fda45ae10d2bc423dea61b94f3a2521c5c074b0c
[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
39 /* Prototypes */
40 static int check_tracing_group(const char *grp_name);
41 static int ask_sessiond(enum lttcomm_command_type lct, void **buf);
42 static int recv_data_sessiond(void *buf, size_t len);
43 static int send_data_sessiond(void);
44 static int set_session_daemon_path(void);
45
46 /* Variables */
47 static char *tracing_group;
48 static int connected;
49
50 /*
51 * send_data_sessiond
52 *
53 * Send lttcomm_session_msg to the session daemon.
54 *
55 * On success, return 0
56 * On error, return error code
57 */
58 static int send_data_sessiond(void)
59 {
60 int ret;
61
62 if (!connected) {
63 ret = -ENOTCONN;
64 goto end;
65 }
66
67 ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
68
69 end:
70 return ret;
71 }
72
73 /*
74 * recv_data_sessiond
75 *
76 * Receive data from the sessiond socket.
77 *
78 * On success, return 0
79 * On error, return recv() error code
80 */
81 static int recv_data_sessiond(void *buf, size_t len)
82 {
83 int ret;
84
85 if (!connected) {
86 ret = -ENOTCONN;
87 goto end;
88 }
89
90 ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
91 if (ret < 0) {
92 goto end;
93 }
94
95 end:
96 return ret;
97 }
98
99 /*
100 * ask_sessiond
101 *
102 * Ask the session daemon a specific command
103 * and put the data into buf.
104 *
105 * Return size of data (only payload, not header).
106 */
107 static int ask_sessiond(enum lttcomm_command_type lct, void **buf)
108 {
109 int ret;
110 size_t size;
111 void *data = NULL;
112 struct lttcomm_lttng_msg llm;
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_list_apps
172 *
173 * Ask the session daemon for all UST traceable
174 * applications.
175 *
176 * Return the number of pids.
177 * On error, return negative value.
178 */
179 int lttng_ust_list_apps(pid_t **pids)
180 {
181 int ret;
182
183 ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
184 if (ret < 0) {
185 return ret;
186 }
187
188 return ret / sizeof(pid_t);
189 }
190
191 /*
192 * lttng_list_sessions
193 *
194 * Ask the session daemon for all available sessions.
195 *
196 * Return number of session.
197 * On error, return negative value.
198 */
199 int lttng_list_sessions(struct lttng_session **sessions)
200 {
201 int ret;
202
203 ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
204 if (ret < 0) {
205 return ret;
206 }
207
208 return ret / sizeof(struct lttng_session);
209 }
210
211 /*
212 * lttng_connect_sessiond
213 *
214 * Connect to the LTTng session daemon.
215 * On success, return 0
216 * On error, return a negative value
217 */
218 int lttng_connect_sessiond(void)
219 {
220 int ret;
221
222 ret = set_session_daemon_path();
223 if (ret < 0) {
224 return ret;
225 }
226
227 /* Connect to the sesssion daemon */
228 ret = lttcomm_connect_unix_sock(sessiond_sock_path);
229 if (ret < 0) {
230 return ret;
231 }
232
233 sessiond_socket = ret;
234 connected = 1;
235
236 return 0;
237 }
238
239 /*
240 * lttng_set_tracing_group
241 *
242 * Set tracing group variable with name. This function
243 * allocate memory pointed by tracing_group.
244 */
245 int lttng_set_tracing_group(const char *name)
246 {
247 if (asprintf(&tracing_group, "%s", name) < 0) {
248 return -ENOMEM;
249 }
250
251 return 0;
252 }
253
254 /*
255 * lttng_check_session_daemon
256 *
257 * Return 0 if a sesssion daemon is available
258 * else return -1
259 */
260 int lttng_check_session_daemon(void)
261 {
262 int ret;
263
264 ret = set_session_daemon_path();
265 if (ret < 0) {
266 return ret;
267 }
268
269 /* If socket exist, we consider the daemon started */
270 ret = access(sessiond_sock_path, F_OK);
271 if (ret < 0) {
272 return ret;
273 }
274
275 return 0;
276 }
277
278 /*
279 * set_session_daemon_path
280 *
281 * Set sessiond socket path by putting it in
282 * the global sessiond_sock_path variable.
283 */
284 static int set_session_daemon_path(void)
285 {
286 int ret;
287
288 /* Are we in the tracing group ? */
289 ret = check_tracing_group(tracing_group);
290 if (ret < 0) {
291 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
292 getenv("HOME")) < 0) {
293 return -ENOMEM;
294 }
295 } else {
296 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
297 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
298 }
299
300 return 0;
301 }
302
303 /*
304 * check_tracing_group
305 *
306 * Check if the specified group name exist.
307 * If yes, 0, else -1
308 */
309 static int check_tracing_group(const char *grp_name)
310 {
311 struct group *grp_tracing; /* no free(). See getgrnam(3) */
312 gid_t *grp_list;
313 int grp_list_size, grp_id, i;
314 int ret = -1;
315
316 /* Get GID of group 'tracing' */
317 grp_tracing = getgrnam(grp_name);
318 if (grp_tracing == NULL) {
319 /* NULL means not found also. getgrnam(3) */
320 if (errno != 0) {
321 perror("getgrnam");
322 }
323 goto end;
324 }
325
326 /* Get number of supplementary group IDs */
327 grp_list_size = getgroups(0, NULL);
328 if (grp_list_size < 0) {
329 perror("getgroups");
330 goto end;
331 }
332
333 /* Alloc group list of the right size */
334 grp_list = malloc(grp_list_size * sizeof(gid_t));
335 grp_id = getgroups(grp_list_size, grp_list);
336 if (grp_id < -1) {
337 perror("getgroups");
338 goto free_list;
339 }
340
341 for (i = 0; i < grp_list_size; i++) {
342 if (grp_list[i] == grp_tracing->gr_gid) {
343 ret = 0;
344 break;
345 }
346 }
347
348 free_list:
349 free(grp_list);
350
351 end:
352 return ret;
353 }
354
355 /*
356 * lib constructor
357 */
358 static void __attribute__((constructor)) init()
359 {
360 /* Set default session group */
361 lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
362 }
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