René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ffi: closed library still callable via fast path, SIGSEGV instead of ERR_FFI_LIBRARY_CLOSED","articleBody":"### Version\n\nmain\n\n### Platform\n\n```text\nN/A\n```\n\n### Subsystem\n\nffi\n\n### What steps will reproduce the bug?\n\n`repro.c`\n```c\ndouble multiply_f64(double a, double b) {\n  return a * b;\n}\n```\n\nCompile it with\n```sh\n$ cc -shared -fPIC -o repro.so repro.c   # macOS: -o repro.dylib\n```\n\n`repro.js`\n```js\nimport { dlopen, suffix } from 'node:ffi';\n\nconst { lib, functions } = dlopen(`./repro.${suffix}`, {\n  multiply_f64: { arguments: ['f64', 'f64'], return: 'f64' },\n});\n\nfunction hot(a, b) { return functions.multiply_f64(a, b); }\n\n%PrepareFunctionForOptimization(hot);\nhot(2, 3);\n%OptimizeFunctionOnNextCall(hot);\n\nconsole.log('pre-close:', hot(2, 3));      // 6, now through the trampoline\n\nlib.close();\n\nconsole.log('after close:', hot(2, 3));    // SIGSEGV\n```\n\nRun it with\n```sh\n$ node --no-warnings --experimental-ffi --allow-natives-syntax repro.js\n```\n\n### How often does it reproduce? Is there a required condition?\n\nAlways\n\n### What is the expected behavior? Why is that the expected behavior?\n\nThe call after `close()` throws `ERR_FFI_LIBRARY_CLOSED`\n\n### What do you see instead?\n\n```console\npre-close: 6\nzsh: segmentation fault (core dumped)\n```\n\nThe call after `close()` throws `segmentation fault`\n\n### Additional information\n\n_No response_","author":{"url":"https://github.com/trivikr","@type":"Person","name":"trivikr"},"datePublished":"2026-07-31T01:32:07Z","url":"https://github.com/nodejs/node/issues/64854"}