WDS_SharedBufferAlloc()

DWORD DLLCALLCONV WDS_SharedBufferAlloc	(	_In_ UINT64	qwBytes,
		_In_ DWORD	dwOptions,
		_Outptr_ WD_KERNEL_BUFFER **	ppKerBuf
	)

Allocates a memory buffer that can be shared between the user mode and the kernel mode ("shared buffer"), and returns user-mode and kernel-mode virtual address space mappings of the allocated buffer.

Parameters

[in]	qwBytes	The size of the buffer to allocate, in bytes
[in]	dwOptions	Kernel buffer options bit-mask, which can consist of a combination of the enumeration values listed below. KER_BUF_ALLOC_NON_CONTIG: Allocates a non contiguous buffer KER_BUF_ALLOC_CONTIG: Allocates a physically contiguous buffer KER_BUF_ALLOC_CACHED: Allocates a cached buffer. This option can be set with KER_BUF_ALLOC_NON_CONTIG or KER_BUF_ALLOC_CONTIG buffer
[out]	ppKerBuf	Pointer to a WD_KERNEL_BUFFER pointer, to be filled by the function. The caller should use *ppBuf->pUserAddr usermode mapped address. When the buffer is no longer needed, (*ppBuf) should be passed to WDS_SharedBufferFree()

Returns

Returns WD_STATUS_SUCCESS (0) on success, or an appropriate error code otherwise

Remarks

This function is currently only supported from the user mode. This function is supported only for Windows and Linux.

// Static global pointer is used only for simplicity
static WD_KERNEL_BUFFER *pSharedKerBuf = NULL;
 
static void IpcKerBufAllocAndShare(void)
{
    DWORD size = 0x100;
    DWORD dwStatus;
    DWORD dwOptions = KER_BUF_ALLOC_CONTIG; // Or any other WD_KER_BUF_OPTION
 
    /* If kernel buffer was allocated in the past, release it */
    dwStatus = WDS_SharedBufferFree(pSharedKerBuf);
    if (WD_STATUS_SUCCESS != dwStatus)
    {
        printf("Failed freeing shared buffer. Error [0x%lx - %s]\n",
            dwStatus, Stat2Str(dwStatus));
    }
    dwStatus = WDS_SharedBufferAlloc(size, dwOptions, &pSharedKerBuf);
    if (WD_STATUS_SUCCESS != dwStatus)
    {
        printf("Failed allocating shared kernel buffer. size [%lu], "
            "Error [0x%lx - %s]\n", size, dwStatus, Stat2Str(dwStatus));
        return;
    }
 
    printf("Successful kernel buffer allocation. UserAddr [0x%"UPRI"x], "
        "KernelAddr [0x%"KPRI"x], size [%lu]\n", pSharedKerBuf->pUserAddr,
        pSharedKerBuf->pKernelAddr, size);
}