stage0 VS ccan

Somewhat tangential, but I'm curious how big the bootstrap seed for Nix is. That is, if you wanted to build the entire world, what's a minimum set of binaries you'd need?

Guix has put quite a bit of work into this, AFAIU, and it's getting close to being bootstrappable all the way from stage0 [0]. Curious if some group is also working on similar things for Nix.

[0]:https://github.com/oriansj/stage0

https://www.bootstrappable.org/ has some good info. Reading the source of https://github.com/oriansj/stage0 is also very enlightening. It's set its goal to be understandable by 70% of programmers.

Even if they aren't, people absolutely should be able to bootstrap new platforms from scratch. It's important to have confidence in our tools, in our ability to rebuild from scratch, and to be safe against the "trusting trust" attack among other things.

Lately I've been catching up on the state of the art in bootstrapping. Check out the live-bootstrap project. stage0 starts with a seed "compiler" of a couple hundred bytes that basically turns hex codes into bytes while stripping comments. A series of such text files per architecture work their way up to a full macro assembler, which is then used to write a mostly architecture-independent minimal C compiler, which then builds a larger compiler written in this subset of C. This then bootstraps a Scheme in which a full C compiler (mescc) is written, which then builds TinyCC, which then builds GCC 4, which works its way up to modern GCC for C++... It's a fascinating read:

https://github.com/oriansj/stage0

https://github.com/fosslinux/live-bootstrap/blob/master/part...

Even if no one is "using" this it should still be a primary motivator for keeping C simple.

One countermeasure not mentioned here is bootstrapping a compiler with a program small enough to be manually verified. The stage0 project is under 1KB (small enough that the binary can be, and has been, manually checked against the hand written assembly), and GNU Guix (a system for reproducible, isolated builds) is currently working on moving it's bootstrap speed to stage0. That means that, fairly soon, there will be a large set of software that doesn't have a connection to an original C compiler.

Hilarious!

But I remember the first time I saw such a program which never freed anything: jitterbug, the simple bug tracker which ran as a CGI script.

It indeed allows a very simple style!

Meanwhile, use ccan/tal (https://github.com/rustyrussell/ccan/blob/master/ccan/tal/_i...) and be happy :)

There's CCAN, maintained by kernel hacker Rusty Russell: http://ccodearchive.net/

Please note that the above link has been claimed by squatters and isn’t the right link for CCAN anymore! The maintainer suggests [1] just using the GitHub repo [2] instead.

[1] https://lists.ozlabs.org/pipermail/ccan/2022-September/00141...

[2] https://github.com/rustyrussell/ccan/

This is a great learning exercise but not very useful because using void* creates practical problems that the compiler cant help you with. IMHO, for a nice vector in C look at https://github.com/rustyrussell/ccan/blob/master/ccan/darray/darray.h

For more advanced intrusive lists in C, I've found that ccan's tlist2 (https://github.com/rustyrussell/ccan/blob/master/ccan/tlist2...) provides a decent model here.

Compared to the linux kernel's intrusive lists, it also tracks the offset of the list_node within the structure contained by the list, which eliminates another class of problems. It does still have the "using the iterator after the for loop is over" issue discussed in this article, but it also already tracks the types as Linus proposed doing in the article to resolve the issue.

ccan library https://github.com/rustyrussell/ccan I think it is used also in the linux kernel(?)

ccan (analagous to cpan, but for C rather than Perl.)

You could use a discriminated union in your list node. You could use a void pointer in your list node, allocate space as needed and memcpy the date into this space, or don't allocate and store pointers to the original data. You could use an intrusive list, like this.

The fallacy in the article is that anyone should code these functions. There's plenty of public domain libraries that do this correctly.

https://github.com/rustyrussell/ccan/blob/master/ccan/endian...