To compile any one of them (say, one called foo.c):

prompt> gcc -o foo foo.c -Wall -pthread

And then, to run it:

prompt> ./foo

(maybe with some optional arguments)

Each of the following questions provides a code skeleton; your job is to fill in the code to make it work given semaphores. You will be using native semaphores. Good luck!

Questions

The first problem is just to implement and test a solution to the fork/join problem, as described in the text. Even though this solution is described in the text, the act of typing it in on your own is worthwhile; even Bach would rewrite Vivaldi, allowing one soon-to-be master to learn from an existing one. See fork-join.c for details. Add the call sleep(1) to the child to ensure it is working.
Let’s now generalize this a bit by investigating the rendezvous problem. The problem is as follows: you have two threads, each of which is about to enter the rendezvous point in the code. Neither should exit this part of the code before the other enters it. Consider using two semaphores for this task, and see rendezvous.c for details.
Now go one step further by implementing a general solution to barrier synchronization. Assume there are ...

Exercise

How