Function prlimit64 

pub unsafe fn prlimit64(
    pid: Pid,
    resource: Resource,
    new_rlim: Option<&rlimit64>,
    old_rlim: Option<&mut rlimit64>,
) -> Result<(), Errno>

Call the prlimit64 syscall

Safety

Technically, calling this function can’t violate Safety in the rust-language sense. It’s been conservatively marked unsafe though, since in particular lowering resource limits may result in those limits being exceeded, and resource limits being exceeded can result in surprising behaviors that may terminate the process or exercise rarely-used error-handling paths - primarily receiving fatal-by-default signals or related syscalls failing.