A File Manager extension sends an FM_GETDRIVEINFO message to retrieve drive information from the active File Manager window.
wParam
Not used.
lParam
Points to an FMS_GETDRIVEINFO structure that receives drive information. The FMS_GETDRIVEINFO structure has the following form:
#include <wfext.h>
typedef struct tagFMS_GETDRIVEINFO { /* fmsgdi */
DWORD dwTotalSpace;
DWORD dwFreeSpace;
char szPath[260];
char szVolume[14];
char szShare[128];
} FMS_GETDRIVEINFO, FAR *LPFMS_GETDRIVEINFO;
The return value is always nonzero.