Hi All, this article discusses FILETIME handling on NT and 9[58] and puts up the question how to best cope with it in XEmacs (native and mingw32). Please bear with me while I give Craig two anserws. Other may fast-forward to My analysis: Craig> Are these files on an NTFS disk or FAT disk? These files are all on NTFS. Craig> My files are on a FAT32 disk. Craig> Does NTFS store the timestamp as a GMT integer like unix? Yes, that's it. Here's an extract from MSDN, which is still true for NT4: FileTimeToLocalFileTime() Adjusts for Daylight Saving Time Last reviewed: September 25, 1995 Article ID: Q128126 The information in this article applies to: Microsoft Win32 Application Programming Interface (API) included with: - Microsoft Windows NT version 3.5 SUMMARY Under NTFS, the API GetFileTime() returns the create time, last access time, and last write time for the specified file. The times returned in the FILETIME structures are in Universal Coordinated Time (UTC). This is also the time that NTFS uses. You can use FileTimeToLocalFileTime() to convert a file time to a local time. However, if you automatically adjust for Daylight Saving Time, FileTimeToLocalFileTime() will adjust for Daylight Saving Time based on whether the current date should be adjusted for Daylight Saving Time, not based on whether the date represented by the FILETIME structure should be adjusted. The behavior in this situation is different under FAT, but may be changed to match the behavior under NTFS in a future version of Windows NT. <lines deleted by Adrian> The FAT file system stores local time, not UTC. GetFileTime() gets cached UTC times from FAT. In this sample, the time stored is 1pm and the cached time is 9pm. When it becomes Daylight Saving Time, sample codes 1 and 2 will demonstrate the same behavior that they do under NTFS, because 9pm is still used. However, when you restart the machine, the new cached time will be 8pm (UTC = LocalTime + 7). The call to FileTimeToLocalFileTime() cancels the adjustment made by GetFileTime() (LocalTime = UTC - 7). Therefore, sample code 1 will report the correct time under FAT, but sample code 2 will not. On the other hand, FindFirstFile() on FAT always reads the time from the file (stored as local time) and converts it into UTC, adjusting for DST based on the current date. So if FindFirstFile() is called, the date is changed to a different DST season, and then FindFirstFile() is called again, the UTC returned by the two calls will be different. Craig> (FAT and FAT32 do not.) If so, that would explain why you Craig> see the time change in Explorer. Exactly. My analysis: I guess MS ``designed´´ FileTimeToLocalFileTime to interpret a FILETIME according to a computer's current DST and TZ setting because they have no way to know what a FAT FILETIME really means (by design, yeah right) since it is stored in local time. My vote is for doing it RIGHT for NTFS and POSIX partitions, interpreting these as UTC, and interpreting FAT partition file times to be relative to the current TZ and DST. That's all we can do, right? Craig> It is compiled and linked in, but I'm not sure how many of Craig> its functions are called. Andy would probably have a Craig> better idea on that. Could any of you tell me how to distinguish NTFS from FAT partitions both on Windows NT and Windows9[58] safely? After a lot of clicking in MSDN I found DeviceIoControl(BOOL DeviceIoControl( (HANDLE) hDevice, // handle to device of interest IOCTL_DISK_GET_PARTITION_INFO, // dwIoControlCode, control code // of operation to perform NULL, // lpInBuffer is not used; must be NULL 0, // nInBufferSize is not used; must be zero (LPVOID) lpOutBuffer, // pointer to output buffer (DWORD) nOutBufferSize, // size, in bytes, of lpOutBuffer (LPDWORD) lpBytesReturned, // pointer to variable to receive // output byte count (LPOVERLAPPED) lpOverlapped // pointer to OVERLAPPED structure // for asynchronous operation ); which is appealing at first glance. However, hDevice can only be opened directly with CreateFile on NT. 95 is incompatible and requires dealing with VxDs. Am I on the right track? What would be the simplest working way to tell apart NTFS and FAT files on the Windows NT, 95, 98 kindred? Thanks for any help! Adrian