Update open flags from u32 to i32 about fuser

[cberner]

Can you provide a reference to the C & Rust interfaces you're referring to for i32? I looked up the definition in the kernel source code, which I believe is definitive, and it's declared uint32_t: https://elixir.bootlin.com/linux/v5.10-rc1/source/include/uapi/linux/fuse.h#L593

[siscia]

Aw, that is from where the u32 comes from maybe.

The standard open call use standard int: https://man7.org/linux/man-pages/man2/open.2.html
Similarly Rust: https://doc.rust-lang.org/std/os/unix/fs/trait.OpenOptionsExt.html#tymethod.custom_flags
Also fuse expose them as int: http://libfuse.github.io/doxygen/structfuse__file__info.html

I mean, it would be just more convenient for my use case, but it is not that big of an issue, not at all.

[cberner]

Ah yes, I see. I'm going to leave it alone for now, but I have an issue open to review all of the usage of signed vs unsigned, as I know there are other inconsistencies which matter: #65

[siscia]

No problem, I just found this (maybe) inconsistency and I waited to point it out!

I close this!

[cberner]

Re-opening this. I looked into it more and libfuse treats the value as signed, even though its specified as unsigned in the kernel 🤔

https://github.com/libfuse/libfuse/blob/ba3b225a126ebb3c6d4fe27c9f7c73aa4167001e/include/fuse_common.h#L46

I'll address this as part of #65

[siscia]

Thanks for listening to my feedback :)