I'm making an assumption here that you can actually implement signal handlers in Win32, but I don't know if that is true or not. I don't have too much experience programming code dedicated to that platform. :(

If the system does not have its own alarm(), you could probably write something similar by forking off a timing process that waits a specified amount of time and then sends a signal to the running process. If execution completes before the alarm is sent, the timing process could simply be killed off.

Hopefully, you will find a better solution and let us all know what it is. :)