ServeDir: convert io::ErrorKind::NotADirectory to not_found

[syphar]

Motivation

In docs.rs we were seeing server errors on requests like /-/static/index.js/979790 when index.js actually existed.

The error we are seeing was: "Not a directory (os error 20)".

Solution

If I'm not missing something this should be a "not found" error.

I'm not 100% certain if accessing raw_os_error is good enough here, but ErrorKind::NotADirectory is not on stable yet (see io_error_more). Since this is coming from libc I assume this is portable.

I'm happy to add any needed changes, to close this if you disagree with my solution.

[adumbidiot]

Shouldn't this be gated to unix oses?

[syphar]

Shouldn't this be gated to unix oses?

Yep, you're absolutely right, I missed that the code definition I was referring to came from sys in the stdlib, which is OS specific. ( I didn't do too much rust cross-platform code until now)

[Nehliin]

Thanks looks good to me, I wonder if it's worth adding a comment to the ServeDir service highlighting this platform specific difference

[syphar]

Thanks looks good to me, I wonder if it's worth adding a comment to the ServeDir service highlighting this platform specific difference

You mean in the documentation?

[Nehliin]

Yes exactly

[syphar]

I added a short sentence where I believ it could fit

[adumbidiot]

Yep, you're absolutely right, I missed that the code definition I was referring to came from sys in the stdlib, which is OS specific. ( I didn't do too much rust cross-platform code until now)

Not sure what you mean by sys, but the raw os code is specific for each os; on windows error code 20 doesn't have the same meaning as ENOTDIR.

Also, you could probably clean up your implementation a bit with https://doc.rust-lang.org/std/macro.cfg.html, since that looks like what you are trying to emulate with attribute macros.