KsAllocateExtraData function (ks.h)

The KsAllocateExtraData function is used with streaming IRPs to allocate a buffer to contain additional header data. A pointer to the allocated buffer is returned, and the buffer must eventually be freed by the caller.

Syntax

KSDDKAPI NTSTATUS KsAllocateExtraData(
  [in, out] PIRP  Irp,
  [in]      ULONG ExtraSize,
  [out]     PVOID *ExtraBuffer
);

Parameters

[in, out] Irp

Specifies the IRP containing the stream headers. The IRP must have been previously passed to KsProbeStreamIrp to buffer the headers.

[in] ExtraSize

Specifies the size, in bytes, of additional memory to allocate between each stream header. This value must be alignable on an eight-byte boundary. A copy of the headers is placed in the returned buffer, with the extra data size inserted between each header. This must be freed by the caller.

[out] ExtraBuffer

Points to a caller-allocated pointer that, on successful completion, points to a system-allocated buffer containing the stream headers and the requested padding between them. This must be freed by the caller.

Return value

The KsAllocateExtraData function returns STATUS_SUCCESS if successful, or it returns a resource or access error.

Remarks

When KsAllocateExtraData completes successfully, a pointer to a block of memory is returned that contains both the stream data headers from the IRP, specified at Irp, and padding between each header of size specified in ExtraSize. An example of such a resultant buffer is shown below:

When the extra buffer is no longer needed, the memory should be freed using ExFreePool.

Requirements

Requirement	Value
Target Platform	Universal
Header	ks.h (include Ks.h)
Library	Ks.lib
IRQL	< DISPATCH_LEVEL