jbang jdk default <version> fails on Windows

[jcrben]

Describe the bug
Follow-up to #1574 by @quintesse

This is when using "Git Bash" - and particularly the msys bash inside of it.

This is what I see:

Ben@t480-ben dotfiles [master]$ jbang jdk default 21
[jbang] Creation of symbolic link failed C:\Users\Ben\.jbang\currentjdk -> C:\Users\Ben\.jbang\cache\jdks\21
[jbang] Now try creating a hard link instead of symbolic.
[jbang] Creation of hard link failed C:\Users\Ben\.jbang\currentjdk -> C:\Users\Ben\.jbang\cache\jdks\21
[jbang] [ERROR] Failed to create link C:\Users\Ben\.jbang\currentjdk -> C:\Users\Ben\.jbang\cache\jdks\21
[jbang] Run with --verbose for more details

To Reproduce
I'm running bash on Windows 10. uname -a reports MSYS_NT-10.0-19045 t480-ben 3.4.7-25de8b84.x86_64 2023-08-28 21:32 UTC x86_64 Msys

I reproduced this in Powershell IIRC but my main way of working in Windows is inside cygwin / msys.

I execute via the Windows Terminal - I configure a profile like this after installing Git via winget install Git.Git. I'm using /Git/usr/bin/bash.exe which has the cygwin dll included, but not sure that matters.

            {
                "commandline": "%PROGRAMFILES%/Git/usr/bin/bash.exe -i -l",
                "guid": "{00000000-0000-0000-ba54-000000000002}",
                "icon": "%PROGRAMFILES%/Git/mingw64/share/git/git-for-windows.ico",
                "name": "Bash",
                "startingDirectory": "%USERPROFILE%"
            },

scoop install jbang
jbang jdk install 21
jbang jdk default 21

Expected behavior
jbang jdk default 21 should succeed

JBang version

$ jbang version --verbose
[jbang] [0:425] jbang version 0.116.0
Cache: C:\Users\Ben\.jbang\cache
Config: C:\Users\Ben\.jbang
Repository: C:\Users\Ben\.m2\repository
0.116.0

Additional context
I don't think requiring Developer Mode is good - many people developing in Windows are doing it for security reasons and it's hard convince a security department to enable Developer Mode.

As noted earlier in the linked issue, you can't hard link to directories. But there's another option - use junctions instead. fnm did that recently Schniz/fnm#519 - see also kubernetes-sigs/krew#843

An example of creating a junction from my initial dotfiles setup script: powershell.exe New-Item -ItemType Junction -Force -Path $(cygpath -m "$HOME/scoop/persist/vscode/data/user-data/User") -Target $(cygpath -m "$SCRIPT_DIR"/config/vscode/User)

[jcrben]

I dropped into a debugger to see what was happening - fyi it skipped the if condition here which triggers the warning message.

Also these are the jdks I have installed:

[quintesse]

Unfortunately I don't think there's an easy way to create junctions with Java, which is what we'd need.

Edit: btw, on Windows we shouldn't even try to create a Hard Link.
Edit2: Looking at the code I don't see how it even gets there, it should have given you the explanatory warning message...
Edit3: What JDK are you running by default? (typing java -version) and are you running a patched JBang? Because it shows unfamiliar output.

[jcrben]

Not sure about the Java version, will check later. When debugging it's perhaps the vscode embedded (21). Otherwise 17 or 21

As fat as edit3, I was running the latest commit on main last night after running 0.116 from scoop

Looking at the screenshot of my debugging session closely shows you why it got there - Files.isDirectory(src) is false.

As far creating a junction in Java, how about calling powershell? It's built into Windows

[jcrben]

@quintesse for the junction question - to avoid Developer Mode in a place where it isn't permitted - what are your thoughts on just calling powershell or cmd.exe as an external process on Windows? would like to be able to use this in a secured corporate environment

if not, maybe I'll just fork it privately inside the secure environment and maintain the forked version

[quintesse]

See https://github.com/orgs/jbangdev/discussions/1805