Re: [PATCH] posixtm: don't reject a time with "60" as the number of seconds

[Paolo Bonzini]

>      --- -      2009-09-14 14:32:58.934253776 +0200
>      +++ in     2009-09-14 14:32:58.930840392 +0200
>      @@ -1,6 +1,6 @@
>      -12131415.16     13   1260713716 Sun Dec 13 14:15:16 2009
>      -12131415.16     13   1260713716 Sun Dec 13 14:15:16 2009
>      -000001010000.00 13 -62167219200 Sat Jan  1 00:00:00 0
>      +12131415.16     13   1039788916 Fri Dec 13 14:15:16 2002
>      +12131415.16     13   1039788916 Fri Dec 13 14:15:16 2002
>      +000001010000.00 13 -62167132800 Sun Jan  1 00:00:00 0000
>       190112132045.52 13  -2147483648 Fri Dec 13 20:45:52 1901
>       190112132045.53 13  -2147483647 Fri Dec 13 20:45:53 1901
>       190112132046.52 13  -2147483588 Fri Dec 13 20:46:52 1901
>
> Note that the first two differences are to be expected.
> Those tests pass only if 2002 is the current year.
> However, I don't know about the difference in the 3rd line.
> Note the s/Sat/Sun/ change.  The new number of seconds is 86400
> larger than the old one; that's exactly one day's worth of seconds,
> and hence in line with the Sat/Sun change.
>
> I don't yet know if this change is a problem in mktime or due
> to some intervening fix.

cal accepts only years from 1 to 9999, but anyway it implements the 
Julian calendar correctly so it is not useful (you really should try 
"cal 9 1752"!!).  Going backwards from "cal 1 1" you can see that in the 
Julian calendar 01-Jan-0000 was a Thursday, but that's not so relevant.

However cal can help seeing that 01-Jan-0000 is a Saturday in Gregorian 
proleptic calendar (i.e. extending Gregorian calendar before the day 
when it was adopted).  400 years have 146097 days, which is divisible by 
7, and 01-Jan-2000 was a Saturday.

Paolo