ICU-20759 Add ucal_getDefaultTimeZone C API for host OS timezone detection.
diff --git a/icu4c/source/i18n/ucal.cpp b/icu4c/source/i18n/ucal.cpp
index e8f6d2e..927b2d3 100644
--- a/icu4c/source/i18n/ucal.cpp
+++ b/icu4c/source/i18n/ucal.cpp
@@ -34,7 +34,7 @@
static TimeZone*
_createTimeZone(const UChar* zoneID, int32_t len, UErrorCode* ec) {
TimeZone* zone = NULL;
- if (ec!=NULL && U_SUCCESS(*ec)) {
+ if (ec != NULL && U_SUCCESS(*ec)) {
// Note that if zoneID is invalid, we get back GMT. This odd
// behavior is by design and goes back to the JDK. The only
// failure we will see is a memory allocation failure.
@@ -69,7 +69,7 @@
U_CAPI int32_t U_EXPORT2
ucal_getDefaultTimeZone(UChar* result, int32_t resultCapacity, UErrorCode* ec) {
int32_t len = 0;
- if (ec!=NULL && U_SUCCESS(*ec)) {
+ if (ec != NULL && U_SUCCESS(*ec)) {
TimeZone* zone = TimeZone::createDefault();
if (zone == NULL) {
*ec = U_MEMORY_ALLOCATION_ERROR;
@@ -91,6 +91,23 @@
}
}
+U_DRAFT int32_t U_EXPORT2
+ucal_getHostTimeZone(UChar* result, int32_t resultCapacity, UErrorCode* ec) {
+ int32_t len = 0;
+ if (ec != NULL && U_SUCCESS(*ec)) {
+ TimeZone *zone = TimeZone::detectHostTimeZone();
+ if (zone == NULL) {
+ *ec = U_MEMORY_ALLOCATION_ERROR;
+ } else {
+ UnicodeString id;
+ zone->getID(id);
+ delete zone;
+ len = id.extract(result, resultCapacity, *ec);
+ }
+ }
+ return len;
+}
+
U_CAPI int32_t U_EXPORT2
ucal_getDSTSavings(const UChar* zoneID, UErrorCode* ec) {
int32_t result = 0;
diff --git a/icu4c/source/i18n/unicode/ucal.h b/icu4c/source/i18n/unicode/ucal.h
index f31a257..4466223 100644
--- a/icu4c/source/i18n/unicode/ucal.h
+++ b/icu4c/source/i18n/unicode/ucal.h
@@ -657,6 +657,42 @@
U_STABLE void U_EXPORT2
ucal_setDefaultTimeZone(const UChar* zoneID, UErrorCode* ec);
+#ifndef U_HIDE_DRAFT_API
+
+/**
+ * Return the current host time zone. The host time zone is detected from
+ * the current host system configuration by querying the host operating
+ * system. If the host system detection routines fail, or if they specify
+ * a TimeZone or TimeZone offset which is not recognized, then the special
+ * TimeZone "Etc/Unknown" is returned.
+ *
+ * Note that host time zone and the ICU default time zone can be different.
+ *
+ * The ICU default time zone does not change once initialized unless modified
+ * by calling `ucal_setDefaultTimeZone()` or with the C++ TimeZone API,
+ * `TimeZone::adoptDefault(TimeZone*)`.
+ *
+ * If the host operating system configuration has changed since ICU has
+ * initialized then the returned value can be different than the ICU default
+ * time zone, even if the default has not changed.
+ *
+ * <p>This function is not thread safe.</p>
+ *
+ * @param result A buffer to receive the result, or NULL
+ * @param resultCapacity The capacity of the result buffer
+ * @param ec input/output error code
+ * @return The result string length, not including the terminating
+ * null
+ *
+ * @see #UCAL_UNKNOWN_ZONE_ID
+ *
+ * @draft ICU 65
+ */
+U_DRAFT int32_t U_EXPORT2
+ucal_getHostTimeZone(UChar *result, int32_t resultCapacity, UErrorCode *ec);
+
+#endif // U_HIDE_DRAFT_API
+
/**
* Return the amount of time in milliseconds that the clock is
* advanced during daylight savings time for the given time zone, or
diff --git a/icu4c/source/test/cintltst/ccaltst.c b/icu4c/source/test/cintltst/ccaltst.c
index 2ce0546..eaff8f3 100644
--- a/icu4c/source/test/cintltst/ccaltst.c
+++ b/icu4c/source/test/cintltst/ccaltst.c
@@ -228,7 +228,7 @@
log_err("FAIL: ucal_getDSTSavings(PST) => %d, expect %d\n", i, 1*60*60*1000);
}
- /*Test ucal_set/getDefaultTimeZone*/
+ /*Test ucal_set/getDefaultTimeZone and ucal_getHostTimeZone */
status = U_ZERO_ERROR;
i = ucal_getDefaultTimeZone(zone1, UPRV_LENGTHOF(zone1), &status);
if (U_FAILURE(status)) {
@@ -247,6 +247,16 @@
} else {
if (u_strcmp(zone2, EUROPE_PARIS) != 0) {
log_data_err("FAIL: ucal_getDefaultTimeZone() did not return Europe/Paris (Are you missing data?)\n");
+ } else {
+ // Redetect the host timezone, it should be the same as zone1 even though ICU's default timezone has been changed.
+ i = ucal_getHostTimeZone(zone2, UPRV_LENGTHOF(zone2), &status);
+ if (U_FAILURE(status)) {
+ log_err("FAIL: ucal_getHostTimeZone() => %s\n", u_errorName(status));
+ } else {
+ if (u_strcmp(zone1, zone2) != 0) {
+ log_err("FAIL: ucal_getHostTimeZone() should give the same host timezone even if the default changed.\n");
+ }
+ }
}
}
}
