Notify java agent of enabled application contexts
[lttng-tools.git] / src / bin / lttng-sessiond / session.c
1 /*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #define _LGPL_SOURCE
19 #include <limits.h>
20 #include <inttypes.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/stat.h>
25 #include <urcu.h>
26 #include <dirent.h>
27 #include <sys/types.h>
28
29 #include <common/common.h>
30 #include <common/sessiond-comm/sessiond-comm.h>
31
32 #include "session.h"
33
34 /*
35 * NOTES:
36 *
37 * No ltt_session.lock is taken here because those data structure are widely
38 * spread across the lttng-tools code base so before caling functions below
39 * that can read/write a session, the caller MUST acquire the session lock
40 * using session_lock() and session_unlock().
41 */
42
43 /*
44 * Init tracing session list.
45 *
46 * Please see session.h for more explanation and correct usage of the list.
47 */
48 static struct ltt_session_list ltt_session_list = {
49 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
50 .lock = PTHREAD_MUTEX_INITIALIZER,
51 .next_uuid = 0,
52 };
53
54 /* These characters are forbidden in a session name. Used by validate_name. */
55 static const char *forbidden_name_chars = "/";
56
57 /*
58 * Validate the session name for forbidden characters.
59 *
60 * Return 0 on success else -1 meaning a forbidden char. has been found.
61 */
62 static int validate_name(const char *name)
63 {
64 int ret;
65 char *tok, *tmp_name;
66
67 assert(name);
68
69 tmp_name = strdup(name);
70 if (!tmp_name) {
71 /* ENOMEM here. */
72 ret = -1;
73 goto error;
74 }
75
76 tok = strpbrk(tmp_name, forbidden_name_chars);
77 if (tok) {
78 DBG("Session name %s contains a forbidden character", name);
79 /* Forbidden character has been found. */
80 ret = -1;
81 goto error;
82 }
83 ret = 0;
84
85 error:
86 free(tmp_name);
87 return ret;
88 }
89
90 /*
91 * Add a ltt_session structure to the global list.
92 *
93 * The caller MUST acquire the session list lock before.
94 * Returns the unique identifier for the session.
95 */
96 static uint64_t add_session_list(struct ltt_session *ls)
97 {
98 assert(ls);
99
100 cds_list_add(&ls->list, &ltt_session_list.head);
101 return ltt_session_list.next_uuid++;
102 }
103
104 /*
105 * Delete a ltt_session structure to the global list.
106 *
107 * The caller MUST acquire the session list lock before.
108 */
109 static void del_session_list(struct ltt_session *ls)
110 {
111 assert(ls);
112
113 cds_list_del(&ls->list);
114 }
115
116 /*
117 * Return a pointer to the session list.
118 */
119 struct ltt_session_list *session_get_list(void)
120 {
121 return &ltt_session_list;
122 }
123
124 /*
125 * Acquire session list lock
126 */
127 void session_lock_list(void)
128 {
129 pthread_mutex_lock(&ltt_session_list.lock);
130 }
131
132 /*
133 * Release session list lock
134 */
135 void session_unlock_list(void)
136 {
137 pthread_mutex_unlock(&ltt_session_list.lock);
138 }
139
140 /*
141 * Acquire session lock
142 */
143 void session_lock(struct ltt_session *session)
144 {
145 assert(session);
146
147 pthread_mutex_lock(&session->lock);
148 }
149
150 /*
151 * Release session lock
152 */
153 void session_unlock(struct ltt_session *session)
154 {
155 assert(session);
156
157 pthread_mutex_unlock(&session->lock);
158 }
159
160 /*
161 * Return a ltt_session structure ptr that matches name. If no session found,
162 * NULL is returned. This must be called with the session lock held using
163 * session_lock_list and session_unlock_list.
164 */
165 struct ltt_session *session_find_by_name(const char *name)
166 {
167 struct ltt_session *iter;
168
169 assert(name);
170
171 DBG2("Trying to find session by name %s", name);
172
173 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
174 if (strncmp(iter->name, name, NAME_MAX) == 0) {
175 goto found;
176 }
177 }
178
179 iter = NULL;
180
181 found:
182 return iter;
183 }
184
185 /*
186 * Delete session from the session list and free the memory.
187 *
188 * Return -1 if no session is found. On success, return 1;
189 * Should *NOT* be called with RCU read-side lock held.
190 */
191 int session_destroy(struct ltt_session *session)
192 {
193 /* Safety check */
194 assert(session);
195
196 DBG("Destroying session %s", session->name);
197 del_session_list(session);
198 pthread_mutex_destroy(&session->lock);
199
200 consumer_output_put(session->consumer);
201 snapshot_destroy(&session->snapshot);
202 free(session);
203
204 return LTTNG_OK;
205 }
206
207 /*
208 * Create a brand new session and add it to the session list.
209 */
210 int session_create(char *name, uid_t uid, gid_t gid)
211 {
212 int ret;
213 struct ltt_session *new_session;
214
215 /* Allocate session data structure */
216 new_session = zmalloc(sizeof(struct ltt_session));
217 if (new_session == NULL) {
218 PERROR("zmalloc");
219 ret = LTTNG_ERR_FATAL;
220 goto error_malloc;
221 }
222
223 /* Define session name */
224 if (name != NULL) {
225 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
226 ret = LTTNG_ERR_FATAL;
227 goto error_asprintf;
228 }
229 } else {
230 ERR("No session name given");
231 ret = LTTNG_ERR_FATAL;
232 goto error;
233 }
234
235 ret = validate_name(name);
236 if (ret < 0) {
237 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
238 goto error;
239 }
240
241 ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
242 if (ret < 0) {
243 if (errno == ENAMETOOLONG) {
244 new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
245 } else {
246 ret = LTTNG_ERR_FATAL;
247 goto error;
248 }
249 }
250
251 /* Init kernel session */
252 new_session->kernel_session = NULL;
253 new_session->ust_session = NULL;
254
255 /* Init lock */
256 pthread_mutex_init(&new_session->lock, NULL);
257
258 new_session->uid = uid;
259 new_session->gid = gid;
260
261 ret = snapshot_init(&new_session->snapshot);
262 if (ret < 0) {
263 ret = LTTNG_ERR_NOMEM;
264 goto error;
265 }
266
267 /* Add new session to the session list */
268 session_lock_list();
269 new_session->id = add_session_list(new_session);
270 session_unlock_list();
271
272 /*
273 * Consumer is let to NULL since the create_session_uri command will set it
274 * up and, if valid, assign it to the session.
275 */
276
277 DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
278 name, new_session->id, new_session->uid, new_session->gid);
279
280 return LTTNG_OK;
281
282 error:
283 error_asprintf:
284 free(new_session);
285
286 error_malloc:
287 return ret;
288 }
289
290 /*
291 * Check if the UID or GID match the session. Root user has access to all
292 * sessions.
293 */
294 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
295 {
296 assert(session);
297
298 if (uid != session->uid && gid != session->gid && uid != 0) {
299 return 0;
300 } else {
301 return 1;
302 }
303 }
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