Replace daemonize function by std glibc daemon()
[lttng-tools.git] / liblttngctl / liblttngctl.c
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1/*
2 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
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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.
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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 */
33static int sessiond_socket;
34static char sessiond_sock_path[PATH_MAX];
35
36/* Communication structure to ltt-sessiond */
37static struct lttcomm_lttng_msg llm;
38static struct lttcomm_session_msg lsm;
39
40/* Prototypes */
41static int check_tracing_group(const char *grp_name);
42static int ask_sessiond(void);
e065084a 43static int recvfrom_sessiond(void);
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44static int set_session_daemon_path(void);
45static void reset_data_struct(void);
46
47int lttng_connect_sessiond(void);
48int lttng_create_session(const char *name, char *session_id);
49int lttng_check_session_daemon(void);
50
51/* Variables */
52static char *tracing_group;
53static int connected;
54
55/*
56 * ask_sessiond
57 *
e065084a 58 * Send lttcomm_session_msg to the session daemon.
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59 *
60 * On success, return 0
61 * On error, return error code
62 */
63static int ask_sessiond(void)
64{
65 int ret;
66
67 if (!connected) {
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68 ret = -ENOTCONN;
69 goto end;
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70 }
71
72 ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
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73
74end:
75 return ret;
76}
77
78/*
79 * recvfrom_sessiond
80 *
81 * Receive data from the sessiond socket.
82 *
83 * On success, return 0
84 * On error, return recv() error code
85 */
86static int recvfrom_sessiond(void)
87{
88 int ret;
89
90 if (!connected) {
91 ret = -ENOTCONN;
92 goto end;
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93 }
94
95 ret = lttcomm_recv_unix_sock(sessiond_socket, &llm, sizeof(llm));
96 if (ret < 0) {
e065084a 97 goto end;
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98 }
99
100 /* Check return code */
101 if (llm.ret_code != LTTCOMM_OK) {
102 ret = -llm.ret_code;
e065084a 103 goto end;
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104 }
105
e065084a 106end:
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107 return ret;
108}
109
110/*
111 * lttng_get_readable_code
112 *
113 * Return a human readable string of code
114 */
115const char *lttng_get_readable_code(int code)
116{
117 if (code > -LTTCOMM_OK) {
118 return "Ended with errors";
119 }
120
121 return lttcomm_get_readable_code(code);
122}
123
124/*
125 * lttng_create_session
126 *
127 * Create a tracing session using "name" to the session daemon.
128 * If no name is given, the auto session creation is set and
129 * the daemon will take care of finding a name.
130 *
131 * On success, return 0 and session_id point to the uuid str.
132 * On error, negative value is returned.
133 */
134int lttng_create_session(const char *name, char *session_id)
135{
136 int ret;
137
138 lsm.cmd_type = LTTNG_CREATE_SESSION;
139 if (name == NULL) {
140 lsm.u.create_session.auto_session = 1;
141 } else {
142 strncpy(lsm.session_name, name, strlen(name));
143 lsm.u.create_session.auto_session = 0;
144 }
145
146 /* Ask the session daemon */
147 ret = ask_sessiond();
148 if (ret < 0) {
149 goto end;
150 }
151
152 /* Unparse session ID */
153 uuid_unparse(llm.session_id, session_id);
154
155end:
156 reset_data_struct();
157
158 return ret;
159}
160
161/*
162 * lttng_ust_list_apps
163 *
164 * Ask the session daemon for all UST traceable
165 * applications.
166 *
167 * Return the size of pids.
168 */
169size_t lttng_ust_list_apps(pid_t **pids)
170{
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171 int ret, first = 0;
172 size_t size = 0;
173 pid_t *p = NULL;
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174
175 lsm.cmd_type = UST_LIST_APPS;
176
177 ret = ask_sessiond();
178 if (ret < 0) {
179 goto error;
180 }
181
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182 do {
183 ret = recvfrom_sessiond();
184 if (ret < 0) {
185 goto error;
186 }
187
188 if (first == 0) {
189 first = 1;
190 size = llm.num_pckt;
191 p = malloc(sizeof(pid_t) * size);
192 }
193 p[size - llm.num_pckt] = llm.u.list_apps.pid;
194 } while ((llm.num_pckt-1) != 0);
195
196 *pids = p;
fac6795d 197
e065084a 198 return size;
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199
200error:
201 return ret;
202}
203
204/*
205 * lttng_connect_sessiond
206 *
207 * Connect to the LTTng session daemon.
208 * On success, return 0
209 * On error, return a negative value
210 */
211int lttng_connect_sessiond(void)
212{
213 int ret;
214
215 ret = set_session_daemon_path();
216 if (ret < 0) {
217 return ret;
218 }
219
220 /* Connect to the sesssion daemon */
221 ret = lttcomm_connect_unix_sock(sessiond_sock_path);
222 if (ret < 0) {
223 return ret;
224 }
225
226 sessiond_socket = ret;
227 connected = 1;
228
229 return 0;
230}
231
232/*
233 * lttng_set_tracing_group
234 *
235 * Set tracing group variable with name. This function
236 * allocate memory pointed by tracing_group.
237 */
238int lttng_set_tracing_group(const char *name)
239{
240 if (asprintf(&tracing_group, "%s", name) < 0) {
241 return -ENOMEM;
242 }
243
244 return 0;
245}
246
247/*
248 * lttng_check_session_daemon
249 *
250 * Return 0 if a sesssion daemon is available
251 * else return -1
252 */
253int lttng_check_session_daemon(void)
254{
255 int ret;
256
257 ret = set_session_daemon_path();
258 if (ret < 0) {
259 return ret;
260 }
261
262 /* If socket exist, we consider the daemon started */
263 ret = access(sessiond_sock_path, F_OK);
264 if (ret < 0) {
265 return ret;
266 }
267
268 return 0;
269}
270
271/*
272 * reset_data_struct
273 *
274 * Reset session daemon structures.
275 */
276static void reset_data_struct(void)
277{
278 memset(&lsm, 0, sizeof(lsm));
279 memset(&llm, 0, sizeof(llm));
280}
281
282/*
283 * set_session_daemon_path
284 *
285 * Set sessiond socket path by putting it in
286 * the global sessiond_sock_path variable.
287 */
288static int set_session_daemon_path(void)
289{
290 int ret;
291
292 /* Are we in the tracing group ? */
293 ret = check_tracing_group(tracing_group);
294 if (ret < 0) {
295 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
296 getenv("HOME")) < 0) {
297 return -ENOMEM;
298 }
299 } else {
300 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
301 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
302 }
303
304 return 0;
305}
306
307/*
308 * check_tracing_group
309 *
310 * Check if the specified group name exist.
311 * If yes, 0, else -1
312 */
313static int check_tracing_group(const char *grp_name)
314{
315 struct group *grp_tracing; /* no free(). See getgrnam(3) */
316 gid_t *grp_list;
317 int grp_list_size, grp_id, i;
318 int ret = -1;
319
320 /* Get GID of group 'tracing' */
321 grp_tracing = getgrnam(grp_name);
322 if (grp_tracing == NULL) {
323 /* NULL means not found also. getgrnam(3) */
324 if (errno != 0) {
325 perror("getgrnam");
326 }
327 goto end;
328 }
329
330 /* Get number of supplementary group IDs */
331 grp_list_size = getgroups(0, NULL);
332 if (grp_list_size < 0) {
333 perror("getgroups");
334 goto end;
335 }
336
337 /* Alloc group list of the right size */
338 grp_list = malloc(grp_list_size * sizeof(gid_t));
339 grp_id = getgroups(grp_list_size, grp_list);
340 if (grp_id < -1) {
341 perror("getgroups");
342 goto free_list;
343 }
344
345 for (i = 0; i < grp_list_size; i++) {
346 if (grp_list[i] == grp_tracing->gr_gid) {
347 ret = 0;
348 break;
349 }
350 }
351
352free_list:
353 free(grp_list);
354
355end:
356 return ret;
357}
358
359/*
360 * lib constructor
361 */
362static void __attribute__((constructor)) init()
363{
364 /* Set default session group */
365 lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
366}
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