bugGNU FreeIPMI - Bugs: bug #31758, Leap years are not included into...

 
 

bug #31758: Leap years are not included into the formula

Submitter:  Albert Chu <chu11>
Submitted:  Thu 02 Dec 2010 06:39:58 PM UTC
   
 
Category:  libfreeipmi Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Improper Behaviour
Status:  None Privacy:  Public
Assigned to:  None Open/Closed:  Closed
Operating System:  None
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Fri 03 Dec 2010 01:01:23 AM UTC, comment #2: 

Should be fixed in the next release of FreeIPMI (0.8.12)

Albert Chu <chu11>
Group administrator
Thu 02 Dec 2010 06:43:31 PM UTC, comment #1: 

(Note: Due to Savannah restore, original bug disappeared.  This bug is a resubmission from user "BR")

BR,

I think you're absolutely right.  There is a leap year calculation bug.  I'll need to look into how to do this right and in a way that's portable, but your suggestion below is probably right on target with what I should do.

Thanks,
Al

Albert Chu <chu11>
Group administrator
Thu 02 Dec 2010 06:39:58 PM UTC, original submission:  

Hello,


I want to inform you about a possible bug in your library.
It touches the calculation of the difference in epoch


file: freeipmi-0.8.11/libfreeipmi/src/fru-parse/ipmi-fru-parse-data.c
336.      /* In FRU, epoch is 0:00 hrs 1/1/96
337.       *
338.       * So convert into ansi epoch
339.       *
340.       * 26 years difference in epoch
341.       * 365 days/year
342.       * etc.
343.       *
344.       */
345.      mfg_date_time_tmp += (26 365 24 60 60);
346.      (*mfg_date_time) = mfg_date_time_tmp;


This formula doesn't take leap years and so it misses six days
Years: 1972, 1976, 1980, 1984, 1988, 1992


Here are GNU date output in comparison to your formula:
$ date -d "1996-01-01 00:00:00" +%s
  820447200
$ calc "26 365 24 60 60"
  819936000


I'm not certain with the whole library architecture. Maybe you are correcting this in some other place or there is a doublebug? Please check if it is not better to use something like this:
 
// this code gives the same result as `date`
#include <stdio.h>
#include <time.h>

int main()
{
    struct tm t;

    t.tm_year = 96;
    t.tm_mon = 0;
    t.tm_mday = 1;
    t.tm_hour = 0;
    t.tm_min = 0;
    t.tm_sec = 0;

    time_t result = mktime(&t);

    printf("1996-01-01 00:00:00 = %d\n", result);

    return 0;
}


Appreciate your work.
BR

Albert Chu <chu11>
Group administrator

 

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    Date Changed by Updated Field Previous Value => Replaced by
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