dotnet · pavelsavara · Nov 7, 2025 · Nov 7, 2025 · Nov 7, 2025 · Nov 7, 2025
diff --git a/eng/native.props b/eng/native.props
diff --git a/eng/native.wasm.targets b/eng/native.wasm.targets
@@ -0,0 +1,78 @@
+<Project>
+  <ItemGroup>
+    <PackageReference Condition="'$(TargetsWasm)' == 'true'" Include="Microsoft.NETCore.Runtime.ICU.Transport" PrivateAssets="all" Version="$(MicrosoftNETCoreRuntimeICUTransportVersion)" GeneratePathProperty="true" />
+    <PackageReference Condition="'$(TargetsWasm)' == 'true'" Include="System.Runtime.TimeZoneData" PrivateAssets="all" Version="$(SystemRuntimeTimeZoneDataVersion)" GeneratePathProperty="true" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <_RuntimeVariant />
+    <_RuntimeVariant Condition="'$(WasmEnableThreads)' == 'true'">-threads</_RuntimeVariant>
+
+    <_IcuDir Condition="'$(PkgMicrosoft_NETCore_Runtime_ICU_Transport)' != '' and '$(TargetsWasm)' == 'true'">$(PkgMicrosoft_NETCore_Runtime_ICU_Transport)/runtimes/$(TargetOS)-$(TargetArchitecture)$(_RuntimeVariant)/native</_IcuDir>
+    <_TzdDir Condition="'$(PkgSystem_Runtime_TimeZoneData)' != '' and '$(TargetsWasm)' == 'true'">$([MSBuild]::NormalizePath('$(PkgSystem_Runtime_TimeZoneData)', 'contentFiles', 'any', 'any', 'data'))</_TzdDir>
+  </PropertyGroup>
+
+  <ItemGroup>
+      <NativeCMakeArg Condition="'$(_IcuDir)' != ''" Include="-cmakeargs &quot;-DCMAKE_ICU_DIR=$(_IcuDir)&quot;" />
+      <NativeCMakeArg Condition="'$(_TzdDir)' != ''" Include="-cmakeargs &quot;-DCMAKE_TZD_DIR=$(_TzdDir)&quot;" />
+      <NativeCMakeArg Condition="'$(RuntimeFlavor)' == 'Mono'" Include="-cmakeargs &quot;-DCLR_CMAKE_RUNTIME_MONO=1&quot;" />
+      <NativeCMakeArg Condition="'$(RuntimeFlavor)' == 'CoreCLR'" Include="-cmakeargs &quot;-DCLR_CMAKE_RUNTIME_CORECLR=1&quot;" />
+      <NativeCMakeArg Include="-cmakeargs &quot;-DCMAKE_PRODUCT_VERSION=$(ProductVersion)&quot;" />
+      <NativeCMakeArg Include="-cmakeargs &quot;-DCMAKE_CONTINUOUS_INTEGRATION_BUILD=$(ContinuousIntegrationBuild)&quot;" />
+      <NativeCMakeArg Include="-cmakeargs &quot;-DCMAKE_NET_CORE_APP_CURRENT_VERSION=$(NetCoreAppCurrentVersion)&quot;" />
+      <NativeCMakeArg Include="-cmakeargs &quot;-DCMAKE_BUILD_LIBRARIES_CONFIGURATION=$(LibrariesConfiguration)&quot;" />
+      <NativeCMakeArg Include="-cmakeargs &quot;-DCMAKE_BUILD_RUNTIME_CONFIGURATION=$(RuntimeConfiguration)&quot;" />
+      <NativeCMakeArg Condition="'$(TargetsBrowser)' == 'true' and '$(RuntimeFlavor)' == 'CoreCLR'" Include="-cmakeargs &quot;-DBUILD_LIBS_NATIVE_BROWSER=1&quot;" />
+  </ItemGroup>
+
+  <Target Name="GenerateEmccExports" Condition="'$(TargetsBrowser)' == 'true'">
+    <ItemGroup>
+      <EmccExportedRuntimeMethod Include="FS" />
+      <EmccExportedRuntimeMethod Include="out" />
+      <EmccExportedRuntimeMethod Include="err" />
+      <EmccExportedRuntimeMethod Include="ccall" />
+      <EmccExportedRuntimeMethod Include="cwrap" />
+      <EmccExportedRuntimeMethod Include="setValue" />
+      <EmccExportedRuntimeMethod Include="getValue" />
+      <EmccExportedRuntimeMethod Include="UTF8ToString" />
+      <EmccExportedRuntimeMethod Include="UTF8ArrayToString" />
+      <EmccExportedRuntimeMethod Include="lengthBytesUTF8" />
+      <EmccExportedRuntimeMethod Include="stringToUTF8Array" />
+      <EmccExportedRuntimeMethod Include="FS_createPath" />
+      <EmccExportedRuntimeMethod Include="FS_createDataFile" />
+      <EmccExportedRuntimeMethod Include="removeRunDependency" />
+      <EmccExportedRuntimeMethod Include="addRunDependency" />
+      <EmccExportedRuntimeMethod Include="addFunction" />
+      <EmccExportedRuntimeMethod Include="safeSetTimeout" />
+      <EmccExportedRuntimeMethod Include="runtimeKeepalivePush" />
+      <EmccExportedRuntimeMethod Include="runtimeKeepalivePop" />
+      <EmccExportedRuntimeMethod Include="maybeExit" />
+      <EmccExportedRuntimeMethod Include="abort" />
+
+      <EmccExportedFunction Include="_free" />
+      <EmccExportedFunction Include="_htons" />
+      <EmccExportedFunction Include="_malloc" />
+      <EmccExportedFunction Include="_sbrk" />
+      <EmccExportedFunction Include="_memalign" />
+      <EmccExportedFunction Include="_posix_memalign" />
+      <EmccExportedFunction Include="_memset" />
+      <EmccExportedFunction Include="_ntohs" />
+      <EmccExportedFunction Include="stackAlloc" />
+      <EmccExportedFunction Include="stackRestore" />
+      <EmccExportedFunction Include="stackSave" />
+      <!-- TODO-WASM hide -->
+      <EmccExportedFunction Include="_GetDotNetRuntimeContractDescriptor" />
+    </ItemGroup>
+    <PropertyGroup>
+      <_EmccExportedRuntimeMethods>@(EmccExportedRuntimeMethod -> '%(Identity)',',')</_EmccExportedRuntimeMethods>
+      <_EmccExportedFunctions>@(EmccExportedFunction -> '%(Identity)',',')</_EmccExportedFunctions>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <NativeCMakeArg Condition="'$(TargetsBrowser)' == 'true'" Include="-cmakeargs &quot;-DCMAKE_EMCC_EXPORTED_RUNTIME_METHODS=$(_EmccExportedRuntimeMethods)&quot;" />
+      <NativeCMakeArg Condition="'$(TargetsBrowser)' == 'true'" Include="-cmakeargs &quot;-DCMAKE_EMCC_EXPORTED_FUNCTIONS=$(_EmccExportedFunctions)&quot;" />
+    </ItemGroup>
+
+  </Target>
+
+</Project>
diff --git a/src/coreclr/hosts/corerun/CMakeLists.txt b/src/coreclr/hosts/corerun/CMakeLists.txt
@@ -62,20 +62,23 @@ else()
                 "${STATIC_LIB_DESTINATION}/libSystem.Native.Browser.js")
             set(JS_SYSTEM_BROWSER_UTILS
                 "${STATIC_LIB_DESTINATION}/libSystem.Browser.Utils.js")
-            set(JS_CORE_RUN_PRE
-                "${CMAKE_CURRENT_SOURCE_DIR}/wasm/libCorerun.pre.js")
+            set(JS_CORE_RUN
+                "${CMAKE_CURRENT_SOURCE_DIR}/wasm/libCorerun.extpost.js")
             set_target_properties(corerun PROPERTIES
-                LINK_DEPENDS "${JS_CORE_RUN_PRE};${JS_SYSTEM_NATIVE_BROWSER};${JS_SYSTEM_BROWSER_UTILS};"
-                LINK_FLAGS "--pre-js ${JS_CORE_RUN_PRE} --js-library ${JS_SYSTEM_NATIVE_BROWSER} --js-library ${JS_SYSTEM_BROWSER_UTILS}"
+                LINK_DEPENDS "${JS_CORE_RUN};${JS_SYSTEM_NATIVE_BROWSER};${JS_SYSTEM_BROWSER_UTILS};"
+                LINK_FLAGS "--js-library ${JS_SYSTEM_NATIVE_BROWSER} --js-library ${JS_SYSTEM_BROWSER_UTILS} --extern-post-js ${JS_CORE_RUN}"
                 RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}")
             target_link_options(corerun PRIVATE
                 -sEXIT_RUNTIME=0
                 -sINITIAL_MEMORY=134217728
                 -sMAXIMUM_MEMORY=2147483648
                 -sALLOW_MEMORY_GROWTH=1
                 -sSTACK_SIZE=5MB
-                -sEXPORTED_RUNTIME_METHODS=cwrap,ccall,HEAP8,HEAPU8,HEAP16,HEAPU16,HEAP32,HEAPU32,HEAP64,HEAPU64,HEAPF32,HEAPF64,safeSetTimeout,maybeExit,exitJS,abort,lengthBytesUTF8,UTF8ToString,stringToUTF8Array
-                -sEXPORTED_FUNCTIONS=_main,_GetDotNetRuntimeContractDescriptor
+                -sMODULARIZE=1
+                -sEXPORT_ES6=1
+                -sEXPORTED_RUNTIME_METHODS=ENV,${CMAKE_EMCC_EXPORTED_RUNTIME_METHODS}
+                -sEXPORTED_FUNCTIONS=_main,${CMAKE_EMCC_EXPORTED_FUNCTIONS}
+                -sEXPORT_NAME=createDotnetRuntime
                 -sENVIRONMENT=node,shell,web
                 -Wl,-error-limit=0)
 
@@ -96,7 +99,7 @@ else()
                 # If not running in the browser, add
                 # Node.js file system support.
                 target_link_options(corerun PRIVATE
-                    -lnoderawfs.js
+                    -sNODERAWFS=1
                     -lnodefs.js)
             endif()
         endif()

diff --git a/src/coreclr/hosts/corerun/wasm/libCorerun.extpost.js b/src/coreclr/hosts/corerun/wasm/libCorerun.extpost.js
@@ -0,0 +1,43 @@
+//
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+/* eslint-disable no-undef */
+/* eslint-disable space-before-function-paren */
+/* eslint-disable @typescript-eslint/no-unused-vars */
+var fetch = fetch || undefined; var dotnetNativeModuleLoaded = false; var dotnetInternals = null;
+export function selfRun() {
+    const Module = {};
+    const corePreRun = () => {
+        // copy all node/shell env variables to emscripten env
+        if (globalThis.process && globalThis.process.env) {
+            for (const [key, value] of Object.entries(process.env)) {
+                Module.ENV[key] = value;
+            }
+        }
+
+        Module.ENV["DOTNET_SYSTEM_GLOBALIZATION_INVARIANT"] = "true";
+    };
+    Module.preRun = [corePreRun];
+
+    const runtimeApi = {
+        Module,
+        INTERNAL: {},
+        runtimeId: 0,
+        runtimeBuildInfo: {
+            productVersion: "corerun",
+            gitHash: "corerun",
+            buildConfiguration: "corerun",
+            wasmEnableThreads: false,
+            wasmEnableSIMD: true,
+            wasmEnableExceptionHandling: true,
+        },
+    };
+    dotnetInternals = [
+        runtimeApi,
+        [],
+    ];
+
+    createDotnetRuntime(runtimeApi.Module);
+}
+selfRun();
diff --git a/src/coreclr/hosts/corerun/wasm/libCorerun.pre.js b/src/coreclr/hosts/corerun/wasm/libCorerun.pre.js
diff --git a/src/coreclr/runtime.proj b/src/coreclr/runtime.proj
@@ -11,11 +11,11 @@
     <ProjectReference Condition="'$(HasCdacBuildTool)' == 'true'" Include="tools\cdac-build-tool\cdac-build-tool.csproj" ReferenceOutputAssembly="false" GlobalPropertiesToRemove="$(NativeBuildPartitionPropertiesToRemove)" />
   </ItemGroup>
 
-  <Import Project="$(RepositoryEngineeringDir)native.props" />
+  <Import Project="$(RepositoryEngineeringDir)native.wasm.targets" />
   <Import Project="$(RepositoryEngineeringDir)nativepgo.targets" />
 
   <Target Name="BuildRuntime"
-          DependsOnTargets="GetPgoDataPackagePath"
+          DependsOnTargets="GetPgoDataPackagePath;GenerateEmccExports"
           BeforeTargets="Build">
     <ItemGroup>
       <_CMakeArgs Include="$(CMakeArgs)" />

diff --git a/src/coreclr/vm/wasm/callhelpers.cpp b/src/coreclr/vm/wasm/callhelpers.cpp
@@ -484,6 +484,12 @@ namespace
         (*fptr)(ARG_I32(0), ARG_I32(1), ARG_I32(2), ARG_IND(3), ARG_IND(4), ARG_I32(5));
     }
 
+    void CallFunc_I32_I32_IND_RetVoid (PCODE pcode, int8_t *pArgs, int8_t *pRet)
+    {
+        void (*fptr)(int32_t, int32_t, int32_t) = (void (*)(int32_t, int32_t, int32_t))pcode;
+        (*fptr)(ARG_I32(0), ARG_I32(1), ARG_IND(2));
+    }
+
     void CallFunc_I32_I32_IND_IND_I32_RetVoid (PCODE pcode, int8_t *pArgs, int8_t *pRet)
     {
         void (*fptr)(int32_t, int32_t, int32_t, int32_t, int32_t) = (void (*)(int32_t, int32_t, int32_t, int32_t, int32_t))pcode;
@@ -709,6 +715,7 @@ const StringToWasmSigThunk g_wasmThunks[] = {
     { "viiinn", (void*)&CallFunc_I32_I32_I32_IND_IND_RetVoid },
     { "viiinni", (void*)&CallFunc_I32_I32_I32_IND_IND_I32_RetVoid },
     { "viinni", (void*)&CallFunc_I32_I32_IND_IND_I32_RetVoid },
+    { "viin", (void*)&CallFunc_I32_I32_IND_RetVoid },
     { "viinnii", (void*)&CallFunc_I32_I32_IND_IND_I32_I32_RetVoid },
     { "vil", (void*)&CallFunc_I32_I64_RetVoid },
     { "vili", (void*)&CallFunc_I32_I64_I32_RetVoid },
@@ -752,7 +759,7 @@ static void Call_System_Private_CoreLib_System_Threading_ThreadPool_BackgroundJo
     // Lazy lookup of MethodDesc for the function export scenario.
     if (!MD_System_Private_CoreLib_System_Threading_ThreadPool_BackgroundJobHandler_Void_RetVoid)
     {
-        LookupMethodByName("System.Threading.ThreadPool, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, System.Private.CoreLib", "BackgroundJobHandler", &MD_System_Private_CoreLib_System_Threading_ThreadPool_BackgroundJobHandler_Void_RetVoid);
+        LookupMethodByName("System.Threading.ThreadPool, System.Private.CoreLib", "BackgroundJobHandler", &MD_System_Private_CoreLib_System_Threading_ThreadPool_BackgroundJobHandler_Void_RetVoid);
     }
     ExecuteInterpretedMethodFromUnmanaged(MD_System_Private_CoreLib_System_Threading_ThreadPool_BackgroundJobHandler_Void_RetVoid, nullptr, 0, nullptr);
 }
@@ -768,7 +775,7 @@ static void Call_System_Private_CoreLib_System_Threading_TimerQueue_TimerHandler
     // Lazy lookup of MethodDesc for the function export scenario.
     if (!MD_System_Private_CoreLib_System_Threading_TimerQueue_TimerHandler_Void_RetVoid)
     {
-        LookupMethodByName("System.Threading.TimerQueue, System.Private.CoreLib, Version=10.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e, System.Private.CoreLib", "TimerHandler", &MD_System_Private_CoreLib_System_Threading_TimerQueue_TimerHandler_Void_RetVoid);
+        LookupMethodByName("System.Threading.TimerQueue, System.Private.CoreLib", "TimerHandler", &MD_System_Private_CoreLib_System_Threading_TimerQueue_TimerHandler_Void_RetVoid);
     }
     ExecuteInterpretedMethodFromUnmanaged(MD_System_Private_CoreLib_System_Threading_TimerQueue_TimerHandler_Void_RetVoid, nullptr, 0, nullptr);
 }

diff --git a/src/native/corehost/browserhost/CMakeLists.txt b/src/native/corehost/browserhost/CMakeLists.txt
@@ -113,10 +113,12 @@ target_link_options(browserhost PRIVATE
     -sMODULARIZE=1
     -sEXPORT_ES6=1
     -sEXIT_RUNTIME=0
-    -sEXPORTED_RUNTIME_METHODS=BROWSER_HOST,cwrap,ccall,HEAP8,HEAPU8,HEAP16,HEAPU16,HEAP32,HEAPU32,HEAP64,HEAPU64,HEAPF32,HEAPF64,safeSetTimeout,maybeExit,exitJS,abort,lengthBytesUTF8,UTF8ToString,stringToUTF8Array
-    -sEXPORTED_FUNCTIONS=_posix_memalign,_malloc,_free,stackAlloc,stackRestore,stackSave,___cpp_exception,_GetDotNetRuntimeContractDescriptor,_BrowserHost_InitializeCoreCLR,_BrowserHost_ExecuteAssembly
+    -sEXPORTED_RUNTIME_METHODS=BROWSER_HOST,${CMAKE_EMCC_EXPORTED_RUNTIME_METHODS}
+    -sEXPORTED_FUNCTIONS=_BrowserHost_InitializeCoreCLR,_BrowserHost_ExecuteAssembly,${CMAKE_EMCC_EXPORTED_FUNCTIONS}
     -sEXPORT_NAME=createDotnetRuntime
-    -lnodefs.js)
+    -sENVIRONMENT=web,webview,worker,node,shell
+    -lnodefs.js
+    -Wl,-error-limit=0)
 
 target_link_libraries(browserhost PUBLIC
     BrowserHost-Static

diff --git a/src/native/corehost/browserhost/browserhost.cpp b/src/native/corehost/browserhost/browserhost.cpp
@@ -68,11 +68,11 @@ static const void* pinvoke_override(const char* library_name, const char* entry_
     {
         return SystemResolveDllImport(entry_point_name);
     }
-    if (strcmp(library_name, "libSystem.JavaScript") == 0)
+    if (strcmp(library_name, "libSystem.JavaScript.Native") == 0)
     {
         return SystemJSResolveDllImport(entry_point_name);
     }
-    if (strcmp(library_name, "libSystem.Runtime.InteropServices.JavaScript") == 0)
+    if (strcmp(library_name, "libSystem.Runtime.InteropServices.JavaScript.Native") == 0)
     {
         return SystemJSInteropResolveDllImport(entry_point_name);
     }

diff --git a/src/native/corehost/browserhost/host/host.ts b/src/native/corehost/browserhost/host/host.ts
@@ -1,12 +1,12 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-import type { CharPtr, VoidPtr, VoidPtrPtr } from "./types";
+import type { CharPtr, VfsAsset, VoidPtr, VoidPtrPtr } from "./types";
 import { } from "./cross-linked"; // ensure ambient symbols are declared
 
 const loadedAssemblies: Map<string, { ptr: number, length: number }> = new Map();
 
-export function registerDllBytes(bytes: Uint8Array, asset: { name: string }) {
+export function registerDllBytes(bytes: Uint8Array, asset: { name: string, virtualPath: string }) {
     const sp = Module.stackSave();
     try {
         const sizeOfPtr = 4;
@@ -16,13 +16,52 @@ export function registerDllBytes(bytes: Uint8Array, asset: { name: string }) {
         }
 
         const ptr = Module.HEAPU32[ptrPtr as any >>> 2];
-        Module.HEAPU8.set(bytes, ptr);
+        Module.HEAPU8.set(bytes, ptr >>> 0);
         loadedAssemblies.set(asset.name, { ptr, length: bytes.length });
+        loadedAssemblies.set(asset.virtualPath, { ptr, length: bytes.length });
     } finally {
         Module.stackRestore(sp);
     }
 }
 
+export function installVfsFile(bytes: Uint8Array, asset: VfsAsset) {
+    const virtualName: string = typeof (asset.virtualPath) === "string"
+        ? asset.virtualPath
+        : asset.name;
+    const lastSlash = virtualName.lastIndexOf("/");
+    let parentDirectory = (lastSlash > 0)
+        ? virtualName.substring(0, lastSlash)
+        : null;
+    let fileName = (lastSlash > 0)
+        ? virtualName.substring(lastSlash + 1)
+        : virtualName;
+    if (fileName.startsWith("/"))
+        fileName = fileName.substring(1);
+    if (parentDirectory) {
+        if (!parentDirectory.startsWith("/"))
+            parentDirectory = "/" + parentDirectory;
+
+        if (parentDirectory.startsWith("/managed")) {
+            throw new Error("Cannot create files under /managed virtual directory as it is reserved for NodeFS mounting");
+        }
+
+        dotnetLogger.debug(`Creating directory '${parentDirectory}'`);
+
+        Module.FS_createPath(
+            "/", parentDirectory, true, true // fixme: should canWrite be false?
+        );
+    } else {
+        parentDirectory = "/";
+    }
+
+    dotnetLogger.debug(`Creating file '${fileName}' in directory '${parentDirectory}'`);
+
+    Module.FS_createDataFile(
+        parentDirectory, fileName,
+        bytes, true /* canRead */, true /* canWrite */, true /* canOwn */
+    );
+}
+
 // bool BrowserHost_ExternalAssemblyProbe(const char* pathPtr, /*out*/ void **outDataStartPtr, /*out*/ int64_t* outSize);
 export function BrowserHost_ExternalAssemblyProbe(pathPtr: CharPtr, outDataStartPtr: VoidPtrPtr, outSize: VoidPtr) {
     const path = Module.UTF8ToString(pathPtr);