Use more efficient platform detection API (PowerShell#16760)

* Use more efficient platform detection API

Use static and const new OperatingSystem class API to avoid string comparisons and extra allocations.

* Remove unused variable

Author: iSazonov

src/Microsoft.PowerShell.Commands.Management/commands/management/ComputerUnix.cs

@@ -67,7 +67,7 @@ public sealed class StopComputerCommand : CommandLineCmdletBase
         protected override void BeginProcessing()
         {
             var args = "-P now";
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            if (Platform.IsMacOS)
             {
                 args = "now";
             }

src/Microsoft.PowerShell.Commands.Utility/commands/utility/UnblockFile.cs

@@ -137,7 +137,7 @@ protected override void ProcessRecord()
                 }
             }
 #else
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+            if (Platform.IsLinux)
             {
                 string errorMessage = UnblockFileStrings.LinuxNotSupported;
                 Exception e = new PlatformNotSupportedException(errorMessage);

src/Microsoft.PowerShell.GlobalTool.Shim/GlobalToolShim.cs

@@ -26,7 +26,7 @@ public static class EntryPoint
         public static int Main(string[] args)
         {
             var currentPath = new FileInfo(System.Reflection.Assembly.GetEntryAssembly().Location).Directory.FullName;
-            var isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+            var isWindows = Platform.IsWindows;
 
             string platformFolder = isWindows ? WinFolderName : UnixFolderName;
 

src/System.Management.Automation/CoreCLR/CorePsAssemblyLoadContext.cs

@@ -540,17 +540,17 @@ private static string GetNativeDllSubFolderName(out string ext)
             ext = string.Empty;
             var processArch = RuntimeInformation.ProcessArchitecture.ToString().ToLowerInvariant();
 
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (Platform.IsWindows)
             {
                 folderName = "win-" + processArch;
                 ext = ".dll";
             }
-            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+            else if (Platform.IsLinux)
             {
                 folderName = "linux-" + processArch;
                 ext = ".so";
             }
-            else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            else if (Platform.IsMacOS)
             {
                 folderName = "osx-x64";
                 ext = ".dylib";

src/System.Management.Automation/CoreCLR/CorePsPlatform.cs

@@ -22,7 +22,7 @@ public static bool IsLinux
         {
             get
             {
-                return RuntimeInformation.IsOSPlatform(OSPlatform.Linux);
+                return OperatingSystem.IsLinux();
             }
         }
 
@@ -33,7 +33,7 @@ public static bool IsMacOS
         {
             get
             {
-                return RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
+                return OperatingSystem.IsMacOS();
             }
         }
 
@@ -44,7 +44,7 @@ public static bool IsWindows
         {
             get
             {
-                return RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
+                return OperatingSystem.IsWindows();
             }
         }
 

src/System.Management.Automation/namespaces/FileSystemProvider.cs

@@ -469,9 +469,7 @@ protected override ProviderInfo Start(ProviderInfo providerInfo)
 #if !UNIX
             // The placeholder mode management APIs Rtl(Set|Query)(Process|Thread)PlaceholderCompatibilityMode
             // are only supported starting with Windows 10 version 1803 (build 17134)
-            Version minBuildForPlaceHolderAPIs = new Version(10, 0, 17134, 0);
-
-            if (Environment.OSVersion.Version >= minBuildForPlaceHolderAPIs)
+            if (OperatingSystem.IsWindowsVersionAtLeast(10, 0, 17134, 0))
             {
                 // let's be safe, don't change the PlaceHolderCompatibilityMode if the current one is not what we expect
                 if (NativeMethods.RtlQueryProcessPlaceholderCompatibilityMode() == NativeMethods.PHCM_DISGUISE_PLACEHOLDER)
@@ -2724,8 +2722,7 @@ private static bool WinCreateSymbolicLink(string path, string strTargetPath, boo
             // The new AllowUnprivilegedCreate is only available on Win10 build 14972 or newer
             var flags = isDirectory ? NativeMethods.SymbolicLinkFlags.Directory : NativeMethods.SymbolicLinkFlags.File;
 
-            Version minBuildOfDeveloperMode = new Version(10, 0, 14972, 0);
-            if (Environment.OSVersion.Version >= minBuildOfDeveloperMode)
+            if (OperatingSystem.IsWindowsVersionAtLeast(10, 0, 14972, 0))
             {
                 flags |= NativeMethods.SymbolicLinkFlags.AllowUnprivilegedCreate;
             }

src/System.Management.Automation/security/SecuritySupport.cs

@@ -1213,7 +1213,7 @@ private void ResolveFromStoreById(ResolutionPurpose purpose, out ErrorRecord err
                     storeCU.Open(OpenFlags.ReadOnly);
                     X509Certificate2Collection storeCerts = storeCU.Certificates;
 
-                    if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+                    if (Platform.IsWindows)
                     {
                         using (var storeLM = new X509Store("my", StoreLocation.LocalMachine))
                         {

src/powershell/Program.cs

@@ -5,6 +5,7 @@
 
 using System;
 using System.IO;
+using System.Management.Automation;
 using System.Reflection;
 using System.Runtime.InteropServices;
 
@@ -89,7 +90,7 @@ private static void AttemptExecPwshLogin(string[] args)
                 return;
             }
 
-            bool isLinux = RuntimeInformation.IsOSPlatform(OSPlatform.Linux);
+            bool isLinux = Platform.IsLinux;
 
             // The first byte (ASCII char) of the name of this process, used to detect '-' for login
             byte procNameFirstByte;

test/perf/benchmarks/Engine.ScriptBlock.cs

@@ -36,7 +36,7 @@ public IEnumerable<string> ValuesForScript()
             yield return @"[System.IO.Path]::HasExtension('')";
 
             // Test on COM method invocation.
-            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            if (Platform.IsWindows)
             {
                 yield return @"$sh=New-Object -ComObject Shell.Application; $sh.Namespace('c:\')";
                 yield return @"$fs=New-Object -ComObject scripting.filesystemobject; $fs.Drives";
@@ -54,7 +54,7 @@ public void GlobalSetup()
             // believe that there is no need to run many ops in each interation. However, the subsequent runs
             // of this method is much faster than the first run, and this causes 'MinIterationTime' warnings
             // to our benchmarks and make the benchmark results not reliable.
-            // Calling this method once in 'GlobalSetup' is a workaround. 
+            // Calling this method once in 'GlobalSetup' is a workaround.
             // See https://github.com/dotnet/BenchmarkDotNet/issues/837#issuecomment-828600157
             scriptBlock.Invoke();
         }