fix: use syscall/js for interop

go_wasm.patch

@@ -1,8 +1,8 @@
 diff --git a/go_wasm.js b/go_wasm.js
-index 8021b44..21cfd42 100644
+index 8021b44..a4836ba 100644
 --- a/go_wasm.js
 +++ b/go_wasm.js
-@@ -4,135 +4,11 @@
+@@ -4,135 +4,10 @@
  //
  // This file has been modified for use by the TinyGo compiler.
 
@@ -132,14 +132,71 @@ index 8021b44..21cfd42 100644
 -
  	const encoder = new TextEncoder("utf-8");
  	const decoder = new TextDecoder("utf-8");
- 	var logLine = [];
+-	var logLine = [];
 
 -	global.Go = class {
 +	export class Go {
  		constructor() {
  			this._callbackTimeouts = new Map();
  			this._nextCallbackTimeoutID = 1;
-@@ -307,10 +183,15 @@
+@@ -249,50 +124,12 @@
+ 			this.importObject = {
+ 				wasi_snapshot_preview1: {
+ 					// https://github.com/WebAssembly/WASI/blob/main/phases/snapshot/docs.md#fd_write
+-					fd_write: function(fd, iovs_ptr, iovs_len, nwritten_ptr) {
+-						let nwritten = 0;
+-						if (fd == 1) {
+-							for (let iovs_i=0; iovs_i<iovs_len;iovs_i++) {
+-								let iov_ptr = iovs_ptr+iovs_i*8; // assuming wasm32
+-								let ptr = mem().getUint32(iov_ptr + 0, true);
+-								let len = mem().getUint32(iov_ptr + 4, true);
+-								nwritten += len;
+-								for (let i=0; i<len; i++) {
+-									let c = mem().getUint8(ptr+i);
+-									if (c == 13) { // CR
+-										// ignore
+-									} else if (c == 10) { // LF
+-										// write line
+-										let line = decoder.decode(new Uint8Array(logLine));
+-										logLine = [];
+-										console.log(line);
+-									} else {
+-										logLine.push(c);
+-									}
+-								}
+-							}
+-						} else {
+-							console.error('invalid file descriptor:', fd);
+-						}
+-						mem().setUint32(nwritten_ptr, nwritten, true);
+-						return 0;
+-					},
+-					fd_close: () => 0,      // dummy
+-					fd_fdstat_get: () => 0, // dummy
+-					fd_seek: () => 0,       // dummy
+-					"proc_exit": (code) => {
+-						if (global.process) {
+-							// Node.js
+-							process.exit(code);
+-						} else {
+-							// Can't exit in a browser.
+-							throw 'trying to exit with code ' + code;
+-						}
+-					},
+-					random_get: (bufPtr, bufLen) => {
+-						crypto.getRandomValues(loadSlice(bufPtr, bufLen));
+-						return 0;
+-					},
++					fd_write() {},
++					fd_close() {},
++					fd_fdstat_get() {},
++					fd_seek() {},
++					proc_exit() {},
++					random_get() {}
+ 				},
+ 				env: {
+ 					// func ticks() float64
+@@ -307,10 +144,15 @@
  					},
 
  					// func finalizeRef(v ref)
@@ -159,39 +216,30 @@ index 8021b44..21cfd42 100644
  					},
 
  					// func stringVal(value string) ref
-@@ -456,6 +337,22 @@
- 			};
- 		}
-
-+		storeString(str) {
-+			const addr = this._inst.exports.getBuffer();
-+			const buf = this._inst.exports.memory.buffer;
-+
-+			const mem = new Uint8Array(buf);
-+			const view = mem.subarray(addr);
-+			return encoder.encodeInto(str, view).written;
-+		}
-+
-+		loadString(len) {
-+			const addr = this._inst.exports.getBuffer();
-+			const buf = this._inst.exports.memory.buffer;
-+
-+			return decoder.decode(new DataView(buf, addr, len));
-+		}
-+
- 		async run(instance) {
- 			this._inst = instance;
- 			this._values = [ // JS values that Go currently has references to, indexed by reference id
-@@ -464,7 +361,7 @@
+@@ -464,7 +306,12 @@
  				null,
  				true,
  				false,
 -				global,
-+				"undefined" != typeof globalThis ? globalThis : global || self,
++				// fake global
++				{
++					set format(fn){ instance.format = fn; },
++					Array,
++					Object,
++				},
  				this,
  			];
  			this._goRefCounts = []; // number of references that Go has to a JS value, indexed by reference id
-@@ -511,25 +408,3 @@
+@@ -472,8 +319,6 @@
+ 			this._idPool = [];      // unused ids that have been garbage collected
+ 			this.exited = false;    // whether the Go program has exited
+
+-			const mem = new DataView(this._inst.exports.memory.buffer)
+-
+ 			while (true) {
+ 				const callbackPromise = new Promise((resolve) => {
+ 					this._resolveCallbackPromise = () => {
+@@ -511,25 +356,3 @@
  			};
  		}
  	}

lib.js

@@ -1,10 +1,10 @@
 import { Go } from "./go_wasm.js";
 const go = new Go();
 
-let mod;
+let inst;
 
 export default async function init(wasm_url) {
-    if (!mod) {
+    if (!inst) {
         if (!wasm_url) {
             wasm_url = new URL("lib.wasm", import.meta.url);
         }
@@ -17,28 +17,35 @@ export default async function init(wasm_url) {
             typeof __webpack_require__ !== "function" &&
             wasm_url.protocol === "file:"
         ) {
-            const fs = await import("node:fs");
-            const bytes = fs.readFileSync(wasm_url);
-            mod = new WebAssembly.Module(bytes);
-        } else if ("compileStreaming" in WebAssembly) {
-            mod = await WebAssembly.compileStreaming(fetch(wasm_url));
+            inst = import("node:fs/promises")
+                .then((fs) => fs.readFile(wasm_url))
+                .then((bytes) =>
+                    WebAssembly.instantiate(bytes, go.importObject)
+                );
+        } else if ("instantiateStreaming" in WebAssembly) {
+            inst = WebAssembly.instantiateStreaming(
+                fetch(wasm_url),
+                go.importObject
+            );
         } else {
-            const response = await fetch(wasm_url);
-            const bytes = await response.arrayBuffer();
-            mod = new WebAssembly.Module(bytes);
+            inst = fetch(wasm_url)
+                .then((response) => response.arrayBuffer())
+                .then((bytes) =>
+                    WebAssembly.instantiate(bytes, go.importObject)
+                );
         }
+        inst = (await inst).instance;
+        go.run(inst);
     }
+
+    await inst;
 }
 
 export function format(input) {
-    const inst = new WebAssembly.Instance(mod, go.importObject);
-    go.run(inst);
-
-    const input_len = go.storeString(input);
-    const output_len = inst.exports.format(input_len);
-    if (output_len < 0) {
-        throw new Error(go.loadString(-output_len));
+    const [err, result] = inst.format(input);
+    if (err) {
+        throw new Error(result);
     }
 
-    return go.loadString(output_len);
+    return result;
 }

src/lib.go

@@ -1,31 +1,23 @@
 package main
 
-import "go/format"
+import (
+	"go/format"
+	"syscall/js"
+)
 
-const buf_len = 8192
+func Format(this js.Value, args []js.Value) any {
+	input := ([]byte)(args[0].String())
 
-var buf [buf_len]byte
-
-//go:export getBuffer
-func GetBuffer() *byte {
-	return &buf[0]
-}
-
-//go:export format
-func Format(input_len uint) int {
-	input := buf[:input_len]
 	output, err := format.Source(input)
 	if err != nil {
-		return -copy(buf[:], []byte(err.Error()))
+		return []interface{}{true, err.Error()}
 	}
-	result := len(output)
 
-	if result > buf_len {
-		return -copy(buf[:], []byte("Buffer out of memory"))
-	}
-
-	copy(buf[:], output)
-	return result
+	return []interface{}{false, string(output)}
 }
 
-func main() {}
+func main() {
+	done := make(chan bool)
+	js.Global().Set("format", js.FuncOf(Format))
+	<-done
+}