Cast uint64_t to FILETIME

Question

I'm trying to get byte array from file, interpret it like uint64_t and then cast this uint to FILETIME

After googling around and debugging a bit I've stuck at following wrong working code.

uint64_t win_filetime = *(uint64_t*)(&(((char*)buf)[(int)FILETIME_OFFSET]));
//at this moment win_filetime = 0x01cb3f90e7b52500

where buf contains needed bytes at FILETIME_OFFSET

Then trying to cast t1 = *(FILETIME *)(&win_filetime); or

t1.dwLowDateTime = (DWORD)win_filetime;
t1.dwHighDateTime = (DWORD)(win_filetime >> 32);

to pass it to the function

tm FILETIME_to_time_t(const FILETIME *lpFileTime) {

  time_t result;

  SYSTEMTIME st;

  struct tm tmp;

  FileTimeToSystemTime(lpFileTime,&st);

  memset(&tmp,0,sizeof(struct tm));

  tmp.tm_mday = st.wDay;
  tmp.tm_mon  = st.wMonth - 1;
  tmp.tm_year = st.wYear - 1900;

  tmp.tm_sec  = st.wSecond;
  tmp.tm_min  = st.wMinute;
  tmp.tm_hour = st.wHour;

  return tmp;
} 

Function FILETIME_to_time_t() returns rubbish(ie year = 110)

Sample value from file: 0025B5E7903FCB0100 that HexWorkshop correctly parsing as 11:23:10 19.08.2010

Maybe there is lack of endianness conversion or another thing that I'm unable to spot now?

Answer 1

It seems your code is OK, it's just that the year shows 110 because you subtract 1900 in your code when populating the struct tm . That's standard though-- struct tm is supposed to contain the year minus 1900. You just need to be careful when printing the value.