[apple/xnu.git] / osfmk / ipc / mach_port.c

/*
 * Copyright (c) 2000-2007 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/*
 * Mach Operating System
 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
 * 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 ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS 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.
 */
/*
 * NOTICE: This file was modified by McAfee Research in 2004 to introduce
 * support for mandatory and extensible security protections.  This notice
 * is included in support of clause 2.2 (b) of the Apple Public License,
 * Version 2.0.
 * Copyright (c) 2005-2006 SPARTA, Inc.
 */
/*
 */
/*
 *      File:   ipc/mach_port.c
 *      Author: Rich Draves
 *      Date:   1989
 *
 *      Exported kernel calls.  See mach/mach_port.defs.
 */

#include <mach_debug.h>

#include <mach/port.h>
#include <mach/kern_return.h>
#include <mach/notify.h>
#include <mach/mach_param.h>
#include <mach/vm_param.h>
#include <mach/vm_prot.h>
#include <mach/vm_map.h>
#include <kern/task.h>
#include <kern/counters.h>
#include <kern/thread.h>
#include <kern/kalloc.h>
#include <kern/exc_guard.h>
#include <mach/mach_port_server.h>
#include <vm/vm_map.h>
#include <vm/vm_kern.h>
#include <ipc/port.h>
#include <ipc/ipc_entry.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_object.h>
#include <ipc/ipc_notify.h>
#include <ipc/ipc_port.h>
#include <ipc/ipc_pset.h>
#include <ipc/ipc_right.h>
#include <ipc/ipc_kmsg.h>
#include <kern/misc_protos.h>
#include <security/mac_mach_internal.h>

#if IMPORTANCE_INHERITANCE
#include <ipc/ipc_importance.h>
#endif


/* Zeroed template of qos flags */

static mach_port_qos_t  qos_template;

/*
 *      Routine:        mach_port_names_helper
 *      Purpose:
 *              A helper function for mach_port_names.
 *
 *      Conditions:
 *              Space containing entry is [at least] read-locked.
 */
static void
mach_port_names_helper(
        ipc_port_timestamp_t    timestamp,
        ipc_entry_t             entry,
        mach_port_name_t        name,
        mach_port_name_t        *names,
        mach_port_type_t        *types,
        ipc_entry_num_t         *actualp)
{
        ipc_entry_bits_t bits;
        ipc_port_request_index_t request;
        mach_port_type_t type = 0;
        ipc_entry_num_t actual;
        ipc_port_t port;

        bits = entry->ie_bits;
        request = entry->ie_request;
        port = ip_object_to_port(entry->ie_object);

        if (bits & MACH_PORT_TYPE_RECEIVE) {
                assert(IP_VALID(port));

                if (request != IE_REQ_NONE) {
                        ip_lock(port);
                        require_ip_active(port);
                        type |= ipc_port_request_type(port, name, request);
                        ip_unlock(port);
                }
        } else if (bits & MACH_PORT_TYPE_SEND_RIGHTS) {
                mach_port_type_t reqtype;

                assert(IP_VALID(port));
                ip_lock(port);

                reqtype = (request != IE_REQ_NONE) ?
                    ipc_port_request_type(port, name, request) : 0;

                /*
                 * If the port is alive, or was alive when the mach_port_names
                 * started, then return that fact.  Otherwise, pretend we found
                 * a dead name entry.
                 */
                if (ip_active(port) || IP_TIMESTAMP_ORDER(timestamp, port->ip_timestamp)) {
                        type |= reqtype;
                } else {
                        bits &= ~(IE_BITS_TYPE_MASK);
                        bits |= MACH_PORT_TYPE_DEAD_NAME;
                        /* account for additional reference for dead-name notification */
                        if (reqtype != 0) {
                                bits++;
                        }
                }
                ip_unlock(port);
        }

        type |= IE_BITS_TYPE(bits);

        actual = *actualp;
        names[actual] = name;
        types[actual] = type;
        *actualp = actual + 1;
}

/*
 *      Routine:        mach_port_names [kernel call]
 *      Purpose:
 *              Retrieves a list of the rights present in the space,
 *              along with type information.  (Same as returned
 *              by mach_port_type.)  The names are returned in
 *              no particular order, but they (and the type info)
 *              are an accurate snapshot of the space.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Arrays of names and types returned.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
mach_port_names(
        ipc_space_t             space,
        mach_port_name_t        **namesp,
        mach_msg_type_number_t  *namesCnt,
        mach_port_type_t        **typesp,
        mach_msg_type_number_t  *typesCnt)
{
        ipc_entry_t table;
        ipc_entry_num_t tsize;
        mach_port_index_t index;
        ipc_entry_num_t actual; /* this many names */
        ipc_port_timestamp_t timestamp; /* logical time of this operation */
        mach_port_name_t *names;
        mach_port_type_t *types;
        kern_return_t kr;

        vm_size_t size;         /* size of allocated memory */
        vm_offset_t addr1;      /* allocated memory, for names */
        vm_offset_t addr2;      /* allocated memory, for types */
        vm_map_copy_t memory1;  /* copied-in memory, for names */
        vm_map_copy_t memory2;  /* copied-in memory, for types */

        /* safe simplifying assumption */
        static_assert(sizeof(mach_port_name_t) == sizeof(mach_port_type_t));

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        size = 0;

        for (;;) {
                ipc_entry_num_t bound;
                vm_size_t size_needed;

                is_read_lock(space);
                if (!is_active(space)) {
                        is_read_unlock(space);
                        if (size != 0) {
                                kmem_free(ipc_kernel_map, addr1, size);
                                kmem_free(ipc_kernel_map, addr2, size);
                        }
                        return KERN_INVALID_TASK;
                }

                /* upper bound on number of names in the space */
                bound = space->is_table_size;
                size_needed = vm_map_round_page(
                        (bound * sizeof(mach_port_name_t)),
                        VM_MAP_PAGE_MASK(ipc_kernel_map));

                if (size_needed <= size) {
                        break;
                }

                is_read_unlock(space);

                if (size != 0) {
                        kmem_free(ipc_kernel_map, addr1, size);
                        kmem_free(ipc_kernel_map, addr2, size);
                }
                size = size_needed;

                kr = vm_allocate_kernel(ipc_kernel_map, &addr1, size, VM_FLAGS_ANYWHERE, VM_KERN_MEMORY_IPC);
                if (kr != KERN_SUCCESS) {
                        return KERN_RESOURCE_SHORTAGE;
                }

                kr = vm_allocate_kernel(ipc_kernel_map, &addr2, size, VM_FLAGS_ANYWHERE, VM_KERN_MEMORY_IPC);
                if (kr != KERN_SUCCESS) {
                        kmem_free(ipc_kernel_map, addr1, size);
                        return KERN_RESOURCE_SHORTAGE;
                }

                /* can't fault while we hold locks */

                kr = vm_map_wire_kernel(
                        ipc_kernel_map,
                        vm_map_trunc_page(addr1,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        vm_map_round_page(addr1 + size,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        VM_PROT_READ | VM_PROT_WRITE, VM_KERN_MEMORY_IPC,
                        FALSE);
                if (kr != KERN_SUCCESS) {
                        kmem_free(ipc_kernel_map, addr1, size);
                        kmem_free(ipc_kernel_map, addr2, size);
                        return KERN_RESOURCE_SHORTAGE;
                }

                kr = vm_map_wire_kernel(
                        ipc_kernel_map,
                        vm_map_trunc_page(addr2,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        vm_map_round_page(addr2 + size,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        VM_PROT_READ | VM_PROT_WRITE,
                        VM_KERN_MEMORY_IPC,
                        FALSE);
                if (kr != KERN_SUCCESS) {
                        kmem_free(ipc_kernel_map, addr1, size);
                        kmem_free(ipc_kernel_map, addr2, size);
                        return KERN_RESOURCE_SHORTAGE;
                }
        }
        /* space is read-locked and active */

        names = (mach_port_name_t *) addr1;
        types = (mach_port_type_t *) addr2;
        actual = 0;

        timestamp = ipc_port_timestamp();

        table = space->is_table;
        tsize = space->is_table_size;

        for (index = 0; index < tsize; index++) {
                ipc_entry_t entry = &table[index];
                ipc_entry_bits_t bits = entry->ie_bits;

                if (IE_BITS_TYPE(bits) != MACH_PORT_TYPE_NONE) {
                        mach_port_name_t name;

                        name = MACH_PORT_MAKE(index, IE_BITS_GEN(bits));
                        mach_port_names_helper(timestamp, entry, name, names,
                            types, &actual);
                }
        }

        is_read_unlock(space);

        if (actual == 0) {
                memory1 = VM_MAP_COPY_NULL;
                memory2 = VM_MAP_COPY_NULL;

                if (size != 0) {
                        kmem_free(ipc_kernel_map, addr1, size);
                        kmem_free(ipc_kernel_map, addr2, size);
                }
        } else {
                vm_size_t size_used;
                vm_size_t vm_size_used;

                size_used = actual * sizeof(mach_port_name_t);
                vm_size_used =
                    vm_map_round_page(size_used,
                    VM_MAP_PAGE_MASK(ipc_kernel_map));

                /*
                 *      Make used memory pageable and get it into
                 *      copied-in form.  Free any unused memory.
                 */

                kr = vm_map_unwire(
                        ipc_kernel_map,
                        vm_map_trunc_page(addr1,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        vm_map_round_page(addr1 + vm_size_used,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        FALSE);
                assert(kr == KERN_SUCCESS);

                kr = vm_map_unwire(
                        ipc_kernel_map,
                        vm_map_trunc_page(addr2,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        vm_map_round_page(addr2 + vm_size_used,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        FALSE);
                assert(kr == KERN_SUCCESS);

                kr = vm_map_copyin(ipc_kernel_map, (vm_map_address_t)addr1,
                    (vm_map_size_t)size_used, TRUE, &memory1);
                assert(kr == KERN_SUCCESS);

                kr = vm_map_copyin(ipc_kernel_map, (vm_map_address_t)addr2,
                    (vm_map_size_t)size_used, TRUE, &memory2);
                assert(kr == KERN_SUCCESS);

                if (vm_size_used != size) {
                        kmem_free(ipc_kernel_map,
                            addr1 + vm_size_used, size - vm_size_used);
                        kmem_free(ipc_kernel_map,
                            addr2 + vm_size_used, size - vm_size_used);
                }
        }

        *namesp = (mach_port_name_t *) memory1;
        *namesCnt = actual;
        *typesp = (mach_port_type_t *) memory2;
        *typesCnt = actual;
        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_type [kernel call]
 *      Purpose:
 *              Retrieves the type of a right in the space.
 *              The type is a bitwise combination of one or more
 *              of the following type bits:
 *                      MACH_PORT_TYPE_SEND
 *                      MACH_PORT_TYPE_RECEIVE
 *                      MACH_PORT_TYPE_SEND_ONCE
 *                      MACH_PORT_TYPE_PORT_SET
 *                      MACH_PORT_TYPE_DEAD_NAME
 *              In addition, the following pseudo-type bits may be present:
 *                      MACH_PORT_TYPE_DNREQUEST
 *                              A dead-name notification is requested.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Type is returned.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 */

kern_return_t
mach_port_type(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_type_t        *typep)
{
        mach_port_urefs_t urefs;
        ipc_entry_t entry;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (name == MACH_PORT_NULL) {
                return KERN_INVALID_NAME;
        }

        if (name == MACH_PORT_DEAD) {
                *typep = MACH_PORT_TYPE_DEAD_NAME;
                return KERN_SUCCESS;
        }

        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* space is write-locked and active */
        kr = ipc_right_info(space, name, entry, typep, &urefs);
        /* space is unlocked */

#if 1
        /* JMM - workaround rdar://problem/9121297 (CF being too picky on these bits). */
        *typep &= ~(MACH_PORT_TYPE_SPREQUEST | MACH_PORT_TYPE_SPREQUEST_DELAYED);
#endif

        return kr;
}

/*
 *      Routine:        mach_port_rename [kernel call]
 *      Purpose:
 *              Changes the name denoting a right,
 *              from oname to nname.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The right is renamed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The oname doesn't denote a right.
 *              KERN_INVALID_VALUE      The nname isn't a legal name.
 *              KERN_NAME_EXISTS        The nname already denotes a right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *
 *      This interface is obsolete and always returns
 *      KERN_NOT_SUPPORTED.
 */

kern_return_t
mach_port_rename(
        __unused ipc_space_t            space,
        __unused mach_port_name_t       oname,
        __unused mach_port_name_t       nname)
{
        return KERN_NOT_SUPPORTED;
}


/*
 *      Routine:        mach_port_allocate_name [kernel call]
 *      Purpose:
 *              Allocates a right in a space, using a specific name
 *              for the new right.  Possible rights:
 *                      MACH_PORT_RIGHT_RECEIVE
 *                      MACH_PORT_RIGHT_PORT_SET
 *                      MACH_PORT_RIGHT_DEAD_NAME
 *
 *              A new port (allocated with MACH_PORT_RIGHT_RECEIVE)
 *              has no extant send or send-once rights and no queued
 *              messages.  Its queue limit is MACH_PORT_QLIMIT_DEFAULT
 *              and its make-send count is 0.  It is not a member of
 *              a port set.  It has no registered no-senders or
 *              port-destroyed notification requests.
 *
 *              A new port set has no members.
 *
 *              A new dead name has one user reference.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The right is allocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      The name isn't a legal name.
 *              KERN_INVALID_VALUE      "right" isn't a legal kind of right.
 *              KERN_NAME_EXISTS        The name already denotes a right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *
 *      Restrictions on name allocation:  NT bits are reserved by kernel,
 *      must be set on any chosen name.  Can't do this at all in kernel
 *      loaded server.
 */

kern_return_t
mach_port_allocate_name(
        ipc_space_t             space,
        mach_port_right_t       right,
        mach_port_name_t        name)
{
        kern_return_t           kr;
        mach_port_qos_t         qos = qos_template;

        qos.name = TRUE;

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_VALUE;
        }

        kr = mach_port_allocate_full(space, right, MACH_PORT_NULL,
            &qos, &name);
        return kr;
}

/*
 *      Routine:        mach_port_allocate [kernel call]
 *      Purpose:
 *              Allocates a right in a space.  Like mach_port_allocate_name,
 *              except that the implementation picks a name for the right.
 *              The name may be any legal name in the space that doesn't
 *              currently denote a right.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The right is allocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      "right" isn't a legal kind of right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *              KERN_NO_SPACE           No room in space for another right.
 */

kern_return_t
mach_port_allocate(
        ipc_space_t             space,
        mach_port_right_t       right,
        mach_port_name_t        *namep)
{
        kern_return_t           kr;
        mach_port_qos_t         qos = qos_template;

        kr = mach_port_allocate_full(space, right, MACH_PORT_NULL,
            &qos, namep);
        return kr;
}

/*
 *      Routine:        mach_port_allocate_qos [kernel call]
 *      Purpose:
 *              Allocates a right, with qos options, in a space.  Like
 *              mach_port_allocate_name, except that the implementation
 *              picks a name for the right. The name may be any legal name
 *              in the space that doesn't currently denote a right.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The right is allocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      "right" isn't a legal kind of right.
 *              KERN_INVALID_ARGUMENT   The qos request was invalid.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *              KERN_NO_SPACE           No room in space for another right.
 */

kern_return_t
mach_port_allocate_qos(
        ipc_space_t             space,
        mach_port_right_t       right,
        mach_port_qos_t         *qosp,
        mach_port_name_t        *namep)
{
        kern_return_t           kr;

        if (qosp->name) {
                return KERN_INVALID_ARGUMENT;
        }
        kr = mach_port_allocate_full(space, right, MACH_PORT_NULL,
            qosp, namep);
        return kr;
}

/*
 *      Routine:        mach_port_allocate_full [kernel call]
 *      Purpose:
 *              Allocates a right in a space.  Supports the
 *              special case of specifying a name. The name may
 *      be any legal name in the space that doesn't
 *              currently denote a right.
 *
 *      While we no longer support users requesting
 *      preallocated message for the port, we still
 *      check for errors in such requests and then
 *      just clear the request.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The right is allocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      "right" isn't a legal kind of right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *              KERN_NO_SPACE           No room in space for another right.
 */

kern_return_t
mach_port_allocate_full(
        ipc_space_t             space,
        mach_port_right_t       right,
        mach_port_t             proto,
        mach_port_qos_t         *qosp,
        mach_port_name_t        *namep)
{
        kern_return_t           kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (proto != MACH_PORT_NULL) {
                return KERN_INVALID_VALUE;
        }

        if (qosp->name) {
                if (!MACH_PORT_VALID(*namep)) {
                        return KERN_INVALID_VALUE;
                }
        }

        /*
         * Don't actually honor prealloc requests from user-space
         * (for security reasons, and because it isn't guaranteed anyway).
         * Keep old errors for legacy reasons.
         */
        if (qosp->prealloc) {
                if (qosp->len > MACH_MSG_SIZE_MAX - MAX_TRAILER_SIZE) {
                        return KERN_RESOURCE_SHORTAGE;
                }
                if (right != MACH_PORT_RIGHT_RECEIVE) {
                        return KERN_INVALID_VALUE;
                }
                qosp->prealloc = 0;
        }

        kr = mach_port_allocate_internal(space, right, qosp, namep);
        return kr;
}


/*
 *      Routine:        mach_port_allocate_internal [kernel private]
 *      Purpose:
 *              Allocates a right in a space.  Supports all of the
 *              special cases, a specific name, a real-time port, etc.
 *              The name may be any legal name in the space that doesn't
 *              currently denote a right.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The right is allocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      "right" isn't a legal kind of right.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *              KERN_NO_SPACE           No room in space for another right.
 */
kern_return_t
mach_port_allocate_internal(
        ipc_space_t             space,
        mach_port_right_t       right,
        mach_port_qos_t         *qosp,
        mach_port_name_t        *namep)
{
        kern_return_t   kr;

        assert(space != IS_NULL);

        switch (right) {
        case MACH_PORT_RIGHT_RECEIVE:
        {
                ipc_kmsg_t      kmsg = IKM_NULL;
                ipc_port_t      port;

                /*
                 * For in-kernel uses, only allow small (from the kmsg zone)
                 * preallocated messages for the port.
                 */
                if (qosp->prealloc) {
                        mach_msg_size_t size = qosp->len;

                        if (size > IKM_SAVED_MSG_SIZE - MAX_TRAILER_SIZE) {
                                panic("mach_port_allocate_internal: too large a prealloc kmsg");
                        }
                        kmsg = (ipc_kmsg_t)ipc_kmsg_prealloc(size + MAX_TRAILER_SIZE);
                        if (kmsg == IKM_NULL) {
                                return KERN_RESOURCE_SHORTAGE;
                        }
                }

                if (qosp->name) {
                        kr = ipc_port_alloc_name(space, *namep, &port);
                } else {
                        kr = ipc_port_alloc(space, FALSE, namep, &port);
                }
                if (kr == KERN_SUCCESS) {
                        if (kmsg != IKM_NULL) {
                                ipc_kmsg_set_prealloc(kmsg, port);
                        }
                        ip_unlock(port);
                } else if (kmsg != IKM_NULL) {
                        ipc_kmsg_free(kmsg);
                }
                break;
        }

        case MACH_PORT_RIGHT_PORT_SET:
        {
                ipc_pset_t      pset;

                if (qosp->name) {
                        kr = ipc_pset_alloc_name(space, *namep, &pset);
                } else {
                        kr = ipc_pset_alloc(space, namep, &pset);
                }
                if (kr == KERN_SUCCESS) {
                        ips_unlock(pset);
                }
                break;
        }

        case MACH_PORT_RIGHT_DEAD_NAME:
                kr = ipc_object_alloc_dead(space, namep);
                break;

        default:
                kr = KERN_INVALID_VALUE;
                break;
        }

        return kr;
}

/*
 *      Routine:        mach_port_destroy [kernel call]
 *      Purpose:
 *              Cleans up and destroys all rights denoted by a name
 *              in a space.  The destruction of a receive right
 *              destroys the port, unless a port-destroyed request
 *              has been made for it; the destruction of a port-set right
 *              destroys the port set.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The name is destroyed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 */

kern_return_t
mach_port_destroy(
        ipc_space_t             space,
        mach_port_name_t        name)
{
        ipc_entry_t entry;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_SUCCESS;
        }

        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_NAME);
                return kr;
        }
        /* space is write-locked and active */

        kr = ipc_right_destroy(space, name, entry, TRUE, 0); /* unlocks space */
        return kr;
}

/*
 *      Routine:        mach_port_deallocate [kernel call]
 *      Purpose:
 *              Deallocates a user reference from a send right,
 *              send-once right, dead-name right or a port_set right.
 *              May deallocate the right, if this is the last uref,
 *              and destroy the name, if it doesn't denote
 *              other rights.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            The uref is deallocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      The right isn't correct.
 */

kern_return_t
mach_port_deallocate(
        ipc_space_t             space,
        mach_port_name_t        name)
{
        ipc_entry_t entry;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_SUCCESS;
        }

        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_NAME);
                return kr;
        }
        /* space is write-locked */

        kr = ipc_right_dealloc(space, name, entry); /* unlocks space */
        return kr;
}

/*
 *      Routine:        mach_port_get_refs [kernel call]
 *      Purpose:
 *              Retrieves the number of user references held by a right.
 *              Receive rights, port-set rights, and send-once rights
 *              always have one user reference.  Returns zero if the
 *              name denotes a right, but not the queried right.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Number of urefs returned.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      "right" isn't a legal value.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 */

kern_return_t
mach_port_get_refs(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_right_t       right,
        mach_port_urefs_t       *urefsp)
{
        mach_port_type_t type;
        mach_port_urefs_t urefs;
        ipc_entry_t entry;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (right >= MACH_PORT_RIGHT_NUMBER) {
                return KERN_INVALID_VALUE;
        }

        if (!MACH_PORT_VALID(name)) {
                if (right == MACH_PORT_RIGHT_SEND ||
                    right == MACH_PORT_RIGHT_SEND_ONCE) {
                        *urefsp = 1;
                        return KERN_SUCCESS;
                }
                return KERN_INVALID_NAME;
        }

        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* space is write-locked and active */
        kr = ipc_right_info(space, name, entry, &type, &urefs);
        /* space is unlocked */

        if (kr != KERN_SUCCESS) {
                return kr;
        }

        if (type & MACH_PORT_TYPE(right)) {
                switch (right) {
                case MACH_PORT_RIGHT_SEND_ONCE:
                        assert(urefs == 1);
                /* fall-through */

                case MACH_PORT_RIGHT_PORT_SET:
                case MACH_PORT_RIGHT_RECEIVE:
                        *urefsp = 1;
                        break;

                case MACH_PORT_RIGHT_DEAD_NAME:
                case MACH_PORT_RIGHT_SEND:
                        assert(urefs > 0);
                        *urefsp = urefs;
                        break;

                default:
                        panic("mach_port_get_refs: strange rights");
                }
        } else {
                *urefsp = 0;
        }

        return kr;
}

/*
 *      Routine:        mach_port_mod_refs
 *      Purpose:
 *              Modifies the number of user references held by a right.
 *              The resulting number of user references must be non-negative.
 *              If it is zero, the right is deallocated.  If the name
 *              doesn't denote other rights, it is destroyed.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Modified number of urefs.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      "right" isn't a legal value.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote specified right.
 *              KERN_INVALID_VALUE      Impossible modification to urefs.
 *              KERN_UREFS_OVERFLOW     Urefs would overflow.
 */

kern_return_t
mach_port_mod_refs(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_right_t       right,
        mach_port_delta_t       delta)
{
        ipc_entry_t entry;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (right >= MACH_PORT_RIGHT_NUMBER) {
                return KERN_INVALID_VALUE;
        }

        if (!MACH_PORT_VALID(name)) {
                if (right == MACH_PORT_RIGHT_SEND ||
                    right == MACH_PORT_RIGHT_SEND_ONCE) {
                        return KERN_SUCCESS;
                }
                return KERN_INVALID_NAME;
        }

        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_NAME);
                return kr;
        }

        /* space is write-locked and active */

        kr = ipc_right_delta(space, name, entry, right, delta); /* unlocks */
        return kr;
}


/*
 *      Routine:        mach_port_peek [kernel call]
 *      Purpose:
 *              Peek at the message queue for the specified receive
 *              right and return info about a message in the queue.
 *
 *              On input, seqnop points to a sequence number value
 *              to match the message being peeked. If zero is specified
 *              as the seqno, the first message in the queue will be
 *              peeked.
 *
 *              Only the following trailer types are currently supported:
 *                      MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0)
 *
 *                              or'ed with one of these element types:
 *                      MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_NULL)
 *                      MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_SEQNO)
 *                      MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_SENDER)
 *                      MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT)
 *
 *              On input, the value pointed to by trailer_sizep must be
 *              large enough to hold the requested trailer size.
 *
 *              The message sequence number, id, size, requested trailer info
 *              and requested trailer size are returned in their respective
 *              output parameters upon success.
 *
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Matching message found, out parameters set.
 *              KERN_INVALID_TASK       The space is null or dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote receive rights.
 *              KERN_INVALID_VALUE      The input parameter values are out of bounds.
 *              KERN_FAILURE            The requested message was not found.
 */

kern_return_t
mach_port_peek(
        ipc_space_t                     space,
        mach_port_name_t                name,
        mach_msg_trailer_type_t         trailer_type,
        mach_port_seqno_t               *seqnop,
        mach_msg_size_t                 *msg_sizep,
        mach_msg_id_t                   *msg_idp,
        mach_msg_trailer_info_t         trailer_infop,
        mach_msg_type_number_t          *trailer_sizep)
{
        ipc_port_t port;
        kern_return_t kr;
        boolean_t found;
        mach_msg_max_trailer_t max_trailer;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_RIGHT;
        }

        /*
         * We don't allow anything greater than the audit trailer - to avoid
         * leaking the context pointer and to avoid variable-sized context issues.
         */
        if (GET_RCV_ELEMENTS(trailer_type) > MACH_RCV_TRAILER_AUDIT ||
            REQUESTED_TRAILER_SIZE(TRUE, trailer_type) > *trailer_sizep) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_VALUE);
                return KERN_INVALID_VALUE;
        }

        *trailer_sizep = REQUESTED_TRAILER_SIZE(TRUE, trailer_type);

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0,
                    ((KERN_INVALID_NAME == kr) ?
                    kGUARD_EXC_INVALID_NAME :
                    kGUARD_EXC_INVALID_RIGHT));
                return kr;
        }

        /* Port locked and active */

        found = ipc_mqueue_peek(&port->ip_messages, seqnop,
            msg_sizep, msg_idp, &max_trailer, NULL);
        ip_unlock(port);

        if (found != TRUE) {
                return KERN_FAILURE;
        }

        max_trailer.msgh_seqno = *seqnop;
        memcpy(trailer_infop, &max_trailer, *trailer_sizep);

        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_set_mscount [kernel call]
 *      Purpose:
 *              Changes a receive right's make-send count.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Set make-send count.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote receive rights.
 */

kern_return_t
mach_port_set_mscount(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_mscount_t     mscount)
{
        ipc_port_t port;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_RIGHT;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* port is locked and active */

        port->ip_mscount = mscount;
        ip_unlock(port);
        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_set_seqno [kernel call]
 *      Purpose:
 *              Changes a receive right's sequence number.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Set sequence number.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote receive rights.
 */

kern_return_t
mach_port_set_seqno(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_seqno_t       seqno)
{
        ipc_port_t port;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_RIGHT;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                return kr;
        }
        /* port is locked and active */

        ipc_mqueue_set_seqno(&port->ip_messages, seqno);

        ip_unlock(port);
        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_get_context [kernel call]
 *      Purpose:
 *              Returns a receive right's context pointer.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Set context pointer.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote receive rights.
 */

kern_return_t
mach_port_get_context(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_vm_address_t       *context)
{
        ipc_port_t port;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_RIGHT;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* Port locked and active */

        /* For strictly guarded ports, return empty context (which acts as guard) */
        if (port->ip_strict_guard) {
                *context = 0;
        } else {
                *context = port->ip_context;
        }

        ip_unlock(port);
        return KERN_SUCCESS;
}


/*
 *      Routine:        mach_port_set_context [kernel call]
 *      Purpose:
 *              Changes a receive right's context pointer.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Set context pointer.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote receive rights.
 */

kern_return_t
mach_port_set_context(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_vm_address_t       context)
{
        ipc_port_t port;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_RIGHT;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* port is locked and active */
        if (port->ip_strict_guard) {
                uint64_t portguard = port->ip_context;
                ip_unlock(port);
                /* For strictly guarded ports, disallow overwriting context; Raise Exception */
                mach_port_guard_exception(name, context, portguard, kGUARD_EXC_SET_CONTEXT);
                return KERN_INVALID_ARGUMENT;
        }

        port->ip_context = context;

        ip_unlock(port);
        return KERN_SUCCESS;
}


/*
 *      Routine:        mach_port_get_set_status [kernel call]
 *      Purpose:
 *              Retrieves a list of members in a port set.
 *              Returns the space's name for each receive right member.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Retrieved list of members.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote a port set.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
mach_port_get_set_status(
        ipc_space_t                     space,
        mach_port_name_t                name,
        mach_port_name_t                **members,
        mach_msg_type_number_t          *membersCnt)
{
        ipc_entry_num_t actual;         /* this many members */
        ipc_entry_num_t maxnames;       /* space for this many members */
        kern_return_t kr;

        vm_size_t size;         /* size of allocated memory */
        vm_offset_t addr;       /* allocated memory */
        vm_map_copy_t memory;   /* copied-in memory */

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_RIGHT;
        }

        size = VM_MAP_PAGE_SIZE(ipc_kernel_map);        /* initial guess */

        for (;;) {
                mach_port_name_t *names;
                ipc_object_t psobj;
                ipc_pset_t pset;

                kr = vm_allocate_kernel(ipc_kernel_map, &addr, size, VM_FLAGS_ANYWHERE, VM_KERN_MEMORY_IPC);
                if (kr != KERN_SUCCESS) {
                        return KERN_RESOURCE_SHORTAGE;
                }

                /* can't fault while we hold locks */

                kr = vm_map_wire_kernel(ipc_kernel_map, addr, addr + size,
                    VM_PROT_READ | VM_PROT_WRITE, VM_KERN_MEMORY_IPC, FALSE);
                assert(kr == KERN_SUCCESS);

                kr = ipc_object_translate(space, name, MACH_PORT_RIGHT_PORT_SET, &psobj);
                if (kr != KERN_SUCCESS) {
                        kmem_free(ipc_kernel_map, addr, size);
                        return kr;
                }

                /* just use a portset reference from here on out */
                pset = ips_object_to_pset(psobj);
                ips_reference(pset);
                ips_unlock(pset);

                names = (mach_port_name_t *) addr;
                maxnames = (ipc_entry_num_t)(size / sizeof(mach_port_name_t));

                ipc_mqueue_set_gather_member_names(space, &pset->ips_messages, maxnames, names, &actual);

                /* release the portset reference */
                ips_release(pset);

                if (actual <= maxnames) {
                        break;
                }

                /* didn't have enough memory; allocate more */
                kmem_free(ipc_kernel_map, addr, size);
                size = vm_map_round_page(
                        (actual * sizeof(mach_port_name_t)),
                        VM_MAP_PAGE_MASK(ipc_kernel_map)) +
                    VM_MAP_PAGE_SIZE(ipc_kernel_map);
        }

        if (actual == 0) {
                memory = VM_MAP_COPY_NULL;

                kmem_free(ipc_kernel_map, addr, size);
        } else {
                vm_size_t size_used;
                vm_size_t vm_size_used;

                size_used = actual * sizeof(mach_port_name_t);
                vm_size_used = vm_map_round_page(
                        size_used,
                        VM_MAP_PAGE_MASK(ipc_kernel_map));

                /*
                 *      Make used memory pageable and get it into
                 *      copied-in form.  Free any unused memory.
                 */

                kr = vm_map_unwire(
                        ipc_kernel_map,
                        vm_map_trunc_page(addr,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        vm_map_round_page(addr + vm_size_used,
                        VM_MAP_PAGE_MASK(ipc_kernel_map)),
                        FALSE);
                assert(kr == KERN_SUCCESS);

                kr = vm_map_copyin(ipc_kernel_map, (vm_map_address_t)addr,
                    (vm_map_size_t)size_used, TRUE, &memory);
                assert(kr == KERN_SUCCESS);

                if (vm_size_used != size) {
                        kmem_free(ipc_kernel_map,
                            addr + vm_size_used, size - vm_size_used);
                }
        }

        *members = (mach_port_name_t *) memory;
        *membersCnt = actual;
        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_move_member [kernel call]
 *      Purpose:
 *              If after is MACH_PORT_NULL, removes member
 *              from the port set it is in.  Otherwise, adds
 *              member to after, removing it from any set
 *              it might already be in.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Moved the port.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       Member didn't denote a right.
 *              KERN_INVALID_RIGHT      Member didn't denote a receive right.
 *              KERN_INVALID_NAME       After didn't denote a right.
 *              KERN_INVALID_RIGHT      After didn't denote a port set right.
 *              KERN_NOT_IN_SET
 *                      After is MACH_PORT_NULL and Member isn't in a port set.
 */

kern_return_t
mach_port_move_member(
        ipc_space_t             space,
        mach_port_name_t        member,
        mach_port_name_t        after)
{
        ipc_object_t port_obj, ps_obj;
        ipc_port_t port;
        ipc_pset_t nset = IPS_NULL;
        kern_return_t kr;
        uint64_t wq_link_id = 0;
        uint64_t wq_reserved_prepost = 0;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(member)) {
                return KERN_INVALID_RIGHT;
        }

        if (after == MACH_PORT_DEAD) {
                return KERN_INVALID_RIGHT;
        } else if (after == MACH_PORT_NULL) {
                wq_link_id = 0;
        } else {
                /*
                 * We reserve both a link, and
                 * enough prepost objects to complete
                 * the set move atomically - we can't block
                 * while we're holding the space lock, and
                 * the ipc_pset_add calls ipc_mqueue_add
                 * which may have to prepost this port onto
                 * this set.
                 */
                wq_link_id = waitq_link_reserve(NULL);
                wq_reserved_prepost = waitq_prepost_reserve(NULL, 10,
                    WAITQ_DONT_LOCK);
                kr = ipc_pset_lazy_allocate(space, after);
                if (kr != KERN_SUCCESS) {
                        goto done;
                }
        }

        if (after != MACH_PORT_NULL) {
                kr = ipc_object_translate_two(space,
                    member, MACH_PORT_RIGHT_RECEIVE, &port_obj,
                    after, MACH_PORT_RIGHT_PORT_SET, &ps_obj);
        } else {
                kr = ipc_object_translate(space,
                    member, MACH_PORT_RIGHT_RECEIVE, &port_obj);
        }
        if (kr != KERN_SUCCESS) {
                goto done;
        }

        port = ip_object_to_port(port_obj);
        if (after != MACH_PORT_NULL) {
                nset = ips_object_to_pset(ps_obj);
        }
        /* port and nset are locked */

        ipc_pset_remove_from_all(port);

        if (after != MACH_PORT_NULL) {
                kr = ipc_pset_add(nset, port, &wq_link_id, &wq_reserved_prepost);
                ips_unlock(nset);
        }

        ip_unlock(port);

done:
        /*
         * on success the ipc_pset_add() will consume the wq_link_id
         * value (resetting it to 0), so this function is always safe to call.
         */
        waitq_link_release(wq_link_id);
        waitq_prepost_release_reserve(wq_reserved_prepost);

        return kr;
}

/*
 *      Routine:        mach_port_request_notification [kernel call]
 *      Purpose:
 *              Requests a notification.  The caller supplies
 *              a send-once right for the notification to use,
 *              and the call returns the previously registered
 *              send-once right, if any.  Possible types:
 *
 *              MACH_NOTIFY_PORT_DESTROYED
 *                      Requests a port-destroyed notification
 *                      for a receive right.  Sync should be zero.
 *              MACH_NOTIFY_NO_SENDERS
 *                      Requests a no-senders notification for a
 *                      receive right.  If there are currently no
 *                      senders, sync is less than or equal to the
 *                      current make-send count, and a send-once right
 *                      is supplied, then an immediate no-senders
 *                      notification is generated.
 *              MACH_NOTIFY_DEAD_NAME
 *                      Requests a dead-name notification for a send
 *                      or receive right.  If the name is already a
 *                      dead name, sync is non-zero, and a send-once
 *                      right is supplied, then an immediate dead-name
 *                      notification is generated.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Requested a notification.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      Bad id value.
 *              KERN_INVALID_NAME       Name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote appropriate right.
 *              KERN_INVALID_CAPABILITY The notify port is dead.
 *      MACH_NOTIFY_PORT_DESTROYED:
 *              KERN_INVALID_VALUE      Sync isn't zero.
 *              KERN_FAILURE            Re-registering for this notification
 *      MACH_NOTIFY_DEAD_NAME:
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *              KERN_INVALID_ARGUMENT   Name denotes dead name, but
 *                      sync is zero or notify is IP_NULL.
 *              KERN_UREFS_OVERFLOW     Name denotes dead name, but
 *                      generating immediate notif. would overflow urefs.
 */

kern_return_t
mach_port_request_notification(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_msg_id_t           id,
        mach_port_mscount_t     sync,
        ipc_port_t              notify,
        ipc_port_t              *previousp)
{
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (notify == IP_DEAD) {
                return KERN_INVALID_CAPABILITY;
        }

#if     NOTYET
        /*
         *      Requesting notifications on RPC ports is an error.
         */
        {
                ipc_port_t port;
                ipc_entry_t entry;

                kr = ipc_right_lookup_write(space, name, &entry);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }

                port = ip_object_to_port(entry->ie_object);

                if (port->ip_subsystem != NULL) {
                        is_write_unlock(space);
                        panic("mach_port_request_notification: on RPC port!!");
                        return KERN_INVALID_CAPABILITY;
                }
                is_write_unlock(space);
        }
#endif  /* NOTYET */


        switch (id) {
        case MACH_NOTIFY_PORT_DESTROYED: {
                ipc_port_t port;

                if (sync != 0) {
                        return KERN_INVALID_VALUE;
                }

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                /* you cannot register for port death notifications on a kobject */
                if (ip_kotype(port) != IKOT_NONE) {
                        ip_unlock(port);
                        return KERN_INVALID_RIGHT;
                }

                /* Allow only one registeration of this notification */
                if (port->ip_pdrequest != IP_NULL) {
                        ip_unlock(port);
                        mach_port_guard_exception(name, 0, 0, kGUARD_EXC_KERN_FAILURE);
                        return KERN_FAILURE;
                }

                ipc_port_pdrequest(port, notify, previousp);
                /* port is unlocked */
                assert(*previousp == IP_NULL);
                break;
        }

        case MACH_NOTIFY_NO_SENDERS: {
                ipc_port_t port;

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                ipc_port_nsrequest(port, sync, notify, previousp);
                /* port is unlocked */
                break;
        }

        case MACH_NOTIFY_SEND_POSSIBLE:

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_ARGUMENT;
                }

                kr = ipc_right_request_alloc(space, name, sync != 0,
                    TRUE, notify, previousp);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                break;

        case MACH_NOTIFY_DEAD_NAME:

                if (!MACH_PORT_VALID(name)) {
                        /*
                         * Already dead.
                         * Should do immediate delivery check -
                         * will do that in the near future.
                         */
                        return KERN_INVALID_ARGUMENT;
                }

                kr = ipc_right_request_alloc(space, name, sync != 0,
                    FALSE, notify, previousp);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                break;

        default:
                return KERN_INVALID_VALUE;
        }

        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_insert_right [kernel call]
 *      Purpose:
 *              Inserts a right into a space, as if the space
 *              voluntarily received the right in a message,
 *              except that the right gets the specified name.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Inserted the right.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      The name isn't a legal name.
 *              KERN_NAME_EXISTS        The name already denotes a right.
 *              KERN_INVALID_VALUE      Message doesn't carry a port right.
 *              KERN_INVALID_CAPABILITY Port is null or dead.
 *              KERN_UREFS_OVERFLOW     Urefs limit would be exceeded.
 *              KERN_RIGHT_EXISTS       Space has rights under another name.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 */

kern_return_t
mach_port_insert_right(
        ipc_space_t                     space,
        mach_port_name_t                name,
        ipc_port_t                      poly,
        mach_msg_type_name_t            polyPoly)
{
        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name) ||
            !MACH_MSG_TYPE_PORT_ANY_RIGHT(polyPoly)) {
                return KERN_INVALID_VALUE;
        }

        if (!IP_VALID(poly)) {
                return KERN_INVALID_CAPABILITY;
        }

        return ipc_object_copyout_name(space, ip_to_object(poly),
                   polyPoly, name);
}

/*
 *      Routine:        mach_port_extract_right [kernel call]
 *      Purpose:
 *              Extracts a right from a space, as if the space
 *              voluntarily sent the right to the caller.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Extracted the right.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_VALUE      Requested type isn't a port right.
 *              KERN_INVALID_NAME       Name doesn't denote a right.
 *              KERN_INVALID_RIGHT      Name doesn't denote appropriate right.
 */

kern_return_t
mach_port_extract_right(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_msg_type_name_t    msgt_name,
        ipc_port_t              *poly,
        mach_msg_type_name_t    *polyPoly)
{
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_MSG_TYPE_PORT_ANY(msgt_name)) {
                return KERN_INVALID_VALUE;
        }

        if (!MACH_PORT_VALID(name)) {
                /*
                 * really should copy out a dead name, if it is a send or
                 * send-once right being copied, but instead return an
                 * error for now.
                 */
                return KERN_INVALID_RIGHT;
        }

        kr = ipc_object_copyin(space, name, msgt_name, (ipc_object_t *) poly, 0, NULL,
            IPC_KMSG_FLAGS_ALLOW_IMMOVABLE_SEND);

        if (kr == KERN_SUCCESS) {
                *polyPoly = ipc_object_copyin_type(msgt_name);
        }
        return kr;
}

/*
 *      Routine:        mach_port_get_status_helper [helper]
 *      Purpose:
 *              Populates a mach_port_status_t structure with
 *              port information.
 *      Conditions:
 *              Port needs to be locked
 *      Returns:
 *              None.
 */
static void
mach_port_get_status_helper(
        ipc_port_t              port,
        mach_port_status_t      *statusp)
{
        imq_lock(&port->ip_messages);
        /* don't leak set IDs, just indicate that the port is in one or not */
        statusp->mps_pset = !!(port->ip_in_pset);
        statusp->mps_seqno = port->ip_messages.imq_seqno;
        statusp->mps_qlimit = port->ip_messages.imq_qlimit;
        statusp->mps_msgcount = port->ip_messages.imq_msgcount;
        imq_unlock(&port->ip_messages);

        statusp->mps_mscount = port->ip_mscount;
        statusp->mps_sorights = port->ip_sorights;
        statusp->mps_srights = port->ip_srights > 0;
        statusp->mps_pdrequest = port->ip_pdrequest != IP_NULL;
        statusp->mps_nsrequest = port->ip_nsrequest != IP_NULL;
        statusp->mps_flags = 0;
        if (port->ip_impdonation) {
                statusp->mps_flags |= MACH_PORT_STATUS_FLAG_IMP_DONATION;
                if (port->ip_tempowner) {
                        statusp->mps_flags |= MACH_PORT_STATUS_FLAG_TEMPOWNER;
                        if (IIT_NULL != port->ip_imp_task) {
                                statusp->mps_flags |= MACH_PORT_STATUS_FLAG_TASKPTR;
                        }
                }
        }
        if (port->ip_guarded) {
                statusp->mps_flags |= MACH_PORT_STATUS_FLAG_GUARDED;
                if (port->ip_strict_guard) {
                        statusp->mps_flags |= MACH_PORT_STATUS_FLAG_STRICT_GUARD;
                }
                if (port->ip_immovable_receive) {
                        statusp->mps_flags |= MACH_PORT_STATUS_FLAG_GUARD_IMMOVABLE_RECEIVE;
                }
        }
        if (port->ip_no_grant) {
                statusp->mps_flags |= MACH_PORT_STATUS_FLAG_NO_GRANT;
        }
        return;
}



kern_return_t
mach_port_get_attributes(
        ipc_space_t             space,
        mach_port_name_t        name,
        int                     flavor,
        mach_port_info_t        info,
        mach_msg_type_number_t  *count)
{
        ipc_port_t port;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        switch (flavor) {
        case MACH_PORT_LIMITS_INFO: {
                mach_port_limits_t *lp = (mach_port_limits_t *)info;

                if (*count < MACH_PORT_LIMITS_INFO_COUNT) {
                        return KERN_FAILURE;
                }

                if (!MACH_PORT_VALID(name)) {
                        *count = 0;
                        break;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                lp->mpl_qlimit = port->ip_messages.imq_qlimit;
                *count = MACH_PORT_LIMITS_INFO_COUNT;
                ip_unlock(port);
                break;
        }

        case MACH_PORT_RECEIVE_STATUS: {
                mach_port_status_t *statusp = (mach_port_status_t *)info;

                if (*count < MACH_PORT_RECEIVE_STATUS_COUNT) {
                        return KERN_FAILURE;
                }

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */
                mach_port_get_status_helper(port, statusp);
                *count = MACH_PORT_RECEIVE_STATUS_COUNT;
                ip_unlock(port);
                break;
        }

        case MACH_PORT_DNREQUESTS_SIZE: {
                ipc_port_request_t      table;

                if (*count < MACH_PORT_DNREQUESTS_SIZE_COUNT) {
                        return KERN_FAILURE;
                }

                if (!MACH_PORT_VALID(name)) {
                        *(int *)info = 0;
                        break;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                table = port->ip_requests;
                if (table == IPR_NULL) {
                        *(int *)info = 0;
                } else {
                        *(int *)info = table->ipr_size->its_size;
                }
                *count = MACH_PORT_DNREQUESTS_SIZE_COUNT;
                ip_unlock(port);
                break;
        }

        case MACH_PORT_INFO_EXT: {
                mach_port_info_ext_t *mp_info = (mach_port_info_ext_t *)info;
                if (*count < MACH_PORT_INFO_EXT_COUNT) {
                        return KERN_FAILURE;
                }

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */
                mach_port_get_status_helper(port, &mp_info->mpie_status);
                mp_info->mpie_boost_cnt = port->ip_impcount;
                *count = MACH_PORT_INFO_EXT_COUNT;
                ip_unlock(port);
                break;
        }

        default:
                return KERN_INVALID_ARGUMENT;
                /*NOTREACHED*/
        }

        return KERN_SUCCESS;
}

kern_return_t
mach_port_set_attributes(
        ipc_space_t             space,
        mach_port_name_t        name,
        int                     flavor,
        mach_port_info_t        info,
        mach_msg_type_number_t  count)
{
        ipc_port_t port;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        switch (flavor) {
        case MACH_PORT_LIMITS_INFO: {
                mach_port_limits_t *mplp = (mach_port_limits_t *)info;

                if (count < MACH_PORT_LIMITS_INFO_COUNT) {
                        return KERN_FAILURE;
                }

                if (mplp->mpl_qlimit > MACH_PORT_QLIMIT_MAX) {
                        return KERN_INVALID_VALUE;
                }

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                ipc_mqueue_set_qlimit(&port->ip_messages, mplp->mpl_qlimit);
                ip_unlock(port);
                break;
        }
        case MACH_PORT_DNREQUESTS_SIZE: {
                if (count < MACH_PORT_DNREQUESTS_SIZE_COUNT) {
                        return KERN_FAILURE;
                }

                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                kr = ipc_port_request_grow(port, *(int *)info);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                break;
        }
        case MACH_PORT_TEMPOWNER:
                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                ipc_importance_task_t release_imp_task = IIT_NULL;
                natural_t assertcnt = 0;

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }
                /* port is locked and active */

                /*
                 * don't allow temp-owner importance donation if user
                 * associated it with a kobject already (timer, host_notify target),
                 * or is a special reply port.
                 */
                if (ip_is_kobject(port) || port->ip_specialreply) {
                        ip_unlock(port);
                        return KERN_INVALID_ARGUMENT;
                }

                if (port->ip_tempowner != 0) {
                        if (IIT_NULL != port->ip_imp_task) {
                                release_imp_task = port->ip_imp_task;
                                port->ip_imp_task = IIT_NULL;
                                assertcnt = port->ip_impcount;
                        }
                } else {
                        assertcnt = port->ip_impcount;
                }

                port->ip_impdonation = 1;
                port->ip_tempowner = 1;
                ip_unlock(port);

#if IMPORTANCE_INHERITANCE
                /* drop assertions from previous destination task */
                if (release_imp_task != IIT_NULL) {
                        assert(ipc_importance_task_is_any_receiver_type(release_imp_task));
                        if (assertcnt > 0) {
                                ipc_importance_task_drop_internal_assertion(release_imp_task, assertcnt);
                        }
                        ipc_importance_task_release(release_imp_task);
                } else if (assertcnt > 0) {
                        release_imp_task = current_task()->task_imp_base;
                        if (release_imp_task != IIT_NULL &&
                            ipc_importance_task_is_any_receiver_type(release_imp_task)) {
                                ipc_importance_task_drop_internal_assertion(release_imp_task, assertcnt);
                        }
                }
#else
                if (release_imp_task != IIT_NULL) {
                        ipc_importance_task_release(release_imp_task);
                }
#endif /* IMPORTANCE_INHERITANCE */

                break;

#if IMPORTANCE_INHERITANCE
        case MACH_PORT_DENAP_RECEIVER:
        case MACH_PORT_IMPORTANCE_RECEIVER:
                if (!MACH_PORT_VALID(name)) {
                        return KERN_INVALID_RIGHT;
                }

                kr = ipc_port_translate_receive(space, name, &port);
                if (kr != KERN_SUCCESS) {
                        return kr;
                }

                /*
                 * don't allow importance donation if user associated
                 * it with a kobject already (timer, host_notify target),
                 * or is a special reply port.
                 */
                if (ip_is_kobject(port) || port->ip_specialreply) {
                        ip_unlock(port);
                        return KERN_INVALID_ARGUMENT;
                }

                /* port is locked and active */
                port->ip_impdonation = 1;
                ip_unlock(port);

                break;
#endif /* IMPORTANCE_INHERITANCE */

        default:
                return KERN_INVALID_ARGUMENT;
                /*NOTREACHED*/
        }
        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_insert_member [kernel call]
 *      Purpose:
 *              Add the receive right, specified by name, to
 *              a portset.
 *              The port cannot already be a member of the set.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Moved the port.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       name didn't denote a right.
 *              KERN_INVALID_RIGHT      name didn't denote a receive right.
 *              KERN_INVALID_NAME       pset_name didn't denote a right.
 *              KERN_INVALID_RIGHT      pset_name didn't denote a portset right.
 *              KERN_ALREADY_IN_SET     name was already a member of pset.
 */

kern_return_t
mach_port_insert_member(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_name_t        psname)
{
        ipc_object_t obj;
        ipc_object_t psobj;
        kern_return_t kr;
        uint64_t wq_link_id;
        uint64_t wq_reserved_prepost;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name) || !MACH_PORT_VALID(psname)) {
                return KERN_INVALID_RIGHT;
        }

        wq_link_id = waitq_link_reserve(NULL);
        wq_reserved_prepost = waitq_prepost_reserve(NULL, 10,
            WAITQ_DONT_LOCK);
        kr = ipc_pset_lazy_allocate(space, psname);
        if (kr != KERN_SUCCESS) {
                goto done;
        }


        kr = ipc_object_translate_two(space,
            name, MACH_PORT_RIGHT_RECEIVE, &obj,
            psname, MACH_PORT_RIGHT_PORT_SET, &psobj);
        if (kr != KERN_SUCCESS) {
                goto done;
        }

        /* obj and psobj are locked (and were locked in that order) */
        assert(psobj != IO_NULL);
        assert(obj != IO_NULL);

        kr = ipc_pset_add(ips_object_to_pset(psobj), ip_object_to_port(obj),
            &wq_link_id, &wq_reserved_prepost);

        io_unlock(psobj);
        io_unlock(obj);

done:
        /* on success, wq_link_id is reset to 0, so this is always safe */
        waitq_link_release(wq_link_id);
        waitq_prepost_release_reserve(wq_reserved_prepost);

        return kr;
}

/*
 *      Routine:        mach_port_extract_member [kernel call]
 *      Purpose:
 *              Remove a port from one portset that it is a member of.
 *      Conditions:
 *              Nothing locked.
 *      Returns:
 *              KERN_SUCCESS            Moved the port.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       Member didn't denote a right.
 *              KERN_INVALID_RIGHT      Member didn't denote a receive right.
 *              KERN_INVALID_NAME       After didn't denote a right.
 *              KERN_INVALID_RIGHT      After didn't denote a port set right.
 *              KERN_NOT_IN_SET
 *                      After is MACH_PORT_NULL and Member isn't in a port set.
 */

kern_return_t
mach_port_extract_member(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_name_t        psname)
{
        ipc_object_t psobj;
        ipc_object_t obj;
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name) || !MACH_PORT_VALID(psname)) {
                return KERN_INVALID_RIGHT;
        }

        kr = ipc_object_translate_two(space,
            name, MACH_PORT_RIGHT_RECEIVE, &obj,
            psname, MACH_PORT_RIGHT_PORT_SET, &psobj);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* obj and psobj are both locked (and were locked in that order) */
        assert(psobj != IO_NULL);
        assert(obj != IO_NULL);

        kr = ipc_pset_remove(ips_object_to_pset(psobj), ip_object_to_port(obj));

        io_unlock(psobj);
        io_unlock(obj);

        return kr;
}

/*
 *      task_set_port_space:
 *
 *      Set port name space of task to specified size.
 */
kern_return_t
task_set_port_space(
        ipc_space_t     space,
        int             table_entries)
{
        kern_return_t kr;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        is_write_lock(space);

        if (!is_active(space)) {
                is_write_unlock(space);
                return KERN_INVALID_TASK;
        }

        kr = ipc_entry_grow_table(space, table_entries);
        if (kr == KERN_SUCCESS) {
                is_write_unlock(space);
        }
        return kr;
}

/*
 *      Routine:        mach_port_guard_locked [helper routine]
 *      Purpose:
 *              Sets a new guard for a locked port.
 *      Conditions:
 *              Port Locked.
 *      Returns:
 *              KERN_SUCCESS            Port Guarded.
 *              KERN_INVALID_ARGUMENT   Port already contains a context/guard.
 */
static kern_return_t
mach_port_guard_locked(
        ipc_port_t              port,
        uint64_t                guard,
        uint64_t                flags)
{
        if (port->ip_context) {
                return KERN_INVALID_ARGUMENT;
        }

        int strict = (flags & MPG_STRICT)? 1 : 0;
        int immovable_receive = (flags & MPG_IMMOVABLE_RECEIVE)? 1 : 0;

        imq_lock(&port->ip_messages);
        port->ip_context = guard;
        port->ip_guarded = 1;
        port->ip_strict_guard = strict;
        /* ip_immovable_receive bit is sticky and can't be un-guarded */
        if (!port->ip_immovable_receive) {
                port->ip_immovable_receive = immovable_receive;
        }
        imq_unlock(&port->ip_messages);

        return KERN_SUCCESS;
}

/*
 *      Routine:        mach_port_unguard_locked [helper routine]
 *      Purpose:
 *              Removes guard for a locked port.
 *      Conditions:
 *              Port Locked.
 *      Returns:
 *              KERN_SUCCESS            Port Unguarded.
 *              KERN_INVALID_ARGUMENT   Port is either unguarded already or guard mismatch.
 *                                      This also raises a EXC_GUARD exception.
 */
static kern_return_t
mach_port_unguard_locked(
        ipc_port_t              port,
        mach_port_name_t        name,
        uint64_t                guard)
{
        /* Port locked and active */
        if (!port->ip_guarded) {
                /* Port already unguarded; Raise exception */
                mach_port_guard_exception(name, guard, 0, kGUARD_EXC_UNGUARDED);
                return KERN_INVALID_ARGUMENT;
        }

        if (port->ip_context != guard) {
                /* Incorrect guard; Raise exception */
                mach_port_guard_exception(name, guard, port->ip_context, kGUARD_EXC_INCORRECT_GUARD);
                return KERN_INVALID_ARGUMENT;
        }

        imq_lock(&port->ip_messages);
        port->ip_context = 0;
        port->ip_guarded = port->ip_strict_guard = 0;
        /* Don't clear the ip_immovable_receive bit */
        imq_unlock(&port->ip_messages);

        return KERN_SUCCESS;
}


/*
 *      Routine:        mach_port_guard_exception [helper routine]
 *      Purpose:
 *              Marks the thread with AST_GUARD for mach port guard violation.
 *              Also saves exception info in thread structure.
 *      Conditions:
 *              None.
 *      Returns:
 *              KERN_FAILURE            Thread marked with AST_GUARD.
 */
void
mach_port_guard_exception(
        mach_port_name_t        name,
        __unused uint64_t       inguard,
        uint64_t                        portguard,
        unsigned                        reason)
{
        mach_exception_code_t code = 0;
        EXC_GUARD_ENCODE_TYPE(code, GUARD_TYPE_MACH_PORT);
        EXC_GUARD_ENCODE_FLAVOR(code, reason);
        EXC_GUARD_ENCODE_TARGET(code, name);
        mach_exception_subcode_t subcode = (uint64_t)portguard;
        thread_t t = current_thread();
        boolean_t fatal = FALSE;
        if (t->task->task_exc_guard & TASK_EXC_GUARD_MP_FATAL) {
                fatal = TRUE;
        } else if (reason <= MAX_FATAL_kGUARD_EXC_CODE) {
                fatal = TRUE;
        }
        thread_guard_violation(t, code, subcode, fatal);
}


/*
 *      Routine:        mach_port_guard_ast
 *      Purpose:
 *              Raises an exception for mach port guard violation.
 *      Conditions:
 *              None.
 *      Returns:
 *              None.
 */

void
mach_port_guard_ast(thread_t t,
    mach_exception_data_type_t code, mach_exception_data_type_t subcode)
{
        unsigned int reason = EXC_GUARD_DECODE_GUARD_FLAVOR(code);
        task_t task = t->task;
        unsigned int behavior = task->task_exc_guard;
        assert(task == current_task());
        assert(task != kernel_task);

        switch (reason) {
        /*
         * Fatal Mach port guards - always delivered synchronously
         */
        case kGUARD_EXC_DESTROY:
        case kGUARD_EXC_MOD_REFS:
        case kGUARD_EXC_SET_CONTEXT:
        case kGUARD_EXC_UNGUARDED:
        case kGUARD_EXC_INCORRECT_GUARD:
        case kGUARD_EXC_IMMOVABLE:
        case kGUARD_EXC_STRICT_REPLY:
                task_exception_notify(EXC_GUARD, code, subcode);
                task_bsdtask_kill(task);
                break;

        default:
                /*
                 * Mach port guards controlled by task settings.
                 */

                /* Is delivery enabled */
                if ((behavior & TASK_EXC_GUARD_MP_DELIVER) == 0) {
                        return;
                }

                /* If only once, make sure we're that once */
                while (behavior & TASK_EXC_GUARD_MP_ONCE) {
                        uint32_t new_behavior = behavior & ~TASK_EXC_GUARD_MP_DELIVER;

                        if (OSCompareAndSwap(behavior, new_behavior, &task->task_exc_guard)) {
                                break;
                        }
                        behavior = task->task_exc_guard;
                        if ((behavior & TASK_EXC_GUARD_MP_DELIVER) == 0) {
                                return;
                        }
                }

                /* Raise exception via corpse fork or synchronously */
                if ((task->task_exc_guard & TASK_EXC_GUARD_MP_CORPSE) &&
                    (task->task_exc_guard & TASK_EXC_GUARD_MP_FATAL) == 0) {
                        task_violated_guard(code, subcode, NULL);
                } else {
                        task_exception_notify(EXC_GUARD, code, subcode);
                }

                /* Terminate the task if desired */
                if (task->task_exc_guard & TASK_EXC_GUARD_MP_FATAL) {
                        task_bsdtask_kill(task);
                }
                break;
        }
}

/*
 *      Routine:        mach_port_construct [kernel call]
 *      Purpose:
 *              Constructs a mach port with the provided set of options.
 *      Conditions:
 *              None.
 *      Returns:
 *              KERN_SUCCESS            The right is allocated.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_RESOURCE_SHORTAGE  Couldn't allocate memory.
 *              KERN_NO_SPACE           No room in space for another right.
 *              KERN_FAILURE            Illegal option values requested.
 */

kern_return_t
mach_port_construct(
        ipc_space_t             space,
        mach_port_options_t     *options,
        uint64_t                context,
        mach_port_name_t        *name)
{
        kern_return_t           kr;
        ipc_port_t              port;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        /* Allocate a new port in the IPC space */
        kr = ipc_port_alloc(space, (options->flags & MPO_INSERT_SEND_RIGHT),
            name, &port);
        if (kr != KERN_SUCCESS) {
                return kr;
        }

        /* Port locked and active */
        if (options->flags & MPO_CONTEXT_AS_GUARD) {
                uint64_t flags = 0;
                if (options->flags & MPO_STRICT) {
                        flags |= MPG_STRICT;
                }
                if (options->flags & MPO_IMMOVABLE_RECEIVE) {
                        flags |= MPG_IMMOVABLE_RECEIVE;
                }
                kr = mach_port_guard_locked(port, (uint64_t) context, flags);
                /* A newly allocated and locked port should always be guarded successfully */
                assert(kr == KERN_SUCCESS);
        } else {
                port->ip_context = context;
        }

        /* Unlock port */
        ip_unlock(port);

        /* Set port attributes as requested */

        if (options->flags & MPO_QLIMIT) {
                kr = mach_port_set_attributes(space, *name, MACH_PORT_LIMITS_INFO,
                    (mach_port_info_t)&options->mpl, sizeof(options->mpl) / sizeof(int));
                if (kr != KERN_SUCCESS) {
                        goto cleanup;
                }
        }

        if (options->flags & MPO_TEMPOWNER) {
                kr = mach_port_set_attributes(space, *name, MACH_PORT_TEMPOWNER, NULL, 0);
                if (kr != KERN_SUCCESS) {
                        goto cleanup;
                }
        }

        if (options->flags & MPO_IMPORTANCE_RECEIVER) {
                kr = mach_port_set_attributes(space, *name, MACH_PORT_IMPORTANCE_RECEIVER, NULL, 0);
                if (kr != KERN_SUCCESS) {
                        goto cleanup;
                }
        }

        if (options->flags & MPO_DENAP_RECEIVER) {
                kr = mach_port_set_attributes(space, *name, MACH_PORT_DENAP_RECEIVER, NULL, 0);
                if (kr != KERN_SUCCESS) {
                        goto cleanup;
                }
        }

        return KERN_SUCCESS;

cleanup:
        /* Attempt to destroy port. If its already destroyed by some other thread, we're done */
        (void) mach_port_destruct(space, *name,
            (options->flags & MPO_INSERT_SEND_RIGHT) ? -1 : 0, context);
        return kr;
}

/*
 *      Routine:        mach_port_destruct [kernel call]
 *      Purpose:
 *              Destroys a mach port with appropriate guard
 *      Conditions:
 *              None.
 *      Returns:
 *              KERN_SUCCESS            The name is destroyed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      The right isn't correct.
 *              KERN_INVALID_VALUE      The delta for send right is incorrect.
 *              KERN_INVALID_ARGUMENT   Port is either unguarded already or guard mismatch.
 *                                      This also raises a EXC_GUARD exception.
 */

kern_return_t
mach_port_destruct(
        ipc_space_t             space,
        mach_port_name_t        name,
        mach_port_delta_t       srdelta,
        uint64_t                guard)
{
        kern_return_t           kr;
        ipc_entry_t             entry;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_NAME;
        }

        /* Remove reference for receive right */
        kr = ipc_right_lookup_write(space, name, &entry);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_NAME);
                return kr;
        }
        /* space is write-locked and active */
        kr = ipc_right_destruct(space, name, entry, srdelta, guard);    /* unlocks */

        return kr;
}

/*
 *      Routine:        mach_port_guard [kernel call]
 *      Purpose:
 *              Guard a mach port with specified guard value.
 *              The context field of the port is used as the guard.
 *      Conditions:
 *              None.
 *      Returns:
 *              KERN_SUCCESS            The name is destroyed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      The right isn't correct.
 *              KERN_INVALID_ARGUMENT   Port already contains a context/guard.
 */
kern_return_t
mach_port_guard(
        ipc_space_t             space,
        mach_port_name_t        name,
        uint64_t                guard,
        boolean_t               strict)
{
        kern_return_t           kr;
        ipc_port_t              port;
        uint64_t flags = 0;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_NAME;
        }

        /* Guard can be applied only to receive rights */
        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0,
                    ((KERN_INVALID_NAME == kr) ?
                    kGUARD_EXC_INVALID_NAME :
                    kGUARD_EXC_INVALID_RIGHT));
                return kr;
        }

        /* Port locked and active */
        if (strict) {
                flags = MPG_STRICT;
        }

        kr = mach_port_guard_locked(port, guard, flags);
        ip_unlock(port);

        if (KERN_INVALID_ARGUMENT == kr) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_ARGUMENT);
        }

        return kr;
}

/*
 *      Routine:        mach_port_unguard [kernel call]
 *      Purpose:
 *              Unguard a mach port with specified guard value.
 *      Conditions:
 *              None.
 *      Returns:
 *              KERN_SUCCESS            The name is destroyed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      The right isn't correct.
 *              KERN_INVALID_ARGUMENT   Port is either unguarded already or guard mismatch.
 *                                      This also raises a EXC_GUARD exception.
 */
kern_return_t
mach_port_unguard(
        ipc_space_t             space,
        mach_port_name_t        name,
        uint64_t                guard)
{
        kern_return_t           kr;
        ipc_port_t              port;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_NAME;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0,
                    ((KERN_INVALID_NAME == kr) ?
                    kGUARD_EXC_INVALID_NAME :
                    kGUARD_EXC_INVALID_RIGHT));
                return kr;
        }

        /* Port locked and active */
        kr = mach_port_unguard_locked(port, name, guard);
        ip_unlock(port);

        return kr;
}

/*
 *      Routine:        mach_port_guard_with_flags [kernel call]
 *      Purpose:
 *              Guard a mach port with specified guard value and guard flags.
 *              The context field of the port is used as the guard.
 *      Conditions:
 *              Should hold receive right for that port
 *      Returns:
 *              KERN_SUCCESS            The name is destroyed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      The right isn't correct.
 *              KERN_INVALID_ARGUMENT   Port already contains a context/guard.
 *              KERN_INVALID_CAPABILITY Cannot set MPG_IMMOVABLE_RECEIVE flag for a port with
 *                                      a movable port-destroyed notification port
 */
kern_return_t
mach_port_guard_with_flags(
        ipc_space_t             space,
        mach_port_name_t        name,
        uint64_t                guard,
        uint64_t                flags)
{
        kern_return_t           kr;
        ipc_port_t              port;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_NAME;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0,
                    ((KERN_INVALID_NAME == kr) ?
                    kGUARD_EXC_INVALID_NAME :
                    kGUARD_EXC_INVALID_RIGHT));
                return kr;
        }

        /* Port locked and active */
        kr = mach_port_guard_locked(port, guard, flags);
        ip_unlock(port);

        if (KERN_INVALID_ARGUMENT == kr) {
                mach_port_guard_exception(name, 0, 0, kGUARD_EXC_INVALID_ARGUMENT);
        }

        return kr;
}

/*
 *      Routine:        mach_port_swap_guard [kernel call]
 *      Purpose:
 *              Swap guard value.
 *      Conditions:
 *              Port should already be guarded.
 *      Returns:
 *              KERN_SUCCESS            The name is destroyed.
 *              KERN_INVALID_TASK       The space is null.
 *              KERN_INVALID_TASK       The space is dead.
 *              KERN_INVALID_NAME       The name doesn't denote a right.
 *              KERN_INVALID_RIGHT      The right isn't correct.
 *              KERN_INVALID_ARGUMENT   Port doesn't contain a guard; is strictly guarded
 *                                      or the old_guard doesnt match the context
 */
kern_return_t
mach_port_swap_guard(
        ipc_space_t             space,
        mach_port_name_t        name,
        uint64_t                old_guard,
        uint64_t                new_guard)
{
        kern_return_t           kr;
        ipc_port_t              port;

        if (space == IS_NULL) {
                return KERN_INVALID_TASK;
        }

        if (!MACH_PORT_VALID(name)) {
                return KERN_INVALID_NAME;
        }

        kr = ipc_port_translate_receive(space, name, &port);
        if (kr != KERN_SUCCESS) {
                mach_port_guard_exception(name, 0, 0,
                    ((KERN_INVALID_NAME == kr) ?
                    kGUARD_EXC_INVALID_NAME :
                    kGUARD_EXC_INVALID_RIGHT));
                return kr;
        }

        /* Port locked and active */
        if (!port->ip_guarded) {
                ip_unlock(port);
                mach_port_guard_exception(name, old_guard, 0, kGUARD_EXC_UNGUARDED);
                return KERN_INVALID_ARGUMENT;
        }

        if (port->ip_strict_guard) {
                uint64_t portguard = port->ip_context;
                ip_unlock(port);
                /* For strictly guarded ports, disallow overwriting context; Raise Exception */
                mach_port_guard_exception(name, old_guard, portguard, kGUARD_EXC_SET_CONTEXT);
                return KERN_INVALID_ARGUMENT;
        }

        if (port->ip_context != old_guard) {
                uint64_t portguard = port->ip_context;
                ip_unlock(port);
                mach_port_guard_exception(name, old_guard, portguard, kGUARD_EXC_INCORRECT_GUARD);
                return KERN_INVALID_ARGUMENT;
        }

        imq_lock(&port->ip_messages);
        port->ip_context = new_guard;
        imq_unlock(&port->ip_messages);

        ip_unlock(port);

        return KERN_SUCCESS;
}