1 files changed, 49 insertions, 0 deletions
diff --git a/src/bun.js/wasi-runner.js b/src/bun.js/wasi-runner.js
new file mode 100644
index 000000000..24ff0a678
--- /dev/null
+++ b/src/bun.js/wasi-runner.js
@@ -0,0 +1,49 @@
+/** --- WASI */
+// wasi is imported into the top of this file
+
+const filePath = process.argv.at(1);
+if (!filePath) {
+  var err = new Error(
+    "To run a wasm file with Bun, the first argument must be a path to a .wasm file",
+  );
+  err.name = "WasmFileNotFound";
+  throw err;
+}
+
+// The module specifier is the resolved path to the wasm file
+
+var {
+  WASM_CWD = process.cwd(),
+  WASM_ROOT_DIR = "/",
+  WASM_ENV_STR = undefined,
+  WASM_USE_ASYNC_INIT = "",
+} = process.env;
+
+var env = process.env;
+if (WASM_ENV_STR?.length) {
+  env = JSON.parse(WASM_ENV_STR);
+}
+
+const wasi = new WASI({
+  args: process.argv.slice(1),
+  env,
+  preopens: {
+    ".": WASM_CWD || process.cwd(),
+    "/": WASM_ROOT_DIR || "/",
+  },
+});
+
+let source = globalThis.wasmSourceBytes;
+if (!source) {
+  const fs = Bun.fs();
+  const file = import.meta.path;
+  source = fs.readFileSync(file);
+}
+
+const wasm = new WebAssembly.Module(source);
+const instance = !WASM_USE_ASYNC_INIT
+  ? new WebAssembly.Instance(wasm, wasi.getImports(wasm))
+  : await WebAssembly.instantiate(wasm, wasi.getImports(wasm));
+wasi.start(instance);
+
+process.exit(0);