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diff --git a/ipc/ipc_pset.c b/ipc/ipc_pset.c
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+/*
+ * Mach Operating System
+ * Copyright (c) 1991,1990,1989Carnegie Mellon University.
+ * Copyright (c) 1993,1994 The University of Utah and
+ * the Computer Systems Laboratory (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ *
+ * CARNEGIE MELLON, THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF
+ * THIS SOFTWARE IN ITS "AS IS" CONDITION, AND DISCLAIM ANY LIABILITY
+ * OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF
+ * THIS SOFTWARE.
+ *
+ * Carnegie Mellon requests users of this software to return to
+ *
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ *
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+ */
+/*
+ *	File:	ipc/ipc_pset.c
+ *	Author:	Rich Draves
+ *	Date:	1989
+ *
+ *	Functions to manipulate IPC port sets.
+ */
+
+#include <mach/port.h>
+#include <mach/kern_return.h>
+#include <mach/message.h>
+#include <ipc/ipc_mqueue.h>
+#include <ipc/ipc_object.h>
+#include <ipc/ipc_pset.h>
+#include <ipc/ipc_right.h>
+#include <ipc/ipc_space.h>
+
+
+/*
+ *	Routine:	ipc_pset_alloc
+ *	Purpose:
+ *		Allocate a port set.
+ *	Conditions:
+ *		Nothing locked.  If successful, the port set is returned
+ *		locked.  (The caller doesn't have a reference.)
+ *	Returns:
+ *		KERN_SUCCESS		The port set is allocated.
+ *		KERN_INVALID_TASK	The space is dead.
+ *		KERN_NO_SPACE		No room for an entry in the space.
+ *		KERN_RESOURCE_SHORTAGE	Couldn't allocate memory.
+ */
+
+kern_return_t
+ipc_pset_alloc(
+	ipc_space_t	space,
+	mach_port_t	*namep,
+	ipc_pset_t	*psetp)
+{
+	ipc_pset_t pset;
+	mach_port_t name;
+	kern_return_t kr;
+
+	kr = ipc_object_alloc(space, IOT_PORT_SET,
+			      MACH_PORT_TYPE_PORT_SET, 0,
+			      &name, (ipc_object_t *) &pset);
+	if (kr != KERN_SUCCESS)
+		return kr;
+	/* pset is locked */
+
+	ipc_target_init(&pset->ips_target, name);
+
+	*namep = name;
+	*psetp = pset;
+	return KERN_SUCCESS;
+}
+
+/*
+ *	Routine:	ipc_pset_alloc_name
+ *	Purpose:
+ *		Allocate a port set, with a specific name.
+ *	Conditions:
+ *		Nothing locked.  If successful, the port set is returned
+ *		locked.  (The caller doesn't have a reference.)
+ *	Returns:
+ *		KERN_SUCCESS		The port set is allocated.
+ *		KERN_INVALID_TASK	The space is dead.
+ *		KERN_NAME_EXISTS	The name already denotes a right.
+ *		KERN_RESOURCE_SHORTAGE	Couldn't allocate memory.
+ */
+
+kern_return_t
+ipc_pset_alloc_name(
+	ipc_space_t	space,
+	mach_port_t	name,
+	ipc_pset_t	*psetp)
+{
+	ipc_pset_t pset;
+	kern_return_t kr;
+
+
+	kr = ipc_object_alloc_name(space, IOT_PORT_SET,
+				   MACH_PORT_TYPE_PORT_SET, 0,
+				   name, (ipc_object_t *) &pset);
+	if (kr != KERN_SUCCESS)
+		return kr;
+	/* pset is locked */
+
+	ipc_target_init(&pset->ips_target, name);
+
+	*psetp = pset;
+	return KERN_SUCCESS;
+}
+
+/*
+ *	Routine:	ipc_pset_add
+ *	Purpose:
+ *		Puts a port into a port set.
+ *		The port set gains a reference.
+ *	Conditions:
+ *		Both port and port set are locked and active.
+ *		The port isn't already in a set.
+ *		The owner of the port set is also receiver for the port.
+ */
+
+void
+ipc_pset_add(
+	ipc_pset_t	pset,
+	ipc_port_t	port)
+{
+	assert(ips_active(pset));
+	assert(ip_active(port));
+	assert(port->ip_pset == IPS_NULL);
+
+	port->ip_pset = pset;
+	port->ip_cur_target = &pset->ips_target;
+	ips_reference(pset);
+
+	imq_lock(&port->ip_messages);
+	imq_lock(&pset->ips_messages);
+
+	/* move messages from port's queue to the port set's queue */
+
+	ipc_mqueue_move(&pset->ips_messages, &port->ip_messages, port);
+	imq_unlock(&pset->ips_messages);
+	assert(ipc_kmsg_queue_empty(&port->ip_messages.imq_messages));
+
+	/* wake up threads waiting to receive from the port */
+
+	ipc_mqueue_changed(&port->ip_messages, MACH_RCV_PORT_CHANGED);
+	assert(ipc_thread_queue_empty(&port->ip_messages.imq_threads));
+	imq_unlock(&port->ip_messages);
+}
+
+/*
+ *	Routine:	ipc_pset_remove
+ *	Purpose:
+ *		Removes a port from a port set.
+ *		The port set loses a reference.
+ *	Conditions:
+ *		Both port and port set are locked.
+ *		The port must be active.
+ */
+
+void
+ipc_pset_remove(
+	ipc_pset_t	pset,
+	ipc_port_t	port)
+{
+	assert(ip_active(port));
+	assert(port->ip_pset == pset);
+
+	port->ip_pset = IPS_NULL;
+	port->ip_cur_target = &port->ip_target;
+	ips_release(pset);
+
+	imq_lock(&port->ip_messages);
+	imq_lock(&pset->ips_messages);
+
+	/* move messages from port set's queue to the port's queue */
+
+	ipc_mqueue_move(&port->ip_messages, &pset->ips_messages, port);
+
+	imq_unlock(&pset->ips_messages);
+	imq_unlock(&port->ip_messages);
+}
+
+/*
+ *	Routine:	ipc_pset_move
+ *	Purpose:
+ *		If nset is IPS_NULL, removes port
+ *		from the port set it is in.  Otherwise, adds
+ *		port to nset, removing it from any set
+ *		it might already be in.
+ *	Conditions:
+ *		The space is read-locked.
+ *	Returns:
+ *		KERN_SUCCESS		Moved the port.
+ *		KERN_NOT_IN_SET		nset is null and port isn't in a set.
+ */
+
+kern_return_t
+ipc_pset_move(
+	ipc_space_t	space,
+	ipc_port_t	port,
+	ipc_pset_t	nset)
+{
+	ipc_pset_t oset;
+
+	/*
+	 *	While we've got the space locked, it holds refs for
+	 *	the port and nset (because of the entries).  Also,
+	 *	they must be alive.  While we've got port locked, it
+	 *	holds a ref for oset, which might not be alive.
+	 */
+
+	ip_lock(port);
+	assert(ip_active(port));
+
+	oset = port->ip_pset;
+
+	if (oset == nset) {
+		/* the port is already in the new set:  a noop */
+
+		is_read_unlock(space);
+	} else if (oset == IPS_NULL) {
+		/* just add port to the new set */
+
+		ips_lock(nset);
+		assert(ips_active(nset));
+		is_read_unlock(space);
+
+		ipc_pset_add(nset, port);
+
+		ips_unlock(nset);
+	} else if (nset == IPS_NULL) {
+		/* just remove port from the old set */
+
+		is_read_unlock(space);
+		ips_lock(oset);
+
+		ipc_pset_remove(oset, port);
+
+		if (ips_active(oset))
+			ips_unlock(oset);
+		else {
+			ips_check_unlock(oset);
+			oset = IPS_NULL; /* trigger KERN_NOT_IN_SET */
+		}
+	} else {
+		/* atomically move port from oset to nset */
+
+		if (oset < nset) {
+			ips_lock(oset);
+			ips_lock(nset);
+		} else {
+			ips_lock(nset);
+			ips_lock(oset);
+		}
+
+		is_read_unlock(space);
+		assert(ips_active(nset));
+
+		ipc_pset_remove(oset, port);
+		ipc_pset_add(nset, port);
+
+		ips_unlock(nset);
+		ips_check_unlock(oset);	/* KERN_NOT_IN_SET not a possibility */
+	}
+
+	ip_unlock(port);
+
+	return (((nset == IPS_NULL) && (oset == IPS_NULL)) ?
+		KERN_NOT_IN_SET : KERN_SUCCESS);
+}
+
+/*
+ *	Routine:	ipc_pset_destroy
+ *	Purpose:
+ *		Destroys a port_set.
+ *
+ *		Doesn't remove members from the port set;
+ *		that happens lazily.  As members are removed,
+ *		their messages are removed from the queue.
+ *	Conditions:
+ *		The port_set is locked and alive.
+ *		The caller has a reference, which is consumed.
+ *		Afterwards, the port_set is unlocked and dead.
+ */
+
+void
+ipc_pset_destroy(
+	ipc_pset_t	pset)
+{
+	assert(ips_active(pset));
+
+	pset->ips_object.io_bits &= ~IO_BITS_ACTIVE;
+
+	imq_lock(&pset->ips_messages);
+	ipc_mqueue_changed(&pset->ips_messages, MACH_RCV_PORT_DIED);
+	imq_unlock(&pset->ips_messages);
+
+	/* Common destruction for the IPC target.  */
+	ipc_target_terminate(&pset->ips_target);
+
+	ips_release(pset);	/* consume the ref our caller gave us */
+	ips_check_unlock(pset);
+}
+
+#include <mach_kdb.h>
+
+
+#if	MACH_KDB
+#define	printf	kdbprintf
+
+/*
+ *	Routine:	ipc_pset_print
+ *	Purpose:
+ *		Pretty-print a port set for kdb.
+ */
+
+void
+ipc_pset_print(
+	ipc_pset_t	pset)
+{
+	extern int indent;
+
+	printf("pset 0x%x\n", pset);
+
+	indent += 2;
+
+	ipc_object_print(&pset->ips_object);
+	iprintf("local_name = 0x%x\n", pset->ips_local_name);
+	iprintf("kmsgs = 0x%x", pset->ips_messages.imq_messages.ikmq_base);
+	printf(",rcvrs = 0x%x\n", pset->ips_messages.imq_threads.ithq_base);
+
+	indent -=2;
+}
+
+#endif	MACH_KDB