From 5f3ae152140e626bc8535da34f3f5e148dd1fa24 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Laban?= <jerome.laban@nventive.com>
Date: Tue, 29 Mar 2022 10:57:42 -0400
Subject: [PATCH] feat: Add support for emscripten module exports (#66868)

---
 src/mono/wasm/runtime/dotnet.d.ts |  1 +
 src/mono/wasm/runtime/startup.ts  | 19 +++++++++++++++++++
 src/mono/wasm/runtime/types.ts    |  1 +
 3 files changed, 21 insertions(+)

diff --git a/src/mono/wasm/runtime/dotnet.d.ts b/src/mono/wasm/runtime/dotnet.d.ts
index d6a86af0a32..617b572e757 100644
--- a/src/mono/wasm/runtime/dotnet.d.ts
+++ b/src/mono/wasm/runtime/dotnet.d.ts
@@ -197,6 +197,7 @@ declare type DotnetModuleConfig = {
     onConfigLoaded?: (config: MonoConfig) => Promise<void>;
     onDotnetReady?: () => void;
     imports?: DotnetModuleConfigImports;
+    exports?: string[];
 } & Partial<EmscriptenModule>;
 declare type DotnetModuleConfigImports = {
     require?: (name: string) => any;
diff --git a/src/mono/wasm/runtime/startup.ts b/src/mono/wasm/runtime/startup.ts
index 9112a35defb..aa10c272496 100644
--- a/src/mono/wasm/runtime/startup.ts
+++ b/src/mono/wasm/runtime/startup.ts
@@ -266,6 +266,8 @@ function _apply_configuration_from_args(config: MonoConfig) {
 }
 
 function finalize_startup(config: MonoConfig | MonoConfigError | undefined): void {
+    const globalThisAny = globalThis as any;
+
     try {
         if (!config || config.isError) {
             return;
@@ -276,6 +278,23 @@ function finalize_startup(config: MonoConfig | MonoConfigError | undefined): voi
 
         const moduleExt = Module as DotnetModule;
 
+        if(!Module.disableDotnet6Compatibility && Module.exports){
+            // Export emscripten defined in module through EXPORTED_RUNTIME_METHODS
+            // Useful to export IDBFS or other similar types generally exposed as 
+            // global types when emscripten is not modularized.
+            for (let i = 0; i < Module.exports.length; ++i) {
+                const exportName = Module.exports[i];
+                const exportValue = (<any>Module)[exportName];
+
+                if(exportValue) {
+                    globalThisAny[exportName] = exportValue;
+                }
+                else{
+                    console.warn(`MONO_WASM: The exported symbol ${exportName} could not be found in the emscripten module`);
+                }
+            }
+        }
+
         try {
             _apply_configuration_from_args(config);
 
diff --git a/src/mono/wasm/runtime/types.ts b/src/mono/wasm/runtime/types.ts
index cc0d1b24583..aa7481fa076 100644
--- a/src/mono/wasm/runtime/types.ts
+++ b/src/mono/wasm/runtime/types.ts
@@ -166,6 +166,7 @@ export type DotnetModuleConfig = {
     onDotnetReady?: () => void;
 
     imports?: DotnetModuleConfigImports;
+    exports?: string[];
 } & Partial<EmscriptenModule>
 
 export type DotnetModuleConfigImports = {
-- 
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