You can mmap files in Rust just fine, but it’s generally as dangerous as it is in C.
It has a very specific meaning in Rust: the user can cause memory unsafety if they make a mistake.
> I think a better word is “error-prone.”
The issue with the connotation there is that it's not about the rate of problems, it's about them going from "impossible" to "possible."
“A commission attributed the primary cause to general poor software design and development practices rather than single-out specific coding errors. In particular, the software was designed so that it was realistically impossible to test it in a clean automated way.“
Ergo, concurrency doesn’t kill people, people do.
most rust folks who use mmap don't mark the region as Celled, which means they risk UB in the form of incorrect behavior because the compiler assumes that the memory region is untouchable outside the single Rust program, and that's not true
(it's also not true generally b/c /dev/mem and /proc/pid/mem exist, but it's beyond Rust's scope that the OS allows intrusion like that)
Dangerous means dangerous. It's not up for interpretation.
Languages have multiple, very different words, for exactly this reason.
Rust has plenty of situations where you do unsafe things but wrap that in safe APIs. If you’re returning regions of that mmapped file, for example, a lifetime can be associated to those references to ensure that those are valid for the duration of the file being mmapped in the program.
It can be used to ensure that if you need to write back to that mmapped file (inside the same program) that there are no existing references to it, because those would be invalid after an update to the file. You need to do the same in C, but there are no guardrails you can build in C to make that same assurance.
I've never heard of this trick. And my first reaction is "That would be a nightmare of memory unsafety if I did it in C++"
What's it used for? IPC?
I know some very skilled C++ and Rust developers who can pull it off. If you're at that skill level, Rust is not going to get in your way because you're just going to use unsafe and throw some sanitizers and fuzzers at it. I wouldn't trust myself to implement it.
