spicychickensauce
Get proper file creation (birth) time on Linux
File.stat gives me a pretty useless value for ctime. As documented it is “the last time the file or the inode was changed“.
Using stat via bash gives me a correct creation time via the Birth field.
I understand why that’s the case, as Elixir just calls out to :file.read_file_info and the birth field is a somewhat recent thing in Linux and I could not find a way to read it yet from Erlang.
Does anyone know of a way to get that field without shelling out to bash? Is there maybe a package that has implemented a NIF for that?
Or do I need to write my own NIF?
If so, Rust seems to get this one right: Metadata in std::fs - Rust
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spicychickensauce
Yeah, I wouldn’t call 2017 new, but I guess new enough that it’s not in all standard libraries yet.
Python also doesn’t have it, but ruby, node, rust and zig do.
Anyway, I went ahead with the plan and created a small rustler NIF:
https://github.com/spicychickensauce/file_statx
Now I just need to figure out how to publish this to hex such that a user doesn’t need to compile the thing?
Looks like rustler_precompiled is the way to go.
joram
It does not, it calls fstat. It looks like on Windows the ctime is the same as Rust’s created.
garrison
I was quite surprised Python didn’t have it; they usually have everything. Apparently there has been an open issue/PR for several years now. Strangely it seems to have become active again recently.
A nif seems like the way to go but maybe also consider opening an Erlang/OTP issue as this seems like something that should be updated to me. At least before 2038 
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