Patch FS for module resolution

[pauldraper]

Is your feature request related to a problem? Please describe.

I am customizing module/package.json location, necessary for good interop with Bazel build tool. Namely, I need to transparently customize file locations.

I cannot use symlinks because they change Node.js module resolution algorithm. (I cannot use preserve symlinks, because then hoisting becomes much more difficult, or at least compared to https://nodejs.org/api/modules.html#modules_package_manager_tips.)

I cannot use hardlinks because they may not be on the same file system.

Describe the solution you'd like

Monkeypatch the fs module (or process.binding('fs')), the same approach taken by npm's former tink project https://github.com/npm/tink

However, cjs/loader makes that impossible with code like

const { internalModuleStat } = internalBinding('fs');

Then internalModuleStat is impossible to monkey patch.

I'd like some way of monkeypatching that. Tink is dead, but I assume it had some plan.

Even if that code were

const binding = internalBinding('fs');

fs.internalModuleStat

Describe alternatives you've considered

Reimplement the node module algorithm and override at at different level like Module._load. This seems very complicated, involves package.json parsing, etc. Plus I'd need to repeat with other tools in the ecosystem.

I could LD_PRELOAD inject glibc, but I'd have to do that for each platform.

[pauldraper]

If I monkeypatch path.toNamespacedPath, I think I can get everything to work. (EDIT: Nope, there's more.)

The crux of the matter is that -- unlike most other tools -- Node.js and its ecosystem assign essential behavior to symlinks. So some other mechanism (like in-process patching) is need for transparent file management.

FWIW, in-process FS patching is not unique, if this particular reason is. See https://docs.oracle.com/javase/8/docs/technotes/guides/io/fsp/filesystemprovider.html

[merceyz]

Similar to #33423

[pauldraper]

Indeed. Closing this in favor.