Pádraig Brady wrote: > How about the attached instead that just uses > a somewhat degraded but simpler error() equivalent.
That looks safe, though it could be simplified: use inttostr instead of repeating its body, and since !!p == !!errnum there's no need to have those duplicate conditions. Plus, just use STDERR_FILENO rather than fiddling with fileno (stderr), and async_safe_error should be _Noreturn and should unconditionally call _exit. And, I wouldn't bother looking at dup2's return value, any more than we look at close's.
