Use the same currentTime implementation for all Native targets

It seems like the only reason to use NSDate.date() is to obtain
an object. The POSIX implementation is more accurate.

Author: dkhalanskyjb

core/darwin/src/internal/TimeZoneNative.kt

@@ -7,8 +7,6 @@
 package kotlinx.datetime.internal
 
 import kotlinx.cinterop.*
-import kotlinx.datetime.Instant
-import kotlinx.datetime.toKotlinInstant
 import kotlinx.datetime.internal.*
 import platform.Foundation.*
 
@@ -65,9 +63,5 @@ internal actual fun currentSystemDefaultZone(): Pair<String, TimeZoneRules?> {
           that's hard to avoid.
     */
     NSTimeZone.resetSystemTimeZone()
-    val zone = NSTimeZone.systemTimeZone
-    val zoneId = zone.name
-    return zoneId to null
+    return NSTimeZone.systemTimeZone.name to null
 }
-
-internal actual fun currentTime(): Instant = NSDate.date().toKotlinInstant()

core/linux/src/internal/TimeZoneNative.kt

@@ -3,36 +3,12 @@
  * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
  */
 
-@file:OptIn(ExperimentalForeignApi::class)
-
 package kotlinx.datetime.internal
 
-import kotlinx.cinterop.*
-import kotlinx.datetime.Instant
-import platform.posix.*
-
 internal actual val systemTzdb: TimeZoneDatabase = TzdbOnFilesystem()
 
 internal actual fun currentSystemDefaultZone(): Pair<String, TimeZoneRules?> {
     val zoneId = pathToSystemDefault()?.second?.toString()
         ?: throw IllegalStateException("Failed to get the system timezone")
     return zoneId to null
 }
-
-@OptIn(UnsafeNumber::class)
-internal actual fun currentTime(): Instant = memScoped {
-    val tm = alloc<timespec>()
-    val error = clock_gettime(CLOCK_REALTIME, tm.ptr)
-    if (error != 0) {
-        val errorStr: String = strerror(errno)?.toKString() ?: "Unknown error"
-        throw IllegalStateException("Could not obtain the current clock readings from the system: $errorStr")
-    }
-    val seconds: Long = tm.tv_sec.convert<Long>()
-    val nanoseconds: Int = tm.tv_nsec.convert<Int>()
-    try {
-        require(nanoseconds in 0 until NANOS_PER_ONE)
-        return Instant(seconds, nanoseconds)
-    } catch (e: IllegalArgumentException) {
-        throw IllegalStateException("The readings from the system clock are not representable as an Instant")
-    }
-}

core/native/src/internal/Platform.kt

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2019-2024 JetBrains s.r.o. and contributors.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+
+package kotlinx.datetime.internal
+
+import kotlinx.cinterop.*
+import kotlinx.datetime.*
+import platform.posix.*
+
+internal expect val systemTzdb: TimeZoneDatabase
+
+internal expect fun currentSystemDefaultZone(): Pair<String, TimeZoneRules?>
+
+@OptIn(ExperimentalForeignApi::class, UnsafeNumber::class)
+internal fun currentTime(): Instant = memScoped {
+    val tm = alloc<timespec>()
+    val error = clock_gettime(CLOCK_REALTIME.convert(), tm.ptr)
+    check(error == 0) { "Error when reading the system clock: ${strerror(errno)?.toKString() ?: "Unknown error"}" }
+    try {
+        require(tm.tv_nsec in 0 until NANOS_PER_ONE)
+        Instant(tm.tv_sec.convert(), tm.tv_nsec.convert())
+    } catch (e: IllegalArgumentException) {
+        throw IllegalStateException("The readings from the system clock (${tm.tv_sec} seconds, ${tm.tv_nsec} nanoseconds) are not representable as an Instant")
+    }
+}

core/native/src/internal/TimeZoneNative.kt

@@ -3,27 +3,10 @@
  * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
  */
 
-@file:OptIn(ExperimentalForeignApi::class)
 package kotlinx.datetime.internal
 
-import kotlinx.cinterop.*
-import kotlinx.datetime.*
-import platform.posix.*
-
 internal actual val systemTzdb: TimeZoneDatabase get() = tzdbInRegistry
 
 internal actual fun currentSystemDefaultZone(): Pair<String, TimeZoneRules?> = tzdbInRegistry.currentSystemDefault()
 
-internal actual fun currentTime(): Instant = memScoped {
-    val tm = alloc<timespec>()
-    val error = clock_gettime(CLOCK_REALTIME, tm.ptr)
-    check(error == 0) { "Error when reading the system clock: ${strerror(errno)}" }
-    try {
-        require(tm.tv_nsec in 0 until NANOS_PER_ONE)
-        Instant(tm.tv_sec, tm.tv_nsec)
-    } catch (e: IllegalArgumentException) {
-        throw IllegalStateException("The readings from the system clock (${tm.tv_sec} seconds, ${tm.tv_nsec} nanoseconds) are not representable as an Instant")
-    }
-}
-
 private val tzdbInRegistry = TzdbInRegistry()