Don't spawen session daemon on version command
[lttng-tools.git] / src / bin / lttng / lttng.c
CommitLineData
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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 modify
5 * it under the terms of the GNU General Public License as published by
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6 * as published by the Free Software Foundation; only version 2
7 * of the License.
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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 along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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17 */
18
19#define _GNU_SOURCE
fac6795d 20#include <getopt.h>
f3ed775e 21#include <signal.h>
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22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
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25#include <sys/types.h>
26#include <sys/wait.h>
fac6795d 27#include <unistd.h>
3bd1e081 28#include <config.h>
fac6795d 29
5b97ec60 30#include <lttng/lttng.h>
db758600 31#include <common/error.h>
fac6795d 32
c399183f 33#include "command.h"
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34
35/* Variables */
36static char *progname;
fac6795d 37
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38int opt_quiet;
39int opt_verbose;
40static int opt_no_sessiond;
41static char *opt_sessiond_path;
8db8d1dc 42static pid_t sessiond_pid;
5a532b68 43static volatile int recv_child_signal;
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44
45enum {
f3ed775e 46 OPT_SESSION_PATH,
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47 OPT_DUMP_OPTIONS,
48 OPT_DUMP_COMMANDS,
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49};
50
51/* Getopt options. No first level command. */
52static struct option long_options[] = {
53 {"help", 0, NULL, 'h'},
54 {"group", 1, NULL, 'g'},
55 {"verbose", 0, NULL, 'v'},
56 {"quiet", 0, NULL, 'q'},
8490ae7b 57 {"no-sessiond", 0, NULL, 'n'},
f3ed775e 58 {"sessiond-path", 1, NULL, OPT_SESSION_PATH},
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59 {"list-options", 0, NULL, OPT_DUMP_OPTIONS},
60 {"list-commands", 0, NULL, OPT_DUMP_COMMANDS},
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61 {NULL, 0, NULL, 0}
62};
63
64/* First level command */
65static struct cmd_struct commands[] = {
66 { "list", cmd_list},
67 { "create", cmd_create},
68 { "destroy", cmd_destroy},
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69 { "start", cmd_start},
70 { "stop", cmd_stop},
71 { "enable-event", cmd_enable_events},
e953ef25 72 { "disable-event", cmd_disable_events},
d36b8583 73 { "enable-channel", cmd_enable_channels},
26cc6b4e 74 { "disable-channel", cmd_disable_channels},
d65106b1 75 { "add-context", cmd_add_context},
3087ef18 76 { "set-session", cmd_set_session},
eb9cb8b7 77 { "version", cmd_version},
d0254c7c 78 { "calibrate", cmd_calibrate},
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79 { NULL, NULL} /* Array closure */
80};
81
82static void usage(FILE *ofp)
8c0faa1d 83{
f3ed775e 84 fprintf(ofp, "LTTng Trace Control " VERSION"\n\n");
852fdd0c 85 fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND>\n");
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86 fprintf(ofp, "\n");
87 fprintf(ofp, "Options:\n");
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88 fprintf(ofp, " -h, --help Show this help\n");
89 fprintf(ofp, " --list-options Simple listing of lttng options\n");
90 fprintf(ofp, " --list-commands Simple listing of lttng commands\n");
91 fprintf(ofp, " -v, --verbose Increase verbosity\n");
92 fprintf(ofp, " -q, --quiet Quiet mode\n");
93 fprintf(ofp, " -g, --group NAME Unix tracing group name. (default: tracing)\n");
94 fprintf(ofp, " -n, --no-sessiond Don't spawn a session daemon\n");
95 fprintf(ofp, " --sessiond-path PATH Session daemon full path\n");
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96 fprintf(ofp, "\n");
97 fprintf(ofp, "Commands:\n");
852fdd0c 98 fprintf(ofp, " add-context Add context to event and/or channel\n");
d0254c7c 99 fprintf(ofp, " calibrate Quantify LTTng overhead\n");
f3ed775e 100 fprintf(ofp, " create Create tracing session\n");
852fdd0c 101 fprintf(ofp, " destroy Tear down tracing session\n");
d36b8583 102 fprintf(ofp, " enable-channel Enable tracing channel\n");
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103 fprintf(ofp, " enable-event Enable tracing event\n");
104 fprintf(ofp, " disable-channel Disable tracing channel\n");
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105 fprintf(ofp, " disable-event Disable tracing event\n");
106 fprintf(ofp, " list List possible tracing options\n");
3087ef18 107 fprintf(ofp, " set-session Set current session name\n");
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108 fprintf(ofp, " start Start tracing\n");
109 fprintf(ofp, " stop Stop tracing\n");
110 fprintf(ofp, " version Show version information\n");
111 fprintf(ofp, "\n");
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112 fprintf(ofp, "Each command also has its own -h, --help option.\n");
113 fprintf(ofp, "\n");
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114 fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
115 fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
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116}
117
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118/*
119 * list_options
120 *
121 * List options line by line. This is mostly for bash auto completion and to
122 * avoid difficult parsing.
123 */
124static void list_options(FILE *ofp)
125{
126 int i = 0;
127 struct option *option = NULL;
128
129 option = &long_options[i];
130 while (option->name != NULL) {
131 fprintf(ofp, "--%s\n", option->name);
132
133 if (isprint(option->val)) {
134 fprintf(ofp, "-%c\n", option->val);
135 }
136
137 i++;
138 option = &long_options[i];
139 }
140}
141
142/*
143 * list_commands
144 *
145 * List commands line by line. This is mostly for bash auto completion and to
146 * avoid difficult parsing.
147 */
148static void list_commands(FILE *ofp)
149{
150 int i = 0;
151 struct cmd_struct *cmd = NULL;
152
153 cmd = &commands[i];
154 while (cmd->name != NULL) {
155 fprintf(ofp, "%s\n", cmd->name);
156 i++;
157 cmd = &commands[i];
158 }
159}
160
7442b2ba 161/*
f3ed775e 162 * clean_exit
96243366 163 */
f3ed775e 164static void clean_exit(int code)
96243366 165{
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166 DBG("Clean exit");
167 exit(code);
894be886 168}
96243366 169
894be886 170/*
f3ed775e 171 * sighandler
2ef84c95 172 *
f3ed775e 173 * Signal handler for the daemon
2ef84c95 174 */
f3ed775e 175static void sighandler(int sig)
2ef84c95 176{
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177 int status;
178
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179 switch (sig) {
180 case SIGTERM:
99bab54f 181 DBG("SIGTERM caught");
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182 clean_exit(EXIT_FAILURE);
183 break;
184 case SIGCHLD:
99bab54f 185 DBG("SIGCHLD caught");
8db8d1dc 186 waitpid(sessiond_pid, &status, 0);
5a532b68 187 recv_child_signal = 1;
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188 /* Indicate that the session daemon died */
189 sessiond_pid = 0;
190 ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
191 break;
192 case SIGUSR1:
193 /* Notify is done */
5a532b68 194 recv_child_signal = 1;
99bab54f 195 DBG("SIGUSR1 caught");
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196 break;
197 default:
99bab54f 198 DBG("Unknown signal %d caught", sig);
f3ed775e 199 break;
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200 }
201
f3ed775e 202 return;
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203}
204
205/*
f3ed775e 206 * set_signal_handler
894be886 207 *
f3ed775e 208 * Setup signal handler for SIGCHLD and SIGTERM.
894be886 209 */
f3ed775e 210static int set_signal_handler(void)
894be886 211{
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212 int ret = 0;
213 struct sigaction sa;
214 sigset_t sigset;
33a2b854 215
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216 if ((ret = sigemptyset(&sigset)) < 0) {
217 perror("sigemptyset");
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218 goto end;
219 }
220
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221 sa.sa_handler = sighandler;
222 sa.sa_mask = sigset;
223 sa.sa_flags = 0;
8db8d1dc 224 if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
f3ed775e 225 perror("sigaction");
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226 goto end;
227 }
228
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229 if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
230 perror("sigaction");
231 goto end;
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232 }
233
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234 if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
235 perror("sigaction");
236 goto end;
237 }
238
96243366 239end:
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240 return ret;
241}
242
fac6795d 243/*
f3ed775e 244 * handle_command
fac6795d 245 *
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246 * Handle the full argv list of a first level command. Will find the command
247 * in the global commands array and call the function callback associated.
1c9f7941 248 *
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249 * If command not found, return -1
250 * else, return function command error code.
1c9f7941 251 */
f3ed775e 252static int handle_command(int argc, char **argv)
1c9f7941 253{
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254 int i = 0, ret;
255 struct cmd_struct *cmd;
1c9f7941 256
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257 if (*argv == NULL) {
258 ret = CMD_SUCCESS;
47b74d63 259 goto end;
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260 }
261
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262 cmd = &commands[i];
263 while (cmd->func != NULL) {
264 /* Find command */
265 if (strcmp(argv[0], cmd->name) == 0) {
266 ret = cmd->func(argc, (const char**) argv);
267 switch (ret) {
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268 case CMD_WARNING:
269 WARN("Some command(s) went wrong");
270 break;
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271 case CMD_ERROR:
272 ERR("Command error");
273 break;
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274 case CMD_UNDEFINED:
275 ERR("Undefined command");
276 break;
277 case CMD_FATAL:
278 ERR("Fatal error");
279 break;
280 }
281 goto end;
894be886 282 }
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283 i++;
284 cmd = &commands[i];
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285 }
286
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287 /* Command not found */
288 ret = -1;
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289
290end:
f3ed775e 291 return ret;
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292}
293
5b8719f5
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294/*
295 * spawn_sessiond
296 *
297 * Spawn a session daemon by forking and execv.
298 */
299static int spawn_sessiond(char *pathname)
300{
301 int ret = 0;
302 pid_t pid;
303
f3ed775e 304 MSG("Spawning a session daemon");
5a532b68 305 recv_child_signal = 0;
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306 pid = fork();
307 if (pid == 0) {
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308 /*
309 * Spawn session daemon and tell
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310 * it to signal us when ready.
311 */
32258573 312 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
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313 /* execlp only returns if error happened */
314 if (errno == ENOENT) {
315 ERR("No session daemon found. Use --sessiond-path.");
316 } else {
317 perror("execlp");
5b8719f5 318 }
5a532b68 319 kill(getppid(), SIGTERM); /* wake parent */
5e16da05 320 exit(EXIT_FAILURE);
5b8719f5 321 } else if (pid > 0) {
8db8d1dc 322 sessiond_pid = pid;
5a532b68 323 /*
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324 * Wait for lttng-sessiond to start. We need to use a flag to check if
325 * the signal has been sent to us, because the child can be scheduled
326 * before the parent, and thus send the signal before this check. In
327 * the signal handler, we set the recv_child_signal flag, so anytime we
328 * check it after the fork is fine. Note that sleep() is interrupted
329 * before the 1 second delay as soon as the signal is received, so it
330 * will not cause visible delay for the user.
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331 */
332 while (!recv_child_signal) {
333 sleep(1);
334 }
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335 /*
336 * The signal handler will nullify sessiond_pid on SIGCHLD
337 */
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338 if (!sessiond_pid) {
339 exit(EXIT_FAILURE);
340 }
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341 goto end;
342 } else {
343 perror("fork");
344 ret = -1;
345 goto end;
346 }
347
348end:
349 return ret;
350}
351
fac6795d 352/*
f3ed775e 353 * check_sessiond
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354 *
355 * Check if the session daemon is available using
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356 * the liblttngctl API for the check. If not, try to
357 * spawn a daemon.
fac6795d 358 */
f3ed775e 359static int check_sessiond(void)
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360{
361 int ret;
5e16da05 362 char *pathname = NULL, *alloc_pathname = NULL;
fac6795d 363
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364 ret = lttng_session_daemon_alive();
365 if (ret == 0) { /* not alive */
5b8719f5
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366 /* Try command line option path */
367 if (opt_sessiond_path != NULL) {
368 ret = access(opt_sessiond_path, F_OK | X_OK);
369 if (ret < 0) {
3183dbb0 370 ERR("No such file or access denied: %s", opt_sessiond_path);
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371 goto end;
372 }
373 pathname = opt_sessiond_path;
374 } else {
375 /* Try LTTNG_SESSIOND_PATH env variable */
bbccc3d2 376 pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
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377 }
378
379 /* Let's rock and roll */
380 if (pathname == NULL) {
32258573 381 ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
5b8719f5 382 if (ret < 0) {
3f5fa9ed 383 perror("asprintf spawn sessiond");
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384 goto end;
385 }
5e16da05 386 pathname = alloc_pathname;
5b8719f5
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387 }
388
389 ret = spawn_sessiond(pathname);
5e16da05 390 free(alloc_pathname);
5b8719f5 391 if (ret < 0) {
3183dbb0 392 ERR("Problem occurred when starting %s", pathname);
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393 goto end;
394 }
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395 }
396
5b8719f5 397end:
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398 return ret;
399}
400
bcfa8a05 401/*
679b4943
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402 * Check args for specific options that *must* not trigger a session daemon
403 * execution.
404 *
405 * Return 1 if match else 0.
bcfa8a05 406 */
679b4943 407static int check_args_no_sessiond(int argc, char **argv)
bcfa8a05
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408{
409 int i;
410
411 for (i = 0; i < argc; i++) {
ba2926ef
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412 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
413 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
3183dbb0 414 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
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415 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
416 strncmp(argv[i], "version", sizeof("version"))) {
bcfa8a05
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417 return 1;
418 }
419 }
420
421 return 0;
422}
423
5b8719f5 424/*
3183dbb0 425 * Parse command line arguments.
5b8719f5 426 *
3183dbb0 427 * Return 0 if OK, else -1
5b8719f5 428 */
f3ed775e 429static int parse_args(int argc, char **argv)
5b8719f5 430{
f3ed775e 431 int opt, ret;
5b8719f5 432
f3ed775e
DG
433 if (argc < 2) {
434 usage(stderr);
435 clean_exit(EXIT_FAILURE);
5b8719f5
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436 }
437
8490ae7b 438 while ((opt = getopt_long(argc, argv, "+hnvqg:", long_options, NULL)) != -1) {
f3ed775e
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439 switch (opt) {
440 case 'h':
3183dbb0
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441 usage(stdout);
442 goto end;
f3ed775e 443 case 'v':
b551a063 444 opt_verbose += 1;
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445 break;
446 case 'q':
447 opt_quiet = 1;
448 break;
449 case 'g':
450 lttng_set_tracing_group(optarg);
451 break;
8490ae7b 452 case 'n':
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DG
453 opt_no_sessiond = 1;
454 break;
455 case OPT_SESSION_PATH:
456 opt_sessiond_path = strdup(optarg);
457 break;
865abf65
SM
458 case OPT_DUMP_OPTIONS:
459 list_options(stdout);
460 ret = 0;
3183dbb0 461 goto end;
865abf65
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462 case OPT_DUMP_COMMANDS:
463 list_commands(stdout);
464 ret = 0;
3183dbb0 465 goto end;
f3ed775e
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466 default:
467 usage(stderr);
468 goto error;
469 }
5b8719f5 470 }
fac6795d 471
f3ed775e
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472 /* If both options are specified, quiet wins */
473 if (opt_verbose && opt_quiet) {
474 opt_verbose = 0;
5b8719f5
DG
475 }
476
f3ed775e 477 /* Spawn session daemon if needed */
679b4943 478 if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
bcfa8a05 479 (check_sessiond() < 0)) {
f3ed775e 480 goto error;
5b8719f5
DG
481 }
482
f3ed775e
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483 /* No leftovers, print usage and quit */
484 if ((argc - optind) == 0) {
485 usage(stderr);
486 goto error;
487 }
7442b2ba 488
f3ed775e
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489 /*
490 * Handle leftovers which is a first level command with the trailing
491 * options.
492 */
493 ret = handle_command(argc - optind, argv + optind);
494 if (ret < 0) {
495 if (ret == -1) {
496 usage(stderr);
f3ed775e 497 } else {
9a745bc7 498 ERR("%s", lttng_strerror(ret));
f3ed775e 499 }
1fff1faa 500 goto error;
96243366
DG
501 }
502
3183dbb0 503end:
1fff1faa 504 return 0;
f3ed775e
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505
506error:
507 return -1;
fac6795d
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508}
509
f3ed775e 510
fac6795d 511/*
5b8719f5 512 * main
fac6795d
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513 */
514int main(int argc, char *argv[])
515{
516 int ret;
517
518 progname = argv[0] ? argv[0] : "lttng";
519
99bab54f 520 /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
4666e71c
DG
521 if (strncmp(progname, "drtrace", 7) == 0 ||
522 strncmp("compudj", getenv("USER"), 7) == 0) {
523 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
fac6795d
DG
524 }
525
5b8719f5
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526 ret = set_signal_handler();
527 if (ret < 0) {
87378cf5 528 clean_exit(ret);
5b8719f5
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529 }
530
f3ed775e 531 ret = parse_args(argc, argv);
1fff1faa
DG
532 if (ret < 0) {
533 clean_exit(EXIT_FAILURE);
534 }
87378cf5 535
fac6795d
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536 return 0;
537}
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