9base

revived minimalist port of Plan 9 userland to Unix
git clone git://git.suckless.org/9base
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date.c (1961B)

      1 #include <u.h>
      2 #include <stdlib.h> /* setenv etc. */
      3 #define NOPLAN9DEFINES
      4 #include <libc.h>
      5 #include <time.h>
      6 
      7 #define _HAVETIMEGM 1
      8 #define _HAVETMZONE 1
      9 #define _HAVETMTZOFF 1
     10 
     11 #if defined(__linux__)
     12 #	undef _HAVETMZONE
     13 #	undef _HAVETMTZOFF
     14 
     15 #elif defined(__sun__)
     16 #	undef _HAVETIMEGM
     17 #	undef _HAVETMZONE
     18 #	undef _HAVETMTZOFF
     19 
     20 #endif
     21 
     22 static Tm bigtm;
     23 
     24 static void
     25 tm2Tm(struct tm *tm, Tm *bigtm)
     26 {
     27 	char *s;
     28 
     29 	memset(bigtm, 0, sizeof *bigtm);
     30 	bigtm->sec = tm->tm_sec;
     31 	bigtm->min = tm->tm_min;
     32 	bigtm->hour = tm->tm_hour;
     33 	bigtm->mday = tm->tm_mday;
     34 	bigtm->mon = tm->tm_mon;
     35 	bigtm->year = tm->tm_year;
     36 	bigtm->wday = tm->tm_wday;
     37 	strftime(bigtm->zone, sizeof bigtm->zone, "%Z", tm);
     38 #ifdef _HAVETZOFF
     39 	bigtm->tzoff = tm->tm_gmtoff;
     40 #endif
     41 	
     42 	if(bigtm->zone[0] == 0){
     43 		s = getenv("TIMEZONE");
     44 		if(s){
     45 			strecpy(bigtm->zone, bigtm->zone+4, s);
     46 			free(s);
     47 		}
     48 	}
     49 }
     50 
     51 static void
     52 Tm2tm(Tm *bigtm, struct tm *tm)
     53 {
     54 	memset(tm, 0, sizeof *tm);
     55 	tm->tm_sec = bigtm->sec;
     56 	tm->tm_min = bigtm->min;
     57 	tm->tm_hour = bigtm->hour;
     58 	tm->tm_mday = bigtm->mday;
     59 	tm->tm_mon = bigtm->mon;
     60 	tm->tm_year = bigtm->year;
     61 	tm->tm_wday = bigtm->wday;
     62 #ifdef _HAVETMZONE
     63 	tm->tm_zone = bigtm->zone;
     64 #endif
     65 #ifdef _HAVETZOFF
     66 	tm->tm_gmtoff = bigtm->tzoff;
     67 #endif
     68 }
     69 
     70 Tm*
     71 p9gmtime(long x)
     72 {
     73 	time_t t;
     74 	struct tm tm;
     75 
     76 	t = (time_t)x;
     77 	tm = *gmtime(&t);
     78 	tm2Tm(&tm, &bigtm);
     79 	return &bigtm;
     80 }
     81 
     82 Tm*
     83 p9localtime(long x)
     84 {
     85 	time_t t;
     86 	struct tm tm;
     87 
     88 	t = (time_t)x;
     89 	tm = *localtime(&t);
     90 	tm2Tm(&tm, &bigtm);
     91 	return &bigtm;
     92 }
     93 
     94 #if !defined(_HAVETIMEGM)
     95 static time_t
     96 timegm(struct tm *tm)
     97 {
     98 	time_t ret;
     99 	char *tz;
    100 	char *s;
    101 
    102 	tz = getenv("TZ");
    103 	putenv("TZ=");
    104 	tzset();
    105 	ret = mktime(tm);
    106 	if(tz){
    107 		s = smprint("TZ=%s", tz);
    108 		if(s)
    109 			putenv(s);
    110 	}
    111 	return ret;
    112 }
    113 #endif
    114 
    115 long
    116 p9tm2sec(Tm *bigtm)
    117 {
    118 	struct tm tm;
    119 
    120 	Tm2tm(bigtm, &tm);
    121 	if(strcmp(bigtm->zone, "GMT") == 0 || strcmp(bigtm->zone, "UCT") == 0)
    122 		return timegm(&tm);
    123 	return mktime(&tm);	/* local time zone */
    124 }
    125