Fix: Win10 symlink require privilege

[vunhatchuong]

Problem

1. Symlink on Windows 10 Powershell required privilege, so we need to use cmd to create a symlink with mklink. See issue Bug: Windows 10 Symlink required privilege #174

2. filepath.EvalSymlinks doesn't work correctly on Windows. A fix is currently being proposed: os,path/filepath: make os.Readlink and filepath.EvalSymlinks on Windows (mostly) only evaluate symlinks golang/go#63703

[kevincobain2000]

Thanks
Please wait for @juev's review

[juev]

We have a file, gobrew_windows.go, which houses the code used only in windows.

It seems that you need to create a separate function like evalSymlinks, for which gobrew_unix.go will have a normal implementation, and in gobrew_windows.go will be specific to windows.

And the code will be easier to read.

[juev]

I need a little more time to check what is offered in
golang/go#63703

I don't quite understand why a call is made specifically ps in this case

[juev]

It is also necessary to remove the checks on the operating system and add a function like symlink, which we will implement differently depending on the type of operating system in our file.

Again, because I don't have windows at hand, I need a little more time.

And the question is, why in one case do you call ps, and here you call cmd? Why such a spread?

[vunhatchuong]

To my knowledge, there's no easy way to eval a symlink with cmd, and I use cmd because it doesn't require privilege to create symlinks.

I'll remove the GOOs check, I've never coded cross-platform code before.

[vunhatchuong]

[juev]

@kevincobain2000 has become much better now, but I still don't like the idea of calling third-party programs from the code.

In addition, Windows has a lot of shell, that is, many launch options and each may have its own problems.

In my opinion, if we have a problem with creating a simlink, we can simply copy the directory from a certain version to the current directory.

For example, when it is necessary to switch the version:

1. Remove the directory with the current version from versions
2. Move or copy the version from current to versions
3. Clear the current directory
4. Copy the directory from versions/{version} to current

If it is not available, we download from the Internet accordingly.

Here you still need to think about how to solve the problem with copying the bin directory. But it seems that it is much easier than starting individual processes.

What do you think?

[kevincobain2000]

Hi @juev
Thanks for the review.
I also do not prefer shell invoked as separate exec.

Your suggestion on version switch is good, it can be done natively - all in GO.
But again, it is windows, I didn't intend to support powershell in the first place, people could just wsl instead.

Having said all that, if calling a separate powershell command, temporarily solves this issue, then it is cool.
The same implementation will never get merged if it was a unix based os, and would code in GO.
Also I have a windows machine now, but hate the idea of powershell in the first place. But people want it so be it as dirty as it can get.

[kevincobain2000]

If you are ok then I am also ok for this merge. It's not like it is changing anything for unix based os.

[kevincobain2000]

Let me know if you are ok with merge @juev

[juev]

Yes, I disagree with the implementation. It could have been implemented much more correctly.
It's not clear if everything works in sl, why use cmd or ps?

But since we hardly change the usual functionality, so be it.

[kevincobain2000]

Thanks @juev will merge it after dinner