--- In advanced_delphi@yahoogroups.com, "Glenn Lawler" <gblaw...@...> wrote: > > We have a number of applications which are editors of different kinds where > we have included a feature which warns the user that the file he is editing > has been changed since it was loaded. This feature has worked just fine until > Vista. It works fine about 80% of the time in Vista, but produces a false > indication about 20% of the time. > > What we originally did with these programs is use the FileAge function to > return the integer which represents the file timestamp, and save it in an > internal variable. Then, whenever the user saves the file, we get the FileAge > again and verify that it has not changed. This has worked reliably with all > versions of Windows until Vista. With Vista, a difference of 2 seconds or > less occurs about 20% of the time even when I know the file has not been > changed. This 2 second difference reminded me of the 2 second file time > resolution > limit in DOS, and since FileAge returns an integer containing both > the date and time, I assumed it may be subject to a similar > resolution limit. > > In an attempt to get around this problem in Vista, I changed one of the apps > to use the API to get the file time from the directory listing: > > var > FindHandle: THandle; > FindData: TWin32FindData; > LocalFileTime: TFileTime; > > FindHandle:=FindFirstFile(PChar(FileName),FindData); > if FindHandle <> INVALID_HANDLE_VALUE then begin > FileTimeToLocalFileTime(FindData.ftLastWriteTime,LocalFileTime); > FindClose(FindHandle); > end; > > We then use this API comparison to determine if the file has been changed: > > if CompareFileTime(NewEditFileTimeStamp,EditFileTimeStamp) <> 0 then > > Using this method, we still have the same problem. This appears to be a quirk > in Vista, so the best I am hoping for is some kind of a workaround. It would > seem there must be some reliable way to check the timestamps on files to > determine if they have changed. > > Any ideas would be greatly appreciated. > > Glenn Lawler > www.incodesystems.com >
Would the API "GetFileTime" be of any help? Declare Function GetFileTime Lib "kernel32" Alias "GetFileTime" (ByVal hFile As Long, lpCreationTime As FILETIME, lpLastAccessTime As FILETIME, lpLastWriteTime As FILETIME) As Long The FILETIME structure looks like... Type FILETIME dwLowDateTime As Long dwHighDateTime As Long End Type David
