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cal: correct gregorian week numbering 

Jan 1 is always First week, and year always has 53 weeks.  The week 53
may be cut short, e.g., it may and often has fewer than 7 days.  Every
year 28 year intervals US week numbering continues all the way to 54th
week, such as 1972, 2000, and 2028.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1249486
Reported-by: Michal Toth
Signed-off-by: Sami Kerola <kerolasa@iki.fi>
This commit is contained in:
Sami Kerola 2015-08-27 14:21:26 +01:00 committed by Karel Zak
parent 32c9ce4baf
commit efafeaf684
1 changed files with 15 additions and 18 deletions
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33
misc-utils/cal.c
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@ -390,8 +390,8 @@ int main(int argc, char **argv)
if (optarg) {
ctl.req.week = strtos32_or_err(optarg,
_("invalid week argument"));
if (ctl.req.week < 1 || 53 < ctl.req.week)
errx(EXIT_FAILURE,_("illegal week value: use 1-53"));
if (ctl.req.week < 1 || 54 < ctl.req.week)
errx(EXIT_FAILURE,_("illegal week value: use 1-54"));
}
ctl.weektype = WEEK_NUM_US; /* default per weekstart */
break;
@ -604,15 +604,13 @@ static void cal_fill_month(struct cal_month *month, const struct cal_control *ct
int weeknum = week_number(1, month->month, month->year, ctl);
weeklines = MAXDAYS / DAYS_IN_WEEK - weeklines / DAYS_IN_WEEK;
for (i = 0; i < MAXDAYS / DAYS_IN_WEEK; i++) {
if (0 < weeklines)
if (0 < weeklines) {
if (52 < weeknum)
weeknum = week_number(month->days[i * DAYS_IN_WEEK], month->month, month->year, ctl);
month->weeks[i] = weeknum++;
else
} else
month->weeks[i] = SPACE;
weeklines--;
if (i == 0 && (52 < weeknum || (month->year == 1753 && 51 < weeknum)))
weeknum = week_number(month->days[DAYS_IN_WEEK * (i + 1)], 1, month->year, ctl);
else if (52 < weeknum)
weeknum = week_number(31, 12, month->year, ctl);
}
}
}
@ -839,7 +837,7 @@ static int day_in_week(int day, int month, int32_t year)
/*
* week_number
* return the week number of a given date, 1..53.
* return the week number of a given date, 1..54.
* Supports ISO-8601 and North American modes.
* Day may be given as Julian day of the year mode, in which
* case the month is disregarded entirely.
@ -847,17 +845,16 @@ static int day_in_week(int day, int month, int32_t year)
static int week_number(int day, int month, int32_t year, const struct cal_control *ctl)
{
int fday = 0, yday;
int wday = day_in_week(1, 1, year);
const int wday = day_in_week(1, 1, year);
if (ctl->weektype & WEEK_NUM_ISO)
fday = wday + (wday >= FRIDAY ? -2 : 5);
else
/* WEEK_NUM_US
* - according to gcal, the first Sun is in the first week
* - according to wikipedia, the first Sat is in the first week
*/
fday = wday + (wday == SUNDAY ? 6 : -1);
else {
/* WEEK_NUM_US: Jan 1 is always First week, that may
* begin previous year. That means there is very seldom
* more than 52 weeks, */
fday = wday + 6;
}
/* For julian dates the month can be set to 1, the global julian
* variable cannot be relied upon here, because we may recurse
* internally for 31.12. which would not work. */
@ -882,7 +879,7 @@ static int week_number(int day, int month, int32_t year, const struct cal_contro
&& day_in_week(day, month, year) <= WEDNESDAY
&& day_in_week(31, 12, year) >= MONDAY
&& day_in_week(31, 12, year) <= WEDNESDAY)
return week_number(1, 1, year + 1, ctl);
return week_number(1, 1, year + 1, ctl);
return (yday + fday) / 7;
}