Comment by tjchear
Comment by tjchear 2 days ago
What’s stopping other Unix-like systems from adopting the everything is a file philosophy?
Comment by tjchear 2 days ago
What’s stopping other Unix-like systems from adopting the everything is a file philosophy?
> Probably that not everything can be cleanly abstracted as a file.
I would say almost nothing can be cleanly abstracted as a file. That’s why we got ioctl (https://en.wikipedia.org/wiki/Ioctl), which is a bad API (calls mean “do something with this file descriptor” with only conventions introducing some consistency)
If everything can be represented as a Foo or as a Bar, then this actually clears up the discussion, allowing the relative merits of each representation to be discussed. If something is a universal paradigm, all the better to compare it to alternatives, because one will likely be settled on (and then mottled with hacks over time; organic abstraction sprawl FTW).
There's also /dev/tcp in Linux
exec 5<>/dev/tcp/www.google.com/80
echo -e "GET / HTTP/1.1\r\nhost: www.google.com\r\nConnection: close\r\n\r\n" >&5
cat <&5The fact that everything is not a file. No OS actually implements that idea including Plan9. For example, directories are not files. Plan9 re-uses a few of the APIs for them, but you can't use write() on a directory, you can only read them.
Pretending everything is a file was never a good idea and is based on an untrue understanding of computing. The everything-is-an-object phase the industry went through was much closer to reality.
Consider how you represent a GUI window as a file. A file is just a flat byte array at heart, so:
1. What's the data format inside the file? Is it a raw bitmap? Series of rendering instructions? How do you communicate that to the window server, or vice-versa? What about ancillary data like window border styles?
2. Is the file a real file on a real filesystem, or is it an entry in a virtual file system? If the latter then you often lose a lot of the basic features that makes "everything is a file" attractive, like the ability to move files around or arrange them in a user controlled directory hierarchy. VFS like procfs are pretty limited. You can't even add your own entries like adding symlinks to procfs directories.
3. How do you receive callbacks about your window? At this point you start to conclude that you can't use one file to represent a useful object like a window, you'd need at least a data and a control file where the latter is some sort of socket speaking some sort of RPC protocol. But now you have an atomicity problem.
4. What exactly is the benefit again? You won't be able to use the shell to do much with these window files.
And so on. For this reason Plan9's GUI API looked similar to that of any other OS: a C library that wrapped the underlying file "protocol". Developers didn't interact with the system using the file metaphor, because it didn't deliver value.
All the post-UNIX operating system designs ignored this idea because it was just a bad one. Microsoft invested heavily in COM and NeXT invested in the idea of typed, IDL-defined Mach ports.
Sure, why would they? COM was rendered irrelevant by the move to the web. Microsoft lost out on the app serving side, and when they dropped the ball on ActiveX by not having proper UI design or sandboxing they lost out on the client too. Probably the primary use case outside of legacy OPC is IT departments writing PowerShell scripts or Office plugins (though those are JS based now too).
COM has been legacy tech for decades now. Even Microsoft's own security teams publish blog posts enthusiastically explaining how they found this strange ancient tech from some Windows archaeological dig site, lol. Maybe one day I'll be able to mint money by doing maintenance consulting for some old DCOM based systems, the sort of thing where knowing what an OXID resolver is can help and AI can't do it well because there's not enough example code on GitHub.
Because since Windows Vista all new APIs are COM based, Win32 C API is basically stuck on Windows XP view of the universe, with minor exceptions here and there.
Anyone that has to deal with Windows programming quickly discovers that COM is not the legacy people talk about on the Internet.
Probably the fact that it's a pretty terrible idea. It means you take a normal properly typed API and smush it down into some poorly specified text format that you now have to write probably-broken parsers for. I often find bugs in programs that interact with `/proc` on Linux because they don't expect some output (e.g. spaces in paths, or optional entries).
The only reasons people think it's a good idea in the first place is a) every programming language can read files so it sort of gives you an API that works with any language (but a really bad one), and b) it's easy to poke around in from the command line.
Essentially it's a hacky cop-out for a proper language-neutral API system. In fairness it's not like Linux actually came up with a better alternative. I think the closest is probably DBus which isn't exactly the same.
Maybe something like FIDL is a proper solution but I have only read a little about it: https://fuchsia.dev/fuchsia-src/get-started/learn/fidl/fidl
Probably that not everything can be cleanly abstracted as a file.
One might want to, e. G., have fine control over a how a network connection is handled. You can abstract that as a file but it becomes increasingly complicated and can make API design painful.