1/*
2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/*
29 * @OSF_COPYRIGHT@
30 *
31 */
32
33#include <kern/sync_sema.h>
34#include <kern/sync_lock.h>
35#include <kern/ipc_kobject.h>
36#include <kern/ipc_sync.h>
37#include <ipc/port.h>
38#include <ipc/ipc_space.h>
39#include <ipc/ipc_port.h>
40#include <mach/mach_types.h>
41#include <mach/semaphore.h>
42#include <mach/lock_set_server.h>
43#include <mach/mach_port_server.h>
44#include <mach/port.h>
45
46
47/*
48 * Routine: port_name_to_semaphore
49 * Purpose:
50 * Convert from a port name in the current space to a semaphore.
51 * Produces a semaphore ref, which may be null.
52 * Conditions:
53 * Nothing locked.
54 */
55kern_return_t
56port_name_to_semaphore(
57 mach_port_name_t name,
58 semaphore_t *semaphorep)
59{
60 ipc_port_t kern_port;
61 kern_return_t kr;
62
63 if (!MACH_PORT_VALID(name)) {
64 *semaphorep = SEMAPHORE_NULL;
65 return KERN_INVALID_NAME;
66 }
67
68 kr = ipc_object_translate(current_space(), name, MACH_PORT_RIGHT_SEND,
69 (ipc_object_t *) &kern_port);
70 if (kr != KERN_SUCCESS) {
71 *semaphorep = SEMAPHORE_NULL;
72 return kr;
73 }
74 /* have the port locked */
75 assert(IP_VALID(kern_port));
76
77 *semaphorep = convert_port_to_semaphore(kern_port);
78 if (*semaphorep == SEMAPHORE_NULL) {
79 /* the port is valid, but doesn't denote a semaphore */
80 kr = KERN_INVALID_CAPABILITY;
81 } else {
82 kr = KERN_SUCCESS;
83 }
84 ip_unlock(kern_port);
85
86 return kr;
87}
88
89/*
90 * Routine: convert_port_to_semaphore
91 * Purpose:
92 * Convert from a port to a semaphore.
93 * Doesn't consume the port [send-right] ref;
94 * produces a semaphore ref, which may be null.
95 * Conditions:
96 * Caller has a send-right reference to port.
97 * Port may or may not be locked.
98 */
99semaphore_t
100convert_port_to_semaphore (ipc_port_t port)
101{
102
103 if (IP_VALID(port)) {
104 semaphore_t semaphore;
105
106 /*
107 * No need to lock because we have a reference on the
108 * port, and if it is a true semaphore port, that reference
109 * keeps the semaphore bound to the port (and active).
110 */
111 if (ip_kotype(port) == IKOT_SEMAPHORE) {
112 assert(ip_active(port));
113 semaphore = (semaphore_t) port->ip_kobject;
114 semaphore_reference(semaphore);
115 return (semaphore);
116 }
117 }
118 return SEMAPHORE_NULL;
119}
120
121
122/*
123 * Routine: convert_semaphore_to_port
124 * Purpose:
125 * Convert a semaphore reference to a send right to a
126 * semaphore port.
127 *
128 * Consumes the semaphore reference. If the semaphore
129 * port currently has no send rights (or doesn't exist
130 * yet), the reference is donated to the port to represent
131 * all extant send rights collectively.
132 */
133ipc_port_t
134convert_semaphore_to_port (semaphore_t semaphore)
135{
136 ipc_port_t port, send;
137
138 if (semaphore == SEMAPHORE_NULL)
139 return (IP_NULL);
140
141 /* caller is donating a reference */
142 port = semaphore->port;
143
144 if (!IP_VALID(port)) {
145 port = ipc_port_alloc_kernel();
146 assert(IP_VALID(port));
147 ipc_kobject_set_atomically(port, (ipc_kobject_t) semaphore, IKOT_SEMAPHORE);
148
149 /* If we lose the race, deallocate and pick up the other guy's port */
150 if (!OSCompareAndSwapPtr(IP_NULL, port, &semaphore->port)) {
151 ipc_port_dealloc_kernel(port);
152 port = semaphore->port;
153 assert(ip_kotype(port) == IKOT_SEMAPHORE);
154 assert(port->ip_kobject == (ipc_kobject_t)semaphore);
155 }
156 }
157
158 ip_lock(port);
159 assert(ip_active(port));
160 send = ipc_port_make_send_locked(port);
161
162 if (1 == port->ip_srights) {
163 ipc_port_t old_notify;
164
165 /* transfer our ref to the port, and arm the no-senders notification */
166 assert(IP_NULL == port->ip_nsrequest);
167 ipc_port_nsrequest(port, port->ip_mscount, ipc_port_make_sonce_locked(port), &old_notify);
168 /* port unlocked */
169 assert(IP_NULL == old_notify);
170 } else {
171 /* piggyback on the existing port reference, so consume ours */
172 ip_unlock(port);
173 semaphore_dereference(semaphore);
174 }
175 return (send);
176}
177
178/*
179 * Routine: semaphore_notify
180 * Purpose:
181 * Called whenever the Mach port system detects no-senders
182 * on the semaphore port.
183 *
184 * When a send-right is first created, a no-senders
185 * notification is armed (and a semaphore reference is donated).
186 *
187 * A no-senders notification will be posted when no one else holds a
188 * send-right (reference) to the semaphore's port. This notification function
189 * will consume the semaphore reference donated to the extant collection of
190 * send-rights.
191 */
192void
193semaphore_notify(mach_msg_header_t *msg)
194{
195 mach_no_senders_notification_t *notification = (void *)msg;
196 ipc_port_t port = notification->not_header.msgh_remote_port;
197 semaphore_t semaphore;
198
199 assert(ip_active(port));
200 assert(IKOT_SEMAPHORE == ip_kotype(port));
201 semaphore = (semaphore_t)port->ip_kobject;
202
203 semaphore_dereference(semaphore);
204}
205
206lock_set_t
207convert_port_to_lock_set (__unused ipc_port_t port)
208{
209 return (LOCK_SET_NULL);
210}
211
212ipc_port_t
213convert_lock_set_to_port (__unused lock_set_t lock_set)
214{
215 return (IP_NULL);
216}
217
218