Support async instantiation in Node.js

src/closure-externs/node-externs.js

@@ -131,6 +131,14 @@ fs.Stats.prototype.ctimeMs;
  */
 fs.Stats.prototype.blksize;
 
+/**
+ * @param {string|!Buffer|!URL} path
+ * @param {{type: (string|undefined)}=} options
+ * @return {!Promise<!Blob>}
+ * @nosideeffects
+ */
+fs.openAsBlob = function (path, options) {};
+
 /**
  * @param {string} p
  * @return {boolean}

src/postamble_minimal.js

@@ -107,7 +107,7 @@ function run() {
 #else
   // Run a persistent (never-exiting) application starting at main().
   _main({{{ argc_argv() }}});
-#endif 
+#endif
 
 #if STACK_OVERFLOW_CHECK
   checkStackCookie();
@@ -189,10 +189,13 @@ var imports = {
 {{{
 #if EXPORT_ES6 && !ENVIRONMENT_MAY_BE_AUDIO_WORKLET
 const moduleUrl = `new URL('${TARGET_BASENAME}.wasm', import.meta.url)`;
+const nodeWasmPath = `require('node:url').fileURLToPath(${moduleUrl})`;
 #elif !EXPORT_ES6 || AUDIO_WORKLET
 const moduleUrl = `'${TARGET_BASENAME}.wasm'`;
+const nodeWasmPath = `__dirname + '/${TARGET_BASENAME}.wasm'`;
 #else
 const moduleUrl = `ENVIRONMENT_IS_AUDIO_WORKLET ? '${TARGET_BASENAME}.wasm' : new URL('${TARGET_BASENAME}.wasm', import.meta.url)`;
+const nodeWasmPath = `__dirname + '/${TARGET_BASENAME}.wasm'`;
 #endif
 }}}
 // https://caniuse.com/#feat=wasm and https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/instantiateStreaming
@@ -206,13 +209,18 @@ assert(WebAssembly.instantiateStreaming || Module['wasm'], 'Must load WebAssembl
 instantiatePromise =
 #endif
 (WebAssembly.instantiateStreaming
-#if ENVIRONMENT_MAY_BE_NODE
-  // Avoid using instantiateStreaming() on Node.js since the `fetch()` API
-  // does not support `file://` URLs.
-  // See: https://github.com/emscripten-core/emscripten/pull/16917
-  && !ENVIRONMENT_IS_NODE
-#endif
-  ? WebAssembly.instantiateStreaming(fetch({{{ moduleUrl }}}), imports)
+  ? (ENVIRONMENT_IS_NODE
+      // Avoid using `fetch()` API on Node.js since it does not support `file://`
+      // URLs. Instead, provide a Response that wraps a blob with the correct
+      // MIME type.
+      // See: https://github.com/emscripten-core/emscripten/pull/16917
+      ? WebAssembly.instantiateStreaming(
+          require('node:fs')
+            .openAsBlob({{{ nodeWasmPath }}})
+            .then((blob) => new Response(blob, { headers: { 'Content-Type': 'application/wasm' } })),
+          imports,
+        )
+      : WebAssembly.instantiateStreaming(fetch({{{ moduleUrl }}}), imports))
   : WebAssembly.instantiate(Module['wasm'], imports)).then((output) => {
 #else
 #if MODULARIZE || AUDIO_WORKLET

src/preamble.js

@@ -708,9 +708,8 @@ async function instantiateAsync(binary, binaryFile, imports) {
       && !isFileURI(binaryFile)
 #endif
 #if ENVIRONMENT_MAY_BE_NODE
-      // Avoid using instantiateStreaming() on Node.js since the `fetch()` API
-      // does not support `file://` URLs.
-      // See: https://github.com/emscripten-core/emscripten/pull/16917
+      // Node.js is handled in its own branch below, since it can't use fetch()
+      // to stream a `file://` URL
       && !ENVIRONMENT_IS_NODE
 #endif
 #if ENVIRONMENT_MAY_BE_SHELL
@@ -730,6 +729,30 @@ async function instantiateAsync(binary, binaryFile, imports) {
       // fall back of instantiateArrayBuffer below
     };
   }
+#if ENVIRONMENT_MAY_BE_NODE
+  else if (!binary && ENVIRONMENT_IS_NODE) {
+    // Avoid using `fetch()` API on Node.js since it does not support `file://`
+    // URLs. Instead, provide a Response that wraps a fs read stream with the
+    // correct MIME type.
+    // See: https://github.com/emscripten-core/emscripten/pull/16917
+    try {
+      var url = require('node:url');
+      var nodeBinaryFile = isFileURI(binaryFile) ? url.fileURLToPath(binaryFile) : binaryFile;
+      var response = fs.openAsBlob(nodeBinaryFile).then(
+        (blob) =>
+          new Response(blob, {
+            headers: { 'Content-Type': 'application/wasm' },
+          }),
+      );
+      var instantiationResult = await WebAssembly.instantiateStreaming(response, imports);
+      return instantiationResult;
+    } catch (reason) {
+      err(`wasm streaming compile failed: ${reason}`);
+      err('falling back to ArrayBuffer instantiation');
+      // fall back of instantiateArrayBuffer below
+    };
+  }
+#endif
 #endif // !SINGLE_FILE
   return instantiateArrayBuffer(binaryFile, imports);
 }

test/codesize/test_codesize_cxx_ctors1.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 19224,
-  "a.out.js.gz": 8124,
+  "a.out.js": 19537,
+  "a.out.js.gz": 8228,
   "a.out.nodebug.wasm": 133971,
   "a.out.nodebug.wasm.gz": 51271,
-  "total": 153195,
-  "total_gz": 59395,
+  "total": 153508,
+  "total_gz": 59499,
   "sent": [
     "__cxa_throw",
     "_abort_js",

test/codesize/test_codesize_cxx_ctors2.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 19201,
-  "a.out.js.gz": 8107,
+  "a.out.js": 19514,
+  "a.out.js.gz": 8211,
   "a.out.nodebug.wasm": 133403,
   "a.out.nodebug.wasm.gz": 50959,
-  "total": 152604,
-  "total_gz": 59066,
+  "total": 152917,
+  "total_gz": 59170,
   "sent": [
     "__cxa_throw",
     "_abort_js",

test/codesize/test_codesize_cxx_except.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 22917,
-  "a.out.js.gz": 9082,
+  "a.out.js": 23229,
+  "a.out.js.gz": 9190,
   "a.out.nodebug.wasm": 176383,
   "a.out.nodebug.wasm.gz": 58776,
-  "total": 199300,
-  "total_gz": 67858,
+  "total": 199612,
+  "total_gz": 67966,
   "sent": [
     "__cxa_begin_catch",
     "__cxa_end_catch",

test/codesize/test_codesize_cxx_except_wasm.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 19023,
-  "a.out.js.gz": 8039,
+  "a.out.js": 19336,
+  "a.out.js.gz": 8147,
   "a.out.nodebug.wasm": 149640,
   "a.out.nodebug.wasm.gz": 56311,
-  "total": 168663,
-  "total_gz": 64350,
+  "total": 168976,
+  "total_gz": 64458,
   "sent": [
     "_abort_js",
     "_tzset_js",

test/codesize/test_codesize_cxx_except_wasm_legacy.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 19101,
-  "a.out.js.gz": 8065,
+  "a.out.js": 19414,
+  "a.out.js.gz": 8171,
   "a.out.nodebug.wasm": 147422,
   "a.out.nodebug.wasm.gz": 55982,
-  "total": 166523,
-  "total_gz": 64047,
+  "total": 166836,
+  "total_gz": 64153,
   "sent": [
     "_abort_js",
     "_tzset_js",

test/codesize/test_codesize_cxx_lto.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 18568,
-  "a.out.js.gz": 7818,
+  "a.out.js": 18881,
+  "a.out.js.gz": 7926,
   "a.out.nodebug.wasm": 101064,
   "a.out.nodebug.wasm.gz": 38292,
-  "total": 119632,
-  "total_gz": 46110,
+  "total": 119945,
+  "total_gz": 46218,
   "sent": [
     "a (emscripten_resize_heap)",
     "b (_setitimer_js)",

test/codesize/test_codesize_cxx_mangle.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 22967,
-  "a.out.js.gz": 9103,
+  "a.out.js": 23279,
+  "a.out.js.gz": 9210,
   "a.out.nodebug.wasm": 242663,
   "a.out.nodebug.wasm.gz": 81001,
-  "total": 265630,
-  "total_gz": 90104,
+  "total": 265942,
+  "total_gz": 90211,
   "sent": [
     "__cxa_begin_catch",
     "__cxa_end_catch",

test/codesize/test_codesize_cxx_noexcept.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 19224,
-  "a.out.js.gz": 8124,
+  "a.out.js": 19537,
+  "a.out.js.gz": 8228,
   "a.out.nodebug.wasm": 135882,
   "a.out.nodebug.wasm.gz": 51885,
-  "total": 155106,
-  "total_gz": 60009,
+  "total": 155419,
+  "total_gz": 60113,
   "sent": [
     "__cxa_throw",
     "_abort_js",

test/codesize/test_codesize_cxx_wasmfs.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 6604,
-  "a.out.js.gz": 3154,
+  "a.out.js": 6917,
+  "a.out.js.gz": 3266,
   "a.out.nodebug.wasm": 173607,
   "a.out.nodebug.wasm.gz": 64636,
-  "total": 180211,
-  "total_gz": 67790,
+  "total": 180524,
+  "total_gz": 67902,
   "sent": [
     "__cxa_throw",
     "_abort_js",

test/codesize/test_codesize_file_preload.expected.js

@@ -428,6 +428,25 @@ async function instantiateAsync(binary, binaryFile, imports) {
       err(`wasm streaming compile failed: ${reason}`);
       err("falling back to ArrayBuffer instantiation");
     }
+  } else if (!binary && ENVIRONMENT_IS_NODE) {
+    // Avoid using `fetch()` API on Node.js since it does not support `file://`
+    // URLs. Instead, provide a Response that wraps a fs read stream with the
+    // correct MIME type.
+    // See: https://github.com/emscripten-core/emscripten/pull/16917
+    try {
+      var url = require("node:url");
+      var nodeBinaryFile = isFileURI(binaryFile) ? url.fileURLToPath(binaryFile) : binaryFile;
+      var response = fs.openAsBlob(nodeBinaryFile).then(blob => new Response(blob, {
+        headers: {
+          "Content-Type": "application/wasm"
+        }
+      }));
+      var instantiationResult = await WebAssembly.instantiateStreaming(response, imports);
+      return instantiationResult;
+    } catch (reason) {
+      err(`wasm streaming compile failed: ${reason}`);
+      err("falling back to ArrayBuffer instantiation");
+    }
   }
   return instantiateArrayBuffer(binaryFile, imports);
 }

test/codesize/test_codesize_file_preload.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 22203,
-  "a.out.js.gz": 9267,
+  "a.out.js": 22516,
+  "a.out.js.gz": 9367,
   "a.out.nodebug.wasm": 1198,
   "a.out.nodebug.wasm.gz": 730,
-  "total": 23401,
-  "total_gz": 9997,
+  "total": 23714,
+  "total_gz": 10097,
   "sent": [
     "a (fd_write)"
   ],

test/codesize/test_codesize_files_js_fs.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 17871,
-  "a.out.js.gz": 7460,
+  "a.out.js": 18184,
+  "a.out.js.gz": 7571,
   "a.out.nodebug.wasm": 381,
   "a.out.nodebug.wasm.gz": 258,
-  "total": 18252,
-  "total_gz": 7718,
+  "total": 18565,
+  "total_gz": 7829,
   "sent": [
     "a (fd_write)",
     "b (fd_read)",

test/codesize/test_codesize_files_wasmfs.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 4979,
-  "a.out.js.gz": 2409,
+  "a.out.js": 5292,
+  "a.out.js.gz": 2518,
   "a.out.nodebug.wasm": 58252,
   "a.out.nodebug.wasm.gz": 18292,
-  "total": 63231,
-  "total_gz": 20701,
+  "total": 63544,
+  "total_gz": 20810,
   "sent": [
     "a (emscripten_date_now)",
     "b (emscripten_err)",

test/codesize/test_codesize_hello_O0.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 23596,
-  "a.out.js.gz": 8582,
+  "a.out.js": 23986,
+  "a.out.js.gz": 8693,
   "a.out.nodebug.wasm": 14279,
   "a.out.nodebug.wasm.gz": 7101,
-  "total": 37875,
-  "total_gz": 15683,
+  "total": 38265,
+  "total_gz": 15794,
   "sent": [
     "fd_write"
   ],

test/codesize/test_codesize_hello_O1.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 5516,
-  "a.out.js.gz": 2242,
+  "a.out.js": 5906,
+  "a.out.js.gz": 2362,
   "a.out.nodebug.wasm": 2050,
   "a.out.nodebug.wasm.gz": 1231,
-  "total": 7566,
-  "total_gz": 3473,
+  "total": 7956,
+  "total_gz": 3593,
   "sent": [
     "fd_write"
   ],

test/codesize/test_codesize_hello_O2.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 3855,
-  "a.out.js.gz": 1966,
+  "a.out.js": 4167,
+  "a.out.js.gz": 2074,
   "a.out.nodebug.wasm": 1444,
   "a.out.nodebug.wasm.gz": 922,
-  "total": 5299,
-  "total_gz": 2888,
+  "total": 5611,
+  "total_gz": 2996,
   "sent": [
     "fd_write"
   ],

test/codesize/test_codesize_hello_O3.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 3797,
-  "a.out.js.gz": 1925,
+  "a.out.js": 4109,
+  "a.out.js.gz": 2032,
   "a.out.nodebug.wasm": 1198,
   "a.out.nodebug.wasm.gz": 730,
-  "total": 4995,
-  "total_gz": 2655,
+  "total": 5307,
+  "total_gz": 2762,
   "sent": [
     "a (fd_write)"
   ],

test/codesize/test_codesize_hello_Os.json

@@ -1,10 +1,10 @@
 {
-  "a.out.js": 3797,
-  "a.out.js.gz": 1925,
+  "a.out.js": 4109,
+  "a.out.js.gz": 2032,
   "a.out.nodebug.wasm": 1188,
   "a.out.nodebug.wasm.gz": 732,
-  "total": 4985,
-  "total_gz": 2657,
+  "total": 5297,
+  "total_gz": 2764,
   "sent": [
     "a (fd_write)"
   ],