wasm_exec.js raw
1 // Copyright 2018 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
4
5 "use strict";
6
7 (() => {
8 const enosys = () => {
9 const err = new Error("not implemented");
10 err.code = "ENOSYS";
11 return err;
12 };
13
14 if (!globalThis.fs) {
15 let outputBuf = "";
16 globalThis.fs = {
17 constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1, O_DIRECTORY: -1 }, // unused
18 writeSync(fd, buf) {
19 outputBuf += decoder.decode(buf);
20 const nl = outputBuf.lastIndexOf("\n");
21 if (nl != -1) {
22 console.log(outputBuf.substring(0, nl));
23 outputBuf = outputBuf.substring(nl + 1);
24 }
25 return buf.length;
26 },
27 write(fd, buf, offset, length, position, callback) {
28 if (offset !== 0 || length !== buf.length || position !== null) {
29 callback(enosys());
30 return;
31 }
32 const n = this.writeSync(fd, buf);
33 callback(null, n);
34 },
35 chmod(path, mode, callback) { callback(enosys()); },
36 chown(path, uid, gid, callback) { callback(enosys()); },
37 close(fd, callback) { callback(enosys()); },
38 fchmod(fd, mode, callback) { callback(enosys()); },
39 fchown(fd, uid, gid, callback) { callback(enosys()); },
40 fstat(fd, callback) { callback(enosys()); },
41 fsync(fd, callback) { callback(null); },
42 ftruncate(fd, length, callback) { callback(enosys()); },
43 lchown(path, uid, gid, callback) { callback(enosys()); },
44 link(path, link, callback) { callback(enosys()); },
45 lstat(path, callback) { callback(enosys()); },
46 mkdir(path, perm, callback) { callback(enosys()); },
47 open(path, flags, mode, callback) { callback(enosys()); },
48 read(fd, buffer, offset, length, position, callback) { callback(enosys()); },
49 readdir(path, callback) { callback(enosys()); },
50 readlink(path, callback) { callback(enosys()); },
51 rename(from, to, callback) { callback(enosys()); },
52 rmdir(path, callback) { callback(enosys()); },
53 stat(path, callback) { callback(enosys()); },
54 symlink(path, link, callback) { callback(enosys()); },
55 truncate(path, length, callback) { callback(enosys()); },
56 unlink(path, callback) { callback(enosys()); },
57 utimes(path, atime, mtime, callback) { callback(enosys()); },
58 };
59 }
60
61 if (!globalThis.process) {
62 globalThis.process = {
63 getuid() { return -1; },
64 getgid() { return -1; },
65 geteuid() { return -1; },
66 getegid() { return -1; },
67 getgroups() { throw enosys(); },
68 pid: -1,
69 ppid: -1,
70 umask() { throw enosys(); },
71 cwd() { throw enosys(); },
72 chdir() { throw enosys(); },
73 }
74 }
75
76 if (!globalThis.path) {
77 globalThis.path = {
78 resolve(...pathSegments) {
79 return pathSegments.join("/");
80 }
81 }
82 }
83
84 if (!globalThis.crypto) {
85 throw new Error("globalThis.crypto is not available, polyfill required (crypto.getRandomValues only)");
86 }
87
88 if (!globalThis.performance) {
89 throw new Error("globalThis.performance is not available, polyfill required (performance.now only)");
90 }
91
92 if (!globalThis.TextEncoder) {
93 throw new Error("globalThis.TextEncoder is not available, polyfill required");
94 }
95
96 if (!globalThis.TextDecoder) {
97 throw new Error("globalThis.TextDecoder is not available, polyfill required");
98 }
99
100 const encoder = new TextEncoder("utf-8");
101 const decoder = new TextDecoder("utf-8");
102
103 globalThis.Go = class {
104 constructor() {
105 this.argv = ["js"];
106 this.env = {};
107 this.exit = (code) => {
108 if (code !== 0) {
109 console.warn("exit code:", code);
110 }
111 };
112 this._exitPromise = new Promise((resolve) => {
113 this._resolveExitPromise = resolve;
114 });
115 this._pendingEvent = null;
116 this._scheduledTimeouts = new Map();
117 this._nextCallbackTimeoutID = 1;
118
119 const setInt64 = (addr, v) => {
120 this.mem.setUint32(addr + 0, v, true);
121 this.mem.setUint32(addr + 4, Math.floor(v / 4294967296), true);
122 }
123
124 const setInt32 = (addr, v) => {
125 this.mem.setUint32(addr + 0, v, true);
126 }
127
128 const getInt64 = (addr) => {
129 const low = this.mem.getUint32(addr + 0, true);
130 const high = this.mem.getInt32(addr + 4, true);
131 return low + high * 4294967296;
132 }
133
134 const loadValue = (addr) => {
135 const f = this.mem.getFloat64(addr, true);
136 if (f === 0) {
137 return undefined;
138 }
139 if (!isNaN(f)) {
140 return f;
141 }
142
143 const id = this.mem.getUint32(addr, true);
144 return this._values[id];
145 }
146
147 const storeValue = (addr, v) => {
148 const nanHead = 0x7FF80000;
149
150 if (typeof v === "number" && v !== 0) {
151 if (isNaN(v)) {
152 this.mem.setUint32(addr + 4, nanHead, true);
153 this.mem.setUint32(addr, 0, true);
154 return;
155 }
156 this.mem.setFloat64(addr, v, true);
157 return;
158 }
159
160 if (v === undefined) {
161 this.mem.setFloat64(addr, 0, true);
162 return;
163 }
164
165 let id = this._ids.get(v);
166 if (id === undefined) {
167 id = this._idPool.pop();
168 if (id === undefined) {
169 id = this._values.length;
170 }
171 this._values[id] = v;
172 this._goRefCounts[id] = 0;
173 this._ids.set(v, id);
174 }
175 this._goRefCounts[id]++;
176 let typeFlag = 0;
177 switch (typeof v) {
178 case "object":
179 if (v !== null) {
180 typeFlag = 1;
181 }
182 break;
183 case "string":
184 typeFlag = 2;
185 break;
186 case "symbol":
187 typeFlag = 3;
188 break;
189 case "function":
190 typeFlag = 4;
191 break;
192 }
193 this.mem.setUint32(addr + 4, nanHead | typeFlag, true);
194 this.mem.setUint32(addr, id, true);
195 }
196
197 const loadSlice = (addr) => {
198 const array = getInt64(addr + 0);
199 const len = getInt64(addr + 8);
200 return new Uint8Array(this._inst.exports.mem.buffer, array, len);
201 }
202
203 const loadSliceOfValues = (addr) => {
204 const array = getInt64(addr + 0);
205 const len = getInt64(addr + 8);
206 const a = new Array(len);
207 for (let i = 0; i < len; i++) {
208 a[i] = loadValue(array + i * 8);
209 }
210 return a;
211 }
212
213 const loadString = (addr) => {
214 const saddr = getInt64(addr + 0);
215 const len = getInt64(addr + 8);
216 return decoder.decode(new DataView(this._inst.exports.mem.buffer, saddr, len));
217 }
218
219 const testCallExport = (a, b) => {
220 this._inst.exports.testExport0();
221 return this._inst.exports.testExport(a, b);
222 }
223
224 const timeOrigin = Date.now() - performance.now();
225 this.importObject = {
226 _gotest: {
227 add: (a, b) => a + b,
228 callExport: testCallExport,
229 },
230 gojs: {
231 // Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters)
232 // may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported
233 // function. A goroutine can switch to a new stack if the current stack is too small (see morestack function).
234 // This changes the SP, thus we have to update the SP used by the imported function.
235
236 // func wasmExit(code int32)
237 "runtime.wasmExit": (sp) => {
238 sp >>>= 0;
239 const code = this.mem.getInt32(sp + 8, true);
240 this.exited = true;
241 delete this._inst;
242 delete this._values;
243 delete this._goRefCounts;
244 delete this._ids;
245 delete this._idPool;
246 this.exit(code);
247 },
248
249 // func wasmWrite(fd uintptr, p unsafe.Pointer, n int32)
250 "runtime.wasmWrite": (sp) => {
251 sp >>>= 0;
252 const fd = getInt64(sp + 8);
253 const p = getInt64(sp + 16);
254 const n = this.mem.getInt32(sp + 24, true);
255 fs.writeSync(fd, new Uint8Array(this._inst.exports.mem.buffer, p, n));
256 },
257
258 // func resetMemoryDataView()
259 "runtime.resetMemoryDataView": (sp) => {
260 sp >>>= 0;
261 this.mem = new DataView(this._inst.exports.mem.buffer);
262 },
263
264 // func nanotime1() int64
265 "runtime.nanotime1": (sp) => {
266 sp >>>= 0;
267 setInt64(sp + 8, (timeOrigin + performance.now()) * 1000000);
268 },
269
270 // func walltime() (sec int64, nsec int32)
271 "runtime.walltime": (sp) => {
272 sp >>>= 0;
273 const msec = (new Date).getTime();
274 setInt64(sp + 8, msec / 1000);
275 this.mem.setInt32(sp + 16, (msec % 1000) * 1000000, true);
276 },
277
278 // func scheduleTimeoutEvent(delay int64) int32
279 "runtime.scheduleTimeoutEvent": (sp) => {
280 sp >>>= 0;
281 const id = this._nextCallbackTimeoutID;
282 this._nextCallbackTimeoutID++;
283 this._scheduledTimeouts.set(id, setTimeout(
284 () => {
285 this._resume();
286 while (this._scheduledTimeouts.has(id)) {
287 // for some reason Go failed to register the timeout event, log and try again
288 // (temporary workaround for https://github.com/golang/go/issues/28975)
289 console.warn("scheduleTimeoutEvent: missed timeout event");
290 this._resume();
291 }
292 },
293 getInt64(sp + 8),
294 ));
295 this.mem.setInt32(sp + 16, id, true);
296 },
297
298 // func clearTimeoutEvent(id int32)
299 "runtime.clearTimeoutEvent": (sp) => {
300 sp >>>= 0;
301 const id = this.mem.getInt32(sp + 8, true);
302 clearTimeout(this._scheduledTimeouts.get(id));
303 this._scheduledTimeouts.delete(id);
304 },
305
306 // func getRandomData(r []byte)
307 "runtime.getRandomData": (sp) => {
308 sp >>>= 0;
309 crypto.getRandomValues(loadSlice(sp + 8));
310 },
311
312 // func finalizeRef(v ref)
313 "syscall/js.finalizeRef": (sp) => {
314 sp >>>= 0;
315 const id = this.mem.getUint32(sp + 8, true);
316 this._goRefCounts[id]--;
317 if (this._goRefCounts[id] === 0) {
318 const v = this._values[id];
319 this._values[id] = null;
320 this._ids.delete(v);
321 this._idPool.push(id);
322 }
323 },
324
325 // func stringVal(value string) ref
326 "syscall/js.stringVal": (sp) => {
327 sp >>>= 0;
328 storeValue(sp + 24, loadString(sp + 8));
329 },
330
331 // func valueGet(v ref, p string) ref
332 "syscall/js.valueGet": (sp) => {
333 sp >>>= 0;
334 const result = Reflect.get(loadValue(sp + 8), loadString(sp + 16));
335 sp = this._inst.exports.getsp() >>> 0; // see comment above
336 storeValue(sp + 32, result);
337 },
338
339 // func valueSet(v ref, p string, x ref)
340 "syscall/js.valueSet": (sp) => {
341 sp >>>= 0;
342 Reflect.set(loadValue(sp + 8), loadString(sp + 16), loadValue(sp + 32));
343 },
344
345 // func valueDelete(v ref, p string)
346 "syscall/js.valueDelete": (sp) => {
347 sp >>>= 0;
348 Reflect.deleteProperty(loadValue(sp + 8), loadString(sp + 16));
349 },
350
351 // func valueIndex(v ref, i int) ref
352 "syscall/js.valueIndex": (sp) => {
353 sp >>>= 0;
354 storeValue(sp + 24, Reflect.get(loadValue(sp + 8), getInt64(sp + 16)));
355 },
356
357 // valueSetIndex(v ref, i int, x ref)
358 "syscall/js.valueSetIndex": (sp) => {
359 sp >>>= 0;
360 Reflect.set(loadValue(sp + 8), getInt64(sp + 16), loadValue(sp + 24));
361 },
362
363 // func valueCall(v ref, m string, args []ref) (ref, bool)
364 "syscall/js.valueCall": (sp) => {
365 sp >>>= 0;
366 try {
367 const v = loadValue(sp + 8);
368 const m = Reflect.get(v, loadString(sp + 16));
369 const args = loadSliceOfValues(sp + 32);
370 const result = Reflect.apply(m, v, args);
371 sp = this._inst.exports.getsp() >>> 0; // see comment above
372 storeValue(sp + 56, result);
373 this.mem.setUint8(sp + 64, 1);
374 } catch (err) {
375 sp = this._inst.exports.getsp() >>> 0; // see comment above
376 storeValue(sp + 56, err);
377 this.mem.setUint8(sp + 64, 0);
378 }
379 },
380
381 // func valueInvoke(v ref, args []ref) (ref, bool)
382 "syscall/js.valueInvoke": (sp) => {
383 sp >>>= 0;
384 try {
385 const v = loadValue(sp + 8);
386 const args = loadSliceOfValues(sp + 16);
387 const result = Reflect.apply(v, undefined, args);
388 sp = this._inst.exports.getsp() >>> 0; // see comment above
389 storeValue(sp + 40, result);
390 this.mem.setUint8(sp + 48, 1);
391 } catch (err) {
392 sp = this._inst.exports.getsp() >>> 0; // see comment above
393 storeValue(sp + 40, err);
394 this.mem.setUint8(sp + 48, 0);
395 }
396 },
397
398 // func valueNew(v ref, args []ref) (ref, bool)
399 "syscall/js.valueNew": (sp) => {
400 sp >>>= 0;
401 try {
402 const v = loadValue(sp + 8);
403 const args = loadSliceOfValues(sp + 16);
404 const result = Reflect.construct(v, args);
405 sp = this._inst.exports.getsp() >>> 0; // see comment above
406 storeValue(sp + 40, result);
407 this.mem.setUint8(sp + 48, 1);
408 } catch (err) {
409 sp = this._inst.exports.getsp() >>> 0; // see comment above
410 storeValue(sp + 40, err);
411 this.mem.setUint8(sp + 48, 0);
412 }
413 },
414
415 // func valueLength(v ref) int
416 "syscall/js.valueLength": (sp) => {
417 sp >>>= 0;
418 setInt64(sp + 16, parseInt(loadValue(sp + 8).length));
419 },
420
421 // valuePrepareString(v ref) (ref, int)
422 "syscall/js.valuePrepareString": (sp) => {
423 sp >>>= 0;
424 const str = encoder.encode(String(loadValue(sp + 8)));
425 storeValue(sp + 16, str);
426 setInt64(sp + 24, str.length);
427 },
428
429 // valueLoadString(v ref, b []byte)
430 "syscall/js.valueLoadString": (sp) => {
431 sp >>>= 0;
432 const str = loadValue(sp + 8);
433 loadSlice(sp + 16).set(str);
434 },
435
436 // func valueInstanceOf(v ref, t ref) bool
437 "syscall/js.valueInstanceOf": (sp) => {
438 sp >>>= 0;
439 this.mem.setUint8(sp + 24, (loadValue(sp + 8) instanceof loadValue(sp + 16)) ? 1 : 0);
440 },
441
442 // func copyBytesToGo(dst []byte, src ref) (int, bool)
443 "syscall/js.copyBytesToGo": (sp) => {
444 sp >>>= 0;
445 const dst = loadSlice(sp + 8);
446 const src = loadValue(sp + 32);
447 if (!(src instanceof Uint8Array || src instanceof Uint8ClampedArray)) {
448 this.mem.setUint8(sp + 48, 0);
449 return;
450 }
451 const toCopy = src.subarray(0, dst.length);
452 dst.set(toCopy);
453 setInt64(sp + 40, toCopy.length);
454 this.mem.setUint8(sp + 48, 1);
455 },
456
457 // func copyBytesToJS(dst ref, src []byte) (int, bool)
458 "syscall/js.copyBytesToJS": (sp) => {
459 sp >>>= 0;
460 const dst = loadValue(sp + 8);
461 const src = loadSlice(sp + 16);
462 if (!(dst instanceof Uint8Array || dst instanceof Uint8ClampedArray)) {
463 this.mem.setUint8(sp + 48, 0);
464 return;
465 }
466 const toCopy = src.subarray(0, dst.length);
467 dst.set(toCopy);
468 setInt64(sp + 40, toCopy.length);
469 this.mem.setUint8(sp + 48, 1);
470 },
471
472 "debug": (value) => {
473 console.log(value);
474 },
475 }
476 };
477 }
478
479 async run(instance) {
480 if (!(instance instanceof WebAssembly.Instance)) {
481 throw new Error("Go.run: WebAssembly.Instance expected");
482 }
483 this._inst = instance;
484 this.mem = new DataView(this._inst.exports.mem.buffer);
485 this._values = [ // JS values that Go currently has references to, indexed by reference id
486 NaN,
487 0,
488 null,
489 true,
490 false,
491 globalThis,
492 this,
493 ];
494 this._goRefCounts = new Array(this._values.length).fill(Infinity); // number of references that Go has to a JS value, indexed by reference id
495 this._ids = new Map([ // mapping from JS values to reference ids
496 [0, 1],
497 [null, 2],
498 [true, 3],
499 [false, 4],
500 [globalThis, 5],
501 [this, 6],
502 ]);
503 this._idPool = []; // unused ids that have been garbage collected
504 this.exited = false; // whether the Go program has exited
505
506 // Pass command line arguments and environment variables to WebAssembly by writing them to the linear memory.
507 let offset = 4096;
508
509 const strPtr = (str) => {
510 const ptr = offset;
511 const bytes = encoder.encode(str + "\0");
512 new Uint8Array(this.mem.buffer, offset, bytes.length).set(bytes);
513 offset += bytes.length;
514 if (offset % 8 !== 0) {
515 offset += 8 - (offset % 8);
516 }
517 return ptr;
518 };
519
520 const argc = this.argv.length;
521
522 const argvPtrs = [];
523 this.argv.forEach((arg) => {
524 argvPtrs.push(strPtr(arg));
525 });
526 argvPtrs.push(0);
527
528 const keys = Object.keys(this.env).sort();
529 keys.forEach((key) => {
530 argvPtrs.push(strPtr(`${key}=${this.env[key]}`));
531 });
532 argvPtrs.push(0);
533
534 const argv = offset;
535 argvPtrs.forEach((ptr) => {
536 this.mem.setUint32(offset, ptr, true);
537 this.mem.setUint32(offset + 4, 0, true);
538 offset += 8;
539 });
540
541 // The linker guarantees global data starts from at least wasmMinDataAddr.
542 // Keep in sync with cmd/link/internal/ld/data.go:wasmMinDataAddr.
543 const wasmMinDataAddr = 4096 + 8192;
544 if (offset >= wasmMinDataAddr) {
545 throw new Error("total length of command line and environment variables exceeds limit");
546 }
547
548 this._inst.exports.run(argc, argv);
549 if (this.exited) {
550 this._resolveExitPromise();
551 }
552 await this._exitPromise;
553 }
554
555 _resume() {
556 if (this.exited) {
557 throw new Error("Go program has already exited");
558 }
559 this._inst.exports.resume();
560 if (this.exited) {
561 this._resolveExitPromise();
562 }
563 }
564
565 _makeFuncWrapper(id) {
566 const go = this;
567 return function () {
568 const event = { id: id, this: this, args: arguments };
569 go._pendingEvent = event;
570 go._resume();
571 return event.result;
572 };
573 }
574 }
575 })();
576