[Dwedit]

Windows allows unmatched surrogate pairs in filenames, invalid for UTF-16. Likewise, Linux allows invalid UTF-8 byte sequences in filenames.

Because invalid UTF-16 strings could show up in places within Windows, someone made a UTF-8 variant called "WTF-8", which allows unmatched surrogate pairs to survive a round trip.

[bombela]

Indeed, Linux allows anything but "/" and "\0" in filenames. Those days its reasonable to refuse utf8 filenames. But one must always validate first!

[mananaysiempre]

> Indeed, Linux allows anything but "/" and "\0" in filenames.

For what it’s worth, NT allows any 16-bit quantity but L'\\' (0x005C) in filenames (even nulls); it’s the Win32 layer on top of it that imposes all the other weird restrictions and mappings.

[Dwedit]

The NT Object Namespace itself indeed has no restrictions on filename characters except for "\", but once you reach a real filesystem like NTFS or FAT, the forbidden characters continue to be blocked.

https://projectzero.google/2016/02/the-definitive-guide-on-w...