msgids(2)							   System Calls 							 msgids(2)

NAME

       msgids - discover all message queue identifiers

SYNOPSIS

       #include <sys/msg.h>

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

DESCRIPTION

       The  msgids()  function copies all active message queue 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 message queue 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 message queue 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 message queue identifiers in the system, buf is ignored.

RETURN VALUES

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

ERRORS

       The msgids() function will fail if:

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

USAGE

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

EXAMPLES

       Example 1 msgids() example

       This is sample C code indicating how to use the msgids() function (see msgsnap(2)):

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

	      for (;;) {
		   if (msgids(ids, nids, &n) != 0) {
			perror("msgids");
			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_msgid(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), msgctl(2), msgget(2), msgsnap(2), msgrcv(2), msgsnd(2), attributes(5)

SunOS 5.11							    8 Mar 2000								 msgids(2)