Re: [libvirt] [PATCH v2 3/3] qemu-config: Add new -add-fd command line option

Another idea: a hybrid approach - the _first_ -add-fd 4 directly adds 4 to the set, all other -add-fd 4 end up adding dup(4) instead (well, fcntl(F_DUPFD_CLOEXEC), but you get the picture). That is, do the duplicate scanning, and if there is no duplicate, use the fd directly; if there IS a duplicate, then put a unique fd number as a copy into the remaining sets. That way, you don't have to do a final close() sweep across the -add-fd arguments passed on the command line, and you still don't have to worry about duplicated fds across multiple sets causing mayhem in qemu_close().