fc6ff3cc1ac92b41e28184dd04dc03944ba054ce
[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_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(struct lttng_handle *handle)
429 {
430 struct lttcomm_session_msg lsm;
431
432 if (!handle) {
433 return -1;
434 }
435
436 lsm.cmd_type = LTTNG_START_TRACE;
437 copy_string(lsm.session.name, handle->session_name,
438 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(struct lttng_handle *handle)
447 {
448 struct lttcomm_session_msg lsm;
449
450 lsm.cmd_type = LTTNG_STOP_TRACE;
451 copy_string(lsm.session.name, handle->session_name,
452 sizeof(lsm.session.name));
453
454 return ask_sessiond(&lsm, NULL);
455 }
456
457 /*
458 * Add context to event or/and channel.
459 */
460 int lttng_add_context(struct lttng_handle *handle,
461 struct lttng_event_context *ctx, const char *event_name,
462 const char *channel_name)
463 {
464 struct lttcomm_session_msg lsm;
465
466 if (!handle) {
467 return -1;
468 }
469
470 lsm.cmd_type = LTTNG_ADD_CONTEXT;
471
472 /* Copy channel name */
473 copy_string(lsm.u.context.channel_name, channel_name,
474 sizeof(lsm.u.context.channel_name));
475 /* Copy event name */
476 copy_string(lsm.u.context.event_name, event_name,
477 sizeof(lsm.u.context.event_name));
478
479 copy_lttng_domain(&lsm.domain, &handle->domain);
480
481 if (ctx) {
482 memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
483 }
484
485 copy_string(lsm.session.name, handle->session_name,
486 sizeof(lsm.session.name));
487
488 return ask_sessiond(&lsm, NULL);
489 }
490
491 /*
492 * Enable event
493 */
494 int lttng_enable_event(struct lttng_handle *handle,
495 struct lttng_event *ev, const char *channel_name)
496 {
497 struct lttcomm_session_msg lsm;
498
499 if (!handle || ev == NULL) {
500 return -1;
501 }
502
503 if (channel_name == NULL) {
504 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME,
505 sizeof(lsm.u.enable.channel_name));
506 } else {
507 copy_string(lsm.u.enable.channel_name, channel_name,
508 sizeof(lsm.u.enable.channel_name));
509 }
510
511 copy_lttng_domain(&lsm.domain, &handle->domain);
512
513 if (ev->name[0] != '\0') {
514 lsm.cmd_type = LTTNG_ENABLE_EVENT;
515 } else {
516 lsm.cmd_type = LTTNG_ENABLE_ALL_EVENT;
517 }
518 memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
519
520 copy_string(lsm.session.name, handle->session_name,
521 sizeof(lsm.session.name));
522
523 return ask_sessiond(&lsm, NULL);
524 }
525
526 /*
527 * Disable event of a channel and domain.
528 */
529 int lttng_disable_event(struct lttng_handle *handle, const char *name,
530 const char *channel_name)
531 {
532 struct lttcomm_session_msg lsm;
533
534 if (!handle) {
535 return -1;
536 }
537
538 if (channel_name) {
539 copy_string(lsm.u.disable.channel_name, channel_name,
540 sizeof(lsm.u.disable.channel_name));
541 } else {
542 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME,
543 sizeof(lsm.u.disable.channel_name));
544 }
545
546 copy_lttng_domain(&lsm.domain, &handle->domain);
547
548 if (name != NULL) {
549 copy_string(lsm.u.disable.name, name, sizeof(lsm.u.disable.name));
550 lsm.cmd_type = LTTNG_DISABLE_EVENT;
551 } else {
552 lsm.cmd_type = LTTNG_DISABLE_ALL_EVENT;
553 }
554
555 copy_string(lsm.session.name, handle->session_name,
556 sizeof(lsm.session.name));
557
558 return ask_sessiond(&lsm, NULL);
559 }
560
561 /*
562 * Enable channel per domain
563 */
564 int lttng_enable_channel(struct lttng_handle *handle,
565 struct lttng_channel *chan)
566 {
567 struct lttcomm_session_msg lsm;
568
569 if (!handle) {
570 return -1;
571 }
572
573 if (chan) {
574 memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
575 }
576
577 lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
578
579 copy_lttng_domain(&lsm.domain, &handle->domain);
580
581 copy_string(lsm.session.name, handle->session_name,
582 sizeof(lsm.session.name));
583
584 return ask_sessiond(&lsm, NULL);
585 }
586
587 /*
588 * All tracing will be stopped for registered events of the channel.
589 */
590 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
591 {
592 struct lttcomm_session_msg lsm;
593
594 if (!handle) {
595 return -1;
596 }
597
598 if (name) {
599 copy_string(lsm.u.disable.channel_name, name,
600 sizeof(lsm.u.disable.channel_name));
601 }
602
603 lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
604
605 copy_lttng_domain(&lsm.domain, &handle->domain);
606
607 copy_string(lsm.session.name, handle->session_name,
608 sizeof(lsm.session.name));
609
610 return ask_sessiond(&lsm, NULL);
611 }
612
613 /*
614 * List all available tracepoints of domain.
615 *
616 * Return the size (bytes) of the list and set the events array.
617 * On error, return negative value.
618 */
619 int lttng_list_tracepoints(struct lttng_handle *handle,
620 struct lttng_event **events)
621 {
622 int ret;
623 struct lttcomm_session_msg lsm;
624
625 if (!handle) {
626 return -1;
627 }
628
629 lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
630 copy_lttng_domain(&lsm.domain, &handle->domain);
631
632 ret = ask_sessiond(&lsm, (void **) events);
633 if (ret < 0) {
634 return ret;
635 }
636
637 return ret / sizeof(struct lttng_event);
638 }
639
640 /*
641 * Return a human readable string of code
642 */
643 const char *lttng_strerror(int code)
644 {
645 if (code > -LTTCOMM_OK) {
646 return "Ended with errors";
647 }
648
649 return lttcomm_get_readable_code(code);
650 }
651
652 /*
653 * Create a brand new session using name.
654 */
655 int lttng_create_session(const char *name, const char *path)
656 {
657 struct lttcomm_session_msg lsm;
658
659 lsm.cmd_type = LTTNG_CREATE_SESSION;
660 copy_string(lsm.session.name, name, sizeof(lsm.session.name));
661 copy_string(lsm.session.path, path, sizeof(lsm.session.path));
662
663 return ask_sessiond(&lsm, NULL);
664 }
665
666 /*
667 * Destroy session using name.
668 */
669 int lttng_destroy_session(struct lttng_handle *handle)
670 {
671 struct lttcomm_session_msg lsm;
672
673 if (!handle) {
674 return -1;
675 }
676
677 lsm.cmd_type = LTTNG_DESTROY_SESSION;
678 copy_string(lsm.session.name, handle->session_name,
679 sizeof(lsm.session.name));
680
681 return ask_sessiond(&lsm, NULL);
682 }
683
684 /*
685 * Ask the session daemon for all available sessions.
686 *
687 * Return number of session.
688 * On error, return negative value.
689 */
690 int lttng_list_sessions(struct lttng_session **sessions)
691 {
692 int ret;
693 struct lttcomm_session_msg lsm;
694
695 lsm.cmd_type = LTTNG_LIST_SESSIONS;
696 ret = ask_sessiond(&lsm, (void**) sessions);
697 if (ret < 0) {
698 return ret;
699 }
700
701 return ret / sizeof(struct lttng_session);
702 }
703
704 /*
705 * List domain of a session.
706 */
707 int lttng_list_domains(struct lttng_handle *handle,
708 struct lttng_domain **domains)
709 {
710 int ret;
711 struct lttcomm_session_msg lsm;
712
713 if (!handle) {
714 return -1;
715 }
716
717 lsm.cmd_type = LTTNG_LIST_DOMAINS;
718
719 copy_string(lsm.session.name, handle->session_name,
720 sizeof(lsm.session.name));
721
722 ret = ask_sessiond(&lsm, (void**) domains);
723 if (ret < 0) {
724 return ret;
725 }
726
727 return ret / sizeof(struct lttng_domain);
728 }
729
730 /*
731 * List channels of a session
732 */
733 int lttng_list_channels(struct lttng_handle *handle,
734 struct lttng_channel **channels)
735 {
736 int ret;
737 struct lttcomm_session_msg lsm;
738
739 if (!handle) {
740 return -1;
741 }
742
743 lsm.cmd_type = LTTNG_LIST_CHANNELS;
744 copy_string(lsm.session.name, handle->session_name,
745 sizeof(lsm.session.name));
746
747 copy_lttng_domain(&lsm.domain, &handle->domain);
748
749 ret = ask_sessiond(&lsm, (void**) channels);
750 if (ret < 0) {
751 return ret;
752 }
753
754 return ret / sizeof(struct lttng_channel);
755 }
756
757 /*
758 * List events of a session channel.
759 */
760 int lttng_list_events(struct lttng_handle *handle,
761 const char *channel_name, struct lttng_event **events)
762 {
763 int ret;
764 struct lttcomm_session_msg lsm;
765
766 if (!handle) {
767 return -1;
768 }
769
770 lsm.cmd_type = LTTNG_LIST_EVENTS;
771 copy_string(lsm.session.name, handle->session_name,
772 sizeof(lsm.session.name));
773 copy_string(lsm.u.list.channel_name, channel_name,
774 sizeof(lsm.u.list.channel_name));
775
776 copy_lttng_domain(&lsm.domain, &handle->domain);
777
778 ret = ask_sessiond(&lsm, (void**) events);
779 if (ret < 0) {
780 return ret;
781 }
782
783 return ret / sizeof(struct lttng_event);
784 }
785
786 /*
787 * Set tracing group variable with name. This function allocate memory pointed
788 * by tracing_group.
789 */
790 int lttng_set_tracing_group(const char *name)
791 {
792 if (asprintf(&tracing_group, "%s", name) < 0) {
793 return -ENOMEM;
794 }
795
796 return 0;
797 }
798
799 /*
800 * lttng_calibrate
801 */
802 int lttng_calibrate(struct lttng_handle *handle,
803 struct lttng_calibrate *calibrate)
804 {
805 struct lttcomm_session_msg lsm;
806
807 if (!handle) {
808 return -1;
809 }
810
811 lsm.cmd_type = LTTNG_CALIBRATE;
812 copy_lttng_domain(&lsm.domain, &handle->domain);
813
814 memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
815
816 return ask_sessiond(&lsm, NULL);
817 }
818
819 /*
820 * Set default channel attributes.
821 */
822 void lttng_channel_set_default_attr(struct lttng_domain *domain,
823 struct lttng_channel_attr *attr)
824 {
825 /* Safety check */
826 if (attr == NULL || domain == NULL) {
827 return;
828 }
829
830 switch (domain->type) {
831 case LTTNG_DOMAIN_KERNEL:
832 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
833 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
834 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
835
836 attr->subbuf_size = DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE;
837 attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
838 attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
839 break;
840 case LTTNG_DOMAIN_UST:
841 case LTTNG_DOMAIN_UST_EXEC_NAME:
842 case LTTNG_DOMAIN_UST_PID:
843 case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
844 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
845 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
846 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
847
848 attr->subbuf_size = DEFAULT_UST_CHANNEL_SUBBUF_SIZE;
849 attr->num_subbuf = DEFAULT_UST_CHANNEL_SUBBUF_NUM;
850 attr->output = DEFAULT_UST_CHANNEL_OUTPUT;
851 break;
852 default:
853 /* Default behavior */
854 memset(attr, 0, sizeof(struct lttng_channel_attr));
855 break;
856 }
857 }
858
859 /*
860 * Check if session daemon is alive.
861 *
862 * Return 1 if alive or 0 if not.
863 * On error return -1
864 */
865 int lttng_session_daemon_alive(void)
866 {
867 int ret;
868
869 ret = set_session_daemon_path();
870 if (ret < 0) {
871 /* Error */
872 return ret;
873 }
874
875 if (strlen(sessiond_sock_path) == 0) {
876 /* No socket path set. Weird error */
877 return -1;
878 }
879
880 ret = try_connect_sessiond(sessiond_sock_path);
881 if (ret < 0) {
882 /* Not alive */
883 return 0;
884 }
885
886 /* Is alive */
887 return 1;
888 }
889
890 /*
891 * lib constructor
892 */
893 static void __attribute__((constructor)) init()
894 {
895 /* Set default session group */
896 lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
897 }
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