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LibC: Implement tzset with time zone awareness in accordance with POSIX

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This commit is contained in:
Timothy Flynn 2022-01-24 14:42:51 -05:00 • committed by Linus Groh
parent 6095500263
commit b1ea585149
2 changed files with 100 additions and 5 deletions
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41
Userland/Libraries/LibC/time.cpp
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@ -11,7 +11,9 @@
#include <LibTimeZone/TimeZone.h>
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/time.h>
#include <sys/times.h>
@ -358,15 +360,44 @@ long altzone;
char* tzname[2];
int daylight;
static char __tzname_standard[TZNAME_MAX];
static char __tzname_daylight[TZNAME_MAX];
constexpr const char* __utc = "UTC";
void tzset()
{
// FIXME: Here we pretend we are in UTC+0.
timezone = 0;
daylight = 0;
tzname[0] = const_cast<char*>(__utc);
tzname[1] = const_cast<char*>(__utc);
// FIXME: Actually parse the TZ environment variable, described here:
// https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08
StringView time_zone;
if (char* tz = getenv("TZ"); tz != nullptr)
time_zone = tz;
else
time_zone = TimeZone::current_time_zone();
auto set_default_values = []() {
timezone = 0;
altzone = 0;
daylight = 0;
tzname[0] = const_cast<char*>(__utc);
tzname[1] = const_cast<char*>(__utc);
};
if (auto offsets = TimeZone::get_named_time_zone_offsets(time_zone, AK::Time::now_realtime()); offsets.has_value()) {
if (!offsets->at(0).name.copy_characters_to_buffer(__tzname_standard, TZNAME_MAX))
return set_default_values();
if (!offsets->at(1).name.copy_characters_to_buffer(__tzname_daylight, TZNAME_MAX))
return set_default_values();
// timezone and altzone are seconds west of UTC, i.e. the offsets are negated.
timezone = -offsets->at(0).seconds;
altzone = -offsets->at(1).seconds;
daylight = timezone != altzone;
tzname[0] = __tzname_standard;
tzname[1] = __tzname_daylight;
} else {
set_default_values();
}
}
clock_t clock()