Catching up on misc. string and comment fixes
[lttng-tools.git] / src / lib / lttng-ctl / lttng-ctl.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 <common/common.h>
32 #include <common/defaults.h>
33 #include <common/sessiond-comm/sessiond-comm.h>
34 #include <lttng/lttng.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 /*
70 case LTTNG_DOMAIN_UST_EXEC_NAME:
71 case LTTNG_DOMAIN_UST_PID:
72 case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
73 */
74 memcpy(dst, src, sizeof(struct lttng_domain));
75 break;
76 default:
77 dst->type = LTTNG_DOMAIN_KERNEL;
78 break;
79 }
80 }
81 }
82
83 /*
84 * Send lttcomm_session_msg to the session daemon.
85 *
86 * On success, return 0
87 * On error, return error code
88 */
89 static int send_session_msg(struct lttcomm_session_msg *lsm)
90 {
91 int ret;
92
93 if (!connected) {
94 ret = -ENOTCONN;
95 goto end;
96 }
97
98 ret = lttcomm_send_creds_unix_sock(sessiond_socket, lsm,
99 sizeof(struct lttcomm_session_msg));
100
101 end:
102 return ret;
103 }
104
105 /*
106 * Receive data from the sessiond socket.
107 *
108 * On success, return 0
109 * On error, return recv() error code
110 */
111 static int recv_data_sessiond(void *buf, size_t len)
112 {
113 int ret;
114
115 if (!connected) {
116 ret = -ENOTCONN;
117 goto end;
118 }
119
120 ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
121
122 end:
123 return ret;
124 }
125
126 /*
127 * Check if the specified group name exist.
128 *
129 * If yes return 1, else return -1.
130 */
131 static int check_tracing_group(const char *grp_name)
132 {
133 struct group *grp_tracing; /* no free(). See getgrnam(3) */
134 gid_t *grp_list;
135 int grp_list_size, grp_id, i;
136 int ret = -1;
137
138 /* Get GID of group 'tracing' */
139 grp_tracing = getgrnam(grp_name);
140 if (grp_tracing == NULL) {
141 /* NULL means not found also. getgrnam(3) */
142 if (errno != 0) {
143 perror("getgrnam");
144 }
145 goto end;
146 }
147
148 /* Get number of supplementary group IDs */
149 grp_list_size = getgroups(0, NULL);
150 if (grp_list_size < 0) {
151 perror("getgroups");
152 goto end;
153 }
154
155 /* Alloc group list of the right size */
156 grp_list = malloc(grp_list_size * sizeof(gid_t));
157 if (!grp_list) {
158 ret = -1;
159 goto end;
160 }
161 grp_id = getgroups(grp_list_size, grp_list);
162 if (grp_id < -1) {
163 perror("getgroups");
164 goto free_list;
165 }
166
167 for (i = 0; i < grp_list_size; i++) {
168 if (grp_list[i] == grp_tracing->gr_gid) {
169 ret = 1;
170 break;
171 }
172 }
173
174 free_list:
175 free(grp_list);
176
177 end:
178 return ret;
179 }
180
181 /*
182 * Try connect to session daemon with sock_path.
183 *
184 * Return 0 on success, else -1
185 */
186 static int try_connect_sessiond(const char *sock_path)
187 {
188 int ret;
189
190 /* If socket exist, we check if the daemon listens for connect. */
191 ret = access(sock_path, F_OK);
192 if (ret < 0) {
193 /* Not alive */
194 return -1;
195 }
196
197 ret = lttcomm_connect_unix_sock(sock_path);
198 if (ret < 0) {
199 /* Not alive */
200 return -1;
201 }
202
203 ret = lttcomm_close_unix_sock(ret);
204 if (ret < 0) {
205 perror("lttcomm_close_unix_sock");
206 }
207
208 return 0;
209 }
210
211 /*
212 * Set sessiond socket path by putting it in the global sessiond_sock_path
213 * variable.
214 */
215 static int set_session_daemon_path(void)
216 {
217 int ret;
218 int in_tgroup = 0; /* In tracing group */
219 uid_t uid;
220
221 uid = getuid();
222
223 if (uid != 0) {
224 /* Are we in the tracing group ? */
225 in_tgroup = check_tracing_group(tracing_group);
226 }
227
228 if (uid == 0) {
229 /* Root */
230 copy_string(sessiond_sock_path,
231 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
232 sizeof(sessiond_sock_path));
233 } else if (in_tgroup) {
234 /* Tracing group */
235 copy_string(sessiond_sock_path,
236 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
237 sizeof(sessiond_sock_path));
238
239 ret = try_connect_sessiond(sessiond_sock_path);
240 if (ret < 0) {
241 /* Global session daemon not available */
242 if (snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
243 DEFAULT_HOME_CLIENT_UNIX_SOCK,
244 getenv("HOME")) < 0) {
245 return -ENOMEM;
246 }
247 }
248 } else {
249 /* Not in tracing group and not root, default */
250 if (snprintf(sessiond_sock_path, PATH_MAX,
251 DEFAULT_HOME_CLIENT_UNIX_SOCK,
252 getenv("HOME")) < 0) {
253 return -ENOMEM;
254 }
255 }
256
257 return 0;
258 }
259
260 /*
261 * Connect to the LTTng session daemon.
262 *
263 * On success, return 0. On error, return -1.
264 */
265 static int connect_sessiond(void)
266 {
267 int ret;
268
269 ret = set_session_daemon_path();
270 if (ret < 0) {
271 return ret;
272 }
273
274 /* Connect to the sesssion daemon */
275 ret = lttcomm_connect_unix_sock(sessiond_sock_path);
276 if (ret < 0) {
277 return ret;
278 }
279
280 sessiond_socket = ret;
281 connected = 1;
282
283 return 0;
284 }
285
286 /*
287 * Clean disconnect the session daemon.
288 */
289 static int disconnect_sessiond(void)
290 {
291 int ret = 0;
292
293 if (connected) {
294 ret = lttcomm_close_unix_sock(sessiond_socket);
295 sessiond_socket = 0;
296 connected = 0;
297 }
298
299 return ret;
300 }
301
302 /*
303 * Ask the session daemon a specific command and put the data into buf.
304 *
305 * Return size of data (only payload, not header) or a negative error code.
306 */
307 static int ask_sessiond(struct lttcomm_session_msg *lsm, void **buf)
308 {
309 int ret;
310 size_t size;
311 void *data = NULL;
312 struct lttcomm_lttng_msg llm;
313
314 ret = connect_sessiond();
315 if (ret < 0) {
316 goto end;
317 }
318
319 /* Send command to session daemon */
320 ret = send_session_msg(lsm);
321 if (ret < 0) {
322 goto end;
323 }
324
325 /* Get header from data transmission */
326 ret = recv_data_sessiond(&llm, sizeof(llm));
327 if (ret < 0) {
328 goto end;
329 }
330
331 /* Check error code if OK */
332 if (llm.ret_code != LTTCOMM_OK) {
333 ret = -llm.ret_code;
334 goto end;
335 }
336
337 size = llm.data_size;
338 if (size == 0) {
339 /* If client free with size 0 */
340 if (buf != NULL) {
341 *buf = NULL;
342 }
343 ret = 0;
344 goto end;
345 }
346
347 data = (void*) malloc(size);
348
349 /* Get payload data */
350 ret = recv_data_sessiond(data, size);
351 if (ret < 0) {
352 free(data);
353 goto end;
354 }
355
356 /*
357 * Extra protection not to dereference a NULL pointer. If buf is NULL at
358 * this point, an error is returned and data is freed.
359 */
360 if (buf == NULL) {
361 ret = -1;
362 free(data);
363 goto end;
364 }
365
366 *buf = data;
367 ret = size;
368
369 end:
370 disconnect_sessiond();
371 return ret;
372 }
373
374 /*
375 * Create lttng handle and return pointer.
376 */
377 struct lttng_handle *lttng_create_handle(const char *session_name,
378 struct lttng_domain *domain)
379 {
380 struct lttng_handle *handle;
381
382 handle = malloc(sizeof(struct lttng_handle));
383 if (handle == NULL) {
384 perror("malloc handle");
385 goto end;
386 }
387
388 /* Copy session name */
389 copy_string(handle->session_name, session_name,
390 sizeof(handle->session_name));
391
392 /* Copy lttng domain */
393 copy_lttng_domain(&handle->domain, domain);
394
395 end:
396 return handle;
397 }
398
399 /*
400 * Destroy handle by free(3) the pointer.
401 */
402 void lttng_destroy_handle(struct lttng_handle *handle)
403 {
404 if (handle) {
405 free(handle);
406 }
407 }
408
409 /*
410 * Register an outside consumer.
411 */
412 int lttng_register_consumer(struct lttng_handle *handle,
413 const char *socket_path)
414 {
415 struct lttcomm_session_msg lsm;
416
417 lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
418 copy_string(lsm.session.name, handle->session_name,
419 sizeof(lsm.session.name));
420 copy_lttng_domain(&lsm.domain, &handle->domain);
421
422 copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
423
424 return ask_sessiond(&lsm, NULL);
425 }
426
427 /*
428 * Start tracing for all trace of the session.
429 */
430 int lttng_start_tracing(const char *session_name)
431 {
432 struct lttcomm_session_msg lsm;
433
434 if (session_name == NULL) {
435 return -1;
436 }
437
438 lsm.cmd_type = LTTNG_START_TRACE;
439
440 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
441
442 return ask_sessiond(&lsm, NULL);
443 }
444
445 /*
446 * Stop tracing for all trace of the session.
447 */
448 int lttng_stop_tracing(const char *session_name)
449 {
450 struct lttcomm_session_msg lsm;
451
452 if (session_name == NULL) {
453 return -1;
454 }
455
456 lsm.cmd_type = LTTNG_STOP_TRACE;
457
458 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
459
460 return ask_sessiond(&lsm, NULL);
461 }
462
463 /*
464 * Add context to event or/and channel.
465 *
466 * Returns the size of the returned payload data or a negative error code.
467 */
468 int lttng_add_context(struct lttng_handle *handle,
469 struct lttng_event_context *ctx, const char *event_name,
470 const char *channel_name)
471 {
472 struct lttcomm_session_msg lsm;
473
474 /* Safety check. Both are mandatory */
475 if (handle == NULL || ctx == NULL) {
476 return -1;
477 }
478
479 lsm.cmd_type = LTTNG_ADD_CONTEXT;
480
481 /* Copy channel name */
482 copy_string(lsm.u.context.channel_name, channel_name,
483 sizeof(lsm.u.context.channel_name));
484 /* Copy event name */
485 copy_string(lsm.u.context.event_name, event_name,
486 sizeof(lsm.u.context.event_name));
487
488 copy_lttng_domain(&lsm.domain, &handle->domain);
489
490 memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
491
492 copy_string(lsm.session.name, handle->session_name,
493 sizeof(lsm.session.name));
494
495 return ask_sessiond(&lsm, NULL);
496 }
497
498 /*
499 * Enable event
500 */
501 int lttng_enable_event(struct lttng_handle *handle,
502 struct lttng_event *ev, const char *channel_name)
503 {
504 struct lttcomm_session_msg lsm;
505
506 if (handle == NULL || ev == NULL) {
507 return -1;
508 }
509
510 /* If no channel name, we put the default name */
511 if (channel_name == NULL) {
512 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME,
513 sizeof(lsm.u.enable.channel_name));
514 } else {
515 copy_string(lsm.u.enable.channel_name, channel_name,
516 sizeof(lsm.u.enable.channel_name));
517 }
518
519 copy_lttng_domain(&lsm.domain, &handle->domain);
520
521 if (ev->name[0] != '\0') {
522 lsm.cmd_type = LTTNG_ENABLE_EVENT;
523 } else {
524 lsm.cmd_type = LTTNG_ENABLE_ALL_EVENT;
525 }
526 memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
527
528 copy_string(lsm.session.name, handle->session_name,
529 sizeof(lsm.session.name));
530
531 return ask_sessiond(&lsm, NULL);
532 }
533
534 /*
535 * Disable event of a channel and domain.
536 */
537 int lttng_disable_event(struct lttng_handle *handle, const char *name,
538 const char *channel_name)
539 {
540 struct lttcomm_session_msg lsm;
541
542 if (handle == NULL) {
543 return -1;
544 }
545
546 if (channel_name) {
547 copy_string(lsm.u.disable.channel_name, channel_name,
548 sizeof(lsm.u.disable.channel_name));
549 } else {
550 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME,
551 sizeof(lsm.u.disable.channel_name));
552 }
553
554 copy_lttng_domain(&lsm.domain, &handle->domain);
555
556 if (name != NULL) {
557 copy_string(lsm.u.disable.name, name, sizeof(lsm.u.disable.name));
558 lsm.cmd_type = LTTNG_DISABLE_EVENT;
559 } else {
560 lsm.cmd_type = LTTNG_DISABLE_ALL_EVENT;
561 }
562
563 copy_string(lsm.session.name, handle->session_name,
564 sizeof(lsm.session.name));
565
566 return ask_sessiond(&lsm, NULL);
567 }
568
569 /*
570 * Enable channel per domain
571 */
572 int lttng_enable_channel(struct lttng_handle *handle,
573 struct lttng_channel *chan)
574 {
575 struct lttcomm_session_msg lsm;
576
577 /*
578 * NULL arguments are forbidden. No default values.
579 */
580 if (handle == NULL || chan == NULL) {
581 return -1;
582 }
583
584 memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
585
586 lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
587
588 copy_lttng_domain(&lsm.domain, &handle->domain);
589
590 copy_string(lsm.session.name, handle->session_name,
591 sizeof(lsm.session.name));
592
593 return ask_sessiond(&lsm, NULL);
594 }
595
596 /*
597 * All tracing will be stopped for registered events of the channel.
598 */
599 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
600 {
601 struct lttcomm_session_msg lsm;
602
603 /* Safety check. Both are mandatory */
604 if (handle == NULL || name == NULL) {
605 return -1;
606 }
607
608 lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
609
610 copy_string(lsm.u.disable.channel_name, name,
611 sizeof(lsm.u.disable.channel_name));
612
613 copy_lttng_domain(&lsm.domain, &handle->domain);
614
615 copy_string(lsm.session.name, handle->session_name,
616 sizeof(lsm.session.name));
617
618 return ask_sessiond(&lsm, NULL);
619 }
620
621 /*
622 * List all available tracepoints of domain.
623 *
624 * Return the size (bytes) of the list and set the events array.
625 * On error, return negative value.
626 */
627 int lttng_list_tracepoints(struct lttng_handle *handle,
628 struct lttng_event **events)
629 {
630 int ret;
631 struct lttcomm_session_msg lsm;
632
633 if (handle == NULL) {
634 return -1;
635 }
636
637 lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
638 copy_lttng_domain(&lsm.domain, &handle->domain);
639
640 ret = ask_sessiond(&lsm, (void **) events);
641 if (ret < 0) {
642 return ret;
643 }
644
645 return ret / sizeof(struct lttng_event);
646 }
647
648 /*
649 * Return a human readable string of code
650 */
651 const char *lttng_strerror(int code)
652 {
653 if (code > -LTTCOMM_OK) {
654 return "Ended with errors";
655 }
656
657 return lttcomm_get_readable_code(code);
658 }
659
660 /*
661 * Create a brand new session using name.
662 */
663 int lttng_create_session(const char *name, const char *path)
664 {
665 struct lttcomm_session_msg lsm;
666
667 lsm.cmd_type = LTTNG_CREATE_SESSION;
668 copy_string(lsm.session.name, name, sizeof(lsm.session.name));
669 copy_string(lsm.session.path, path, sizeof(lsm.session.path));
670
671 return ask_sessiond(&lsm, NULL);
672 }
673
674 /*
675 * Destroy session using name.
676 */
677 int lttng_destroy_session(const char *session_name)
678 {
679 struct lttcomm_session_msg lsm;
680
681 if (session_name == NULL) {
682 return -1;
683 }
684
685 lsm.cmd_type = LTTNG_DESTROY_SESSION;
686
687 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
688
689 return ask_sessiond(&lsm, NULL);
690 }
691
692 /*
693 * Ask the session daemon for all available sessions.
694 *
695 * Return number of session.
696 * On error, return negative value.
697 */
698 int lttng_list_sessions(struct lttng_session **sessions)
699 {
700 int ret;
701 struct lttcomm_session_msg lsm;
702
703 lsm.cmd_type = LTTNG_LIST_SESSIONS;
704 ret = ask_sessiond(&lsm, (void**) sessions);
705 if (ret < 0) {
706 return ret;
707 }
708
709 return ret / sizeof(struct lttng_session);
710 }
711
712 /*
713 * List domain of a session.
714 */
715 int lttng_list_domains(const char *session_name,
716 struct lttng_domain **domains)
717 {
718 int ret;
719 struct lttcomm_session_msg lsm;
720
721 if (session_name == NULL) {
722 return -1;
723 }
724
725 lsm.cmd_type = LTTNG_LIST_DOMAINS;
726
727 copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
728
729 ret = ask_sessiond(&lsm, (void**) domains);
730 if (ret < 0) {
731 return ret;
732 }
733
734 return ret / sizeof(struct lttng_domain);
735 }
736
737 /*
738 * List channels of a session
739 */
740 int lttng_list_channels(struct lttng_handle *handle,
741 struct lttng_channel **channels)
742 {
743 int ret;
744 struct lttcomm_session_msg lsm;
745
746 if (handle == NULL) {
747 return -1;
748 }
749
750 lsm.cmd_type = LTTNG_LIST_CHANNELS;
751 copy_string(lsm.session.name, handle->session_name,
752 sizeof(lsm.session.name));
753
754 copy_lttng_domain(&lsm.domain, &handle->domain);
755
756 ret = ask_sessiond(&lsm, (void**) channels);
757 if (ret < 0) {
758 return ret;
759 }
760
761 return ret / sizeof(struct lttng_channel);
762 }
763
764 /*
765 * List events of a session channel.
766 */
767 int lttng_list_events(struct lttng_handle *handle,
768 const char *channel_name, struct lttng_event **events)
769 {
770 int ret;
771 struct lttcomm_session_msg lsm;
772
773 /* Safety check. An handle and channel name are mandatory */
774 if (handle == NULL || channel_name == NULL) {
775 return -1;
776 }
777
778 lsm.cmd_type = LTTNG_LIST_EVENTS;
779 copy_string(lsm.session.name, handle->session_name,
780 sizeof(lsm.session.name));
781 copy_string(lsm.u.list.channel_name, channel_name,
782 sizeof(lsm.u.list.channel_name));
783
784 copy_lttng_domain(&lsm.domain, &handle->domain);
785
786 ret = ask_sessiond(&lsm, (void**) events);
787 if (ret < 0) {
788 return ret;
789 }
790
791 return ret / sizeof(struct lttng_event);
792 }
793
794 /*
795 * Set tracing group variable with name. This function allocate memory pointed
796 * by tracing_group.
797 */
798 int lttng_set_tracing_group(const char *name)
799 {
800 if (name == NULL) {
801 return -1;
802 }
803
804 if (asprintf(&tracing_group, "%s", name) < 0) {
805 return -ENOMEM;
806 }
807
808 return 0;
809 }
810
811 /*
812 * Returns size of returned session payload data or a negative error code.
813 */
814 int lttng_calibrate(struct lttng_handle *handle,
815 struct lttng_calibrate *calibrate)
816 {
817 struct lttcomm_session_msg lsm;
818
819 /* Safety check. NULL pointer are forbidden */
820 if (handle == NULL || calibrate == NULL) {
821 return -1;
822 }
823
824 lsm.cmd_type = LTTNG_CALIBRATE;
825 copy_lttng_domain(&lsm.domain, &handle->domain);
826
827 memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
828
829 return ask_sessiond(&lsm, NULL);
830 }
831
832 /*
833 * Set default channel attributes.
834 */
835 void lttng_channel_set_default_attr(struct lttng_domain *domain,
836 struct lttng_channel_attr *attr)
837 {
838 /* Safety check */
839 if (attr == NULL || domain == NULL) {
840 return;
841 }
842
843 switch (domain->type) {
844 case LTTNG_DOMAIN_KERNEL:
845 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
846 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
847 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
848
849 attr->subbuf_size = DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE;
850 attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
851 attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
852 break;
853 case LTTNG_DOMAIN_UST:
854 #if 0
855 case LTTNG_DOMAIN_UST_EXEC_NAME:
856 case LTTNG_DOMAIN_UST_PID:
857 case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
858 #endif
859 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
860 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
861 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
862
863 attr->subbuf_size = DEFAULT_UST_CHANNEL_SUBBUF_SIZE;
864 attr->num_subbuf = DEFAULT_UST_CHANNEL_SUBBUF_NUM;
865 attr->output = DEFAULT_UST_CHANNEL_OUTPUT;
866 break;
867 default:
868 /* Default behavior */
869 memset(attr, 0, sizeof(struct lttng_channel_attr));
870 break;
871 }
872 }
873
874 /*
875 * Check if session daemon is alive.
876 *
877 * Return 1 if alive or 0 if not.
878 * On error return -1
879 */
880 int lttng_session_daemon_alive(void)
881 {
882 int ret;
883
884 ret = set_session_daemon_path();
885 if (ret < 0) {
886 /* Error */
887 return ret;
888 }
889
890 if (strlen(sessiond_sock_path) == 0) {
891 /* No socket path set. Weird error */
892 return -1;
893 }
894
895 ret = try_connect_sessiond(sessiond_sock_path);
896 if (ret < 0) {
897 /* Not alive */
898 return 0;
899 }
900
901 /* Is alive */
902 return 1;
903 }
904
905 /*
906 * lib constructor
907 */
908 static void __attribute__((constructor)) init()
909 {
910 /* Set default session group */
911 lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
912 }
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