On Fri, Apr 25, 2025 at 09:35:27AM -0700, Linus Torvalds wrote: > Now, if filesystem people were to see the light, and have a proper and > well-designed case insensitivity, that might change. But I've never > seen even a *whiff* of that. I have only seen bad code that > understands neither how UTF-8 works, nor how unicode works (or rather: > how unicode does *not* work - code that uses the unicode comparison > functions without a deeper understanding of what the implications > are). > > Your comments blaming unicode is only another sign of that. > > Because no, the problem with bad case folding isn't in unicode. > > It's in filesystem people who didn't understand - and still don't, > after decades - that you MUST NOT just blindly follow some external > case folding table that you don't understand and that can change over > time. I think this is something that NTFS actually got right. Each filesystem carries with it a 128KiB table that maps each codepoint to its case-insensitive equivalent. So there's no ambiguity about "which version of the unicode standard are we using", "Does the user care about Turkish language rules?", "Is Aachen a German or Danish word?". The sysadmin specified all that when they created the filesystem, and it doesn't matter what the Unicode standard changes in the future; if you need to change how the filesystem sorts things, you can update the table. It's not the perfect solution, but it might be the least-bad one I've seen.
