The coreutils Rust rewrite story is pretty funny.
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@darkuncle @lcamtuf
During my tenure at Google I was astonished at how many engineers would clearly admit they didn't understand why something was the way it was, so they rewrote it. This *repeatedly* bit them in the ass.@ChuckMcManis @lcamtuf sometimes that's the only way to learn, but it's also often the most effective way to learn
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
Joel spolsky had a great blogpost about exactly this didn't he
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Joel spolsky had a great blogpost about exactly this didn't he
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf See this all the time - people storm in trying to change things before trying to understand how the current things work. People who don't learn from what's been done before. Society doesn't progress from efforts like theirs. You only make progress by learning from and building on top of what came before.
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf
I learned C++ after Modula-2 and before C.
I learned programming earlier.Learning a programming language isn't learning programming (extracting requirements, specification, design, coding, test etc).
I looked at Rust. C++ certainly has got too complicated since 1987, but I wonder does Rust *only* help with memory safety?
Main memory safety in general relates to using pointers that are invalid, accessing arrays out of bounds and past the end of strings.
Partly bad libraries & design. -
@lcamtuf See this all the time - people storm in trying to change things before trying to understand how the current things work. People who don't learn from what's been done before. Society doesn't progress from efforts like theirs. You only make progress by learning from and building on top of what came before.
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Deus forbid if they create a functional specification of how the existing utilities work, before converting / rewriting them in a new language
️@simonzerafa @lcamtuf Hahahahahah...
Madness.
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf Yeah, not a good situation - even doing it in "safe C++" or somesuch would have had the same result. Decades of hard-learned lessons should be encoded in decades of well-written unit tests.
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf Welp. Got rent for next month covered.
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@lcamtuf and it's very worth remembering that while the design of rust _does_ prevent many bugs, it's not a get-out-of-bugs-free card. there are many ways to write code wrong, not just memory safety issues!
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@lcamtuf
I learned C++ after Modula-2 and before C.
I learned programming earlier.Learning a programming language isn't learning programming (extracting requirements, specification, design, coding, test etc).
I looked at Rust. C++ certainly has got too complicated since 1987, but I wonder does Rust *only* help with memory safety?
Main memory safety in general relates to using pointers that are invalid, accessing arrays out of bounds and past the end of strings.
Partly bad libraries & design.@raymaccarthy
well allegedly its types are meant to aid in type driven design and better domain modelling; but i dont know if this is actually seen in practice in better code structure. same could be said of cxx + its classes
@lcamtuf -
The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf Et tu, TOCTOU
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@lcamtuf ........ouch
I'm shocked they didn't account for any of that -
@raymaccarthy
well allegedly its types are meant to aid in type driven design and better domain modelling; but i dont know if this is actually seen in practice in better code structure. same could be said of cxx + its classes
@lcamtuf -
@lcamtuf Rustaceans are the problem, not Rust itself. theyre like a lobbing group trying explicitly to boost their future employment demand much more than prioritized on doing the right thing as engineers or for the community. much like the AI VC are "talking up their book" even if its poison for the rest of us
@synlogic4242 Uutils started as someone’s personal project to learn rust, and “write a system utility” is frequently used as a basic exercise for learning. Uutils is doing exactly what it set out to do.
It’s not the fault of uutils that Canonical is dumb.
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf There's also that human habit of getting complacent about all bugs when _some_ types of bugs are either impossible or very very hard to make because of language structure and tooling.
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf a related observation would probably be: why did important, security-critical edge cases get handled without enough documentation to prevent them from reoccurring?
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf Why do we keep calling uutils coreutils a rewrite?
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@synlogic4242 Uutils started as someone’s personal project to learn rust, and “write a system utility” is frequently used as a basic exercise for learning. Uutils is doing exactly what it set out to do.
It’s not the fault of uutils that Canonical is dumb.
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The coreutils Rust rewrite story is pretty funny.
Coreutils are tools like rm, mv, mkdir, etc. Unlike binutils, this isn't a fertile ground for memory safety bugs. But, the rewrite was completed, and in the spirit of progress, Canonical decided to switch.
But do you know what coreutils are a fertile ground for? Race conditions around file creation, deletion, permission setting, and so on. The original code accounted for decades of hard-learned lessons in that space. The Rust rewrite did not:
https://seclists.org/oss-sec/2026/q2/332
PS. I'm not dunking on Rust. It's just that... starting over from scratch has its hidden costs.
@lcamtuf Hey, would you care to elaborate or point me to resources explaining why the coreutils aren't fertile ground for memory safety issues? It's the first time I heard of this
