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Windows Driver Kit DDI reference (nc-vmbuskernelmodeclientlibapi-fn_vmb_channel_send_synchronous_request)

FN_VMB_CHANNEL_SEND_SYNCHRONOUS_REQUEST callback function

Description

[Some information relates to pre-released product which may be substantially modified before it's commercially released. Microsoft makes no warranties, express or implied, with respect to the information provided here.]

The VmbChannelSendSynchronousRequest function sends a packet to the opposite endpoint and waits for a response.

Parameters

`Channel`

A handle for the channel.

`Buffer`

Data to send.

`BufferSize`

The size, in bytes, of the data to send.

`ExternalDataMdl`

A Memory Descriptor List (MDL) that describes an additional buffer to send.

`Flags`

Standard flags.

`CompletionBuffer`

Buffer in which to store completion packet results.

`CompletionBufferSize`

The size, in bytes, of the CompletionBuffer value. This value must be rounded up to nearest 8 bytes, or else the function fails. On success, returns the number of bytes written into CompletionBuffer.

`Timeout`

A timeout in the style of the KeWaitForSingleObject routing. After this time elapses, the packet is cancelled. For a timeout of zero (0), if a packet does not fir in the ring buffer, it is not queued.

Return value

Return code	Description
STATUS_SUCCESS	The functions finished successfully.
STATUS_BUFFER_OVERFLOW	The packet did not fit in the buffer and was not queued.
STATUS_CANCELLED	The packet was canceled.
STATUS_DEVICE_REMOVED	The channel is being shut down.

Prototype

//Declaration

FN_VMB_CHANNEL_SEND_SYNCHRONOUS_REQUEST FnVmbChannelSendSynchronousRequest;

// Definition

NTSTATUS FnVmbChannelSendSynchronousRequest
(
    VMBCHANNEL Channel
    PVOID Buffer
    UINT32 BufferSize
    PMDL ExternalDataMdl
    UINT32 Flags
    PVOID CompletionBuffer
    PUINT32 CompletionBufferSize
    PLARGE_INTEGER Timeout
)
{...}

Remarks

Clients can run this function with any combination of parameters.

The root may only call this if *Timeout == 0 and the VMBUS_CHANNEL_FORMAT_FLAG_WAIT_FOR_COMPLETION flag is not set.

[!IMPORTANT] This function is called through the VMBus Kernel Mode Client Library (KMCL) interface, provided by the Vmbkmcl.sys bus driver. This is a client function accessed from the KMCL_CLIENT_INTERFACE_V1 structure.

For more information, see the Remarks section of the KMCL_CLIENT_INTERFACE_V1.

FN_VMB_CHANNEL_SEND_SYNCHRONOUS_REQUEST - NtDoc