Annotation of prex-old/sys/ipc/object.c, Revision 1.1.1.1
1.1 nbrk 1: /*-
2: * Copyright (c) 2005-2007, Kohsuke Ohtani
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. Neither the name of the author nor the names of any co-contributors
14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: */
29:
30: /*
31: * object.c - object service
32: */
33:
34: /*
35: * An object represents service, state, or policies etc. To manipulate
36: * objects, kernel provide 3 functions: create, delete, lookup.
37: * Prex task will create an object to provide its interface to other
38: * tasks. The tasks will communicate by sending a message to the object
39: * each other. For example, a server task creates some objects and client
40: * task will send a request message to it.
41: *
42: * A substance of object is stored in kernel space, and it is protected
43: * from user mode code. Each object data is managed with the hash table
44: * by using its name string. Usually, an object has a unique name within
45: * a system. Before a task sends a message to the specific object, it must
46: * obtain the object ID by looking up the name of the target object.
47: *
48: * An object can be created without its name. These object can be used as
49: * private objects that are used by threads in same task.
50: */
51:
52: #include <kernel.h>
53: #include <queue.h>
54: #include <kmem.h>
55: #include <sched.h>
56: #include <task.h>
57: #include <ipc.h>
58:
59: #define OBJ_MAXBUCKETS 32 /* Size of object hash buckets */
60:
61: /*
62: * Object hash table
63: *
64: * All objects are hashed by its name string. If an object has no
65: * name, it is linked to index zero.
66: * The scheduler must be locked when this table is touched.
67: */
68: static struct list obj_table[OBJ_MAXBUCKETS];
69:
70: /*
71: * Calculate the hash index for specified name string.
72: * The name can be NULL if the object does not have name.
73: */
74: static u_int
75: object_hash(const char *name)
76: {
77: u_int h = 0;
78:
79: if (name == NULL)
80: return 0;
81: while (*name)
82: h = ((h << 5) + h) + *name++;
83: return h & (OBJ_MAXBUCKETS - 1);
84: }
85:
86: /*
87: * Helper function to find the object from the specified name.
88: * Returns NULL if not found.
89: */
90: static object_t
91: object_find(const char *name)
92: {
93: list_t head, n;
94: object_t obj = NULL;
95:
96: head = &obj_table[object_hash(name)];
97: for (n = list_first(head); n != head; n = list_next(n)) {
98: obj = list_entry(n, struct object, name_link);
99: ASSERT(obj->magic == OBJECT_MAGIC);
100: if (!strncmp(obj->name, name, MAXOBJNAME))
101: break;
102: }
103: if (n == head)
104: return NULL;
105: return obj;
106: }
107:
108: /*
109: * Search an object in the object name space. The object name must
110: * be null-terminated string. The object ID is returned in obj
111: * on success.
112: */
113: int
114: object_lookup(const char *name, object_t *objp)
115: {
116: object_t obj;
117: size_t len;
118: char str[MAXOBJNAME];
119:
120: if (umem_strnlen(name, MAXOBJNAME, &len))
121: return EFAULT;
122: if (len == 0 || len >= MAXOBJNAME)
123: return ESRCH;
124: if (umem_copyin((void *)name, str, len + 1))
125: return EFAULT;
126:
127: sched_lock();
128: obj = object_find(str);
129: sched_unlock();
130:
131: if (obj == NULL)
132: return ENOENT;
133: if (umem_copyout(&obj, objp, sizeof(object_t)))
134: return EFAULT;
135: return 0;
136: }
137:
138: /*
139: * Create a new object.
140: *
141: * The ID of the new object is stored in pobj on success.
142: * The name of the object must be unique in the system. Or, the
143: * object can be created without name by setting NULL as name
144: * argument. This object can be used as a private object which
145: * can be accessed only by threads in same task.
146: */
147: int
148: object_create(const char *name, object_t *objp)
149: {
150: object_t obj = 0;
151: char str[MAXOBJNAME];
152: size_t len;
153:
154: if (name != NULL) {
155: if (umem_strnlen(name, MAXOBJNAME, &len))
156: return EFAULT;
157: if (len >= MAXOBJNAME)
158: return ENAMETOOLONG;
159: if (umem_copyin((void *)name, str, len + 1))
160: return EFAULT;
161: str[len] = '\0';
162: }
163: sched_lock();
164:
165: /*
166: * Check user buffer first. This can reduce the error
167: * recovery for the subsequence resource allocations.
168: */
169: if (umem_copyout(&obj, objp, sizeof(object_t))) {
170: sched_unlock();
171: return EFAULT;
172: }
173: if (object_find(str) != NULL) {
174: sched_unlock();
175: return EEXIST;
176: }
177: if ((obj = kmem_alloc(sizeof(struct object))) == NULL) {
178: sched_unlock();
179: return ENOMEM;
180: }
181: if (name != NULL)
182: strlcpy(obj->name, str, len + 1);
183:
184: queue_init(&obj->sendq);
185: queue_init(&obj->recvq);
186: obj->owner = cur_task();
187: obj->magic = OBJECT_MAGIC;
188: list_insert(&obj_table[object_hash(name)], &obj->name_link);
189: list_insert(&(cur_task()->objects), &obj->task_link);
190:
191: umem_copyout(&obj, objp, sizeof(object_t));
192: sched_unlock();
193: return 0;
194: }
195:
196: /*
197: * Destroy an object.
198: *
199: * A thread can delete the object only when the target object is
200: * created by the thread of the same task.
201: * All pending messages related to the deleted object are
202: * automatically canceled.
203: */
204: int
205: object_destroy(object_t obj)
206: {
207: int err = 0;
208:
209: sched_lock();
210: if (!object_valid(obj)) {
211: err = EINVAL;
212: }
213: else if (obj->owner != cur_task()) {
214: err = EACCES;
215: }
216: else {
217: obj->magic = 0;
218: msg_cancel(obj);
219: list_remove(&obj->task_link);
220: list_remove(&obj->name_link);
221: kmem_free(obj);
222: }
223: sched_unlock();
224: return err;
225: }
226:
227: #if defined(DEBUG) && defined(CONFIG_KDUMP)
228: void
229: object_dump(void)
230: {
231: int i;
232: list_t head, n;
233: object_t obj;
234:
235: printk("Object dump:\n");
236: printk(" object owner task name\n");
237: printk(" -------- ---------- ----------------\n");
238:
239: for (i = 0; i < OBJ_MAXBUCKETS; i++) {
240: head = &obj_table[i];
241: for (n = list_first(head); n != head; n = list_next(n)) {
242: obj = list_entry(n, struct object, name_link);
243: printk(" %08x %08x %s\n", obj, obj->owner,
244: (obj->name ? obj->name : "NoName"));
245: }
246: }
247: }
248: #endif
249:
250: void
251: object_init(void)
252: {
253: int i;
254:
255: for (i = 0; i < OBJ_MAXBUCKETS; i++)
256: list_init(&obj_table[i]);
257: }
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