src: create a getter for kernel version

doc/api/os.md

@@ -389,6 +389,20 @@ operating system response.
 
 Throws a [`SystemError`][] if a user has no `username` or `homedir`.
 
+## `os.version()`
+<!-- YAML
+added: REPLACEME
+-->
+
+* Returns {string}
+
+Returns a string identifying the kernel version.
+
+On POSIX systems, the operating system release is determined by calling
+[uname(3)][]. On Windows, `pRtlGetVersion` is used, and if it is not available,
+`GetVersionExW()` will be used. See
+https://en.wikipedia.org/wiki/Uname#Examples for more information.
+
 ## OS Constants
 
 The following constants are exported by `os.constants`.

lib/os.js

@@ -45,9 +45,8 @@ const {
   getHostname: _getHostname,
   getInterfaceAddresses: _getInterfaceAddresses,
   getLoadAvg,
-  getOSRelease: _getOSRelease,
-  getOSType: _getOSType,
   getPriority: _getPriority,
+  getOSInformation: _getOSInformation,
   getTotalMem,
   getUserInfo,
   getUptime,
@@ -66,17 +65,25 @@ function getCheckedFunction(fn) {
   });
 }
 
+const [
+  type,
+  version,
+  release
+] = _getOSInformation();
+
 const getHomeDirectory = getCheckedFunction(_getHomeDirectory);
 const getHostname = getCheckedFunction(_getHostname);
 const getInterfaceAddresses = getCheckedFunction(_getInterfaceAddresses);
-const getOSRelease = getCheckedFunction(_getOSRelease);
-const getOSType = getCheckedFunction(_getOSType);
+const getOSRelease = () => release;
+const getOSType = () => type;
+const getOSVersion = () => version;
 
 getFreeMem[SymbolToPrimitive] = () => getFreeMem();
 getHostname[SymbolToPrimitive] = () => getHostname();
-getHomeDirectory[SymbolToPrimitive] = () => getHomeDirectory();
-getOSRelease[SymbolToPrimitive] = () => getOSRelease();
+getOSVersion[SymbolToPrimitive] = () => getOSVersion();
 getOSType[SymbolToPrimitive] = () => getOSType();
+getOSRelease[SymbolToPrimitive] = () => getOSRelease();
+getHomeDirectory[SymbolToPrimitive] = () => getHomeDirectory();
 getTotalMem[SymbolToPrimitive] = () => getTotalMem();
 getUptime[SymbolToPrimitive] = () => getUptime();
 
@@ -281,6 +288,7 @@ module.exports = {
   type: getOSType,
   userInfo,
   uptime: getUptime,
+  version: getOSVersion
 };
 
 ObjectDefineProperties(module.exports, {

src/node_os.cc

@@ -75,8 +75,7 @@ static void GetHostname(const FunctionCallbackInfo<Value>& args) {
           .ToLocalChecked());
 }
 
-
-static void GetOSType(const FunctionCallbackInfo<Value>& args) {
+static void GetOSInformation(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   uv_utsname_t info;
   int err = uv_os_uname(&info);
@@ -87,29 +86,18 @@ static void GetOSType(const FunctionCallbackInfo<Value>& args) {
     return args.GetReturnValue().SetUndefined();
   }
 
-  args.GetReturnValue().Set(
-      String::NewFromUtf8(env->isolate(), info.sysname, NewStringType::kNormal)
-          .ToLocalChecked());
-}
-
-
-static void GetOSRelease(const FunctionCallbackInfo<Value>& args) {
-  Environment* env = Environment::GetCurrent(args);
-  uv_utsname_t info;
-  int err = uv_os_uname(&info);
-
-  if (err != 0) {
-    CHECK_GE(args.Length(), 1);
-    env->CollectUVExceptionInfo(args[args.Length() - 1], err, "uv_os_uname");
-    return args.GetReturnValue().SetUndefined();
-  }
+  // [sysname, version, release]
+  Local<Value> osInformation[] = {
+    String::NewFromUtf8(env->isolate(), info.sysname).ToLocalChecked(),
+    String::NewFromUtf8(env->isolate(), info.version).ToLocalChecked(),
+    String::NewFromUtf8(env->isolate(), info.release).ToLocalChecked()
+  };
 
-  args.GetReturnValue().Set(
-      String::NewFromUtf8(env->isolate(), info.release, NewStringType::kNormal)
-          .ToLocalChecked());
+  args.GetReturnValue().Set(Array::New(env->isolate(),
+                                       osInformation,
+                                       arraysize(osInformation)));
 }
 
-
 static void GetCPUInfo(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
   Isolate* isolate = env->isolate();
@@ -398,13 +386,12 @@ void Initialize(Local<Object> target,
   env->SetMethod(target, "getTotalMem", GetTotalMemory);
   env->SetMethod(target, "getFreeMem", GetFreeMemory);
   env->SetMethod(target, "getCPUs", GetCPUInfo);
-  env->SetMethod(target, "getOSType", GetOSType);
-  env->SetMethod(target, "getOSRelease", GetOSRelease);
   env->SetMethod(target, "getInterfaceAddresses", GetInterfaceAddresses);
   env->SetMethod(target, "getHomeDirectory", GetHomeDirectory);
   env->SetMethod(target, "getUserInfo", GetUserInfo);
   env->SetMethod(target, "setPriority", SetPriority);
   env->SetMethod(target, "getPriority", GetPriority);
+  env->SetMethod(target, "getOSInformation", GetOSInformation);
   target->Set(env->context(),
               FIXED_ONE_BYTE_STRING(env->isolate(), "isBigEndian"),
               Boolean::New(env->isolate(), IsBigEndian())).Check();

test/parallel/test-os.js

@@ -194,6 +194,10 @@ const home = os.homedir();
 is.string(home);
 assert.ok(home.includes(path.sep));
 
+const version = os.version();
+assert.strictEqual(typeof version, 'string');
+assert(version);
+
 if (common.isWindows && process.env.USERPROFILE) {
   assert.strictEqual(home, process.env.USERPROFILE);
   delete process.env.USERPROFILE;