YHK - yet another hacker news clone

I don't know much about this. How does that enable vulnerabilities exactly?

i guess that for now only the default will change for new repositories. support for sha1 is not going to be dropped, so most existing repositories won't switch any time soon. if you want to switch then yes, it sounds like a force push might be needed, although it could also be that simply switching is not possible, but that instead you have to create a new repo and import the history from the old repo, forcing everyone to clone the new repo intentionally.

Couldn't you write something that checks every commit's content and message is byte equal to the old tree? One scan through the history to verify it should be relatively simple if not cheap. Should be built into git.

That's odd. Why not compute both sha1 and sha256 for all git objects for the foreseeable future?

Failing that, have a kind of git object that wraps another and says hey this is in sha1 don't mess with it

It's much, much worse than that.

Yes, you do need to do that. However, there is also much more work after that.

Git will not intermingle SHA-256 and SHA-1 enabled repositories, even in things like submodules, so anything used in that manner will need to keep both versions into the indefinite future. If you rely on a submodule that has not yet converted, you will have to convert it yourself and try to keep it up to date, or the forge will have to automatically keep a bidirectional mirror (if you have submodules in various forges, you'll have to wait for all of them to do it), etc.

This means that every SHA referenced anywhere on the internet, in commit messages, in issues, in code comments is now invalid and needs a mapping to find the rewritten one for forever.

It also means that every commit signature ever made is now invalid and will probably have to be stripped from the rewritten new 256 history because it's impossible to resign everything.

Companies like Google and GitHub are working on keeping two versions of each repository so that there can be long stages of ecosystem migrations, but no matter what, it's going to be a huge pain for millions of developers for years to come.

I don't think it's "just for the sake of it". I think they believe that the Rust code will be safer.

The comments gives a link to a recent talk about the motivation for using Rust in Git: https://github.com/bk2204/talk-rust-in-git/blob/dev/presenta...

I wouldn't agree with all of those reasons, but it's very definitely not "just for the sake of it." One of the better reasons so many people look to writing some things in Rust is that we now have pretty ample evidence than trying to write a binary file format parser in C is a cornucopia of CVEs that are just simply absent in Rust, and the excuse of "well, but a sufficiently smart programmer doesn't write bugs in C" doesn't cut it anymore.

Of the codebases i know that have adopted Rust, it has always been because some of their maintainers wanted to do so.

Maybe git's case is different though. Do you have more info about it? Are you a git maintainer who was coerced to use Rust, or do you know of such cases?

fwiw, the use of C is infinitely more "coerced" than the use of Rust.

on my Linux system, C takes ownership of a 'top-level' /usr/include directory, all the kernel APIs have their canonical definitions in C headers, a lot of system features like nsswitch require dynamically linked C libraries etc. etc.

Rust is just something that programs can choose to be written in and that doesn't inconvenience me in any way.

Is all use of Rust "coerced" and "forced on everyone", or is there a way to write things in it that makes sense?

By "proper" I assume you mean relational? Or ACID? Or you mean using existing database software? What is so improper about the way git stores data?

> Good, are there (m)any other plans to ditch the slow files and use proper database?

The filesystem is a proper database, just not a relational one.

Linus focused heavily on performance when he wrote git; he used the filesystem because, as the main Linux kernel maintainer, he knew that the Linux VFS and filesystems were fast enough for these use cases.

(It's the use cases that have changed; it was not expected back then to have more than a few hundred refs in a single repository.)

Yes, Patrick Steinhart (GitLab) has been working not only on reftables and pluggable backends for the references data, but also pluggable backends for object storage, so that you can use any database backend format (sqlite, s3, special large file storage options, etc) to store objects if you want (in addition to loose objects and packfiles).

This is work that Patrick and GitLab have been doing for years now and it's very impressive and nearly complete.

It's not just slowness, but what about case insensitive filesystems?

It is on the horizon: https://github.com/bk2204/talk-rust-in-git uses SHA256

TFA literally notes that one if the key sha256 devs is a github employee and in favor of the transition.

And sha256 is in private preview at GitHub: https://github.com/bk2204/talk-rust-in-git/blob/dev/presenta...

They don't seem to have any problems cramming in ever more AI garbage down our throats.

Priorities!

For reference, what would you say those bad defaults are? (I would like to know if I should consider changing my configuration)

Having switched to jj I totally agree. Change IDs are a huge UX win.

Yeah, "standardizing" change IDs would make it much easier to develop further tooling around it. In particular decentralized review is something that I'd be interested in.

For example, if GitHub is down, that would not be a blocker to access review comments or to do reviews. And maybe you could push your reviews to a GitLab mirror if you want a UI.

JJ and GitButler already create and inject this into the commit headers (using the same interoperable reverse-hex format), which is recognized by Gerrit and some forges like Tangled for incremental commit based review.

I doubt that core Git will adopt it anytime soon as it was not discussed at this years contributor summit (last week) and doesn't seem to be a hot topic on the ML.

What I would like to see is support for `git rebase` not dropping it, which is the current main issue. The `git replay` command, as well as commands based on the same sequencing code (`git history` for example) do not drop custom headers like this, so there is partial non-breakage, but several of the other history editing commands do drop custom headers.

How is this different from branches?

What could be simpler than "$ git stash" and "$ git stash pop" ?

Not sure what you are looking for. What's wrong with stash? What ceremony are you referring to? `git stash` - `git stash pop` is as simple as it gets.

Then you can also do `git diff > changes.diff`. Or simply `rsync -avPh repo/ repo.snap/`, if your repo isn't huge. Or consider putting your repo in a filesystem that can do CoW snapshots.

I always just create a branch

I will always mourn hg losing to git in the DVCS wars, however it was generally considered bad practice to rely on the integer commit references.

Length extension attacks are not an issue for git, because every object has two fields in its header, which is prepended to the object before hashing: the object type and the length in bytes.

But their post-quantum-algorithm also uses sha256. Afaik only asymetric crypto is in danger from quantum computers.

At this point, it does not appear that (reasonably strong and modern) symmetric cryptography (ciphers, hash functions, etc.) is realistically threatened by quantum computing: https://words.filippo.io/128-bits/

As far as I understand, quantum computing can cut it in half, to 128 effective bits. Still way too large to brute force from there.