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WebAssembly: fix execution context for methods that require Window interface #117

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Merged
merged 2 commits into from
Mar 12, 2022
Merged

WebAssembly: fix execution context for methods that require Window interface #117

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b0020d4
wasm: patch window method calls to fix Window interface implementatio…
x1unix Mar 12, 2022
9df8c84
web: add webassembly snippet
x1unix Mar 12, 2022
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5 changes: 5 additions & 0 deletions web/src/services/go/snippets.json
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,11 @@
"label": "Display image",
"snippet": "XN6x3L23Vok",
"icon": "FileImage"
},
{
"label": "WebAssembly",
"snippet": "NCdgXZrYSk4",
"icon": "JS"
}
],
"Other examples": [
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17 changes: 16 additions & 1 deletion web/src/services/go/wasm_exec.js
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Expand Up @@ -19,6 +19,11 @@
// Should be in sync with wasm_exec.js:406 and syscall/js.go:106
const GLOBAL_PREDEF_VALUE_ID = 5;

// x1unix: checks if called function is globalThis method
const isGlobalThisMethod = (methodName, method) => {
return (methodName in window) && (window[methodName] === method)
}

if (!global.TextEncoder) {
global.TextEncoder = require("util").TextEncoder;
}
Expand Down Expand Up @@ -297,9 +302,19 @@ export class Go {
"syscall/js.valueCall": (sp) => {
sp >>>= 0;
try {
const v = loadValue(sp + 8);
// x1unix: method object can be patched at call. See above.
let v = loadValue(sp + 8);
const m = Reflect.get(v, loadString(sp + 16));
const args = loadSliceOfValues(sp + 32);

// x1unix: some built-in functions such as alert() can be called only
// with Window context.
const methodName = loadString(sp + 16);
if (isGlobalThisMethod(methodName, m)) {
console.log(`go|syscall/js.valueCall: "${methodName}" is a window method, patching call...`);
v = window;
}

const result = Reflect.apply(m, v, args);
sp = this._inst.exports.getsp() >>> 0; // see comment above
storeValue(sp + 56, result);
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