localtime: rudimentary, incorrect support for timezone offsets

Makefile

@@ -44,7 +44,7 @@ EMU_ARGS += -smp $(SMP)
 EMU_ARGS += ${EMU_KVM}
 EMU_ARGS += -no-reboot
 EMU_ARGS += -serial mon:stdio
-EMU_ARGS += -rtc base=localtime
+EMU_ARGS += -rtc base=utc
 EMU_ARGS += -soundhw pcspk,ac97
 
 # Configures two network devices on the same network

apps/date.c

@@ -32,7 +32,7 @@ static void show_usage(int argc, char * argv[]) {
 }
 
 int main(int argc, char * argv[]) {
-	char * format = "%a %b %d %T %Y";
+	char * format = "%a %b %d %T %Y %Z";
 	struct tm * timeinfo;
 	struct timeval now;
 	char buf[BUFSIZ] = {0};

base/etc/startup.d/99_runstart.sh

@@ -6,6 +6,9 @@ export-cmd START kcmdline -g start
 export USER=root
 export HOME=/home/root
 
+export TZ=JST
+export TZ_OFFSET=32400
+
 export-cmd GETTY_ARGS qemu-fwcfg opt/org.toaruos.gettyargs
 
 echo -n "Launching startup application..." > /dev/pex/splash

base/usr/include/time.h

@@ -16,6 +16,9 @@ struct tm {
     int tm_wday;   /* Day of the week (0-6, Sunday = 0) */
     int tm_yday;   /* Day in the year (0-365, 1 Jan = 0) */
     int tm_isdst;  /* Daylight saving time */
+
+    const char * _tm_zone_name;
+    int _tm_zone_offset;
 };
 
 extern struct tm *localtime(const time_t *timep);

libc/time/localtime.c

@@ -1,6 +1,8 @@
 #include <time.h>
 #include <sys/time.h>
 #include <stdio.h>
+#include <string.h>
+#include <unistd.h>
 
 #define SEC_DAY 86400
 
@@ -58,73 +60,97 @@ static long secs_of_month(int months, int year) {
 	return days * SEC_DAY;
 }
 
-struct tm *localtime_r(const time_t *timep, struct tm * _timevalue) {
+static struct tm * fill_time(const time_t * timep, struct tm * _timevalue, const char * tzName, int tzOffset) {
 
-	fprintf(stderr, "Hello world? %p %d\n", _timevalue, *timep);
-
-	long seconds = 0; // this needs to be bigger, but whatever
+	time_t timeVal = *timep + tzOffset;
+	_timevalue->_tm_zone_name = tzName;
+	_timevalue->_tm_zone_offset = tzOffset;
 
+	long seconds = 0;
 	long year_sec = 0;
 
-	for (int year = 1970; year < 2100; ++year) {
-		fprintf(stderr, "Checking year %d\n", year);
+	int startYear = timeVal < 0 ? 1900 : 1970;
+
+	for (int year = startYear; year < 2100; ++year) {
 		long added = year_is_leap(year) ? 366 : 365;
-		fprintf(stderr, "adding %d...\n", added);
 		long secs = added * 86400;
 
-		if (seconds + secs > *timep) {
+		if (seconds + secs > timeVal) {
 			_timevalue->tm_year = year - 1900;
 			year_sec = seconds;
-			fprintf(stderr, "The year is %d, year_sec=%d\n", year, year_sec);
 			for (int month = 1; month <= 12; ++month) {
-				fprintf(stderr, "Checking %d\n", month);
 				secs = days_in_month(month, year) * SEC_DAY;
-				fprintf(stderr, "%d vs %d\n", seconds + secs, *timep);
-				if (seconds + secs > *timep) {
-					fprintf(stderr, "The month is %d.\n", month);
+				if (seconds + secs > timeVal) {
 					_timevalue->tm_mon = month - 1;
 					for (int day = 1; day <= days_in_month(month, year); ++day) {
 						secs = 60 * 60 * 24;
-						fprintf(stderr, "Checking day %d, %d vs . %d\n", day, seconds + secs, *timep);
-						if (seconds + secs > *timep) {
-							fprintf(stderr, "The day is %d.\n", day);
+						if (seconds + secs > timeVal) {
 							_timevalue->tm_mday = day;
 							for (int hour = 1; hour <= 24; ++hour) {
 								secs = 60 * 60;
-								if (seconds + secs > *timep) {
-									long remaining = *timep - seconds;
+								if (seconds + secs > timeVal) {
+									long remaining = timeVal - seconds;
 									_timevalue->tm_hour = hour - 1;
 									_timevalue->tm_min = remaining / 60;
-									_timevalue->tm_sec = remaining % 60; // can be 60 on a leap second, ignore that
-									_timevalue->tm_wday = day_of_week(*timep); // oh shit
-									_timevalue->tm_yday = (*timep - year_sec) / SEC_DAY;
-									_timevalue->tm_isdst = 0; // never because UTC
+									_timevalue->tm_sec = remaining % 60;
+									_timevalue->tm_wday = day_of_week(timeVal);
+									_timevalue->tm_yday = (timeVal - year_sec) / SEC_DAY;
+									_timevalue->tm_isdst = 0;
 									return _timevalue;
 								} else {
 									seconds += secs;
 								}
 							}
-							fprintf(stderr, "Failed but this is definitely the right day, returning NULL (seconds = %dbut need %d)\n", seconds, *timep);
 							return NULL;
 						} else {
 							seconds += secs;
 						}
 					}
-					fprintf(stderr, "Failed but this is definitely the right month, returning NULL\n");
 					return NULL;
 				} else {
 					seconds += secs;
 				}
 			}
-			fprintf(stderr, "Failed but this is definitely the right year, returning NULL\n");
 			return NULL;
 		} else {
 			seconds += secs;
 		}
 	}
+	return (void *)0;
+}
 
-	fprintf(stderr, "Uh, no?\n");
-	return (void *)0; /// uh what
+#define HOURS    3600
+#define MINUTES  60
+
+static char * get_timezone(void) {
+	char * tzEnv = getenv("TZ");
+	if (!tzEnv || strlen(tzEnv) != 3) return "UTC";
+	return tzEnv;
+}
+
+static int get_timezone_offset(void) {
+	char * tzOff = getenv("TZ_OFFSET");
+	if (!tzOff) return 0;
+	char * endptr;
+	int out = strtol(tzOff,&endptr,10);
+	if (*endptr) return 0;
+	return out;
+}
+
+struct tm *localtime_r(const time_t *timep, struct tm * _timevalue) {
+	return fill_time(timep, _timevalue, get_timezone(), get_timezone_offset());
+}
+
+struct tm * gmtime_r(const time_t * timep, struct tm * tm) {
+	return fill_time(timep, tm, "UTC", 0);
+}
+
+struct tm * localtime(const time_t *timep) {
+	return fill_time(timep, &_timevalue, get_timezone(), get_timezone_offset());
+}
+
+struct tm *gmtime(const time_t *timep) {
+	return fill_time(timep, &_timevalue, "UTC", 0);
 }
 
 static unsigned int secs_of_years(int years) {
@@ -147,19 +173,7 @@ time_t mktime(struct tm *tm) {
 	  (tm->tm_mday - 1) * 86400 +
 	  (tm->tm_hour) * 3600 +
 	  (tm->tm_min) * 60 +
-	  (tm->tm_sec);
-
+	  (tm->tm_sec) - tm->_tm_zone_offset;
 }
 
-struct tm * gmtime_r(const time_t * timep, struct tm * tm) {
-	return localtime_r(timep, tm);
-}
-
-struct tm * localtime(const time_t *timep) {
-	return localtime_r(timep, &_timevalue);
-}
-
-struct tm *gmtime(const time_t *timep) {
-	return localtime(timep);
-}
 

libc/time/strftime.c

@@ -142,6 +142,9 @@ size_t strftime(char *s, size_t max, const char *fmt, const struct tm *tm) {
 						tm->tm_hour,
 						tm->tm_min);
 				break;
+			case 's':
+				b += sprintf(b, "%ld", mktime((struct tm*)tm));
+				break;
 			case 'S':
 				b += sprintf(b, "%02d", tm->tm_sec);
 				break;
@@ -176,17 +179,20 @@ size_t strftime(char *s, size_t max, const char *fmt, const struct tm *tm) {
 				b += sprintf(b, "%04d", tm->tm_year + 1900);
 				break;
 			case 'z':
-				b += sprintf(b, "+0000");
+				if (tm->_tm_zone_offset >= 0) {
+					b += sprintf(b, "+%04d", tm->_tm_zone_offset);
+				} else {
+					b += sprintf(b, "-%04d", -tm->_tm_zone_offset);
+				}
 				break;
 			case 'Z':
-				b += sprintf(b, "UTC");
+				b += sprintf(b, tm->_tm_zone_name);
 				break;
 			case '%':
 				b += sprintf(b, "%c", '%');
 				break;
 			case 'V':
 			case 'W':
-			case 's':
 			case 'U':
 			case 'G':
 			case 'g':