Re: [Boost-users] [IPC Named Mutex]

Subject: Re: [Boost-users] [IPC Named Mutex]
From: Lorenzo Trivelli (trivelli.lorenzo_at_[hidden])
Date: 2015-06-19 10:41:03

Good evening,
I thought about a solution to find the last boot time stamp (in seconds)
which should work
The only limitation is that on Win2003/XP and earlier it works if and
only of the server
is not running for more than 47 days.
The trick is:

  *  use a combination of GetTickCount(/GetTickCount64 to get the ms
    since last boot
  * Use GetSystemTime to get current system Time
  * Next, with some int64 magic, get the boot time by subtracting the
    elapsed boot time from current time
  * Next, go back to a SYSTEMTIME structure
  * As there are some different time functions involved, it seems that
    the ms part is no completely reliable, but the other members are

do you think it may work ?

here is a little sample:

#include    <windows.h>
#include    <stdio.h>

int main() {
    SYSTEMTIME    st;
    ULONGLONG    tk;
    ULONGLONG    now;
    FILETIME    ft;
    ULONGLONG    u_boot;
    FILETIME    ft_boot;
    SYSTEMTIME    st_boot;

    GetSystemTime(&st);        //current time
    tk =    GetTickCount();        //millisenconds since last boot

    SystemTimeToFileTime(&st,&ft);

    now = * ((ULONGLONG*)  &ft);

   
    u_boot = (now / 10000 - tk) * 10000;

   
    //get a FILETIME back
    ft_boot        =    * ((FILETIME*) &u_boot);
    FileTimeToSystemTime(&ft_boot,&st_boot);

   
    printf("\nFunction Parameters");
    printf("\n\tTick Count             : %u",tk);
    printf("\n\tSystem Time to FileTime: %I64d", now);
    printf("\n\tBoot Time in 100ns     : %I64d", u_boot);

    printf("\nBoot Time Was   : %04d-%02d-%02d %02d:%02d:%02d.%03d",
st_boot.wYear, st_boot.wMonth,st_boot.wDay, st_boot.wHour,
st_boot.wMinute,st_boot.wSecond,st_boot.wMilliseconds);   

}

Regards
L. Trivelli