1 - restore the previous sigaction struct as soon as we are about to shut
off our timeout
2 - restore the previous alarm() timeout, in case an application or similar
had it running before we "borrowed" it for a while.

No, this does not fix the multi-thread problem you get with alarm(). This
patch should correct bug report #478780:
//sourceforge.net/tracker/?func=detail&atid=100976&aid=478780&group_id=976

If not, please post details!