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mtrezza merged 1 commit into from
Mar 16, 2026
+7 −0
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docs: Add documentation to safeRegexTest #10227

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7 changes: 7 additions & 0 deletions src/LiveQuery/QueryTools.js
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,12 @@ var vm = require('vm');
var logger = require('../logger').default;

var regexTimeout = 0;
// IMPORTANT: vmContext is shared across all calls for performance (vm.createContext() is expensive).
// This is safe because safeRegexTest is synchronous — setting the context properties and calling
// runInContext happen in the same event loop tick with no interruption possible. Do NOT add any
// asynchronous operations (await, callbacks, promises) between setting vmContext properties and
// calling script.runInContext, as this would allow other calls to overwrite the context values
// and cause cross-contamination between regex evaluations.
var vmContext = vm.createContext(Object.create(null));
var scriptCache = new Map();
var SCRIPT_CACHE_MAX = 1000;
Expand All @@ -13,6 +19,7 @@ function setRegexTimeout(ms) {
regexTimeout = ms;
}

// IMPORTANT: This function must remain synchronous. See vmContext comment above.
function safeRegexTest(pattern, flags, input) {
try {
if (!regexTimeout) {
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