Re: [PATCH] fat: Optimized FAT bad char check

[zhoumin]

Hi Hirofumi

> Why do you need this change?

I encountered an issue while working on our own bootloader. The problem
occurs when short file names start with `0`. In this case, our bootloader
mistakenly interprets it as the end of the directory entry, causing all
subsequent files in the directory to become invisible.

While comparing our bootloader with the kernel, I found this bad char check
function. Treating the `0x05` deleted flag as a bad character may
potentially disrupt the parsing chain for subsequent files.

In my opinion, adding this judgment aligns with the spec and should not
introduce any negative side effects, even though I haven’t encountered this
situation in practice.

This is the rationale behind this commit, and I would appreciate hearing
your feedback on it.

Thanks,

zhoumin