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53 Appendix B
control codes can then be advertised, and an application can use these
control codes with DeviceIoControl to perform driverspecific functions.
lpInBuffer
[in] Long pointer to a buffer that contains the data required to perform the
operation. This parameter can be NULL if the dwIoControlCode parame-
ter specifies an operation that does not require input data.
nInBufferSize
[in] Size, in bytes, of the buffer pointed to by lpInBuffer.
lpOutBuffer
[out] Long pointer to a buffer that receives the operation.s output data.
This parameter can be NULL if the dwIoControlCode parameter specifies
an operation that does not produce output data.
nOutBufferSize
[in] Size, in bytes, of the buffer pointed to by lpOutBuffer.
lpBytesReturned
[out] Long pointer to a variable that receives the size, in bytes, of the data
stored into the buffer pointed to by lpOutBuffer. The lpBytesReturned
parameter cannot be NULL. Even when an operation produces no output
data, and lpOutBuffer can be NULL, the DeviceIoControl function makes
use of the variable pointed to bylpBytesReturned. After such an opera-
tion, the value of the variable is without meaning.
lpOverlapped
[in] Ignored; set to NULL.
Return Values
Nonzero indicates success. Zero indicates failure. To get extended error
information, call GetLastError.