diff options
| -rw-r--r-- | src/time/strftime.c | 41 |
1 files changed, 38 insertions, 3 deletions
diff --git a/src/time/strftime.c b/src/time/strftime.c index b69a83a4..ab1c6dcf 100644 --- a/src/time/strftime.c +++ b/src/time/strftime.c @@ -8,6 +8,14 @@ const char *__langinfo(nl_item); +static int is_leap(int y) +{ + /* Avoid overflow */ + if (y>INT_MAX-1900) y -= 2000; + y += 1900; + return !(y%4) && ((y%100) || !(y%400)); +} + size_t strftime(char *restrict s, size_t n, const char *restrict f, const struct tm *restrict tm) { nl_item item; @@ -116,10 +124,37 @@ do_fmt: fmt = "%d"; goto number; case 'U': - case 'V': + val = (tm->tm_yday + 7 - tm->tm_wday) / 7; + fmt = "%02d"; + goto number; case 'W': - // FIXME: week number mess.. - continue; + val = (tm->tm_yday + 7 - (tm->tm_wday+6)%7) / 7; + fmt = "%02d"; + goto number; + case 'V': + val = (tm->tm_yday + 7 - (tm->tm_wday+6)%7) / 7; + /* If 1 Jan is just 1-3 days past Monday, + * the previous week is also in this year. */ + if ((tm->tm_wday - tm->tm_yday - 2 + 371) % 7 <= 2) + val++; + if (!val) { + val = 52; + /* If 31 December of prev year a Thursday, + * or Friday of a leap year, then the + * prev year has 53 weeks. */ + int dec31 = (tm->tm_wday - tm->tm_yday - 1 + 7) % 7; + if (dec31 == 4 || (dec31 == 5 && is_leap(tm->tm_year%400-1))) + val++; + } else if (val == 53) { + /* If 1 January is not a Thursday, and not + * a Wednesday of a leap year, then this + * year has only 52 weeks. */ + int jan1 = (tm->tm_wday - tm->tm_yday + 371) % 7; + if (jan1 != 4 && (jan1 != 3 || !is_leap(tm->tm_year))) + val = 1; + } + fmt = "%02d"; + goto number; case 'w': val = tm->tm_wday; fmt = "%d"; |