[tedunangst]

The complication with the linux syscall interface is that it turns the worse is better up to 11. Like setuid works on a per thread basis, which is seriously not what you want, so every program/runtime must do this fun little thread stop and start and thunk dance.

[JoshTriplett]

Yeah, agreed. One of the items on my long TODO list is adding `setuid_process` and `setgid_process` and similar, so that perhaps a decade later when new runtimes can count on the presence of those syscalls, they can stop duplicating that mechanism in userspace.