Hi, I am one of the maintainers of GNU Coreutils. Thanks for the article, it covers some interesting topics. In the little Rust that I have used, I have felt that it is far too easy to write TOCTOU races using std::fs. I hope the standard library gets an API similar to openat eventually.
I just want to mention that I disagree with the section titled "Rule: Resolve Paths Before Comparing Them". Generally, it is better to make calls to fstat and compare the st_dev and st_ino. However, that was mentioned in the article. A side effect that seems less often considered is the performance impact. Here is an example in practice:
$ mkdir -p $(yes a/ | head -n $((32 * 1024)) | tr -d '\n')
$ while cd $(yes a/ | head -n 1024 | tr -d '\n'); do :; done 2>/dev/null
$ echo a > file
$ time cp file copy
real 0m0.010s
user 0m0.002s
sys 0m0.003s
$ time uu_cp file copy
real 0m12.857s
user 0m0.064s
sys 0m12.702s
I know people are very unlikely to do something like that in real life. However, GNU software tends to work very hard to avoid arbitrary limits [1].
Also, the larger point still stands, but the article says "The Rust rewrite has shipped zero of these [memory saftey bugs], over a comparable window of activity." However, this is not true [2]. :)
No need to apologize at all. Doing it in one cd invocation would fail since the file name is longer than PATH_MAX. In that case passing it to a system call would fail with errno set to ENAMETOOLONG.
You could probably make the loop more efficient, but it works good enough. Also, some shells don't allow you to enter directories that deep entirely. It doesn't work on mksh, for example.
> What’s notable is that all of these bugs landed in a production Rust codebase, written by people who knew what they were doing
They knew how to write Rust, but clearly weren't sufficiently experienced with Unix APIs, semantics, and pitfalls. Most of those mistakes are exceedingly amateur from the perspective of long-time GNU coreutils (or BSD or Solaris base) developers, issues that were identified and largely hashed out decades ago, notwithstanding the continued long tail of fixes--mostly just a trickle these days--to the old codebases.
More than that: it seems that Rust stdlib nudges the developer towards using neat APIs at an incorrect level of abstraction, like path-based instead of handle-based file operations. I hope I'm wrong.
Seems pretty impressive they rewrote the coreutils in a new language, with so little Unix experience, and managed to do such a good job with very little bugs or vulns. I would have expected an order of magnitude more at least.
Shows how good Rust is, that even inexperienced Unix devs can write stuff like this and make almost no mistakes.
Someone once coined a related term, "disassembler rage". It's the idea that every mistake looks amateur when examined closely enough. Comes from people sitting in a disassembler and raging the high level programmers who had the gall to e.g. use conditionals instead of a switch statement inside a function call a hundred frames deep.
We're looking solely at the few things they got wrong, and not the thousands of correct lines around them.
When I read the article I came away with the impression that shipping bugs this severe in a rewrite of utils used by hundreds of millions of people daily (hourly?) isn’t ok. I don’t think brushing the bad parts off with “most of the code was really good!” is a fair way to look at this.
Cloudflare crashed a chunk of the internet with a rust app a month or so ago, deploying a bad config file iirc.
Rust isn’t a panacea, it’s a programming language. It’s ok that it’s flawed, all languages are.
I know nobody's perfect and I'm not asking for perfection, but these bugs are pretty alarming? It seems like these supposed coreutils replacements are being written by people who don't know anything about Unix, and also didn't even bother looking at the GNU tools they are trying to replace. Or at least didn't have any curiosity about why the GNU tools work the way they do. Otherwise they might've wondered about why things operate on bytes and file descriptors instead of strings and paths.
I hate to armchair general, but I clicked on this article expecting subtle race conditions or tricky ambiguous corners of the POSIX standard, and instead found that it seems to be amateur hour in uutils.
> It seems like these supposed coreutils replacements are being written by people who don't know anything about Unix, and also didn't even bother looking at the GNU tools they were supposed to be replacing.
They're a group of people who want to replace pro-user software (GPL) with pro-business software (MIT).
Is anyone keeping score on the number of bugs Rust introduces when naïve dipshits rewrite perfectly-working software in Rust, introducing logic bugs in the process?
I just want to mention that I disagree with the section titled "Rule: Resolve Paths Before Comparing Them". Generally, it is better to make calls to fstat and compare the st_dev and st_ino. However, that was mentioned in the article. A side effect that seems less often considered is the performance impact. Here is an example in practice:
I know people are very unlikely to do something like that in real life. However, GNU software tends to work very hard to avoid arbitrary limits [1].Also, the larger point still stands, but the article says "The Rust rewrite has shipped zero of these [memory saftey bugs], over a comparable window of activity." However, this is not true [2]. :)
[1] https://www.gnu.org/prep/standards/standards.html#Semantics [2] https://github.com/advisories/GHSA-w9vv-q986-vj7x
You could probably make the loop more efficient, but it works good enough. Also, some shells don't allow you to enter directories that deep entirely. It doesn't work on mksh, for example.
They knew how to write Rust, but clearly weren't sufficiently experienced with Unix APIs, semantics, and pitfalls. Most of those mistakes are exceedingly amateur from the perspective of long-time GNU coreutils (or BSD or Solaris base) developers, issues that were identified and largely hashed out decades ago, notwithstanding the continued long tail of fixes--mostly just a trickle these days--to the old codebases.
Shows how good Rust is, that even inexperienced Unix devs can write stuff like this and make almost no mistakes.
We're looking solely at the few things they got wrong, and not the thousands of correct lines around them.
Cloudflare crashed a chunk of the internet with a rust app a month or so ago, deploying a bad config file iirc.
Rust isn’t a panacea, it’s a programming language. It’s ok that it’s flawed, all languages are.
I hate to armchair general, but I clicked on this article expecting subtle race conditions or tricky ambiguous corners of the POSIX standard, and instead found that it seems to be amateur hour in uutils.
They're a group of people who want to replace pro-user software (GPL) with pro-business software (MIT).
I don't really want them to achieve their goal.