Fix trace UST destroy channel
[lttng-tools.git] / liblttngctl / lttngctl.c
1 /*
2 * liblttngctl.c
3 *
4 * Linux Trace Toolkit Control Library
5 *
6 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
7 *
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; only
11 * version 2.1 of the License.
12 *
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with this library; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23 #define _GNU_SOURCE
24 #include <grp.h>
25 #include <errno.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <string.h>
29 #include <unistd.h>
30
31 #include <lttng-sessiond-comm.h>
32 #include <lttng-share.h>
33 #include <lttng/lttng.h>
34 #include <lttngerr.h>
35
36 /* Socket to session daemon for communication */
37 static int sessiond_socket;
38 static char sessiond_sock_path[PATH_MAX];
39
40 /* Variables */
41 static char *tracing_group;
42 static int connected;
43
44 /*
45 * Copy string from src to dst and enforce null terminated byte.
46 */
47 static void copy_string(char *dst, const char *src, size_t len)
48 {
49 if (src && dst) {
50 strncpy(dst, src, len);
51 /* Enforce the NULL terminated byte */
52 dst[len - 1] = '\0';
53 } else if (dst) {
54 dst[0] = '\0';
55 }
56 }
57
58 /*
59 * Copy domain to lttcomm_session_msg domain.
60 *
61 * If domain is unknown, default domain will be the kernel.
62 */
63 static void copy_lttng_domain(struct lttng_domain *dst, struct lttng_domain *src)
64 {
65 if (src && dst) {
66 switch (src->type) {
67 case LTTNG_DOMAIN_KERNEL:
68 case LTTNG_DOMAIN_UST:
69 case LTTNG_DOMAIN_UST_EXEC_NAME:
70 case LTTNG_DOMAIN_UST_PID:
71 case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
72 memcpy(dst, src, sizeof(struct lttng_domain));
73 break;
74 default:
75 dst->type = LTTNG_DOMAIN_KERNEL;
76 break;
77 }
78 }
79 }
80
81 /*
82 * Send lttcomm_session_msg to the session daemon.
83 *
84 * On success, return 0
85 * On error, return error code
86 */
87 static int send_session_msg(struct lttcomm_session_msg *lsm)
88 {
89 int ret;
90
91 if (!connected) {
92 ret = -ENOTCONN;
93 goto end;
94 }
95
96 ret = lttcomm_send_creds_unix_sock(sessiond_socket, lsm,
97 sizeof(struct lttcomm_session_msg));
98
99 end:
100 return ret;
101 }
102
103 /*
104 * Receive data from the sessiond socket.
105 *
106 * On success, return 0
107 * On error, return recv() error code
108 */
109 static int recv_data_sessiond(void *buf, size_t len)
110 {
111 int ret;
112
113 if (!connected) {
114 ret = -ENOTCONN;
115 goto end;
116 }
117
118 ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
119
120 end:
121 return ret;
122 }
123
124 /*
125 * Check if the specified group name exist.
126 *
127 * If yes return 1, else return -1.
128 */
129 static int check_tracing_group(const char *grp_name)
130 {
131 struct group *grp_tracing; /* no free(). See getgrnam(3) */
132 gid_t *grp_list;
133 int grp_list_size, grp_id, i;
134 int ret = -1;
135
136 /* Get GID of group 'tracing' */
137 grp_tracing = getgrnam(grp_name);
138 if (grp_tracing == NULL) {
139 /* NULL means not found also. getgrnam(3) */
140 if (errno != 0) {
141 perror("getgrnam");
142 }
143 goto end;
144 }
145
146 /* Get number of supplementary group IDs */
147 grp_list_size = getgroups(0, NULL);
148 if (grp_list_size < 0) {
149 perror("getgroups");
150 goto end;
151 }
152
153 /* Alloc group list of the right size */
154 grp_list = malloc(grp_list_size * sizeof(gid_t));
155 if (!grp_list) {
156 ret = -1;
157 goto end;
158 }
159 grp_id = getgroups(grp_list_size, grp_list);
160 if (grp_id < -1) {
161 perror("getgroups");
162 goto free_list;
163 }
164
165 for (i = 0; i < grp_list_size; i++) {
166 if (grp_list[i] == grp_tracing->gr_gid) {
167 ret = 1;
168 break;
169 }
170 }
171
172 free_list:
173 free(grp_list);
174
175 end:
176 return ret;
177 }
178
179 /*
180 * Try connect to session daemon with sock_path.
181 *
182 * Return 0 on success, else -1
183 */
184 static int try_connect_sessiond(const char *sock_path)
185 {
186 int ret;
187
188 /* If socket exist, we check if the daemon listens for connect. */
189 ret = access(sock_path, F_OK);
190 if (ret < 0) {
191 /* Not alive */
192 return -1;
193 }
194
195 ret = lttcomm_connect_unix_sock(sock_path);
196 if (ret < 0) {
197 /* Not alive */
198 return -1;
199 }
200
201 ret = lttcomm_close_unix_sock(ret);
202 if (ret < 0) {
203 perror("lttcomm_close_unix_sock");
204 }
205
206 return 0;
207 }
208
209 /*
210 * Set sessiond socket path by putting it in the global sessiond_sock_path
211 * variable.
212 */
213 static int set_session_daemon_path(void)
214 {
215 int ret;
216 int in_tgroup = 0; /* In tracing group */
217 uid_t uid;
218
219 uid = getuid();
220
221 if (uid != 0) {
222 /* Are we in the tracing group ? */
223 in_tgroup = check_tracing_group(tracing_group);
224 }
225
226 if (uid == 0) {
227 /* Root */
228 copy_string(sessiond_sock_path,
229 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
230 sizeof(sessiond_sock_path));
231 } else if (in_tgroup) {
232 /* Tracing group */
233 copy_string(sessiond_sock_path,
234 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
235 sizeof(sessiond_sock_path));
236
237 ret = try_connect_sessiond(sessiond_sock_path);
238 if (ret < 0) {
239 /* Global session daemon not available */
240 if (snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
241 DEFAULT_HOME_CLIENT_UNIX_SOCK,
242 getenv("HOME")) < 0) {
243 return -ENOMEM;
244 }
245 }
246 } else {
247 /* Not in tracing group and not root, default */
248 if (snprintf(sessiond_sock_path, PATH_MAX,
249 DEFAULT_HOME_CLIENT_UNIX_SOCK,
250 getenv("HOME")) < 0) {
251 return -ENOMEM;
252 }
253 }
254
255 return 0;
256 }
257
258 /*
259 * Connect to the LTTng session daemon.
260 *
261 * On success, return 0. On error, return -1.
262 */
263 static int connect_sessiond(void)
264 {
265 int ret;
266
267 ret = set_session_daemon_path();
268 if (ret < 0) {
269 return ret;
270 }
271
272 /* Connect to the sesssion daemon */
273 ret = lttcomm_connect_unix_sock(sessiond_sock_path);
274 if (ret < 0) {
275 return ret;
276 }
277
278 sessiond_socket = ret;
279 connected = 1;
280
281 return 0;
282 }
283
284 /*
285 * Clean disconnect the session daemon.
286 */
287 static int disconnect_sessiond(void)
288 {
289 int ret = 0;
290
291 if (connected) {
292 ret = lttcomm_close_unix_sock(sessiond_socket);
293 sessiond_socket = 0;
294 connected = 0;
295 }
296
297 return ret;
298 }
299
300 /*
301 * Ask the session daemon a specific command and put the data into buf.
302 *
303 * Return size of data (only payload, not header).
304 */
305 static int ask_sessiond(struct lttcomm_session_msg *lsm, void **buf)
306 {
307 int ret;
308 size_t size;
309 void *data = NULL;
310 struct lttcomm_lttng_msg llm;
311
312 ret = connect_sessiond();
313 if (ret < 0) {
314 goto end;
315 }
316
317 /* Send command to session daemon */
318 ret = send_session_msg(lsm);
319 if (ret < 0) {
320 goto end;
321 }
322
323 /* Get header from data transmission */
324 ret = recv_data_sessiond(&llm, sizeof(llm));
325 if (ret < 0) {
326 goto end;
327 }
328
329 /* Check error code if OK */
330 if (llm.ret_code != LTTCOMM_OK) {
331 ret = -llm.ret_code;
332 goto end;
333 }
334
335 size = llm.data_size;
336 if (size == 0) {
337 /* If client free with size 0 */
338 if (buf != NULL) {
339 *buf = NULL;
340 }
341 ret = 0;
342 goto end;
343 }
344
345 data = (void*) malloc(size);
346
347 /* Get payload data */
348 ret = recv_data_sessiond(data, size);
349 if (ret < 0) {
350 free(data);
351 goto end;
352 }
353
354 /*
355 * Extra protection not to dereference a NULL pointer. If buf is NULL at
356 * this point, an error is returned and data is freed.
357 */
358 if (buf == NULL) {
359 ret = -1;
360 free(data);
361 goto end;
362 }
363
364 *buf = data;
365 ret = size;
366
367 end:
368 disconnect_sessiond();
369 return ret;
370 }
371
372 /*
373 * Create lttng handle and return pointer.
374 */
375 struct lttng_handle *lttng_create_handle(const char *session_name,
376 struct lttng_domain *domain)
377 {
378 struct lttng_handle *handle;
379
380 handle = malloc(sizeof(struct lttng_handle));
381 if (handle == NULL) {
382 perror("malloc handle");
383 goto end;
384 }
385
386 /* Copy session name */
387 copy_string(handle->session_name, session_name,
388 sizeof(handle->session_name));
389
390 /* Copy lttng domain */
391 copy_lttng_domain(&handle->domain, domain);
392
393 end:
394 return handle;
395 }
396
397 /*
398 * Destroy handle by free(3) the pointer.
399 */
400 void lttng_destroy_handle(struct lttng_handle *handle)
401 {
402 if (handle) {
403 free(handle);
404 }
405 }
406
407 /*
408 * Register an outside consumer.
409 */
410 int lttng_register_consumer(struct lttng_handle *handle,
411 const char *socket_path)
412 {
413 struct lttcomm_session_msg lsm;
414
415 lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
416 copy_string(lsm.session.name, handle->session_name,
417 sizeof(lsm.session.name));
418 copy_lttng_domain(&lsm.domain, &handle->domain);
419
420 copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
421
422 return ask_sessiond(&lsm, NULL);
423 }
424
425 /*
426 * Start tracing for all trace of the session.
427 */
428 int lttng_start_tracing(const char *session_name)
429 {
430 struct lttcomm_session_msg lsm;
431
432 if (session_name == NULL) {
433 return -1;
434 }
435
436 lsm.cmd_type = LTTNG_START_TRACE;
437
438 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
439
440 return ask_sessiond(&lsm, NULL);
441 }
442
443 /*
444 * Stop tracing for all trace of the session.
445 */
446 int lttng_stop_tracing(const char *session_name)
447 {
448 struct lttcomm_session_msg lsm;
449
450 if (session_name == NULL) {
451 return -1;
452 }
453
454 lsm.cmd_type = LTTNG_STOP_TRACE;
455
456 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
457
458 return ask_sessiond(&lsm, NULL);
459 }
460
461 /*
462 * Add context to event or/and channel.
463 */
464 int lttng_add_context(struct lttng_handle *handle,
465 struct lttng_event_context *ctx, const char *event_name,
466 const char *channel_name)
467 {
468 struct lttcomm_session_msg lsm;
469
470 /* Safety check. Both are mandatory */
471 if (handle == NULL || ctx == NULL) {
472 return -1;
473 }
474
475 lsm.cmd_type = LTTNG_ADD_CONTEXT;
476
477 /* Copy channel name */
478 copy_string(lsm.u.context.channel_name, channel_name,
479 sizeof(lsm.u.context.channel_name));
480 /* Copy event name */
481 copy_string(lsm.u.context.event_name, event_name,
482 sizeof(lsm.u.context.event_name));
483
484 copy_lttng_domain(&lsm.domain, &handle->domain);
485
486 memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
487
488 copy_string(lsm.session.name, handle->session_name,
489 sizeof(lsm.session.name));
490
491 return ask_sessiond(&lsm, NULL);
492 }
493
494 /*
495 * Enable event
496 */
497 int lttng_enable_event(struct lttng_handle *handle,
498 struct lttng_event *ev, const char *channel_name)
499 {
500 struct lttcomm_session_msg lsm;
501
502 if (handle == NULL || ev == NULL) {
503 return -1;
504 }
505
506 /* If no channel name, we put the default name */
507 if (channel_name == NULL) {
508 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME,
509 sizeof(lsm.u.enable.channel_name));
510 } else {
511 copy_string(lsm.u.enable.channel_name, channel_name,
512 sizeof(lsm.u.enable.channel_name));
513 }
514
515 copy_lttng_domain(&lsm.domain, &handle->domain);
516
517 if (ev->name[0] != '\0') {
518 lsm.cmd_type = LTTNG_ENABLE_EVENT;
519 } else {
520 lsm.cmd_type = LTTNG_ENABLE_ALL_EVENT;
521 }
522 memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
523
524 copy_string(lsm.session.name, handle->session_name,
525 sizeof(lsm.session.name));
526
527 return ask_sessiond(&lsm, NULL);
528 }
529
530 /*
531 * Disable event of a channel and domain.
532 */
533 int lttng_disable_event(struct lttng_handle *handle, const char *name,
534 const char *channel_name)
535 {
536 struct lttcomm_session_msg lsm;
537
538 if (handle == NULL) {
539 return -1;
540 }
541
542 if (channel_name) {
543 copy_string(lsm.u.disable.channel_name, channel_name,
544 sizeof(lsm.u.disable.channel_name));
545 } else {
546 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME,
547 sizeof(lsm.u.disable.channel_name));
548 }
549
550 copy_lttng_domain(&lsm.domain, &handle->domain);
551
552 if (name != NULL) {
553 copy_string(lsm.u.disable.name, name, sizeof(lsm.u.disable.name));
554 lsm.cmd_type = LTTNG_DISABLE_EVENT;
555 } else {
556 lsm.cmd_type = LTTNG_DISABLE_ALL_EVENT;
557 }
558
559 copy_string(lsm.session.name, handle->session_name,
560 sizeof(lsm.session.name));
561
562 return ask_sessiond(&lsm, NULL);
563 }
564
565 /*
566 * Enable channel per domain
567 */
568 int lttng_enable_channel(struct lttng_handle *handle,
569 struct lttng_channel *chan)
570 {
571 struct lttcomm_session_msg lsm;
572
573 /*
574 * NULL arguments are forbidden. No default values.
575 */
576 if (handle == NULL || chan == NULL) {
577 return -1;
578 }
579
580 memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
581
582 lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
583
584 copy_lttng_domain(&lsm.domain, &handle->domain);
585
586 copy_string(lsm.session.name, handle->session_name,
587 sizeof(lsm.session.name));
588
589 return ask_sessiond(&lsm, NULL);
590 }
591
592 /*
593 * All tracing will be stopped for registered events of the channel.
594 */
595 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
596 {
597 struct lttcomm_session_msg lsm;
598
599 /* Safety check. Both are mandatory */
600 if (handle == NULL || name == NULL) {
601 return -1;
602 }
603
604 lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
605
606 copy_string(lsm.u.disable.channel_name, name,
607 sizeof(lsm.u.disable.channel_name));
608
609 copy_lttng_domain(&lsm.domain, &handle->domain);
610
611 copy_string(lsm.session.name, handle->session_name,
612 sizeof(lsm.session.name));
613
614 return ask_sessiond(&lsm, NULL);
615 }
616
617 /*
618 * List all available tracepoints of domain.
619 *
620 * Return the size (bytes) of the list and set the events array.
621 * On error, return negative value.
622 */
623 int lttng_list_tracepoints(struct lttng_handle *handle,
624 struct lttng_event **events)
625 {
626 int ret;
627 struct lttcomm_session_msg lsm;
628
629 if (handle == NULL) {
630 return -1;
631 }
632
633 lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
634 copy_lttng_domain(&lsm.domain, &handle->domain);
635
636 ret = ask_sessiond(&lsm, (void **) events);
637 if (ret < 0) {
638 return ret;
639 }
640
641 return ret / sizeof(struct lttng_event);
642 }
643
644 /*
645 * Return a human readable string of code
646 */
647 const char *lttng_strerror(int code)
648 {
649 if (code > -LTTCOMM_OK) {
650 return "Ended with errors";
651 }
652
653 return lttcomm_get_readable_code(code);
654 }
655
656 /*
657 * Create a brand new session using name.
658 */
659 int lttng_create_session(const char *name, const char *path)
660 {
661 struct lttcomm_session_msg lsm;
662
663 lsm.cmd_type = LTTNG_CREATE_SESSION;
664 copy_string(lsm.session.name, name, sizeof(lsm.session.name));
665 copy_string(lsm.session.path, path, sizeof(lsm.session.path));
666
667 return ask_sessiond(&lsm, NULL);
668 }
669
670 /*
671 * Destroy session using name.
672 */
673 int lttng_destroy_session(const char *session_name)
674 {
675 struct lttcomm_session_msg lsm;
676
677 if (session_name == NULL) {
678 return -1;
679 }
680
681 lsm.cmd_type = LTTNG_DESTROY_SESSION;
682
683 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
684
685 return ask_sessiond(&lsm, NULL);
686 }
687
688 /*
689 * Ask the session daemon for all available sessions.
690 *
691 * Return number of session.
692 * On error, return negative value.
693 */
694 int lttng_list_sessions(struct lttng_session **sessions)
695 {
696 int ret;
697 struct lttcomm_session_msg lsm;
698
699 lsm.cmd_type = LTTNG_LIST_SESSIONS;
700 ret = ask_sessiond(&lsm, (void**) sessions);
701 if (ret < 0) {
702 return ret;
703 }
704
705 return ret / sizeof(struct lttng_session);
706 }
707
708 /*
709 * List domain of a session.
710 */
711 int lttng_list_domains(const char *session_name,
712 struct lttng_domain **domains)
713 {
714 int ret;
715 struct lttcomm_session_msg lsm;
716
717 if (session_name == NULL) {
718 return -1;
719 }
720
721 lsm.cmd_type = LTTNG_LIST_DOMAINS;
722
723 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
724
725 ret = ask_sessiond(&lsm, (void**) domains);
726 if (ret < 0) {
727 return ret;
728 }
729
730 return ret / sizeof(struct lttng_domain);
731 }
732
733 /*
734 * List channels of a session
735 */
736 int lttng_list_channels(struct lttng_handle *handle,
737 struct lttng_channel **channels)
738 {
739 int ret;
740 struct lttcomm_session_msg lsm;
741
742 if (handle == NULL) {
743 return -1;
744 }
745
746 lsm.cmd_type = LTTNG_LIST_CHANNELS;
747 copy_string(lsm.session.name, handle->session_name,
748 sizeof(lsm.session.name));
749
750 copy_lttng_domain(&lsm.domain, &handle->domain);
751
752 ret = ask_sessiond(&lsm, (void**) channels);
753 if (ret < 0) {
754 return ret;
755 }
756
757 return ret / sizeof(struct lttng_channel);
758 }
759
760 /*
761 * List events of a session channel.
762 */
763 int lttng_list_events(struct lttng_handle *handle,
764 const char *channel_name, struct lttng_event **events)
765 {
766 int ret;
767 struct lttcomm_session_msg lsm;
768
769 /* Safety check. An handle and channel name are mandatory */
770 if (handle == NULL || channel_name == NULL) {
771 return -1;
772 }
773
774 lsm.cmd_type = LTTNG_LIST_EVENTS;
775 copy_string(lsm.session.name, handle->session_name,
776 sizeof(lsm.session.name));
777 copy_string(lsm.u.list.channel_name, channel_name,
778 sizeof(lsm.u.list.channel_name));
779
780 copy_lttng_domain(&lsm.domain, &handle->domain);
781
782 ret = ask_sessiond(&lsm, (void**) events);
783 if (ret < 0) {
784 return ret;
785 }
786
787 return ret / sizeof(struct lttng_event);
788 }
789
790 /*
791 * Set tracing group variable with name. This function allocate memory pointed
792 * by tracing_group.
793 */
794 int lttng_set_tracing_group(const char *name)
795 {
796 if (name == NULL) {
797 return -1;
798 }
799
800 if (asprintf(&tracing_group, "%s", name) < 0) {
801 return -ENOMEM;
802 }
803
804 return 0;
805 }
806
807 /*
808 * lttng_calibrate
809 */
810 int lttng_calibrate(struct lttng_handle *handle,
811 struct lttng_calibrate *calibrate)
812 {
813 struct lttcomm_session_msg lsm;
814
815 /* Safety check. NULL pointer are forbidden */
816 if (handle == NULL || calibrate == NULL) {
817 return -1;
818 }
819
820 lsm.cmd_type = LTTNG_CALIBRATE;
821 copy_lttng_domain(&lsm.domain, &handle->domain);
822
823 memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
824
825 return ask_sessiond(&lsm, NULL);
826 }
827
828 /*
829 * Set default channel attributes.
830 */
831 void lttng_channel_set_default_attr(struct lttng_domain *domain,
832 struct lttng_channel_attr *attr)
833 {
834 /* Safety check */
835 if (attr == NULL || domain == NULL) {
836 return;
837 }
838
839 switch (domain->type) {
840 case LTTNG_DOMAIN_KERNEL:
841 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
842 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
843 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
844
845 attr->subbuf_size = DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE;
846 attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
847 attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
848 break;
849 case LTTNG_DOMAIN_UST:
850 case LTTNG_DOMAIN_UST_EXEC_NAME:
851 case LTTNG_DOMAIN_UST_PID:
852 case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
853 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
854 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
855 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
856
857 attr->subbuf_size = DEFAULT_UST_CHANNEL_SUBBUF_SIZE;
858 attr->num_subbuf = DEFAULT_UST_CHANNEL_SUBBUF_NUM;
859 attr->output = DEFAULT_UST_CHANNEL_OUTPUT;
860 break;
861 default:
862 /* Default behavior */
863 memset(attr, 0, sizeof(struct lttng_channel_attr));
864 break;
865 }
866 }
867
868 /*
869 * Check if session daemon is alive.
870 *
871 * Return 1 if alive or 0 if not.
872 * On error return -1
873 */
874 int lttng_session_daemon_alive(void)
875 {
876 int ret;
877
878 ret = set_session_daemon_path();
879 if (ret < 0) {
880 /* Error */
881 return ret;
882 }
883
884 if (strlen(sessiond_sock_path) == 0) {
885 /* No socket path set. Weird error */
886 return -1;
887 }
888
889 ret = try_connect_sessiond(sessiond_sock_path);
890 if (ret < 0) {
891 /* Not alive */
892 return 0;
893 }
894
895 /* Is alive */
896 return 1;
897 }
898
899 /*
900 * lib constructor
901 */
902 static void __attribute__((constructor)) init()
903 {
904 /* Set default session group */
905 lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
906 }
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