diff options
Diffstat (limited to 'src/time/tzset.c')
| -rw-r--r-- | src/time/tzset.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/src/time/tzset.c b/src/time/tzset.c new file mode 100644 index 00000000..6d69957e --- /dev/null +++ b/src/time/tzset.c @@ -0,0 +1,173 @@ +#include <time.h> +#include <ctype.h> +#include <limits.h> +#include <stdlib.h> +#include <string.h> +#include "libc.h" + +#include "__time.h" + +long __timezone = 0; +int __daylight = 0; +char *__tzname[2] = { 0, 0 }; +int __dst_offset = 0; + +weak_alias(__timezone, timezone); +weak_alias(__daylight, daylight); +weak_alias(__tzname, tzname); +weak_alias(__dst_offset, dst_offset); + +static char std_name[TZNAME_MAX+1]; +static char dst_name[TZNAME_MAX+1]; + +/* all elements are zero-based */ +static struct rule { + char month; + char week; + short day; + int time; +} __dst_start, __dst_end; + +static void zname(char *d, char **s) +{ + int i; + for (i=0; i<TZNAME_MAX && isalpha(d[i]=**s); i++, (*s)++); + d[i] = 0; +} + +static int hhmmss(char **s) +{ + int ofs = strtol(*s, s, 10)*3600; + if (ofs >= 0) { + if (**s == ':') ofs += strtol(*s+1, s, 10)*60; + if (**s == ':') ofs += strtol(*s+1, s, 10); + } else { + if (**s == ':') ofs -= strtol(*s+1, s, 10)*60; + if (**s == ':') ofs -= strtol(*s+1, s, 10); + } + return ofs; +} + +static int dstrule(struct rule *rule, char **s) +{ + if (**s != ',') return -1; + switch (*++*s) { + case 'J': + rule->month = 'J'; + rule->day = strtol(*s+1, s, 10)-1; + break; + case 'M': + rule->month = strtol(*s+1, s, 10)-1; + if (**s != '.' || rule->month < 0 || rule->month > 11) + return -1; + rule->week = strtol(*s+1, s, 10)-1; + if (**s != '.' || rule->week < 0 || rule->week > 4) + return -1; + rule->day = strtol(*s+1, s, 10); + if (rule->day < 0 || rule->day > 6) + return -1; + break; + default: + rule->month = 'L'; + rule->day = strtol(*s+1, s, 10); + break; + } + if (**s == '/') { + (*s)++; + rule->time = hhmmss(s); + } else rule->time = 7200; + return 0; +} + +void tzset(void) +{ + char *z, *a; + + strcpy(std_name, "GMT"); + strcpy(dst_name, "GMT"); + __tzname[0] = std_name; + __tzname[1] = dst_name; + __timezone = 0; + __daylight = 0; + + if (!(z = getenv("TZ")) || !isalpha(*z)) return; + + zname(std_name, &z); + __timezone = hhmmss(&z); + + zname(dst_name, &z); + if (dst_name[0]) __daylight=1; + a = z; + __dst_offset = hhmmss(&z) - __timezone; + if (z==a) __dst_offset = -3600; + + if (dstrule(&__dst_start, &z) || dstrule(&__dst_end, &z)) + __daylight = 0; +} + +void __tzset(void) +{ + static int lock, init; + if (init) return; + LOCK(&lock); + if (!init) tzset(); + init=1; + UNLOCK(&lock); +} + +static int is_leap(int year) +{ + year -= 100; + return !(year&3) && ((year%100) || !(year%400)); +} + +static int cutoff_yday(struct tm *tm, struct rule *rule) +{ + static const char days_in_month[] = {31,28,31,30,31,30,31,31,30,31,30,31}; + static const int first_day[] = {0,31,59,90,120,151,181,212,243,273,304,335}; + int yday, mday, leap; + + switch (rule->month) { + case 'J': + return rule->day + (tm->tm_mon > 1 && is_leap(tm->tm_year)); + case 'L': + return rule->day; + default: + yday = first_day[rule->month]; + leap = is_leap(tm->tm_year); + if (rule->month > 1 && leap) yday++; + mday = (rule->day - (yday + tm->tm_wday - tm->tm_yday) + 1400)%7 + 7*rule->week; + if (mday >= days_in_month[rule->month] + (leap && rule->month == 1)) + mday -= 7; + return mday + yday; + } +} + +struct tm *__dst_adjust(struct tm *tm) +{ + time_t t; + int start, end, secs; + int after_start, before_end; + + if (tm->tm_isdst >= 0) return tm; + if (!__daylight) { + tm->tm_isdst = 0; + return tm; + } + + secs = tm->tm_hour*3600 + tm->tm_min*60 + tm->tm_sec; + start = cutoff_yday(tm, &__dst_start); + end = cutoff_yday(tm, &__dst_end); + + after_start = (tm->tm_yday > start || (tm->tm_yday == start && secs >= __dst_start.time)); + before_end = (tm->tm_yday < end || (tm->tm_yday == end && secs < __dst_end.time)); + + if ((after_start && before_end) || ((end < start) && (after_start || before_end))) { + tm->tm_sec -= __dst_offset; + tm->tm_isdst = 1; + t = __tm_to_time(tm); + return __time_to_tm(t, tm); + } else tm->tm_isdst = 0; + + return tm; +} |