONGLONG StartingOffset;
    LONGLONG ByteRange;
    ULONG ByteCount;
    ULONG WriteByteCount;
    ULONG OriginalByteCount;

    BOOLEAN ReleaseFile = TRUE;

    CD_IO_CONTEXT LocalIoContext;

    PAGED_CODE();

    //
    //  If this is a zero length write then return SUCCESS immediately.
    //

    if (IrpSp->Parameters.Write.Length == 0) {

        CdCompleteRequest( IrpContext, Irp, STATUS_SUCCESS );
        return STATUS_SUCCESS;
    }

    //
    //  Decode the file object and verify we support write on this.  It
    //  must be a volume file.
    //

    TypeOfOpen = CdDecodeFileObject( IrpContext, IrpSp->FileObject, &Fcb, &Ccb );

    // Internal lock object is acquired if return status is STATUS_PENDING
    _Analysis_suppress_lock_checking_(Fcb->Resource);

    if (TypeOfOpen != UserVolumeOpen) {

        CdCompleteRequest( IrpContext, Irp, STATUS_INVALID_DEVICE_REQUEST );
        return STATUS_INVALID_DEVICE_REQUEST;
    }

    //
    //  Examine our input parameters to determine if this is noncached and/or
    //  a paging io operation.
    //

    Wait = BooleanFlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_WAIT );
    SynchronousIo = FlagOn( IrpSp->FileObject->Flags, FO_SYNCHRONOUS_IO );


    //
    //  Extract the range of the Io.
    //

    StartingOffset = IrpSp->Parameters.Write.ByteOffset.QuadPart;
    OriginalByteCount = ByteCount = IrpSp->Parameters.Write.Length;

    ByteRange = StartingOffset + ByteCount;

    //
    //  Acquire the file shared to perform the write.
    //

    CdAcquireFileShared( IrpContext, Fcb );

    //
    //  Use a try-finally to facilitate cleanup.
    //

    _SEH2_TRY {

        //
        //  Verify the Fcb.  Allow writes if this is a DASD handle that is 
        //  dismounting the volume.
        //

        if (!FlagOn( Ccb->Flags, CCB_FLAG_DISMOUNT_ON_CLOSE ))  {

            CdVerifyFcbOperation( IrpContext, Fcb );
        }

        if (!FlagOn( Ccb->Flags, CCB_FLAG_ALLOW_EXTENDED_DASD_IO )) {

            //
            //  Complete the request if it begins beyond the end of file.
            //

            if (StartingOffset >= Fcb->FileSize.QuadPart) {

                try_return( Status = STATUS_END_OF_FILE );
            }

            //
            //  Truncate the write if it extends beyond the end of the file.
            //

            if (ByteRange > Fcb->FileSize.QuadPart) {

                ByteCount = (ULONG) (Fcb->FileSize.QuadPart - StartingOffset);
                ByteRange = Fcb->FileSize.QuadPart;
            }
        }

        //
        //  If we have an unaligned transfer then post this request if
        //  we can't wait.  Unaligned means that the starting offset
        //  is not on a sector boundary or the write is not integral
        //  sectors.
        //

        WriteByteCount = BlockAlign( Fcb->Vcb, ByteCount );

        if (SectorOffset( StartingOffset ) ||
            SectorOffset( WriteByteCount ) ||
            (WriteByteCount > OriginalByteCount)) {

            if (!Wait) {

                CdRaiseStatus( IrpContext, STATUS_CANT_WAIT );
            }

            //
            //  Make sure we don't overwrite the buffer.
            //

            WriteByteCount = ByteCount;
        }

        //
        //  Initialize the IoContext for the write.
        //  If there is a context pointer, we need to make sure it was
        //  allocated and not a stale stack pointer.
        //

        if (IrpContext->IoContext == NULL ||
            !FlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO )) {

            //
            //  If we can wait, use the context on the stack.  Otherwise
            //  we need to allocate one.
            //

            if (Wait) {

                IrpContext->IoContext = &LocalIoContext;
                ClearFlag( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO );

            } else {

                IrpContext->IoContext = CdAllocateIoContext();
                SetFlag( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO );
            }
        }

        RtlZeroMemory( IrpContext->IoContext, sizeof( CD_IO_CONTEXT ) );

        //
        //  Store whether we allocated this context structure in the structure
        //  itself.
        //

        IrpContext->IoContext->AllocatedContext =
            BooleanFlagOn( IrpContext->Flags, IRP_CONTEXT_FLAG_ALLOC_IO );

        if (Wait) {

            KeInitializeEvent( &IrpContext->IoContext->SyncEvent,
                               NotificationEvent,
                               FALSE );

        } else {

            IrpContext->IoContext->ResourceThreadId = ExGetCurrentResourceThread();
            IrpContext->IoContext->Resource = Fcb->Resource;
            IrpContext->IoContext->RequestedByteCount = ByteCount;
        }

        Irp->IoStatus.Information = WriteByteCount;

        //
        //  Set the FO_MODIFIED flag here to trigger a verify when this
        //  handle is closed.  Note that we can err on the conservative
        //  side with no problem, i.e. if we accidently do an extra
        //  verify there is no problem.
        //

        SetFlag( IrpSp->FileObject->Flags, FO_FILE_MODIFIED );

        //
        //  Dasd access is always non-cached. Call the Dasd write routine to
        //  perform the actual write.
        //

        Status = CdVolumeDasdWrite( IrpContext, Fcb, StartingOffset, WriteByteCount );

        //
        //  Don't complete this request now if STATUS_PENDING was returned.
        //

        if (Status == STATUS_PENDING) {

            Irp = NULL;
            ReleaseFile = FALSE;

        //
        //  Test is we should zero part of the buffer or update the
        //  synchronous file position.
        //

        } else {

            //
            //  Convert any unknown error code to IO_ERROR.
            //

            if (!NT_SUCCESS( Status )) {

                //
                //  Set the information field to zero.
                //

                Irp->IoStatus.Information = 0;

                //
                //  Raise if this is a user induced error.
                //

                if (IoIsErrorUserInduced( Status )) {

                    CdRaiseStatus( IrpContext, Status );
                }

                Status = FsRtlNormalizeNtstatus( Status, STATUS_UNEXPECTED_IO_ERROR );

            //
            //  Check if there is any portion of the user's buffer to zero.
            //

            } else if (WriteByteCount != ByteCount) {

                CdMapUserBuffer( IrpContext, &UserBuffer );
                
                SafeZeroMemory( IrpContext,
                                Add2Ptr( UserBuffer,
                                         ByteCount,
                                         PVOID ),
                                WriteByteCount - ByteCount );

                Irp->IoStatus.Information = ByteCount;
            }

            //
            //  Update the file position if this is a synchronous request.
            //

            if (SynchronousIo && NT_SUCCESS( Status )) {

                IrpSp->FileObject->CurrentByteOffset.QuadPart = ByteRange;
            }
        }

    try_exit:  NOTHING;
    } _SEH2_FINALLY {

        //
        //  Release the Fcb.
        //

        if (ReleaseFile) {

            CdReleaseFile( IrpContext, Fcb );
        }
    } _SEH2_END;

    //
    //  Post the request if we got CANT_WAIT.
    //

    if (Status == STATUS_CANT_WAIT) {

        Status = CdFsdPostRequest( IrpContext, Irp );

    //
    //  Otherwise complete the request.
    //

    } else {

        CdCompleteRequest( IrpContext, Irp, Status );
    }

    return Status;
}