2cf79f4ed96987a9b95c59bb373ee1d80d44d1d0
[lttng-tools.git] / liblttngctl / liblttngctl.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
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 */
18
19 #define _GNU_SOURCE
20 #include <errno.h>
21 #include <grp.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <unistd.h>
26
27 #include <lttng/lttng.h>
28
29 #include "liblttsessiondcomm.h"
30 #include "lttngerr.h"
31
32 /* Socket to session daemon for communication */
33 static int sessiond_socket;
34 static char sessiond_sock_path[PATH_MAX];
35
36 /* Communication structure to ltt-sessiond */
37 static struct lttcomm_session_msg lsm;
38 static struct lttcomm_lttng_msg llm;
39
40 /* Prototypes */
41 static int check_tracing_group(const char *grp_name);
42 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf);
43 static int recv_data_sessiond(void *buf, size_t len);
44 static int send_data_sessiond(void);
45 static int set_session_daemon_path(void);
46
47 /* Variables */
48 static char *tracing_group;
49 static int connected;
50
51 /*
52 * send_data_sessiond
53 *
54 * Send lttcomm_session_msg to the session daemon.
55 *
56 * On success, return 0
57 * On error, return error code
58 */
59 static int send_data_sessiond(void)
60 {
61 int ret;
62
63 if (!connected) {
64 ret = -ENOTCONN;
65 goto end;
66 }
67
68 ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
69
70 end:
71 return ret;
72 }
73
74 /*
75 * recv_data_sessiond
76 *
77 * Receive data from the sessiond socket.
78 *
79 * On success, return 0
80 * On error, return recv() error code
81 */
82 static int recv_data_sessiond(void *buf, size_t len)
83 {
84 int ret;
85
86 if (!connected) {
87 ret = -ENOTCONN;
88 goto end;
89 }
90
91 ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
92 if (ret < 0) {
93 goto end;
94 }
95
96 end:
97 return ret;
98 }
99
100 /*
101 * ask_sessiond
102 *
103 * Ask the session daemon a specific command
104 * and put the data into buf.
105 *
106 * Return size of data (only payload, not header).
107 */
108 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf)
109 {
110 int ret;
111 size_t size;
112 void *data = NULL;
113
114 ret = lttng_connect_sessiond();
115 if (ret < 0) {
116 goto end;
117 }
118
119 lsm.cmd_type = lct;
120
121 /* Send command to session daemon */
122 ret = send_data_sessiond();
123 if (ret < 0) {
124 goto end;
125 }
126
127 /* Get header from data transmission */
128 ret = recv_data_sessiond(&llm, sizeof(llm));
129 if (ret < 0) {
130 goto end;
131 }
132
133 /* Check error code if OK */
134 if (llm.ret_code != LTTCOMM_OK) {
135 ret = -llm.ret_code;
136 goto end;
137 }
138
139 size = llm.trace_name_offset + llm.data_size;
140 if (size == 0) {
141 goto end;
142 }
143
144 data = (void*) malloc(size);
145
146 /* Get payload data */
147 ret = recv_data_sessiond(data, size);
148 if (ret < 0) {
149 goto end;
150 }
151
152 *buf = data;
153 ret = size;
154
155 end:
156 lttng_disconnect_sessiond();
157 return ret;
158 }
159
160 /*
161 * BEGIN KERNEL CONTROL
162 */
163
164 /*
165 * lttng_kernel_enable_event
166 *
167 * Enable an event in the kernel tracer.
168 */
169 int lttng_kernel_enable_event(char *event_name)
170 {
171 strncpy(lsm.u.event.event_name, event_name, NAME_MAX);
172 return ask_sessiond(KERNEL_ENABLE_EVENT, NULL);
173 }
174
175 /*
176 * lttng_kernel_disable_event
177 *
178 * Disable an event in the kernel tracer.
179 */
180 int lttng_kernel_disable_event(char *event_name)
181 {
182 strncpy(lsm.u.event.event_name, event_name, NAME_MAX);
183 return ask_sessiond(KERNEL_DISABLE_EVENT, NULL);
184 }
185
186 /*
187 * lttng_kernel_create_session
188 *
189 * Create a session in the kernel tracer.
190 */
191 int lttng_kernel_create_session(void)
192 {
193 return ask_sessiond(KERNEL_CREATE_SESSION, NULL);
194 }
195
196 /*
197 * lttng_kernel_create_channel
198 *
199 * Create a channel in the kernel tracer.
200 */
201 int lttng_kernel_create_channel(void)
202 {
203 return ask_sessiond(KERNEL_CREATE_CHANNEL, NULL);
204 }
205
206 /*
207 * lttng_kernel_start_tracing
208 *
209 * Start kernel tracing.
210 */
211 int lttng_kernel_start_tracing(void)
212 {
213 return ask_sessiond(KERNEL_START_TRACE, NULL);
214 }
215
216 /*
217 * lttng_kernel_stop_tracing
218 *
219 * Stop kernel tracing.
220 */
221 int lttng_kernel_stop_tracing(void)
222 {
223 return ask_sessiond(KERNEL_STOP_TRACE, NULL);
224 }
225
226 /*
227 * END KERNEL CONTROL
228 */
229
230 /*
231 * lttng_get_readable_code
232 *
233 * Return a human readable string of code
234 */
235 const char *lttng_get_readable_code(int code)
236 {
237 if (code > -LTTCOMM_OK) {
238 return "Ended with errors";
239 }
240
241 return lttcomm_get_readable_code(code);
242 }
243
244 /*
245 * lttng_ust_start_trace
246 *
247 * Request a trace start for pid.
248 */
249 int lttng_ust_start_trace(pid_t pid)
250 {
251 int ret;
252
253 lsm.pid = pid;
254 ret = ask_sessiond(UST_START_TRACE, NULL);
255
256 return ret;
257 }
258
259 /*
260 * lttng_ust_stop_trace
261 *
262 * Request a trace stop for pid.
263 */
264 int lttng_ust_stop_trace(pid_t pid)
265 {
266 int ret;
267
268 lsm.pid = pid;
269 ret = ask_sessiond(UST_STOP_TRACE, NULL);
270
271 return ret;
272 }
273
274 /*
275 * lttng_ust_create_trace
276 *
277 * Request a trace creation for pid.
278 */
279 int lttng_ust_create_trace(pid_t pid)
280 {
281 int ret;
282
283 lsm.pid = pid;
284 ret = ask_sessiond(UST_CREATE_TRACE, NULL);
285
286 return ret;
287 }
288
289 /*
290 * lttng_ust_list_apps
291 *
292 * Ask the session daemon for all UST traceable
293 * applications.
294 *
295 * Return the number of pids.
296 * On error, return negative value.
297 */
298 int lttng_ust_list_apps(pid_t **pids)
299 {
300 int ret;
301
302 ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
303 if (ret < 0) {
304 return ret;
305 }
306
307 return ret / sizeof(pid_t);
308 }
309
310 /*
311 * lttng_list_traces
312 *
313 * Ask the session daemon for all traces (kernel and ust)
314 * for the session identified by uuid.
315 *
316 * Return the number of traces.
317 */
318 int lttng_list_traces(uuid_t *uuid, struct lttng_trace **traces)
319 {
320 int ret;
321
322 uuid_copy(lsm.session_uuid, *uuid);
323
324 ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
325 if (ret < 0) {
326 return ret;
327 }
328
329 return ret / sizeof(struct lttng_trace);
330 }
331
332 /*
333 * lttng_create_session
334 *
335 * Create a brand new session using name.
336 */
337 int lttng_create_session(char *name)
338 {
339 int ret;
340
341 strncpy(lsm.session_name, name, sizeof(lsm.session_name));
342 lsm.session_name[sizeof(lsm.session_name) - 1] = '\0';
343
344 ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
345 if (ret < 0) {
346 goto end;
347 }
348
349 end:
350 return ret;
351 }
352
353 /*
354 * lttng_destroy_session
355 *
356 * Destroy session using name.
357 */
358 int lttng_destroy_session(uuid_t *uuid)
359 {
360 int ret;
361
362 uuid_copy(lsm.session_uuid, *uuid);
363
364 ret = ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
365 if (ret < 0) {
366 goto end;
367 }
368
369 end:
370 return ret;
371 }
372
373 /*
374 * lttng_list_sessions
375 *
376 * Ask the session daemon for all available sessions.
377 *
378 * Return number of session.
379 * On error, return negative value.
380 */
381 int lttng_list_sessions(struct lttng_session **sessions)
382 {
383 int ret;
384
385 ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
386 if (ret < 0) {
387 return ret;
388 }
389
390 return ret / sizeof(struct lttng_session);
391 }
392
393 /*
394 * lttng_connect_sessiond
395 *
396 * Connect to the LTTng session daemon.
397 * On success, return 0
398 * On error, return a negative value
399 */
400 int lttng_connect_sessiond(void)
401 {
402 int ret;
403
404 ret = set_session_daemon_path();
405 if (ret < 0) {
406 return ret;
407 }
408
409 /* Connect to the sesssion daemon */
410 ret = lttcomm_connect_unix_sock(sessiond_sock_path);
411 if (ret < 0) {
412 return ret;
413 }
414
415 sessiond_socket = ret;
416 connected = 1;
417
418 return 0;
419 }
420
421 /*
422 * lttng_disconnect_sessiond
423 *
424 * Clean disconnect the session daemon.
425 */
426 int lttng_disconnect_sessiond(void)
427 {
428 int ret = 0;
429
430 if (connected) {
431 ret = lttcomm_close_unix_sock(sessiond_socket);
432 sessiond_socket = 0;
433 connected = 0;
434 }
435
436 return ret;
437 }
438
439 /*
440 * lttng_set_current_session_uuid
441 *
442 * Set the session uuid for current lsm.
443 */
444 void lttng_set_current_session_uuid(uuid_t *uuid)
445 {
446 uuid_copy(lsm.session_uuid, *uuid);
447 }
448
449 /*
450 * lttng_set_tracing_group
451 *
452 * Set tracing group variable with name. This function
453 * allocate memory pointed by tracing_group.
454 */
455 int lttng_set_tracing_group(const char *name)
456 {
457 if (asprintf(&tracing_group, "%s", name) < 0) {
458 return -ENOMEM;
459 }
460
461 return 0;
462 }
463
464 /*
465 * lttng_check_session_daemon
466 *
467 * Return 0 if a sesssion daemon is available
468 * else return -1
469 */
470 int lttng_check_session_daemon(void)
471 {
472 int ret;
473
474 ret = set_session_daemon_path();
475 if (ret < 0) {
476 return ret;
477 }
478
479 /* If socket exist, we consider the daemon started */
480 ret = access(sessiond_sock_path, F_OK);
481 if (ret < 0) {
482 return ret;
483 }
484
485 return 0;
486 }
487
488 /*
489 * set_session_daemon_path
490 *
491 * Set sessiond socket path by putting it in
492 * the global sessiond_sock_path variable.
493 */
494 static int set_session_daemon_path(void)
495 {
496 int ret;
497
498 /* Are we in the tracing group ? */
499 ret = check_tracing_group(tracing_group);
500 if (ret < 0 && getuid() != 0) {
501 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
502 getenv("HOME")) < 0) {
503 return -ENOMEM;
504 }
505 } else {
506 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
507 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
508 }
509
510 return 0;
511 }
512
513 /*
514 * check_tracing_group
515 *
516 * Check if the specified group name exist.
517 * If yes, 0, else -1
518 */
519 static int check_tracing_group(const char *grp_name)
520 {
521 struct group *grp_tracing; /* no free(). See getgrnam(3) */
522 gid_t *grp_list;
523 int grp_list_size, grp_id, i;
524 int ret = -1;
525
526 /* Get GID of group 'tracing' */
527 grp_tracing = getgrnam(grp_name);
528 if (grp_tracing == NULL) {
529 /* NULL means not found also. getgrnam(3) */
530 if (errno != 0) {
531 perror("getgrnam");
532 }
533 goto end;
534 }
535
536 /* Get number of supplementary group IDs */
537 grp_list_size = getgroups(0, NULL);
538 if (grp_list_size < 0) {
539 perror("getgroups");
540 goto end;
541 }
542
543 /* Alloc group list of the right size */
544 grp_list = malloc(grp_list_size * sizeof(gid_t));
545 grp_id = getgroups(grp_list_size, grp_list);
546 if (grp_id < -1) {
547 perror("getgroups");
548 goto free_list;
549 }
550
551 for (i = 0; i < grp_list_size; i++) {
552 if (grp_list[i] == grp_tracing->gr_gid) {
553 ret = 0;
554 break;
555 }
556 }
557
558 free_list:
559 free(grp_list);
560
561 end:
562 return ret;
563 }
564
565 /*
566 * lib constructor
567 */
568 static void __attribute__((constructor)) init()
569 {
570 /* Set default session group */
571 lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
572 }
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