add experimental wasi module support on top of wasm modules

doc/api/cli.md

@@ -190,6 +190,13 @@ added: v12.3.0
 
 Enable experimental WebAssembly module support.
 
+### `--experimental-wasi-modules`
+<!-- YAML
+added: REPLACEME
+-->
+
+Enable experimental [WASI][] module support.
+
 ### `--force-fips`
 <!-- YAML
 added: v6.0.0
@@ -1208,3 +1215,4 @@ greater than `4` (its current default value). For more information, see the
 [experimental ECMAScript Module]: esm.html#esm_resolve_hook
 [libuv threadpool documentation]: http://docs.libuv.org/en/latest/threadpool.html
 [remote code execution]: https://www.owasp.org/index.php/Code_Injection
+[WASI]: https://wasi.dev

doc/api/esm.md

@@ -449,6 +449,11 @@ node --experimental-modules --experimental-wasm-modules index.mjs
 
 would provide the exports interface for the instantiation of `module.wasm`.
 
+### WASI
+
+Additionally, if `--experimental-wasi-modules` is passed, Wasm modules
+conforming to [WASI][] specification will be run.
+
 ## Experimental Loader hooks
 
 **Note: This API is currently being redesigned and will still change.**
@@ -749,3 +754,4 @@ success!
 [ES Module Integration Proposal for Web Assembly]: https://github.com/webassembly/esm-integration
 [dynamic instantiate hook]: #esm_dynamic_instantiate_hook
 [the official standard format]: https://tc39.github.io/ecma262/#sec-modules
+[WASI]: https://wasi.dev

lib/internal/modules/esm/create_dynamic_module.js

@@ -36,8 +36,7 @@ import.meta.done();
     onReady: (cb) => { readyfns.add(cb); },
   };
 
-  if (imports.length)
-    reflect.imports = Object.create(null);
+  reflect.imports = Object.create(null);
 
   callbackMap.set(m, {
     initializeImportMeta: (meta, wrap) => {

lib/internal/modules/esm/translators.js

@@ -6,7 +6,7 @@ const {
   JSON,
   Object,
   SafeMap,
-  StringPrototype
+  StringPrototype,
 } = primordials;
 
 const { NativeModule } = require('internal/bootstrap/loaders');
@@ -22,9 +22,11 @@ const { fileURLToPath, URL } = require('url');
 const { debuglog } = require('internal/util/debuglog');
 const { promisify } = require('internal/util');
 const esmLoader = require('internal/process/esm_loader');
+const { getOptionValue } = require('internal/options');
 const {
   ERR_UNKNOWN_BUILTIN_MODULE
 } = require('internal/errors').codes;
+const WASI = require('internal/wasi');
 const readFileAsync = promisify(fs.readFile);
 const JsonParse = JSON.parse;
 
@@ -154,6 +156,8 @@ translators.set('json', async function jsonStrategy(url) {
   });
 });
 
+const wasiEnabled = getOptionValue('--experimental-wasi-modules');
+
 // Strategy for loading a wasm module
 translators.set('wasm', async function(url) {
   const pathname = fileURLToPath(url);
@@ -167,13 +171,37 @@ translators.set('wasm', async function(url) {
     throw err;
   }
 
-  const imports =
-      WebAssembly.Module.imports(compiled).map(({ module }) => module);
+  let usesWasi = false;
+  const imports = WebAssembly.Module.imports(compiled)
+    .reduce((acc, { module }) => {
+      if (wasiEnabled && module === 'wasi_unstable') {
+        usesWasi = true;
+      } else {
+        acc.push(module);
+      }
+      return acc;
+    }, []);
   const exports = WebAssembly.Module.exports(compiled).map(({ name }) => name);
 
   return createDynamicModule(imports, exports, url, (reflect) => {
+    let wasi;
+    if (usesWasi) {
+      wasi = new WASI(WASI.defaultConfig);
+      reflect.imports.wasi_unstable = wasi.exports;
+    }
+
     const { exports } = new WebAssembly.Instance(compiled, reflect.imports);
     for (const expt of Object.keys(exports))
       reflect.exports[expt].set(exports[expt]);
+
+    if (usesWasi && exports.memory) {
+      wasi.setMemory(exports.memory);
+    }
+
+    if (exports._start) {
+      exports._start();
+    } else if (exports.__wasi_unstable_reactor_start) {
+      exports.__wasi_unstable_reactor_start();
+    }
   });
 });