Libc

I like the approach of attributing variables better to be honest, e.g. Apple's Libc has a header with attributes for some common resource types. https://github.com/apple-oss-distributions/Libc/blob/Libc-16...

Does rust also add an pthread_atfork handler? Otherwise, it seems likely still unsafe for rust to claim to support calling fork (for execv) or posix_spawn, as most libc call realloc on the `environ` contents, but do not appear to take any care to ensure that (v)fork/posix_spawn doesn't happen concurrently with that. Worse yet, the `posix_spawnp` API takes an `envp` parameter and expects you to pass it the global pointer `environ`, which is completely unsynchronized across that fork call. It is not obvious to me that this is a security gap, but certainly it seems to me that this would violate rust's safety claim, if it is not taking added precautions there. The Apple Libc appears to just unconditionally drops the environ lock in the child (https://github.com/apple-oss-distributions/Libc/blob/c5a3293...), while glibc doesn't appear to even

Doesn't musl have the same issue? https://github.com/JuliaLang/julia/issues/34726#issuecomment... I also wonder about OSX's libc. Newer versions seem to have some sort of locking https://github.com/apple-open-source-mirror/Libc/blob/master... but they free pointers so it's not safe from a potential use-after-free client side. but older versions (from 10.9) don't even have any locking: https://github.com/apple-oss-distributions/Libc/blob/Libc-99...