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misc/wasm: expect environment to provide polyfills
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The list of environments to support with wasm_exec.js was becoming too
large to maintain. With this change, wasm_exec.js expects that the
environment provides all necessary polyfills.

The standardized "globalThis" is used for accessing the environment.
wasm_exec.js now only provides stub fallbacks for globalThis.fs and
globalThis.process.

All code specific to Node.js is now in a separate file.

Change-Id: I076febbd94d4d7845260faad972f450f74a7b983
Reviewed-on: https://go-review.googlesource.com/c/go/+/347353
Trust: Richard Musiol <neelance@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
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@neelance
neelance authored and Richard Musiol committed Oct 16, 2021
1 parent ed1c8db commit 680caf1
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2 changes: 1 addition & 1 deletion misc/wasm/go_js_wasm_exec
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Original file line number Diff line number Diff line change
Expand Up @@ -11,4 +11,4 @@ while [ -h "$SOURCE" ]; do
done
DIR="$( cd -P "$( dirname "$SOURCE" )" && pwd )"

exec node "$DIR/wasm_exec.js" "$@"
exec node "$DIR/wasm_exec_node.js" "$@"
115 changes: 16 additions & 99 deletions misc/wasm/wasm_exec.js
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Original file line number Diff line number Diff line change
@@ -1,49 +1,19 @@
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

"use strict";

(() => {
// 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;
}
}

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);
Expand Down Expand Up @@ -88,8 +58,8 @@
};
}

if (!global.process) {
global.process = {
if (!globalThis.process) {
globalThis.process = {
getuid() { return -1; },
getgid() { return -1; },
geteuid() { return -1; },
Expand All @@ -103,47 +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 Down Expand Up @@ -518,7 +467,7 @@
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 @@ -527,7 +476,7 @@
[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 @@ -602,36 +551,4 @@
};
}
}

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);
});
}
})();
49 changes: 49 additions & 0 deletions misc/wasm/wasm_exec_node.js
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

"use strict";

if (process.argv.length < 3) {
console.error("usage: go_js_wasm_exec [wasm binary] [arguments]");
process.exit(1);
}

globalThis.require = require;
globalThis.fs = require("fs");
globalThis.TextEncoder = require("util").TextEncoder;
globalThis.TextDecoder = require("util").TextDecoder;

globalThis.performance = {
now() {
const [sec, nsec] = process.hrtime();
return sec * 1000 + nsec / 1000000;
},
};

const crypto = require("crypto");
globalThis.crypto = {
getRandomValues(b) {
crypto.randomFillSync(b);
},
};

require("./wasm_exec");

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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