dotnet · pavelsavara · Sep 4, 2024 · Aug 30, 2024 · Sep 2, 2024 · Sep 2, 2024
diff --git a/eng/testing/xunit/xunit.console.targets b/eng/testing/xunit/xunit.console.targets
@@ -13,8 +13,8 @@
 
   <ItemGroup>
     <!-- Configures xunit to not print out passing tests with output when diagnostic messages are enabled. -->
-    <SetScriptCommands Condition="'$(TargetOS)' == 'windows'" Include="set XUNIT_HIDE_PASSING_OUTPUT_DIAGNOSTICS=1" />
-    <SetScriptCommands Condition="'$(TargetOS)' != 'windows'" Include="export XUNIT_HIDE_PASSING_OUTPUT_DIAGNOSTICS=1" />
+    <SetScriptCommands Condition="'$(OS)' != 'Windows_NT'" Include="set XUNIT_HIDE_PASSING_OUTPUT_DIAGNOSTICS=1" />
+    <SetScriptCommands Condition="'$(OS)' == 'Windows_NT'" Include="export XUNIT_HIDE_PASSING_OUTPUT_DIAGNOSTICS=1" />
   </ItemGroup>
 
   <PropertyGroup Condition="'$(BundleXunitRunner)' == 'true'">

diff --git a/src/libraries/Common/src/System/Security/Cryptography/Helpers.cs b/src/libraries/Common/src/System/Security/Cryptography/Helpers.cs
@@ -17,9 +17,10 @@ internal static partial class Helpers
 #endif
 
         [UnsupportedOSPlatformGuard("browser")]
+        [UnsupportedOSPlatformGuard("wasi")]
         internal static bool HasSymmetricEncryption { get; } =
 #if NET
-            !OperatingSystem.IsBrowser();
+            !OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi();
 #else
             true;
 #endif
@@ -35,15 +36,17 @@ internal static partial class Helpers
 #if NET
         [UnsupportedOSPlatformGuard("android")]
         [UnsupportedOSPlatformGuard("browser")]
+        [UnsupportedOSPlatformGuard("wasi")]
         public static bool IsRC2Supported => !OperatingSystem.IsAndroid() && !OperatingSystem.IsBrowser();
 #else
         public static bool IsRC2Supported => true;
 #endif
 
         [UnsupportedOSPlatformGuard("browser")]
+        [UnsupportedOSPlatformGuard("wasi")]
         internal static bool HasMD5 { get; } =
 #if NET
-            !OperatingSystem.IsBrowser();
+            !OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi();
 #else
             true;
 #endif

diff --git a/src/libraries/Common/tests/Common.Tests.csproj b/src/libraries/Common/tests/Common.Tests.csproj
@@ -2,7 +2,7 @@
   <PropertyGroup>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <IncludeRemoteExecutor>true</IncludeRemoteExecutor>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-linux;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-osx</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-linux;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-wasi;$(NetCoreAppCurrent)-osx</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(CommonTestPath)System\Collections\DictionaryExtensions.cs"

diff --git a/src/libraries/Common/tests/System/IO/ReparsePointUtilities.cs b/src/libraries/Common/tests/System/IO/ReparsePointUtilities.cs
@@ -76,7 +76,7 @@ public static bool CreateSymbolicLink(string linkPath, string targetPath, bool i
 #if NETFRAMEWORK
         bool isWindows = true;
 #else
-        if (OperatingSystem.IsIOS() || OperatingSystem.IsTvOS() || OperatingSystem.IsMacCatalyst() || OperatingSystem.IsBrowser()) // OSes that don't support Process.Start()
+        if (OperatingSystem.IsIOS() || OperatingSystem.IsTvOS() || OperatingSystem.IsMacCatalyst() || OperatingSystem.IsBrowser() || OperatingSystem.IsWasi()) // OSes that don't support Process.Start()
         {
             return false;
         }

diff --git a/src/libraries/Common/tests/System/Net/Capability.Security.Unix.cs b/src/libraries/Common/tests/System/Net/Capability.Security.Unix.cs
@@ -9,7 +9,7 @@ public static partial class Capability
     {
         public static bool IsNtlmInstalled()
         {
-            if (OperatingSystem.IsBrowser())
+            if (OperatingSystem.IsBrowser() || OperatingSystem.IsWasi() )
             {
                 return false;
             }

diff --git a/src/libraries/Microsoft.Extensions.Configuration.Xml/src/XmlDocumentDecryptor.cs b/src/libraries/Microsoft.Extensions.Configuration.Xml/src/XmlDocumentDecryptor.cs
@@ -102,6 +102,11 @@ public XmlReader CreateDecryptingXmlReader(Stream input, XmlReaderSettings? sett
         [RequiresUnreferencedCode(RequiresUnreferencedCodeMessage)]
         protected virtual XmlReader DecryptDocumentAndCreateXmlReader(XmlDocument document)
         {
+#if !NETSTANDARD2_1 && !NETSTANDARD2_0 && !NETFRAMEWORK // TODO remove with https://github.com/dotnet/runtime/pull/107185
+            if (OperatingSystem.IsWasi()) throw new PlatformNotSupportedException();
+#else
+            #pragma warning disable CA1416
+#endif
             // Perform the actual decryption step, updating the XmlDocument in-place.
             EncryptedXml encryptedXml = _encryptedXmlFactory?.Invoke(document) ?? new EncryptedXml(document);
             encryptedXml.DecryptDocument();

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFileProvider.cs b/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFileProvider.cs
@@ -164,7 +164,7 @@ internal PhysicalFilesWatcher CreateFileWatcher()
             FileSystemWatcher? watcher;
 #if NET
             //  For browser/iOS/tvOS we will proactively fallback to polling since FileSystemWatcher is not supported.
-            if (OperatingSystem.IsBrowser() || (OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()) || OperatingSystem.IsTvOS())
+            if (OperatingSystem.IsBrowser() || OperatingSystem.IsWasi() || (OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()) || OperatingSystem.IsTvOS())
             {
                 UsePollingFileWatcher = true;
                 UseActivePolling = true;

diff --git a/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFilesWatcher.cs b/src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFilesWatcher.cs
@@ -89,7 +89,7 @@ public PhysicalFilesWatcher(
             if (fileSystemWatcher != null)
             {
 #if NET
-                if (OperatingSystem.IsBrowser() || (OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()) || OperatingSystem.IsTvOS())
+                if (OperatingSystem.IsBrowser() || OperatingSystem.IsWasi() || (OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()) || OperatingSystem.IsTvOS())
                 {
                     throw new PlatformNotSupportedException(SR.Format(SR.FileSystemWatcher_PlatformNotSupported, typeof(FileSystemWatcher)));
                 }
@@ -276,6 +276,7 @@ protected virtual void Dispose(bool disposing)
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]
@@ -312,6 +313,7 @@ ex is DirectoryNotFoundException ||
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]
@@ -321,6 +323,7 @@ private void OnChanged(object sender, FileSystemEventArgs e)
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]
@@ -334,6 +337,7 @@ private void OnError(object sender, ErrorEventArgs e)
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]
@@ -360,6 +364,7 @@ ex is SecurityException ||
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]
@@ -400,6 +405,7 @@ private void ReportChangeForMatchedEntries(string path)
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]
@@ -421,6 +427,7 @@ private void TryDisableFileSystemWatcher()
         }
 
         [UnsupportedOSPlatform("browser")]
+        [UnsupportedOSPlatform("wasi")]
         [UnsupportedOSPlatform("ios")]
         [UnsupportedOSPlatform("tvos")]
         [SupportedOSPlatform("maccatalyst")]

diff --git a/src/libraries/Microsoft.Extensions.Hosting.Systemd/src/SystemdNotifier.cs b/src/libraries/Microsoft.Extensions.Hosting.Systemd/src/SystemdNotifier.cs
@@ -41,6 +41,12 @@ public void Notify(ServiceState state)
                 return;
             }
 
+#if !NETSTANDARD2_1 && !NETSTANDARD2_0 && !NETFRAMEWORK // TODO remove with https://github.com/dotnet/runtime/pull/107185
+            if (OperatingSystem.IsWasi()) throw new PlatformNotSupportedException();
+#else
+            #pragma warning disable CA1416
+#endif
+
             using (var socket = new Socket(AddressFamily.Unix, SocketType.Dgram, ProtocolType.Unspecified))
             {
                 var endPoint = new UnixDomainSocketEndPoint(_socketPath!);

diff --git a/src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.netcoreapp.cs b/src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.netcoreapp.cs
@@ -11,7 +11,7 @@ public partial class HostBuilder
     {
         private static void AddLifetime(IServiceCollection services)
         {
-            if (!OperatingSystem.IsAndroid() && !OperatingSystem.IsBrowser() && !OperatingSystem.IsIOS() && !OperatingSystem.IsTvOS())
+            if (!OperatingSystem.IsAndroid() && !OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi() && !OperatingSystem.IsIOS() && !OperatingSystem.IsTvOS())
             {
                 services.AddSingleton<IHostLifetime, ConsoleLifetime>();
             }

diff --git a/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs b/src/libraries/Microsoft.Extensions.Hosting/src/HostingHostBuilderExtensions.cs
@@ -293,7 +293,7 @@ internal static void AddDefaultServices(HostBuilderContext hostingContext, IServ
 
                 logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
 #if NET
-                if (!OperatingSystem.IsBrowser())
+                if (!OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi())
 #endif
                 {
                     logging.AddConsole();

diff --git a/src/libraries/Microsoft.Extensions.Http/src/MetricsFactoryHttpMessageHandlerFilter.cs b/src/libraries/Microsoft.Extensions.Http/src/MetricsFactoryHttpMessageHandlerFilter.cs
@@ -33,7 +33,7 @@ public Action<HttpMessageHandlerBuilder> Configure(Action<HttpMessageHandlerBuil
                     // Don't overwrite factory if one is already set.
                     httpClientHandler.MeterFactory ??= _meterFactory;
                 }
-                else if (!OperatingSystem.IsBrowser() && builder.PrimaryHandler is SocketsHttpHandler socketsHttpHandler)
+                else if (!OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi() && builder.PrimaryHandler is SocketsHttpHandler socketsHttpHandler)
                 {
                     // Don't overwrite factory if one is already set.
                     socketsHttpHandler.MeterFactory ??= _meterFactory;

diff --git a/src/libraries/System.CodeDom/Directory.Build.props b/src/libraries/System.CodeDom/Directory.Build.props
@@ -2,6 +2,6 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser;ios;tvos;maccatalyst</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi;ios;tvos;maccatalyst</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/...ystem/Security/Authentication/ExtendedProtection/ExtendedProtectionPolicyTypeConverter.cs b/...ystem/Security/Authentication/ExtendedProtection/ExtendedProtectionPolicyTypeConverter.cs
@@ -21,6 +21,8 @@ public override bool CanConvertTo(ITypeDescriptorContext? context, [NotNullWhen(
         [UnsupportedOSPlatform("browser")]
         public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
         {
+            if (OperatingSystem.IsWasi()) throw new PlatformNotSupportedException(); // TODO remove with https://github.com/dotnet/runtime/pull/107185
+
             if (destinationType == typeof(InstanceDescriptor))
             {
                 if (value is ExtendedProtectionPolicy policy)

diff --git a/.../Security/Authentication/ExtendedProtection/ExtendedProtectionPolicyTypeConverterTests.cs b/.../Security/Authentication/ExtendedProtection/ExtendedProtectionPolicyTypeConverterTests.cs
@@ -58,6 +58,7 @@ public void ConvertTo_PositiveTests()
 
         [Theory]
         [SkipOnPlatform(TestPlatforms.Browser, "System.Net.Security is not supported on this platform.")]
+        [SkipOnPlatform(TestPlatforms.Wasi, "System.Net.Security is not supported on this platform.")]
         [InlineData(typeof(int))]
         [InlineData(typeof(ExtendedProtectionPolicy))]
         [InlineData(typeof(bool))]

diff --git a/src/libraries/System.Configuration.ConfigurationManager/Directory.Build.props b/src/libraries/System.Configuration.ConfigurationManager/Directory.Build.props
@@ -2,6 +2,6 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/src/libraries/System.Data.Odbc/Directory.Build.props b/src/libraries/System.Data.Odbc/Directory.Build.props
@@ -2,6 +2,6 @@
   <Import Project="..\Directory.Build.props" />
   <PropertyGroup>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/.../System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/MetricsEventSource.cs b/.../System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/MetricsEventSource.cs
@@ -319,15 +319,15 @@ public void OnEventCommand(EventCommandEventArgs command)
                 try
                 {
 #if OS_ISBROWSER_SUPPORT
-                    if (OperatingSystem.IsBrowser())
+                    if (OperatingSystem.IsBrowser() || OperatingSystem.IsWasi())
                     {
                         // AggregationManager uses a dedicated thread to avoid losing data for apps experiencing threadpool starvation
                         // and browser doesn't support Thread.Start()
                         //
                         // This limitation shouldn't really matter because browser also doesn't support out-of-proc EventSource communication
                         // which is the intended scenario for this EventSource. If it matters in the future AggregationManager can be
                         // modified to have some other fallback path that works for browser.
-                        Parent.Error("", "System.Diagnostics.Metrics EventSource not supported on browser");
+                        Parent.Error("", "System.Diagnostics.Metrics EventSource not supported on browser and wasi");
                         return;
                     }
 #endif

diff --git a/...ries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/RuntimeMetrics.cs b/...ries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/Metrics/RuntimeMetrics.cs
@@ -146,7 +146,7 @@ static RuntimeMetrics()
                 unit: "{cpu}",
                 description: "The number of processors available to the process.");
 
-            if (!OperatingSystem.IsBrowser() && !OperatingSystem.IsTvOS() && !(OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()))
+            if (!OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi() && !OperatingSystem.IsTvOS() && !(OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()))
             {
                 s_meter.CreateObservableCounter(
                     "dotnet.process.cpu.time",
@@ -174,7 +174,7 @@ private static IEnumerable<Measurement<long>> GetGarbageCollectionCounts()
         [SupportedOSPlatform("maccatalyst")]
         private static IEnumerable<Measurement<double>> GetCpuTime()
         {
-            Debug.Assert(!OperatingSystem.IsBrowser() && !OperatingSystem.IsTvOS() && !(OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()));
+            Debug.Assert(!OperatingSystem.IsBrowser() && !OperatingSystem.IsWasi() &&!OperatingSystem.IsTvOS() && !(OperatingSystem.IsIOS() && !OperatingSystem.IsMacCatalyst()));
 
             Environment.ProcessCpuUsage processCpuUsage = Environment.CpuUsage;
 

diff --git a/src/libraries/System.Diagnostics.FileVersionInfo/Directory.Build.props b/src/libraries/System.Diagnostics.FileVersionInfo/Directory.Build.props
@@ -3,6 +3,6 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/src/libraries/System.Diagnostics.Process/Directory.Build.props b/src/libraries/System.Diagnostics.Process/Directory.Build.props
@@ -3,6 +3,6 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/...stem.Diagnostics.TextWriterTraceListener/src/System/Diagnostics/XmlWriterTraceListener.cs b/...stem.Diagnostics.TextWriterTraceListener/src/System/Diagnostics/XmlWriterTraceListener.cs
@@ -250,7 +250,7 @@ private void WriteEndHeader()
             string? processName = s_processName;
             if (processName is null)
             {
-                if (OperatingSystem.IsBrowser()) // Process isn't supported on Browser
+                if (OperatingSystem.IsBrowser() || OperatingSystem.IsWasi() ) // Process isn't supported on Browser
                 {
                     processName = string.Empty;
                 }

diff --git a/src/libraries/System.IO.Compression.Brotli/Directory.Build.props b/src/libraries/System.IO.Compression.Brotli/Directory.Build.props
@@ -3,6 +3,6 @@
   <PropertyGroup>
     <StrongNameKeyId>ECMA</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/src/libraries/System.IO.FileSystem.Watcher/Directory.Build.props b/src/libraries/System.IO.FileSystem.Watcher/Directory.Build.props
@@ -3,7 +3,7 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser;ios;tvos</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi;ios;tvos</UnsupportedOSPlatforms>
     <SupportedOSPlatforms>maccatalyst</SupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/src/libraries/System.IO.IsolatedStorage/Directory.Build.props b/src/libraries/System.IO.IsolatedStorage/Directory.Build.props
@@ -3,6 +3,6 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/src/libraries/System.IO.IsolatedStorage/tests/System.IO.IsolatedStorage.Tests.csproj b/src/libraries/System.IO.IsolatedStorage/tests/System.IO.IsolatedStorage.Tests.csproj
@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-maccatalyst;$(NetCoreAppCurrent)-ios;$(NetCoreAppCurrent)-tvos;$(NetCoreAppCurrent)-android</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-wasi;$(NetCoreAppCurrent)-maccatalyst;$(NetCoreAppCurrent)-ios;$(NetCoreAppCurrent)-tvos;$(NetCoreAppCurrent)-android</TargetFrameworks>
     <IgnoreForCI Condition="'$(TargetOS)' == 'browser'">true</IgnoreForCI>
   </PropertyGroup>
   <ItemGroup>

diff --git a/src/libraries/System.IO.MemoryMappedFiles/src/System.IO.MemoryMappedFiles.csproj b/src/libraries/System.IO.MemoryMappedFiles/src/System.IO.MemoryMappedFiles.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent)-unix;$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-wasi;$(NetCoreAppCurrent)</TargetFrameworks>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
   </PropertyGroup>
@@ -86,7 +86,7 @@
     <Compile Include="System\IO\MemoryMappedFiles\MemoryMappedView.Windows.cs" />
   </ItemGroup>
 
-  <ItemGroup Condition="'$(TargetPlatformIdentifier)' == 'unix' or '$(TargetPlatformIdentifier)' == 'browser' ">
+  <ItemGroup Condition="'$(TargetPlatformIdentifier)' == 'unix' or '$(TargetPlatformIdentifier)' == 'browser' or '$(TargetPlatformIdentifier)' == 'wasi' ">
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Libraries.cs"
              Link="Common\Interop\Unix\Interop.Libraries.cs" />
     <Compile Include="$(CommonPath)Interop\Unix\Interop.Errors.cs"

diff --git a/src/libraries/System.IO.MemoryMappedFiles/tests/MemoryMappedFilesTestsBase.Unix.cs b/src/libraries/System.IO.MemoryMappedFiles/tests/MemoryMappedFilesTestsBase.Unix.cs
@@ -14,7 +14,7 @@ public abstract partial class MemoryMappedFilesTestBase : FileCleanupTestBase
         /// <summary>Gets the system's page size.</summary>
         protected static Lazy<int> s_pageSize = new Lazy<int>(() =>
         {
-            if (OperatingSystem.IsBrowser())
+            if (OperatingSystem.IsBrowser() || OperatingSystem.IsWasi())
                 return Environment.SystemPageSize;
 
             int pageSize;

diff --git a/src/libraries/System.IO.Pipes/Directory.Build.props b/src/libraries/System.IO.Pipes/Directory.Build.props
@@ -3,6 +3,6 @@
   <PropertyGroup>
     <StrongNameKeyId>Microsoft</StrongNameKeyId>
     <IncludePlatformAttributes>true</IncludePlatformAttributes>
-    <UnsupportedOSPlatforms>browser</UnsupportedOSPlatforms>
+    <UnsupportedOSPlatforms>browser;wasi</UnsupportedOSPlatforms>
   </PropertyGroup>
 </Project>
diff --git a/src/libraries/System.Linq.Parallel/src/System/Linq/ParallelEnumerable.cs b/src/libraries/System.Linq.Parallel/src/System/Linq/ParallelEnumerable.cs
@@ -66,7 +66,7 @@ public static class ParallelEnumerable
         // be executed in parallel, but will retain PLINQ semantics (exceptions wrapped as aggregates, etc).
 #if !FEATURE_WASM_MANAGED_THREADS
         [System.Runtime.Versioning.SupportedOSPlatformGuard("browser")]
-        internal static bool SinglePartitionMode => OperatingSystem.IsBrowser();
+        internal static bool SinglePartitionMode => OperatingSystem.IsBrowser() || OperatingSystem.IsWasi();
 #else
         internal static bool SinglePartitionMode => false;
 #endif

diff --git a/src/libraries/System.Linq/src/System.Linq.csproj b/src/libraries/System.Linq/src/System.Linq.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-android;$(NetCoreAppCurrent)-ios;$(NetCoreAppCurrent)-tvos</TargetFrameworks>
+    <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppCurrent)-browser;$(NetCoreAppCurrent)-wasi;$(NetCoreAppCurrent)-android;$(NetCoreAppCurrent)-ios;$(NetCoreAppCurrent)-tvos</TargetFrameworks>
     <UseCompilerGeneratedDocXmlFile>false</UseCompilerGeneratedDocXmlFile>
   </PropertyGroup>