Question

Can I have a sem_t (semaphore) object take an a value of more than 1? Since sem_post only increments by 1. Is there a sem_set?

Answer 1

Yes, a sem_t can take on a value of more than 1. You can use sem_init to initialise your semaphore to an abitrary value. Quoting from this link:

To initialize a semaphore, use
sem_init():

  int sem_init(sem_t *sem, int pshared, unsigned int value); 

• sem points to a semaphore object to
  initialize
• pshared is a flag
  indicating whether or not the
  semaphore should be shared with
  fork()ed processes. LinuxThreads does
  not currently support shared
  semaphores
• value is an initial value
  to set the semaphore to

Example of
use:

  sem_init(&sem_name, 0, 10);

I’m not aware of any function that can increment a sem_t by an arbitrary value.