UnixPath and WindowsPath

[ibeckermayer]

Adds a UnixPath and WindowsPath struct for denoting the types of path Strings we expect to hold in our various RDP and TDP structs. Neither type implements any strong validation, since paths (nearly) always originate from the RDP server which we must assume is working correctly. The assumptions made about the types of WindowsPaths we'll receive are based on our experience with RDP so far, since the precise details are not specified in the spec documents.

Before going with this option, I looked into std::path::Path and the path_slash crate (which relies on std::path::Path). I was unable to find any standardized means for handling Windows style paths while running rust on Unix machines, so I opted for the approach taken here.

[espadolini]

it's not clear from the utf16string docs whether they can handle unpaired surrogates

utf16string::WStr has an infallible, lossless conversion to String, so the answer to that question is no, you'll get a utf16string::Utf16Error when trying to create a WStr.

How does the javascript side of things fare with non-unicode paths? If there's nothing sane we can do on that side either, we could just throw some IO error when attempting to write a file with a broken path in the shared directory.

[ibeckermayer]

How does the javascript side of things fare with non-unicode paths? If there's nothing sane we can do on that side either, we could just throw some IO error when attempting to write a file with a broken path in the shared directory.

Apparently JS doesn't fare well with UTF-16 generally. Right now, presuming a utf16string::Utf16Error is returned from from_unicode, a path with invalid UTF-16 will just end the session with an error.

I think that's good enough for now as long as we document it. I've created an issue to explore this in more detail later: #15126

[ibeckermayer]

Apparently JS doesn't fare well with UTF-16 generally.

Oops, I meant to link this Stack Overflow answer. Looking at it again, though, its from 2011, and some of the problem may be ameliorated by now. Nevertheless, I say its low priority and we continue as planned, and I will come back to that issue later on.

[ibeckermayer]

Waiting until #13630 is merged and then will merge this direct into master

[github-actions]

@ibeckermayer See the table below for backport results.

Branch	Result
branch/v10	Failed
branch/v9	Failed