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vinoth

Unity Detecting an USB.

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Hi everyone, I have the same requirement as in the thread at http://www.gamedev.net/community/forums/topic.asp?topic_id=362845&whichpage=1� I wish to determine the type of removable drive, when the drive letter is given. To detect an USB (as per MSDN), I use the 'SetupDiGetDeviceRegistryProperty' method with SPDRP_REMOVAL_POLICY as a parameter. (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/devinst_r/hh/DevInst_r/di-rtns_a60fa017-1c15-45bf-a178-37516bc0aea1.xml.asp) MSDN says: "SPDRP_REMOVAL_POLICY (Windows XP and later) The function retrieves the device's current removal policy as a DWORD containing one of the CM_REMOVAL_POLICY_Xxxx values defined in cfgmgr32.h." My problem: How does this function retrieve this value ? The Output parameter PropertyBuffer is of type PBYTE and when I type cast it and take the value as *((DWORD *)PropertyBuffer), it gives me an invalid value (some garbage other than the CM_REMOVAL_POLICY_ values defined in cfgmgr32.h) Can someone please help ?? Thanks, Vinoth

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You optimistically misunderstood the MSDN explanation.
Says an easily googled MSDN page:
Quote:
Return Value

SetupDiGetDeviceRegistryProperty returns TRUE if the call was successful. Otherwise, it returns FALSE and the logged error can be retrieved with a call to GetLastError. SetupDiGetDeviceRegistryProperty returns the ERROR_INVALID_DATA error code if the requested property does not exist for a device or if the property data is not valid.


So the return value is a generic status code; the important "result" is written into a team of output parameters:
Quote:
PropertyRegDataType
Supplies a pointer to a variable to receive the data type of the property being retrieved. This is one of the standard registry data types.

PropertyBuffer
Supplies a pointer to a buffer to receive the property being retrieved. If set to NULL, with PropertyBufferSize set to zero, the function just returns a value for RequiredSize.

PropertyBufferSize
Supplies the length, in bytes, of PropertyBuffer.

RequiredSize
Optional. If not NULL, it is a caller-supplied pointer to a variable that receives the required size, in bytes, of the property buffer pointed to by PropertyBuffer, based on the property requested by Property.


Isn't it a cute API?

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