Installing to folder without proper write permissions gives non-sensical logger error

[AnToniceQ]

The NeoForge jar installer throws a NullPointerException when a inaccessible folder is inputted.

In this specific example, I tried to install a NeoForge server to /home/jjjjjjj/NeoForgeServer, where jjjjjjj is not a valid user. The issue has been tested only in this specific use case and there may exist more ways to obtain this exception.

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Found on system: 22.04.1-Ubuntu
Using installer: neoforge-21.0.146

[Matyrobbrt]

@AnToniceQ please upload the installer log, which can be found in the directory the installer is in, with the same file name as the installer, but with .log at the end.

[AnToniceQ]

@AnToniceQ please upload the installer log, which can be found in the directory the installer is in, with the same file name as the installer, but with .log at the end.

Dang! Should have done that in the first place. Here is the log that I recreated today:

neoforge-21.0.146-installer.jar.log

EDIT: Now that I think of it, I probably opened this issue in a wrong repo. Should I move this issue to https://github.com/neoforged/LegacyInstaller/ ?

[sciwhiz12]

Confirmed.

The root cause is not with the fact that the installer is trying to install to a non-existent directory -- it is able to do so by my testing, for example with a directory of /home/sciwhiz12/test/server/nonexist (which only the /home/sciwhiz12 part actually exists).

Rather, the root cause is that the installer is told to install to a folder which the current user has no permissions to write to. By default, /home is only writable to the root user, with each home directory underneath having permissions assigned to their respective users. In this case, trying to create a folder underneath /home fails without the proper permissions -- indeed, running the installer as root (via sudo) confirms that the same steps in the issue function normally as expected.

Therefore, the actual issue here is that the installer is giving a non-sensical error of the logger being null rather than a more well-meaning error that the program has no permissions to the target directory. I'll be moving the issue to https://github.com/neoforged/LegacyInstaller for that.

(Additionally, the installer code for running headless fails to log the exception which causes the installer to ultimately fail, which made reproducing this issue require a graphical environment.)