Add wslbridge-backend path from command

[Biswa96]

I've added the -p option to add wslbridge-backend path. With that option, the backend find can be put in anywhere.

[rprichard]

You already closed #23?

I don't think I understand why this option is needed. You've run into a situation where the two files can't be in the same directory, I guess?

I'd prefer something more descriptive than -p. Maybe --backend <PATH>.

It looks like your -p option accepts a Windows-style path rather than a WSL-style path. The Windows-to-WSL path conversion has had some issues, so if there's an option to specify the backend path, maybe it ought to be a WSL-style path to sidestep those issues.

[rprichard]

Even with your change, wslbridge will abort if it can't find the backend executable in the expected location. It's still calling findBackendProgram() even when -p is passed.

Are you trying to package multiple backends to accommodate different distributions, maybe? I've been thinking lately that maybe the backend should be statically linked so it works with non-glibc distributions...

[Biswa96]

May you please accept these changes? This helps in wsltty.appx project.

[rprichard]

Why does the wsltty.appx project need the flag?

[Biswa96]

Because in UWP environment the backend cannot be executed. So it need to copied in LocalAppData. And with that option I can execute backend from that path.

Also with this option users have no restriction to put both files in same directory.

[rprichard]

Ok, that makes sense. I'll try to look at the change soon. Maybe I'll just add a --backend option.

[rprichard]

Not necessary. I already have this behavior written. I'll push it within a day:

  --backend BACKEND
                Overrides the default path to wslbridge-backend. BACKEND is a
                Cygwin-style path (not a WSL path).

It takes a path to the file rather than a path to a directory containing the file. I assume that's not an issue.

[rprichard]

It's just the normal Cygwin rules. /cygdrive/c/foo is OK, as is C:\foo. /foo and \foo, however, will refer to C:\path\to\cygwin\foo, whereas the ordinary Windows rules would interpret it as drive-relative, e.g. C:\foo.

[Biswa96]

Should I close this PR?

[rprichard]

Yes, please close it.