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update js/wasm_exec.js - the Go WASM JS glue
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@johnbartholomew
johnbartholomew committed Apr 17, 2024
1 parent e8e278e commit 2bca3a0
Showing 1 changed file with 35 additions and 103 deletions.
138 changes: 35 additions & 103 deletions doc/js/wasm_exec.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,54 +2,25 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

(() => {
// Map multiple JavaScript environments to a single common API,
// preferring web standards over Node.js API.
//
// Environments considered:
// - Browsers
// - Node.js
// - Electron
// - Parcel
// - Webpack

if (typeof global !== "undefined") {
// global already exists
} else if (typeof window !== "undefined") {
window.global = window;
} else if (typeof self !== "undefined") {
self.global = self;
} else {
throw new Error("cannot export Go (neither global, window nor self is defined)");
}

if (!global.require && typeof require !== "undefined") {
global.require = require;
}

if (!global.fs && global.require) {
const fs = require("fs");
if (typeof fs === "object" && fs !== null && Object.keys(fs).length !== 0) {
global.fs = fs;
}
}
"use strict";

(() => {
const enosys = () => {
const err = new Error("not implemented");
err.code = "ENOSYS";
return err;
};

if (!global.fs) {
if (!globalThis.fs) {
let outputBuf = "";
global.fs = {
globalThis.fs = {
constants: { O_WRONLY: -1, O_RDWR: -1, O_CREAT: -1, O_TRUNC: -1, O_APPEND: -1, O_EXCL: -1 }, // unused
writeSync(fd, buf) {
outputBuf += decoder.decode(buf);
const nl = outputBuf.lastIndexOf("\n");
if (nl != -1) {
console.log(outputBuf.substr(0, nl));
outputBuf = outputBuf.substr(nl + 1);
console.log(outputBuf.substring(0, nl));
outputBuf = outputBuf.substring(nl + 1);
}
return buf.length;
},
Expand Down Expand Up @@ -87,8 +58,8 @@
};
}

if (!global.process) {
global.process = {
if (!globalThis.process) {
globalThis.process = {
getuid() { return -1; },
getgid() { return -1; },
geteuid() { return -1; },
Expand All @@ -102,47 +73,26 @@
}
}

if (!global.crypto && global.require) {
const nodeCrypto = require("crypto");
global.crypto = {
getRandomValues(b) {
nodeCrypto.randomFillSync(b);
},
};
}
if (!global.crypto) {
throw new Error("global.crypto is not available, polyfill required (getRandomValues only)");
if (!globalThis.crypto) {
throw new Error("globalThis.crypto is not available, polyfill required (crypto.getRandomValues only)");
}

if (!global.performance) {
global.performance = {
now() {
const [sec, nsec] = process.hrtime();
return sec * 1000 + nsec / 1000000;
},
};
if (!globalThis.performance) {
throw new Error("globalThis.performance is not available, polyfill required (performance.now only)");
}

if (!global.TextEncoder && global.require) {
global.TextEncoder = require("util").TextEncoder;
}
if (!global.TextEncoder) {
throw new Error("global.TextEncoder is not available, polyfill required");
if (!globalThis.TextEncoder) {
throw new Error("globalThis.TextEncoder is not available, polyfill required");
}

if (!global.TextDecoder && global.require) {
global.TextDecoder = require("util").TextDecoder;
if (!globalThis.TextDecoder) {
throw new Error("globalThis.TextDecoder is not available, polyfill required");
}
if (!global.TextDecoder) {
throw new Error("global.TextDecoder is not available, polyfill required");
}

// End of polyfills for common API.

const encoder = new TextEncoder("utf-8");
const decoder = new TextDecoder("utf-8");

global.Go = class {
globalThis.Go = class {
constructor() {
this.argv = ["js"];
this.env = {};
Expand All @@ -163,6 +113,10 @@
this.mem.setUint32(addr + 4, Math.floor(v / 4294967296), true);
}

const setInt32 = (addr, v) => {
this.mem.setUint32(addr + 0, v, true);
}

const getInt64 = (addr) => {
const low = this.mem.getUint32(addr + 0, true);
const high = this.mem.getInt32(addr + 4, true);
Expand Down Expand Up @@ -256,7 +210,10 @@

const timeOrigin = Date.now() - performance.now();
this.importObject = {
go: {
_gotest: {
add: (a, b) => a + b,
},
gojs: {
// Go's SP does not change as long as no Go code is running. Some operations (e.g. calls, getters and setters)
// may synchronously trigger a Go event handler. This makes Go code get executed in the middle of the imported
// function. A goroutine can switch to a new stack if the current stack is too small (see morestack function).
Expand Down Expand Up @@ -319,7 +276,7 @@
this._resume();
}
},
getInt64(sp + 8) + 1, // setTimeout has been seen to fire up to 1 millisecond early
getInt64(sp + 8),
));
this.mem.setInt32(sp + 16, id, true);
},
Expand Down Expand Up @@ -517,7 +474,7 @@
null,
true,
false,
global,
globalThis,
this,
];
this._goRefCounts = new Array(this._values.length).fill(Infinity); // number of references that Go has to a JS value, indexed by reference id
Expand All @@ -526,7 +483,7 @@
[null, 2],
[true, 3],
[false, 4],
[global, 5],
[globalThis, 5],
[this, 6],
]);
this._idPool = []; // unused ids that have been garbage collected
Expand Down Expand Up @@ -567,6 +524,13 @@
offset += 8;
});

// The linker guarantees global data starts from at least wasmMinDataAddr.
// Keep in sync with cmd/link/internal/ld/data.go:wasmMinDataAddr.
const wasmMinDataAddr = 4096 + 8192;
if (offset >= wasmMinDataAddr) {
throw new Error("total length of command line and environment variables exceeds limit");
}

this._inst.exports.run(argc, argv);
if (this.exited) {
this._resolveExitPromise();
Expand Down Expand Up @@ -594,36 +558,4 @@
};
}
}

if (
typeof module !== "undefined" &&
global.require &&
global.require.main === module &&
global.process &&
global.process.versions &&
!global.process.versions.electron
) {
if (process.argv.length < 3) {
console.error("usage: go_js_wasm_exec [wasm binary] [arguments]");
process.exit(1);
}

const go = new Go();
go.argv = process.argv.slice(2);
go.env = Object.assign({ TMPDIR: require("os").tmpdir() }, process.env);
go.exit = process.exit;
WebAssembly.instantiate(fs.readFileSync(process.argv[2]), go.importObject).then((result) => {
process.on("exit", (code) => { // Node.js exits if no event handler is pending
if (code === 0 && !go.exited) {
// deadlock, make Go print error and stack traces
go._pendingEvent = { id: 0 };
go._resume();
}
});
return go.run(result.instance);
}).catch((err) => {
console.error(err);
process.exit(1);
});
}
})();

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