67 Chapter 4
Parameters:
. hDevice
[in] Handle to the device that is to perform the operation. Call the Create-
File function to obtain a device handle.
. dwIoControlCode
[in] Specifies the control code for the operation. This value identifies the
specific operation to be performed and the type of device on which the
operation is to be performed. No specific values are defined for the dwIo-
ControlCode parameter. However, the writer of a custom device driver
can define IOCTL_XXXX control codes, per the CTL_CODE macro.
These control codes can then be advertised, and an application
can use these control codes with DeviceIoControl to perform driver spe-
cific 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 output data for the opera-
tion. 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
