FIX #71: old symlink should be removed on Windows

[guidoschmidt]

Seems to be a longer journey 😅 ...

just tested version 0.6.2 and unfortunately the old symlink to .zvm/bin is not removed, the change to !errors.Is(err, os.ErrNotExist) seems to fix it. found os.Lstat which checks symbolic links.

Maybe there's a more appropriate way to do this? Looks like there's a newer fs package that can be used for these kind of filesystem checks.

[tristanisham]

Why back to os.ErrExist instead of fs.ErrExist?

[tristanisham]

We could just check to see if the error is nil. If true the file exists.

[guidoschmidt]

I think you can't mix up the os with the fs stuff, as they are different packages? But it's only my educated guess. Honestly it feels like there's way too many ways to do this in golang 😓 the best way maybe is to use os.Lstat and just see if the link is nil? 🤔

[tristanisham]

Thanks for making another PR. These system specific bugs are always a pain but we'll fix this one. I'll be on my Windows developer environment tonight so I can work on this bug directly.

[guidoschmidt]

Oh nice, hope it doesn't give you too much of a headache

[tristanisham]

New bug unlocked. Totally breaks the progress bar when running in command prompt.

[tristanisham]

@guidoschmidt could you please test the changes I've pushed to the PR. For I modified the Symlink function again because for users who are already admins or have enabled symlinks for regular users it was uneccessary and degraded the experience. I also tweaked the Lstat to use the err == nil method since just parsing the errors wasn't working for us.

[tristanisham]

Added a test for our symlink code. It passes so that bit in setBin should be good.

func TestSymlinkExists(t *testing.T) {
	if err := os.Symlink("use_test.go", "symlink.test"); err != nil {
		t.Error(err)
	}

	stat, err := os.Lstat("symlink.test");
	if err != nil {
		t.Errorf("%q: %s", err, stat.Name())
	}

	defer os.Remove("symlink.test")
}