René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Buffer#indexOf()/lastIndexOf()/includes() abort the process when end is not a number","articleBody":"### Version\n\nv27.0.0-nightly20261007aa1bf2cc37 (main at 9899b39b95)\n\n### Platform\n\nLinux x64\n\n### Subsystem\n\nbuffer\n\n### What steps will reproduce the bug?\n\n```js\nconst buf = Buffer.from('abcabc');\n\n// Each of these aborts the process, try/catch does not help:\nbuf.indexOf('a', 0, null);\nbuf.includes(97, 0, null);\nbuf.lastIndexOf(Buffer.from('a'), 5, {});\n\n// These return -1, expected 0:\nbuf.indexOf('a', 0, Infinity);\nbuf.indexOf(97, 0, 1e20);\n```\n\n### How often does it reproduce? Is there a required condition?\n\nAlways. Any `end` other than a number, a string or `undefined` aborts (`null`, booleans, objects, arrays, BigInts, symbols). Numbers outside the int64 range give a wrong result on x64.\n\n### What is the expected behavior? Why is that the expected behavior?\n\n`end` is documented as `{integer}`, so a wrong type should throw `ERR_INVALID_ARG_TYPE` instead of aborting. `Infinity` should be clamped to `buf.length`, the same way `end = 100` already is.\n\n### What do you see instead?\n\n```\n  #  node[788155]: void node::Buffer::(anonymous namespace)::IndexOfString(const FunctionCallbackInfo\u003cValue> &) at ../src/node_buffer.cc:1036\n  #  Assertion failed: args[5]->IsNumber()\n```\n\nand `-1` for the `Infinity` / `1e20` cases.\n\n### Additional information\n\nThe three methods only handle `end` in JS when it is a string (treated as the encoding) or `undefined`; anything else goes straight to the binding. `IndexOfString` and `IndexOfBuffer` do `CHECK(args[5]->IsNumber())` and `SlowIndexOfNumber` does `CHECK(args[4]->IsNumber())`. Numbers are read with `As\u003cInteger>()->Value()`, which for NaN, ±Infinity or values beyond int64 is an undefined double-to-int64 conversion (`INT64_MIN` on x64, which is then clamped to 0).\n\n`end` was added in #62390. I have a fix and will open a PR.\n","author":{"url":"https://github.com/gengjiawen","@type":"Person","name":"gengjiawen"},"datePublished":"2026-10-08T06:33:06Z","url":"https://github.com/nodejs/node/issues/66589"}