[apple/xnu.git] / osfmk / kern / ipc_sync.c

/*
 * Copyright (c) 2000 Apple Computer, 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@
 *
 */

#include <kern/sync_sema.h>
#include <kern/sync_lock.h>
#include <kern/ipc_kobject.h>
#include <kern/ipc_sync.h>
#include <ipc/port.h>
#include <ipc/ipc_space.h>
#include <ipc/ipc_port.h>
#include <mach/mach_types.h>
#include <mach/semaphore.h>
#include <mach/lock_set_server.h>
#include <mach/mach_port_server.h>
#include <mach/port.h>


/*
 *      Routine:        port_name_to_semaphore
 *      Purpose:
 *              Convert from a port name in the current space to a semaphore.
 *              Produces a semaphore ref, which may be null.
 *      Conditions:
 *              Nothing locked.
 */
kern_return_t
port_name_to_semaphore(
        mach_port_name_t        name,
        semaphore_t             *semaphorep)
{
        ipc_port_t kern_port;
        kern_return_t kr;

        if (!MACH_PORT_VALID(name)) {
                *semaphorep = SEMAPHORE_NULL;
                return KERN_INVALID_NAME;
        }

        kr = ipc_port_translate_send(current_space(), name, &kern_port);
        if (kr != KERN_SUCCESS) {
                *semaphorep = SEMAPHORE_NULL;
                return kr;
        }
        /* have the port locked */
        assert(IP_VALID(kern_port));

        *semaphorep = convert_port_to_semaphore(kern_port);
        if (*semaphorep == SEMAPHORE_NULL) {
                /* the port is valid, but doesn't denote a semaphore */
                kr = KERN_INVALID_CAPABILITY;
        } else {
                kr = KERN_SUCCESS;
        }
        ip_unlock(kern_port);

        return kr;
}

/*
 *      Routine:        convert_port_to_semaphore
 *      Purpose:
 *              Convert from a port to a semaphore.
 *              Doesn't consume the port [send-right] ref;
 *              produces a semaphore ref, which may be null.
 *      Conditions:
 *              Caller has a send-right reference to port.
 *              Port may or may not be locked.
 */
semaphore_t
convert_port_to_semaphore(ipc_port_t port)
{
        if (IP_VALID(port)) {
                semaphore_t semaphore;

                /*
                 * No need to lock because we have a reference on the
                 * port, and if it is a true semaphore port, that reference
                 * keeps the semaphore bound to the port (and active).
                 */
                if (ip_kotype(port) == IKOT_SEMAPHORE) {
                        require_ip_active(port);
                        semaphore = (semaphore_t) ip_get_kobject(port);
                        semaphore_reference(semaphore);
                        return semaphore;
                }
        }
        return SEMAPHORE_NULL;
}


/*
 *      Routine:        convert_semaphore_to_port
 *      Purpose:
 *              Convert a semaphore reference to a send right to a
 *              semaphore port.
 *
 *              Consumes the semaphore reference.  If the semaphore
 *              port currently has no send rights (or doesn't exist
 *              yet), the reference is donated to the port to represent
 *              all extant send rights collectively.
 */
ipc_port_t
convert_semaphore_to_port(semaphore_t semaphore)
{
        if (semaphore == SEMAPHORE_NULL) {
                return IP_NULL;
        }

        /*
         * make a send right and donate our reference for
         * semaphore_notify if this is the first send right
         */
        if (!ipc_kobject_make_send_lazy_alloc_port(&semaphore->port,
            (ipc_kobject_t) semaphore, IKOT_SEMAPHORE, IPC_KOBJECT_ALLOC_NONE, false, 0)) {
                semaphore_dereference(semaphore);
        }
        return semaphore->port;
}

/*
 * Routine:     semaphore_notify
 * Purpose:
 *      Called whenever the Mach port system detects no-senders
 *      on the semaphore port.
 *
 *      When a send-right is first created, a no-senders
 *      notification is armed (and a semaphore reference is donated).
 *
 *      A no-senders notification will be posted when no one else holds a
 *      send-right (reference) to the semaphore's port. This notification function
 *      will consume the semaphore reference donated to the extant collection of
 *      send-rights.
 */
void
semaphore_notify(mach_msg_header_t *msg)
{
        mach_no_senders_notification_t *notification = (void *)msg;
        ipc_port_t port = notification->not_header.msgh_remote_port;

        require_ip_active(port);
        assert(IKOT_SEMAPHORE == ip_kotype(port));

        semaphore_dereference((semaphore_t) ip_get_kobject(port));
}

lock_set_t
convert_port_to_lock_set(__unused ipc_port_t port)
{
        return LOCK_SET_NULL;
}

ipc_port_t
convert_lock_set_to_port(__unused lock_set_t lock_set)
{
        return IP_NULL;
}