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 | */ |
55 | kern_return_t |
56 | port_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 | */ |
99 | semaphore_t |
100 | convert_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 | */ |
133 | ipc_port_t |
134 | convert_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 | */ |
192 | void |
193 | semaphore_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 | |
206 | lock_set_t |
207 | convert_port_to_lock_set (__unused ipc_port_t port) |
208 | { |
209 | return (LOCK_SET_NULL); |
210 | } |
211 | |
212 | ipc_port_t |
213 | convert_lock_set_to_port (__unused lock_set_t lock_set) |
214 | { |
215 | return (IP_NULL); |
216 | } |
217 | |
218 | |