path: add Buffer support to join

[kkz13250]

Internalized the handling of Buffer type in the join function in path.js,

[addaleax]

Sorry for the duplicate tag, I saw that this was fixing the same issue as #33395 but not that this was a solution inside the path module itself.

Fwiw, I think having docs and tests would be very helpful here for deciding whether we want to go this route (this would be the first time that Buffer support is added to path).

[mscdex]

I think it's better to solve this at the fs layer instead because that is where we already document that we accept Buffer arguments for path/file names for various functions there. In general it doesn't seem like using Buffers for path/file names is that common anyway (I think it was added awhile back specifically for Windows users?) as many filesystems these days are UTF-8-capable.

[addaleax]

In general it doesn't seem like using Buffers for path/file names is that common anyway (I think it was added awhile back specifically for Windows users?) as many filesystems these days are UTF-8-capable.

It’s more of the reverse situation: Windows/NTFS uses UTF-16 for filenames, which we expose to our users as UTF-8, so strings work just fine there. However, while you could call filesystems on other OSes “UTF-8-capable”, what that means in reality is that no specific encoding is enforced at all. That’s why we have Buffer support in our filesystem APIs.

(That being said, I don’t have a strong opinion here.)

[addaleax]

I’ve renamed the PR to be a bit more accurate, and so it doesn’t get confused with #33395

[bcoe]

@kkz13250 @addaleax I need buffer support for several of path's methods, to be able to eventually call fs.cp(). Also, it fixes potential bugs with fs.rm().

I've started working on an implementation here first before pulling it into Node.js.

Would love feedback, specifically I want to make sure we handle some of the concerns around UTF-16.