Lucent Technologies USS-720 manual 3 I/O File Functions continued, CreateFile, USB Device Driver

USS-720	Preliminary User Guide, Rev. 2
USB Device Driver	February 1999

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.

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