Add shared libraries support for Web to load game module (C++)

Source/Editor/Cooker/Platform/Web/WebPlatformTools.cpp

@@ -70,7 +70,7 @@ bool WebPlatformTools::OnPostProcess(CookingData& data)
     {
         Array<String> files;
         FileSystem::DirectoryGetFiles(files, data.OriginalOutputPath, TEXT("*"), DirectorySearchOption::TopDirectoryOnly);
-        for (String& file : files)
+        for (const String& file : files)
         {
             if (file.EndsWith(TEXT(".js")))
             {
@@ -89,6 +89,19 @@ bool WebPlatformTools::OnPostProcess(CookingData& data)
         return true;
     }
 
+    // Move .wasm assemblies into the data files in order for dlopen to work (blocking)
+    {
+        Array<String> files;
+        FileSystem::DirectoryGetFiles(files, data.OriginalOutputPath, TEXT("*.wasm"), DirectorySearchOption::AllDirectories);
+        StringView gameWasm = StringUtils::GetFileNameWithoutExtension(gameJs);
+        for (const String& file : files)
+        {
+            if (StringUtils::GetFileNameWithoutExtension(file) == gameWasm)
+                continue; // Skip the main game module
+            FileSystem::MoveFile(data.DataOutputPath / StringUtils::GetFileName(file), file, true);
+        }
+    }
+
     // Pack data files into a single file using Emscripten's file_packager tool
     {
         CreateProcessSettings procSettings;

Source/Engine/Platform/Web/WebPlatform.cpp

@@ -11,11 +11,13 @@
 #include "Engine/Core/Collections/Dictionary.h"
 #include "Engine/Platform/CPUInfo.h"
 #include "Engine/Platform/MemoryStats.h"
+#include "Engine/Profiler/ProfilerCPU.h"
 #if !BUILD_RELEASE
 #include "Engine/Core/Types/StringView.h"
 #include "Engine/Utilities/StringConverter.h"
 #endif
 #include <chrono>
+#include <dlfcn.h>
 #include <unistd.h>
 #include <emscripten/emscripten.h>
 #include <emscripten/threading.h>
@@ -279,16 +281,25 @@ bool WebPlatform::SetEnvironmentVariable(const String& name, const String& value
 
 void* WebPlatform::LoadLibrary(const Char* filename)
 {
-    return nullptr;
+    PROFILE_CPU();
+    ZoneText(filename, StringUtils::Length(filename));
+    const StringAsANSI<> filenameANSI(filename);
+    void* result = dlopen(filenameANSI.Get(), RTLD_NOW);
+    if (!result)
+    {
+        LOG(Error, "Failed to load {0} because {1}", filename, String(dlerror()));
+    }
+    return result;
 }
 
 void WebPlatform::FreeLibrary(void* handle)
 {
+    dlclose(handle);
 }
 
 void* WebPlatform::GetProcAddress(void* handle, const char* symbol)
 {
-    return nullptr;
+    return dlsym(handle, symbol);
 }
 
 #endif

Source/Tools/Flax.Build/Build/EngineTarget.cs

@@ -148,8 +148,12 @@ namespace Flax.Build
         {
             if (OutputType == TargetOutputType.Executable && !Configuration.BuildBindingsOnly)
             {
-                if (buildOptions.Platform.Target == TargetPlatform.Android)
+                switch (buildOptions.Platform.Target)
+                {
+                case TargetPlatform.Android:
+                case TargetPlatform.Web:
                     return false;
+                }
                 if (!buildOptions.Platform.HasModularBuildSupport)
                     return false;
                 return !IsMonolithicExecutable || (!buildOptions.Platform.HasExecutableFileReferenceSupport && UseSymbolsExports);

Source/Tools/Flax.Build/Platforms/Web/WebPlatform.cs

@@ -17,10 +17,13 @@ namespace Flax.Build.Platforms
         public override bool HasRequiredSDKsInstalled { get; }
 
         /// <inheritdoc />
-        public override bool HasSharedLibrarySupport => false;
+        public override bool HasSharedLibrarySupport => true;
 
         /// <inheritdoc />
-        public override bool HasModularBuildSupport => false;
+        public override bool HasModularBuildSupport => true;
+
+        /// <inheritdoc />
+        public override bool HasExecutableFileReferenceSupport => true;
 
         /// <inheritdoc />
         public override bool HasDynamicCodeExecutionSupport => false;

Source/Tools/Flax.Build/Platforms/Web/WebToolchain.cs

@@ -132,6 +132,9 @@ namespace Flax.Build.Platforms
             if (options.LinkEnv.LinkTimeCodeGeneration)
                 args.Add("-flto");
 
+            if (options.LinkEnv.Output == LinkerOutput.SharedLibrary)
+                args.Add("-fPIC");
+
             var sanitizers = options.CompileEnv.Sanitizers;
             if (sanitizers.HasFlag(Sanitizer.Address))
                 args.Add("-fsanitize=address");
@@ -259,6 +262,13 @@ namespace Flax.Build.Platforms
                 // Setup file access (Game Cooker packs files with file_packager tool)
                 args.Add("-sFORCE_FILESYSTEM");
                 args.Add("-sLZ4");
+
+                // https://emscripten.org/docs/compiling/Dynamic-Linking.html#dynamic-linking
+                // TODO: use -sMAIN_MODULE=2 and -sSIDE_MODULE=2 to strip unused code (mark public APIs with EMSCRIPTEN_KEEPALIVE)
+                if (options.LinkEnv.Output == LinkerOutput.Executable)
+                    args.Add("-sMAIN_MODULE");
+                else
+                    args.Add("-sSIDE_MODULE");
             }
 
             args.Add("-Wl,--start-group");
@@ -266,6 +276,7 @@ namespace Flax.Build.Platforms
             // Input libraries
             var libraryPaths = new HashSet<string>();
             var dynamicLibExt = Platform.SharedLibraryFileExtension;
+            var executableExt = Platform.ExecutableFileExtension;
             foreach (var library in options.LinkEnv.InputLibraries.Concat(options.Libraries))
             {
                 var dir = Path.GetDirectoryName(library);
@@ -279,7 +290,7 @@ namespace Flax.Build.Platforms
                 {
                     args.Add(string.Format("\"-l{0}\"", library));
                 }
-                else if (string.IsNullOrEmpty(ext))
+                else if (ext == executableExt)
                 {
                     // Skip executable
                 }