René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"vfs: fs.writeFileSync(fd, ...) does not dispatch virtual file descriptors","articleBody":"### Version\n\nmain\n\n### Platform\n\n```text\nmacOS 26.5.0\n```\n\n### Subsystem\n\nvfs\n\n### What steps will reproduce the bug?\n\n```js\nimport fs from 'node:fs';\nimport os from 'node:os';\nimport path from 'node:path';\nimport vfs from 'node:vfs';\n\nconst mountPoint = fs.mkdtempSync(path.join(os.tmpdir(), 'vfs-mount-'));\n\nconst mounted = vfs\n  .create({ emitExperimentalWarning: false })\n  .mount(mountPoint);\n\ntry {\n  const file = path.join(mountPoint, 'file.txt');\n\n  fs.writeFileSync(file, 'abcdef');\n\n  const fd = fs.openSync(file, 'r+');\n\n  try {\n    fs.writeFileSync(fd, 'XY');\n    console.log(fs.readFileSync(file, 'utf8'));\n  } catch (err) {\n    console.log('threw:', err.code, err.syscall);\n  } finally {\n    fs.closeSync(fd);\n  }\n} finally {\n  mounted.unmount();\n  fs.rmSync(mountPoint, { recursive: true, force: true });\n}\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\n```console\nXYcdef\n```\n\nNative `fs.writeFileSync(fd, data)` writes through the already-open descriptor at its current file position, so virtual fds should be dispatched the same way as `fs.readFileSync(fd)` and `fs.readSync(fd, ...)`.\n\n### What do you see instead?\n\nthrows `EBADF` with syscall `write`.\n\n### Additional information\n\n_No response_","author":{"url":"https://github.com/trivikr","@type":"Person","name":"trivikr"},"datePublished":"2026-06-27T06:45:31.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/64164/node/issues/64164"}