time_t 를 FILETIME 로 변경하기.

프로그램을 작성하다 보니.. 파일의 시간을 변경할 일이 발생했다...
Win32 API에서 여러가지 함수를 제공하기는 하는데.. time_t를 바로 지원하지는 않는다. -_-;;;

다행히도 MSDN에서 이를 지원하는 KB가 있어 옮겨 보았다.

How To Convert a UNIX time_t to a Win32 FILETIME or SYSTEMTIME

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Article ID	:	167296
Last Review	:	November 21, 2006
Revision	:	3.3

This article was previously published under Q167296

SUMMARY

Under UNIX platforms, file times are maintained in the form of a ANSI C runtime arithmetic type named 'time_t', which represents seconds since midnight January 1, 1970 UTC (coordinated universal time).

Under Win32 platforms, file times are maintained primarily in the form of a 64-bit FILETIME structure, which represents the number of 100-nanosecond intervals since January 1, 1601 UTC (coordinate universal time).

This article shows how to convert UNIX time to other Win32 time formats.

MORE INFORMATION

The following function converts a filetime in the UNIX time_t format to a Win32 FILETIME format. Note that time_t is a 32-bit value and FILETIME is a 64-bit structure, so the Win32 function, Int32x32To64() is used in the following function:

   #include <winbase.h>
   #include <winnt.h>
   #include <time.h>

   void UnixTimeToFileTime(time_t t, LPFILETIME pft)
   {
     // Note that LONGLONG is a 64-bit value
     LONGLONG ll;

     ll = Int32x32To64(t, 10000000) + 116444736000000000;
     pft->dwLowDateTime = (DWORD)ll;
     pft->dwHighDateTime = ll >> 32;
   }
				

Once the UNIX time is converted to a FILETIME structure, other Win32 time formats can be easily obtained by using Win32 functions such as FileTimeToSystemTime() and FileTimeToDosDateTime().

   void UnixTimeToSystemTime(time_t t, LPSYSTEMTIME pst)
   {
     FILETIME ft;

     UnixTimeToFileTime(t, &ft);
     FileTimeToSystemTime(&ft, pst);
   }
				

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APPLIES TO

•	Microsoft Win32 Application Programming Interface, when used with:
Microsoft Windows 95     Microsoft Windows 98 Standard Edition     Microsoft Windows Millennium Edition     Microsoft Windows NT 3.51 Service Pack 5     Microsoft Windows NT 4.0     Microsoft Windows 2000 Standard Edition     Microsoft Windows XP Professional

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Keywords:

kbdatetime kbhowto kbkernbase kbprogramming KB167296