semids(2) [opensolaris man page]

semids(2)							   System Calls 							 semids(2)

NAME

       semids - discover all semaphore identifiers

SYNOPSIS

       #include <sys/sem.h>

       int semids(int *buf, uint_t nids, uint_t *pnids);

DESCRIPTION

       The  semids() function copies all active semaphore identifiers from the system into the user-defined buffer specified by buf, provided that
       the number of such identifiers is not greater than the number of integers the buffer can contain, as specified by nids.	If the size of the
       buffer is insufficient to contain all of the active semaphore identifiers in the system, none are copied.

       Whether	or  not  the  size of the buffer is sufficient to contain all of them, the number of active semaphore identifiers in the system is
       copied into the unsigned integer pointed to by pnids.

       If nids is 0 or less than the number of active semaphore identifiers in the system, buf is ignored.

RETURN VALUES

       Upon successful completion, semids() returns 0.	Otherwise, -1 is returned and errno is set to indicate the error.

ERRORS

       The semids() function will fail if:

       EFAULT	 The buf or pnids argument points to an illegal address.

USAGE

       The semids() function returns a snapshot of all the active semaphore identifiers in the system.	More may be added and some may be  removed
       before they can be used by the caller.

EXAMPLES

       Example 1 semids() example

       This is sample C code indicating how to use the semids() function.

	 void
	 examine_semids()
	 {
	      int *ids = NULL;
	      uint_t nids = 0;
	      uint_t n;
	      int i;

	      for (;;) {
		   if (semids(ids, nids, &n) != 0) {
			perror("semids");
			exit(1);
		   }
		   if (n <= nids)     /* we got them all */
			break;
		   /* we need a bigger buffer */
		   ids = realloc(ids, (nids = n) * sizeof (int));
	      }

	      for (i = 0; i < n; i++)
		   process_semid(ids[i]);

	      free(ids);
	 }

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ipcrm(1), ipcs(1), Intro(2), semctl(2), semget(2), semop(2), attributes(5)

SunOS 5.11							    8 Mar 2000								 semids(2)

semget(2)							   System Calls 							 semget(2)

NAME

       semget - get set of semaphores

SYNOPSIS

       #include <sys/types.h>
       #include <sys/ipc.h>
       #include <sys/sem.h>

       int semget(key_t key, int nsems, int semflg);

DESCRIPTION

       The semget() function returns the semaphore identifier associated with key.

       A  semaphore  identifier and associated data structure and set containing nsems semaphores (see Intro(2)) are created for key if one of the
       following is true:

	   o	  key is equal to IPC_PRIVATE.

	   o	  key does not already have a semaphore identifier associated with it, and (semflg&IPC_CREAT) is true.

       On creation, the data structure associated with the new semaphore identifier is initialized as follows:

	   o	  sem_perm.cuid, sem_perm.uid, sem_perm.cgid, and sem_perm.gid are set equal to the effective user  ID	and  effective	group  ID,
		  respectively, of the calling process.

	   o	  The access permission bits of sem_perm.mode are set equal to the access permission bits of semflg.

	   o	  sem_nsems is set equal to the value of nsems.

	   o	  sem_otime is set equal to 0 and sem_ctime is set equal to the current time.

RETURN VALUES

       Upon  successful completion, a non-negative integer representing a semaphore identifier is returned. Otherwise, -1 is returned and errno is
       set to indicate the error.

ERRORS

       The semget() function will fail if:

       EACCES	 A semaphore identifier exists for key, but operation permission (see Intro(2)) as specified by the low-order  9  bits	of  semflg
		 would not be granted.

       EEXIST	 A semaphore identifier exists for key but both (semflg&IPC_CREAT) and (semflg&IPC_EXCL) are both true.

       EINVAL	 The nsems argument is either less than or equal to 0 or greater than the system-imposed limit. See NOTES.

		 A semaphore identifier exists for key, but the number of semaphores in the set associated with it is less than nsems and nsems is
		 not equal to 0.

       ENOENT	 A semaphore identifier does not exist for key and (semflg&IPC_CREAT) is false.

       ENOSPC	 A semaphore identifier is to be created but the system-imposed limit on the maximum number of	allowed  semaphores  or  semaphore
		 identifiers system-wide would be exceeded. See NOTES.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       ipcrm(1), ipcs(1), rctladm(1M), Intro(2), semctl(2), semop(2), setrctl(2), ftok(3C), attributes(5), standards(5)

NOTES

       The  system-imposed  limit  on  the  value  of  the nsems argument is the maintained on a per-process basis using the process.max-sem-nsems
       resource control.

       The system-imposed limit on the number of semaphore identifiers is maintained on a per-project basis using the project.max-sem-ids resource
       control. The  zone.max-sem-ids resource control limis the total number of semaphore identifiers that can be allocated by a zone.

       See rctladm(1M) and setrctl(2) for information about using resource controls.

SunOS 5.11							    14 Aug 2006 							 semget(2)