Input date modified when calling mktime64

[tucanus]

Congratulations for this great lib, solved me a sad moment.
I noticed mktime64 correct input_date, but leaving an incorrect year if date is not in safe range.
I modified sources, adding

    /* correct variation of year on input_date */
    input_date->tm_year = year - date.tm_year + safe_date.tm_year - 1900;

after line 542 (copying safe_date on input_date) and it seems to work correctly.
Do you think it is acceptable?
Thank you for your job
-Cristiano

[schwern]

Could you provide a sample program that triggers the bug? Be sure to include the time zone you're in.

[tucanus]

Sure.

#include <iostream>
#include "time64.h"

int main(int argc, char **argv) {
    struct tm tt;
    char buffer[64];
    ::strptime("1/1/2040 12.00.00", "%d/%m/%Y %H.%M.%S", &tt);
    {
        size_t len = ::strftime(buffer, sizeof(buffer), "%d/%m/%Y %H.%M.%S", &tt);
        std::cout << "Input date: " << std::string(buffer, len) << std::endl;
    }
    ::mktime64((struct TM *)&tt);
    {
        size_t len = ::strftime(buffer, sizeof(buffer), "%d/%m/%Y %H.%M.%S", &tt);
        std::cout << "Correct date: " << std::string(buffer, len) << std::endl;
    }
    return 0;
}

Output

Input date: 01/01/2040 12.00.00
Correct date: 01/01/2012 12.00.00

Excuse but I have not understood where I have to include my time zone. I ran this code at CET, if you need to know.

[schwern]

I haven't forgotten about this. I'm off learning a bunch of C so I can do a better job fixing up this project. LMK if there's urgency on getting this integrated.

[VTiTux]

Same issue.
Enter 2038/01/19 3:00:00, return 2010/01/19 3:00:00

[liquidaty]

FYI to workaround this issue, I just commented out the two lines in mktime64 which call copy_tm_to_TM64. Not sure why they are there to begin with but perhaps the author could opine on whether they should stay? If they should, then an alternative workaround would be to revert the year immediately after the second occurrence of copy_tm_to_TM64:

    /* Have to make the year safe in date else it won't fit in safe_date */
    date = *input_date;
[...]
    /* Correct the user's possibly out of bound input date */
    copy_tm_to_TM64(&safe_date, input_date);
+
+    /* revert the year to the original value */
+    input_date->tm_year = year - 1900;