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System Callssemids(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 TYPEATTRIBUTE VALUE
MT-LevelAsync-Signal-Safe

SEE ALSO

 

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


SunOS 5.9Go To TopLast Changed 8 Mar 2000

 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.