[K/N] Implement Platform.availableProcessors

^KT-48179

kotlin-native/backend.native/tests/interop/basics/available_processors.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+import kotlin.native.*
+import kotlin.test.*
+import cstdlib.*
+import kotlinx.cinterop.*
+
+
+@OptIn(kotlin.ExperimentalStdlibApi::class)
+fun main() {
+    val x = Platform.getAvailableProcessors()
+    println(x)
+    assertTrue(x > 0)
+    setenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS", "12345", 1)
+    assertEquals(Platform.getAvailableProcessors(), 12345)
+    setenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS", Long.MAX_VALUE.toString(), 1)
+    assertFailsWith<IllegalStateException> { Platform.getAvailableProcessors() }
+    setenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS", "-1", 1)
+    assertFailsWith<IllegalStateException> { Platform.getAvailableProcessors() }
+    setenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS", "0", 1)
+    assertFailsWith<IllegalStateException> { Platform.getAvailableProcessors() }
+    // windows doesn't support empty env variables
+    if (Platform.osFamily != OsFamily.WINDOWS) {
+        setenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS", "", 1)
+        assertFailsWith<IllegalStateException> { Platform.getAvailableProcessors() }
+    }
+    setenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS", "123aaaa", 1)
+    assertFailsWith<IllegalStateException> { Platform.getAvailableProcessors() }
+    unsetenv("KOTLIN_NATIVE_AVAILABLE_PROCESSORS")
+    assertEquals(Platform.getAvailableProcessors(), x)
+}

kotlin-native/backend.native/tests/interop/basics/cstdlib.def

@@ -0,0 +1,21 @@
+headers = stdlib.h
+compilerOpts.mingw = -D ADD_WINDOWS_ENV_FUNCTIONS
+
+---
+
+#ifdef ADD_WINDOWS_ENV_FUNCTIONS
+static inline int setenv(const char *name, const char *value, int overwrite)
+{
+    int errcode = 0;
+    if (!overwrite) {
+        size_t envsize = 0;
+        errcode = getenv_s(&envsize, NULL, 0, name);
+        if(errcode || envsize) return errcode;
+    }
+    return _putenv_s(name, value);
+}
+static inline int unsetenv(const char *name)
+{
+    return _putenv_s(name, "");
+}
+#endif