lone VS liblinux

I made something somewhat close to that: a freestanding lisp. It targets the Linux kernel directly. No libc.

https://github.com/lone-lang/lone

> register scanning isn't portable

Certainly not but it wasn't particularly hard to implement either. I just wrote some inline assembly for every architecture. Here's my programming language's x86_64 and aarch64 implementations:

https://github.com/lone-lang/lone/blob/master/architecture/x...

https://github.com/lone-lang/lone/blob/master/architecture/a...

Not too long ago, a project of mine was shared here on HN.

https://news.ycombinator.com/item?id=38126052

In that thread I wrote:

> I have this vision in my mind: embedding lone modules into sections of the lone ELF and shipping it out. Zero dependencies, self-contained.

I've been working on that since that day. Proud to say I've gotten it to work and thought I'd make it the subject of my first Show HN. Some free software projects gained features along the way too.

The link is to an article with a proper demonstration, technical details and what happened in the past few weeks.

The complete repository itself can be found here:

https://github.com/lone-lang/lone

I've completely reorganized it since the last thread. Would be very happy if you guys tried it out.

To test my programming language. It's a freestanding lisp interpreter that doesn't link to libc. I wrote the code that handles the environment variables and in order to test it I needed full control over the program's inputs including its environment. The env utility provides this control by emptying the environment and setting only the variables I specify, solving 90% of the problem. Only thing I still can't control is argv[0]. With this new feature upstreamed, my test suite will be complete.

Here's the code if you'd like to take a look:

https://github.com/lone-lang/lone#testing

https://github.com/lone-lang/lone/blob/master/scripts/test.b...

> only to be confronted with the notorious 'incompatible glibc version error'. It's super annoying.

I started making my own freestanding Linux Lisp because of this exact issue. It's nowhere near as performant as something like SBCL but it's small and once compiled has no dependencies and will literally run on any Linux.

https://github.com/lone-lang/lone

I'm taking a break from this project but I plan to add a feature where I can put a Lisp script into the ELF itself so I can just copy it with the scripts included.

The kernel just puts the data contiguously on the stack. Obtaining pointers to them can seem somewhat magical if you're writing a nolibc program but I wouldn't call it horrible.

I implemented it for my programming language with some rather simple assembly code:

https://github.com/lone-lang/lone/blob/master/arch/x86_64.c#...

https://github.com/lone-lang/lone/blob/master/arch/aarch64.c...

> libc isn't really getting in the way here.

For the standard set of system calls, the libc is pretty great. For Linux-specific features, it could take years for glibc to gain support. Perhaps it's gotten better since then, perhaps it still takes years. I don't know.

Years ago I read about the tale of the getrandom system call and the quest to get glibc to support it:

https://lwn.net/Articles/711013/

A kernel hacker wrote in an email:

> maybe the kernel developers should support a libinux.a library that would allow us to bypass glibc when they are being non-helpful

That made a lot of sense to me. I took that concept and kind of ran with it. Started a liblinux project, essentially a libc with nothing but the thinnest possible system call wrappers. Researched quite a bit about glibc's attitude towards Linux to justify it:

https://github.com/matheusmoreira/liblinux#why

Eventually I discovered Linux was already doing the same thing with their own nolibc.h file which they were already using in their own tools. It was a single file back then, by now it's become a sprawling directory full of code:

https://github.com/torvalds/linux/tree/master/tools/include/...

Even asked Greg Kroah-Hartman on reddit about it once:

https://old.reddit.com/r/linux/comments/fx5e4v/im_greg_kroah...

Since the kernel was developing their own awesome headers, I decided to drop liblinux and start lone instead. :)

It gives you access to 100% of Linux's system calls. It eliminates a lot of global state. It gets rid of a lot of legacy libc crap.

Years ago I wrote a fairly referenced rationale in my liblinux project:

https://github.com/matheusmoreira/liblinux/blob/master/READM...

> Now, do I think it would make total sense for syscall wrappers and NSS to be split into their own libs (or dbus interfaces maybe) with stable ABIs to enable other libc's, absolutely!

I worked on this a few years ago: liblinux.

https://github.com/matheusmoreira/liblinux

I'm not developing it anymore though because I found out the Linux kernel itself has a superior nolibc library:

https://github.com/torvalds/linux/tree/master/tools/include/...

It used to be a single header but it looks like they've recently organized it into a proper project!

I wonder if it will become some kind of official kernel library at some point. I asked Greg Kroah-Hartman about this and he mentioned there was once a klibc:

https://old.reddit.com/r/linux/comments/fx5e4v/im_greg_kroah...

> This is something the BSD's got absolutely right.

BSDs, every other operating system really, force us to use the bundled C libraries and the C ABI. I think Linux's approach is better. It has a language-agnostic system call binary interface: it's just a simple calling convention and the system call instruction.

The right place for system call support is the compiler. We should have system_call keywords that cause it to emit code in the aforementioned calling convention. With this single keyword, it's possible to do program literally anything on Linux. Wrappers for every specific system call should be part of every language's standard library with language-specific types and semantics.

I'm not using this stuff professionally, it's just my own home lab's virtual machines with little services implemented as freestanding C programs. Not doing anything fancy right now, much of it was just to see if I could do it.

I've seen other people commenting here on HN saying they're using the same approach so it's defenitely not my invention.

I published some of my work in the form of a liblinux that I use to make system calls:

https://github.com/matheusmoreira/liblinux

I'm not developing it anymore though because I found out the kernel itself has a nolibc library:

https://github.com/torvalds/linux/tree/master/tools/include/...

It used to be a single header but it looks like they've organized it into a proper project.

That's awesome. I didn't know about rwildcard until now. Is it part of GMSL? I searched for rwildcard on gmsl.sourceforge.io but didn't find it.

I think my function is needlessly complicated compared to rwildcard. Here's my code:

https://github.com/matheusmoreira/liblinux/blob/modular-buil...

https://github.com/matheusmoreira/liblinux/blob/modular-buil...

The file? and directory? functions were inspired by GMSL.

I wrote a general recursion function. It takes a function to apply to lists and a function to compute whether an element is a base case.

The recursive file system traversal function applies a directory globbing function to the list of paths and has file? as base case.

The find function filters out any items not matching a given predicate function. It was my intention to provide predicates like C_file? and header_file? but I stopped developing that project before that happened.

I think rwildcard is probably simpler and more efficient!