Annotation of prex-old/sys/ipc/object.c, Revision 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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