Use SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE for symlinking on Windows

[YellPika]

Windows 10 added support for creating symbolic links without administrator privileges when the system is in developer mode, but CreateSymbolicLink will still fail unless SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE is passed as a flag.

directory doesn't seem to expose this functionality. Does it make sense to make it the default?

[Rufflewind]

Do you know what happens if SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE is passed to a Windows system that doesn't support it? It would be nice to have it by default, but I'm concerned about compatibility with older versions of Windows.

[YellPika]

This thread claims that passing the flag on earlier builds of will give ERROR_INVALID_PARAMETER. This could be solved by checking at runtime for Windows 10 build >= 14972.

[Rufflewind]

I'll just check for the error code instead of the build number (which might be difficult on older versions of Windows).

[YellPika]

Thanks!

Could you elaborate on why there would be difficulties on earlier versions of Windows? If we're on anything before Windows 10 then we shouldn't even need to check the build number since this feature doesn't exist.

(Also, your last commit doesn't work for me. Did you mean to pass flags .|. unpriv to c_CreateSymbolicLink?)

[Rufflewind]

Did you mean to pass flags .|. unpriv to c_CreateSymbolicLink?

Yes, my bad. Please try 76e4c21 when you get the chance.

If we're on anything before Windows 10 then we shouldn't even need to check the build number since this feature doesn't exist.

It's just a bit more involved to implement (and might involve more #ifs).

[YellPika]

For some reason I can't pull that changeset. If I click on the link, I can browse the changes, but it's otherwise inaccessible.

In any case, I've applied the patch manually and can confirm that it works.

[Rufflewind]

For some reason I can't pull that changeset.

It was still in my fork at the time: https://github.com/Rufflewind/directory

In any case, I've applied the patch manually and can confirm that it works.

Yay!