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7-4 Lucent Technologies Inc.
USS-720 Preliminary User Guide, Rev. 2
USB Device Driver February 1999
13
3 I/O File Functions (continued)
3.1 CreateFile
The CreateFile I/O file function opens an instance of a particular device and returns an open handle to the device
instance. Details regarding the syntax, parameters, return values, and error codes are listed below.
3.1.1 Syntax
HANDLE
CreateFile(
LPCTSTR lpDevName,
DWORD dwDesiredAccess,
DWORD dwShareMode,
LPSECURITY_ATTRIBUTES lpSecurityAttributes,
DWORD dwCreationDistribution,
DWORD dwFlagsAndAttributes,
HANDLE hTemplateFile
);
3.1.2 Parameters
Input:
lpDevName—Points to a null-terminated string that specifies the symbolic link name of a specific device instance to
open (see Section 4.12 IOCTL_GET_DEVICE_INSTANCES). Note that the symbolic link must be prefixed with
“\\.\”. For example, to retrieve the handle of the symbolic name LPTUSB1, “\\.\LPTUSB1” must be passed to the
lpDevName parameter.
Note: For definitions of other input parameters, refer to CreateFile Function in the
WIN32 SDK
documentation.
Output:
None.
3.1.3 Return Values
If the function succeeds, the return value is an open handle to the device instance.
If the function fails, the return value is INVALID_HANDLE_VALUE. To get extended error information, call
GetLastError.
3.1.4 Notes
See the
Win32 SDK
documentation for complete definitions of parameters.
3.1.5 Error Code
ERROR_ALREADY_OPENED—Device instance is already open.