Add ust create trace feature
[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/liblttngctl.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_command_type 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_command_type lct, void **buf)
109 {
110 int ret;
111 size_t size;
112 void *data = NULL;
113
114 lsm.cmd_type = lct;
115
116 /* Send command to session daemon */
117 ret = send_data_sessiond();
118 if (ret < 0) {
119 goto end;
120 }
121
122 /* Get header from data transmission */
123 ret = recv_data_sessiond(&llm, sizeof(llm));
124 if (ret < 0) {
125 goto end;
126 }
127
128 /* Check error code if OK */
129 if (llm.ret_code != LTTCOMM_OK) {
130 ret = -llm.ret_code;
131 goto end;
132 }
133
134 size = llm.size_payload;
135 if (size == 0) {
136 goto end;
137 }
138
139 data = (void*) malloc(size);
140
141 /* Get payload data */
142 ret = recv_data_sessiond(data, size);
143 if (ret < 0) {
144 goto end;
145 }
146
147 *buf = data;
148 ret = size;
149
150 end:
151 /* Reset lsm data struct */
152 memset(&lsm, 0, sizeof(lsm));
153 return ret;
154 }
155
156 /*
157 * lttng_get_readable_code
158 *
159 * Return a human readable string of code
160 */
161 const char *lttng_get_readable_code(int code)
162 {
163 if (code > -LTTCOMM_OK) {
164 return "Ended with errors";
165 }
166
167 return lttcomm_get_readable_code(code);
168 }
169
170 /*
171 * lttng_ust_create_trace
172 *
173 * Request a trace creation for pid.
174 */
175 int lttng_ust_create_trace(pid_t pid)
176 {
177 int ret;
178
179 lsm.pid = pid;
180 ret = ask_sessiond(UST_CREATE_TRACE, NULL);
181
182 return ret;
183 }
184
185 /*
186 * lttng_ust_list_apps
187 *
188 * Ask the session daemon for all UST traceable
189 * applications.
190 *
191 * Return the number of pids.
192 * On error, return negative value.
193 */
194 int lttng_ust_list_apps(pid_t **pids)
195 {
196 int ret;
197
198 ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
199 if (ret < 0) {
200 return ret;
201 }
202
203 return ret / sizeof(pid_t);
204 }
205
206 /*
207 * lttng_create_session
208 *
209 * Create a brand new session using name. Allocate
210 * the session_id param pointing to the UUID.
211 */
212 int lttng_create_session(char *name, uuid_t *session_id)
213 {
214 int ret;
215
216 strncpy(lsm.session_name, name, sizeof(lsm.session_name));
217 lsm.session_name[sizeof(lsm.session_name) - 1] = '\0';
218
219 ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
220 if (ret < 0) {
221 goto end;
222 }
223
224 uuid_copy(*session_id, llm.session_id);
225
226 end:
227 return ret;
228 }
229
230 /*
231 * lttng_destroy_session
232 *
233 * Destroy session using name.
234 */
235 int lttng_destroy_session(uuid_t *uuid)
236 {
237 int ret;
238
239 uuid_copy(lsm.session_id, *uuid);
240
241 ret = ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
242 if (ret < 0) {
243 goto end;
244 }
245
246 end:
247 return ret;
248 }
249
250 /*
251 * lttng_list_sessions
252 *
253 * Ask the session daemon for all available sessions.
254 *
255 * Return number of session.
256 * On error, return negative value.
257 */
258 int lttng_list_sessions(struct lttng_session **sessions)
259 {
260 int ret;
261
262 ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
263 if (ret < 0) {
264 return ret;
265 }
266
267 return ret / sizeof(struct lttng_session);
268 }
269
270 /*
271 * lttng_connect_sessiond
272 *
273 * Connect to the LTTng session daemon.
274 * On success, return 0
275 * On error, return a negative value
276 */
277 int lttng_connect_sessiond(void)
278 {
279 int ret;
280
281 ret = set_session_daemon_path();
282 if (ret < 0) {
283 return ret;
284 }
285
286 /* Connect to the sesssion daemon */
287 ret = lttcomm_connect_unix_sock(sessiond_sock_path);
288 if (ret < 0) {
289 return ret;
290 }
291
292 sessiond_socket = ret;
293 connected = 1;
294
295 return 0;
296 }
297
298 /*
299 * lttng_disconnect_sessiond
300 *
301 * Clean disconnect the session daemon.
302 */
303 int lttng_disconnect_sessiond(void)
304 {
305 int ret = 0;
306
307 if (connected) {
308 ret = lttcomm_close_unix_sock(sessiond_socket);
309 sessiond_socket = 0;
310 connected = 0;
311 }
312
313 return ret;
314 }
315
316 /*
317 * lttng_set_current_session_uuid
318 *
319 * Set the session uuid for current lsm.
320 */
321 void lttng_set_current_session_uuid(char *uuid)
322 {
323 uuid_parse(uuid, lsm.session_id);
324 }
325
326 /*
327 * lttng_set_tracing_group
328 *
329 * Set tracing group variable with name. This function
330 * allocate memory pointed by tracing_group.
331 */
332 int lttng_set_tracing_group(const char *name)
333 {
334 if (asprintf(&tracing_group, "%s", name) < 0) {
335 return -ENOMEM;
336 }
337
338 return 0;
339 }
340
341 /*
342 * lttng_check_session_daemon
343 *
344 * Return 0 if a sesssion daemon is available
345 * else return -1
346 */
347 int lttng_check_session_daemon(void)
348 {
349 int ret;
350
351 ret = set_session_daemon_path();
352 if (ret < 0) {
353 return ret;
354 }
355
356 /* If socket exist, we consider the daemon started */
357 ret = access(sessiond_sock_path, F_OK);
358 if (ret < 0) {
359 return ret;
360 }
361
362 return 0;
363 }
364
365 /*
366 * set_session_daemon_path
367 *
368 * Set sessiond socket path by putting it in
369 * the global sessiond_sock_path variable.
370 */
371 static int set_session_daemon_path(void)
372 {
373 int ret;
374
375 /* Are we in the tracing group ? */
376 ret = check_tracing_group(tracing_group);
377 if (ret < 0) {
378 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
379 getenv("HOME")) < 0) {
380 return -ENOMEM;
381 }
382 } else {
383 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
384 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
385 }
386
387 return 0;
388 }
389
390 /*
391 * check_tracing_group
392 *
393 * Check if the specified group name exist.
394 * If yes, 0, else -1
395 */
396 static int check_tracing_group(const char *grp_name)
397 {
398 struct group *grp_tracing; /* no free(). See getgrnam(3) */
399 gid_t *grp_list;
400 int grp_list_size, grp_id, i;
401 int ret = -1;
402
403 /* Get GID of group 'tracing' */
404 grp_tracing = getgrnam(grp_name);
405 if (grp_tracing == NULL) {
406 /* NULL means not found also. getgrnam(3) */
407 if (errno != 0) {
408 perror("getgrnam");
409 }
410 goto end;
411 }
412
413 /* Get number of supplementary group IDs */
414 grp_list_size = getgroups(0, NULL);
415 if (grp_list_size < 0) {
416 perror("getgroups");
417 goto end;
418 }
419
420 /* Alloc group list of the right size */
421 grp_list = malloc(grp_list_size * sizeof(gid_t));
422 grp_id = getgroups(grp_list_size, grp_list);
423 if (grp_id < -1) {
424 perror("getgroups");
425 goto free_list;
426 }
427
428 for (i = 0; i < grp_list_size; i++) {
429 if (grp_list[i] == grp_tracing->gr_gid) {
430 ret = 0;
431 break;
432 }
433 }
434
435 free_list:
436 free(grp_list);
437
438 end:
439 return ret;
440 }
441
442 /*
443 * lib constructor
444 */
445 static void __attribute__((constructor)) init()
446 {
447 /* Set default session group */
448 lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
449 }
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