DeviceIoControl Function

The DeviceIoControl function sends a control code directly to a specified device driver, causing the driver to perform the specified action.

BOOL DeviceIoControl(
  HANDLE       hDevice,
  DWORD        dwIoControlCode,
  LPVOID       lpInBuffer,
  DWORD        nInBufferSize,
  LPVOID       lpOutBuffer,
  DWORD        nOutBufferSize,
  LPDWORD      lpBytesReturned,
  LPOVERLAPPED lpOverlapped
);

Parameters

• hDevice

  A handle to the device for which control operations are to be performed. This handle is obtained by calling the CreateFile function.

• dwIoControlCode

  The driver-specified I/O control code (IOCTL) for the operation to perform. This parameter value identifies the specific operation to be performed.

• lpInBuffer

  A pointer to the buffer that contains data required by the driver to perform the specified operation. If this parameter is NULL and the dwIoControlCode parameter specifies an operation that does not require input data, this parameter can be NULL.

• nInBufferSize

  The size, in bytes, of the buffer pointed to by lpInBuffer.

• lpOutBuffer

  A pointer to the buffer that receives output from the specified operation. If this parameter is NULL and the dwIoControlCode parameter specifies an operation that does not produce output data, this parameter can be NULL.

• nOutBufferSize

  The size, in bytes, of the buffer pointed to by lpOutBuffer.

• lpBytesReturned

  A pointer to a DWORD value that receives the size, in bytes, of the data written to the buffer pointed to by lpOutBuffer. If lpOutBuffer is not NULL, this parameter can be NULL. If lpOutBuffer is NULL, this parameter must be NULL.

• lpOverlapped

  A pointer to a OVERLAPPED structure that is used for asynchronous operations. If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, this parameter is required. If hDevice was opened without the FILE_FLAG_OVERLAPPED flag, this parameter can be NULL.

Return Value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails, the return value is zero. To get extended error information, call GetLastError.

// Example of a common IOCTL definition
                    #define IOCTL_MY_DEVICE_GET_STATUS CTL_CODE(FILE_DEVICE_UNKNOWN, 0x0001, METHOD_BUFFERED, FILE_ANY_ACCESS)