lttng enable-channel: disallow --overwrite and --blocking-timeout
[lttng-tools.git] / src / bin / lttng / commands / enable_channels.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 modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #define _LGPL_SOURCE
19 #include <popt.h>
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <sys/stat.h>
24 #include <sys/types.h>
25 #include <unistd.h>
26 #include <inttypes.h>
27 #include <assert.h>
28 #include <ctype.h>
29
30 #include <common/sessiond-comm/sessiond-comm.h>
31 #include <common/utils.h>
32 #include <common/mi-lttng.h>
33
34 #include "../command.h"
35 #include "../utils.h"
36
37
38 static struct lttng_channel chan_opts;
39 static char *opt_channels;
40 static int opt_kernel;
41 static char *opt_session_name;
42 static int opt_userspace;
43 static char *opt_output;
44 static int opt_buffer_uid;
45 static int opt_buffer_pid;
46 static int opt_buffer_global;
47 static struct {
48 bool set;
49 uint64_t interval;
50 } opt_monitor_timer;
51 static struct {
52 bool set;
53 int64_t value;
54 } opt_blocking_timeout;
55
56 static struct mi_writer *writer;
57
58 #ifdef LTTNG_EMBED_HELP
59 static const char help_msg[] =
60 #include <lttng-enable-channel.1.h>
61 ;
62 #endif
63
64 enum {
65 OPT_HELP = 1,
66 OPT_DISCARD,
67 OPT_OVERWRITE,
68 OPT_SUBBUF_SIZE,
69 OPT_NUM_SUBBUF,
70 OPT_SWITCH_TIMER,
71 OPT_MONITOR_TIMER,
72 OPT_READ_TIMER,
73 OPT_USERSPACE,
74 OPT_LIST_OPTIONS,
75 OPT_TRACEFILE_SIZE,
76 OPT_TRACEFILE_COUNT,
77 OPT_BLOCKING_TIMEOUT,
78 };
79
80 static struct lttng_handle *handle;
81
82 const char *output_mmap = "mmap";
83 const char *output_splice = "splice";
84
85 static struct poptOption long_options[] = {
86 /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
87 {"help", 'h', POPT_ARG_NONE, 0, OPT_HELP, 0, 0},
88 {"session", 's', POPT_ARG_STRING, &opt_session_name, 0, 0, 0},
89 {"kernel", 'k', POPT_ARG_VAL, &opt_kernel, 1, 0, 0},
90 {"userspace", 'u', POPT_ARG_NONE, 0, OPT_USERSPACE, 0, 0},
91 {"discard", 0, POPT_ARG_NONE, 0, OPT_DISCARD, 0, 0},
92 {"overwrite", 0, POPT_ARG_NONE, 0, OPT_OVERWRITE, 0, 0},
93 {"subbuf-size", 0, POPT_ARG_STRING, 0, OPT_SUBBUF_SIZE, 0, 0},
94 {"num-subbuf", 0, POPT_ARG_INT, 0, OPT_NUM_SUBBUF, 0, 0},
95 {"switch-timer", 0, POPT_ARG_INT, 0, OPT_SWITCH_TIMER, 0, 0},
96 {"monitor-timer", 0, POPT_ARG_INT, 0, OPT_MONITOR_TIMER, 0, 0},
97 {"read-timer", 0, POPT_ARG_INT, 0, OPT_READ_TIMER, 0, 0},
98 {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
99 {"output", 0, POPT_ARG_STRING, &opt_output, 0, 0, 0},
100 {"buffers-uid", 0, POPT_ARG_VAL, &opt_buffer_uid, 1, 0, 0},
101 {"buffers-pid", 0, POPT_ARG_VAL, &opt_buffer_pid, 1, 0, 0},
102 {"buffers-global", 0, POPT_ARG_VAL, &opt_buffer_global, 1, 0, 0},
103 {"tracefile-size", 'C', POPT_ARG_INT, 0, OPT_TRACEFILE_SIZE, 0, 0},
104 {"tracefile-count", 'W', POPT_ARG_INT, 0, OPT_TRACEFILE_COUNT, 0, 0},
105 {"blocking-timeout", 0, POPT_ARG_INT, 0, OPT_BLOCKING_TIMEOUT, 0, 0},
106 {0, 0, 0, 0, 0, 0, 0}
107 };
108
109 /*
110 * Set default attributes depending on those already defined from the command
111 * line.
112 */
113 static void set_default_attr(struct lttng_domain *dom)
114 {
115 struct lttng_channel_attr default_attr;
116
117 memset(&default_attr, 0, sizeof(default_attr));
118
119 /* Set attributes */
120 lttng_channel_set_default_attr(dom, &default_attr);
121
122 if (chan_opts.attr.overwrite == -1) {
123 chan_opts.attr.overwrite = default_attr.overwrite;
124 }
125 if (chan_opts.attr.subbuf_size == -1) {
126 chan_opts.attr.subbuf_size = default_attr.subbuf_size;
127 }
128 if (chan_opts.attr.num_subbuf == -1) {
129 chan_opts.attr.num_subbuf = default_attr.num_subbuf;
130 }
131 if (chan_opts.attr.switch_timer_interval == -1) {
132 chan_opts.attr.switch_timer_interval = default_attr.switch_timer_interval;
133 }
134 if (chan_opts.attr.read_timer_interval == -1) {
135 chan_opts.attr.read_timer_interval = default_attr.read_timer_interval;
136 }
137 if ((int) chan_opts.attr.output == -1) {
138 chan_opts.attr.output = default_attr.output;
139 }
140 if (chan_opts.attr.tracefile_count == -1) {
141 chan_opts.attr.tracefile_count = default_attr.tracefile_count;
142 }
143 if (chan_opts.attr.tracefile_size == -1) {
144 chan_opts.attr.tracefile_size = default_attr.tracefile_size;
145 }
146 }
147
148 /*
149 * Adding channel using the lttng API.
150 */
151 static int enable_channel(char *session_name)
152 {
153 struct lttng_channel *channel = NULL;
154 int ret = CMD_SUCCESS, warn = 0, error = 0, success = 0;
155 char *channel_name;
156 struct lttng_domain dom;
157
158 memset(&dom, 0, sizeof(dom));
159
160 /* Validate options. */
161 if (opt_kernel) {
162 if (opt_blocking_timeout.set) {
163 ERR("Retry timeout option not supported for kernel domain (-k)");
164 ret = CMD_ERROR;
165 goto error;
166 }
167 }
168
169 /* Create lttng domain */
170 if (opt_kernel) {
171 dom.type = LTTNG_DOMAIN_KERNEL;
172 dom.buf_type = LTTNG_BUFFER_GLOBAL;
173 if (opt_buffer_uid || opt_buffer_pid) {
174 ERR("Buffer type not supported for domain -k");
175 ret = CMD_ERROR;
176 goto error;
177 }
178 } else if (opt_userspace) {
179 dom.type = LTTNG_DOMAIN_UST;
180 if (opt_buffer_pid) {
181 dom.buf_type = LTTNG_BUFFER_PER_PID;
182 } else {
183 if (opt_buffer_global) {
184 ERR("Buffer type not supported for domain -u");
185 ret = CMD_ERROR;
186 goto error;
187 }
188 dom.buf_type = LTTNG_BUFFER_PER_UID;
189 }
190 } else {
191 /* Checked by the caller. */
192 assert(0);
193 }
194
195 set_default_attr(&dom);
196
197 if (chan_opts.attr.tracefile_size == 0 && chan_opts.attr.tracefile_count) {
198 ERR("Missing option --tracefile-size. "
199 "A file count without a size won't do anything.");
200 ret = CMD_ERROR;
201 goto error;
202 }
203
204 if ((chan_opts.attr.tracefile_size > 0) &&
205 (chan_opts.attr.tracefile_size < chan_opts.attr.subbuf_size)) {
206 WARN("Tracefile size rounded up from (%" PRIu64 ") to subbuffer size (%" PRIu64 ")",
207 chan_opts.attr.tracefile_size, chan_opts.attr.subbuf_size);
208 chan_opts.attr.tracefile_size = chan_opts.attr.subbuf_size;
209 }
210
211 /* Setting channel output */
212 if (opt_output) {
213 if (!strncmp(output_mmap, opt_output, strlen(output_mmap))) {
214 chan_opts.attr.output = LTTNG_EVENT_MMAP;
215 } else if (!strncmp(output_splice, opt_output, strlen(output_splice))) {
216 chan_opts.attr.output = LTTNG_EVENT_SPLICE;
217 } else {
218 ERR("Unknown output type %s. Possible values are: %s, %s\n",
219 opt_output, output_mmap, output_splice);
220 ret = CMD_ERROR;
221 goto error;
222 }
223 }
224
225 handle = lttng_create_handle(session_name, &dom);
226 if (handle == NULL) {
227 ret = -1;
228 goto error;
229 }
230
231 /* Mi open channels element */
232 if (lttng_opt_mi) {
233 assert(writer);
234 ret = mi_lttng_channels_open(writer);
235 if (ret) {
236 ret = CMD_ERROR;
237 goto error;
238 }
239 }
240
241 /* Strip channel list (format: chan1,chan2,...) */
242 channel_name = strtok(opt_channels, ",");
243 while (channel_name != NULL) {
244 void *extended_ptr;
245
246 /* Validate channel name's length */
247 if (strlen(channel_name) >= NAME_MAX) {
248 ERR("Channel name is too long (max. %zu characters)",
249 sizeof(chan_opts.name) - 1);
250 error = 1;
251 goto skip_enable;
252 }
253
254 /*
255 * A dynamically-allocated channel is used in order to allow
256 * the configuration of extended attributes (post-2.9).
257 */
258 channel = lttng_channel_create(&dom);
259 if (!channel) {
260 ERR("Unable to create channel object");
261 error = 1;
262 goto error;
263 }
264
265 /* Copy channel name */
266 strcpy(channel->name, channel_name);
267 channel->enabled = 1;
268 extended_ptr = channel->attr.extended.ptr;
269 memcpy(&channel->attr, &chan_opts.attr, sizeof(chan_opts.attr));
270 channel->attr.extended.ptr = extended_ptr;
271 if (opt_monitor_timer.set) {
272 ret = lttng_channel_set_monitor_timer_interval(channel,
273 opt_monitor_timer.interval);
274 if (ret) {
275 ERR("Failed to set the channel's monitor timer interval");
276 error = 1;
277 goto error;
278 }
279 }
280 if (opt_blocking_timeout.set) {
281 ret = lttng_channel_set_blocking_timeout(channel,
282 opt_blocking_timeout.value);
283 if (ret) {
284 ERR("Failed to set the channel's blocking timeout");
285 error = 1;
286 goto error;
287 }
288 }
289
290 DBG("Enabling channel %s", channel_name);
291
292 ret = lttng_enable_channel(handle, channel);
293 if (ret < 0) {
294 success = 0;
295 switch (-ret) {
296 case LTTNG_ERR_KERN_CHAN_EXIST:
297 case LTTNG_ERR_UST_CHAN_EXIST:
298 case LTTNG_ERR_CHAN_EXIST:
299 WARN("Channel %s: %s (session %s)", channel_name,
300 lttng_strerror(ret), session_name);
301 warn = 1;
302 break;
303 case LTTNG_ERR_INVALID_CHANNEL_NAME:
304 ERR("Invalid channel name: \"%s\". "
305 "Channel names may not start with '.', and "
306 "may not contain '/'.", channel_name);
307 error = 1;
308 break;
309 default:
310 ERR("Channel %s: %s (session %s)", channel_name,
311 lttng_strerror(ret), session_name);
312 error = 1;
313 break;
314 }
315 } else {
316 MSG("%s channel %s enabled for session %s",
317 get_domain_str(dom.type), channel_name, session_name);
318 success = 1;
319 }
320
321 skip_enable:
322 if (lttng_opt_mi) {
323 /* Mi print the channel element and leave it open */
324 ret = mi_lttng_channel(writer, channel, 1);
325 if (ret) {
326 ret = CMD_ERROR;
327 goto error;
328 }
329
330 /* Individual Success ? */
331 ret = mi_lttng_writer_write_element_bool(writer,
332 mi_lttng_element_command_success, success);
333 if (ret) {
334 ret = CMD_ERROR;
335 goto error;
336 }
337
338 /* Close channel element */
339 ret = mi_lttng_writer_close_element(writer);
340 if (ret) {
341 ret = CMD_ERROR;
342 goto error;
343 }
344 }
345
346 /* Next channel */
347 channel_name = strtok(NULL, ",");
348 lttng_channel_destroy(channel);
349 channel = NULL;
350 }
351
352 if (lttng_opt_mi) {
353 /* Close channels element */
354 ret = mi_lttng_writer_close_element(writer);
355 if (ret) {
356 ret = CMD_ERROR;
357 goto error;
358 }
359 }
360
361 ret = CMD_SUCCESS;
362
363 error:
364 if (channel) {
365 lttng_channel_destroy(channel);
366 }
367 /* If more important error happen bypass the warning */
368 if (!ret && warn) {
369 ret = CMD_WARNING;
370 }
371 /* If more important error happen bypass the warning */
372 if (!ret && error) {
373 ret = CMD_ERROR;
374 }
375
376 lttng_destroy_handle(handle);
377
378 return ret;
379 }
380
381 /*
382 * Default value for channel configuration.
383 */
384 static void init_channel_config(void)
385 {
386 /*
387 * Put -1 everywhere so we can identify those set by the command line and
388 * those needed to be set by the default values.
389 */
390 memset(&chan_opts.attr, -1, sizeof(chan_opts.attr));
391 chan_opts.attr.extended.ptr = NULL;
392 }
393
394 /*
395 * Add channel to trace session
396 */
397 int cmd_enable_channels(int argc, const char **argv)
398 {
399 int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
400 static poptContext pc;
401 char *session_name = NULL;
402 char *opt_arg = NULL;
403
404 init_channel_config();
405
406 pc = poptGetContext(NULL, argc, argv, long_options, 0);
407 poptReadDefaultConfig(pc, 0);
408
409 while ((opt = poptGetNextOpt(pc)) != -1) {
410 switch (opt) {
411 case OPT_HELP:
412 SHOW_HELP();
413 goto end;
414 case OPT_DISCARD:
415 chan_opts.attr.overwrite = 0;
416 DBG("Channel set to discard");
417 break;
418 case OPT_OVERWRITE:
419 chan_opts.attr.overwrite = 1;
420 DBG("Channel set to overwrite");
421 break;
422 case OPT_SUBBUF_SIZE:
423 {
424 uint64_t rounded_size;
425 int order;
426
427 /* Parse the size */
428 opt_arg = poptGetOptArg(pc);
429 if (utils_parse_size_suffix(opt_arg, &chan_opts.attr.subbuf_size) < 0 || !chan_opts.attr.subbuf_size) {
430 ERR("Wrong value in --subbuf-size parameter: %s", opt_arg);
431 ret = CMD_ERROR;
432 goto end;
433 }
434
435 order = get_count_order_u64(chan_opts.attr.subbuf_size);
436 assert(order >= 0);
437 rounded_size = 1ULL << order;
438 if (rounded_size < chan_opts.attr.subbuf_size) {
439 ERR("The subbuf size (%" PRIu64 ") is rounded and overflows!",
440 chan_opts.attr.subbuf_size);
441 ret = CMD_ERROR;
442 goto end;
443 }
444
445 if (rounded_size != chan_opts.attr.subbuf_size) {
446 WARN("The subbuf size (%" PRIu64 ") is rounded to the next power of 2 (%" PRIu64 ")",
447 chan_opts.attr.subbuf_size, rounded_size);
448 chan_opts.attr.subbuf_size = rounded_size;
449 }
450
451 /* Should now be power of 2 */
452 assert(!((chan_opts.attr.subbuf_size - 1) & chan_opts.attr.subbuf_size));
453
454 DBG("Channel subbuf size set to %" PRIu64, chan_opts.attr.subbuf_size);
455 break;
456 }
457 case OPT_NUM_SUBBUF:
458 {
459 uint64_t rounded_size;
460 int order;
461
462 errno = 0;
463 opt_arg = poptGetOptArg(pc);
464 chan_opts.attr.num_subbuf = strtoull(opt_arg, NULL, 0);
465 if (errno != 0 || !chan_opts.attr.num_subbuf || !isdigit(opt_arg[0])) {
466 ERR("Wrong value in --num-subbuf parameter: %s", opt_arg);
467 ret = CMD_ERROR;
468 goto end;
469 }
470
471 order = get_count_order_u64(chan_opts.attr.num_subbuf);
472 assert(order >= 0);
473 rounded_size = 1ULL << order;
474 if (rounded_size < chan_opts.attr.num_subbuf) {
475 ERR("The number of subbuffers (%" PRIu64 ") is rounded and overflows!",
476 chan_opts.attr.num_subbuf);
477 ret = CMD_ERROR;
478 goto end;
479 }
480
481 if (rounded_size != chan_opts.attr.num_subbuf) {
482 WARN("The number of subbuffers (%" PRIu64 ") is rounded to the next power of 2 (%" PRIu64 ")",
483 chan_opts.attr.num_subbuf, rounded_size);
484 chan_opts.attr.num_subbuf = rounded_size;
485 }
486
487 /* Should now be power of 2 */
488 assert(!((chan_opts.attr.num_subbuf - 1) & chan_opts.attr.num_subbuf));
489
490 DBG("Channel subbuf num set to %" PRIu64, chan_opts.attr.num_subbuf);
491 break;
492 }
493 case OPT_SWITCH_TIMER:
494 {
495 unsigned long v;
496
497 errno = 0;
498 opt_arg = poptGetOptArg(pc);
499 v = strtoul(opt_arg, NULL, 0);
500 if (errno != 0 || !isdigit(opt_arg[0])) {
501 ERR("Wrong value in --switch-timer parameter: %s", opt_arg);
502 ret = CMD_ERROR;
503 goto end;
504 }
505 if (v != (uint32_t) v) {
506 ERR("32-bit overflow in --switch-timer parameter: %s", opt_arg);
507 ret = CMD_ERROR;
508 goto end;
509 }
510 chan_opts.attr.switch_timer_interval = (uint32_t) v;
511 DBG("Channel switch timer interval set to %d", chan_opts.attr.switch_timer_interval);
512 break;
513 }
514 case OPT_READ_TIMER:
515 {
516 unsigned long v;
517
518 errno = 0;
519 opt_arg = poptGetOptArg(pc);
520 v = strtoul(opt_arg, NULL, 0);
521 if (errno != 0 || !isdigit(opt_arg[0])) {
522 ERR("Wrong value in --read-timer parameter: %s", opt_arg);
523 ret = CMD_ERROR;
524 goto end;
525 }
526 if (v != (uint32_t) v) {
527 ERR("32-bit overflow in --read-timer parameter: %s", opt_arg);
528 ret = CMD_ERROR;
529 goto end;
530 }
531 chan_opts.attr.read_timer_interval = (uint32_t) v;
532 DBG("Channel read timer interval set to %d", chan_opts.attr.read_timer_interval);
533 break;
534 }
535 case OPT_MONITOR_TIMER:
536 {
537 unsigned long long v;
538
539 errno = 0;
540 opt_arg = poptGetOptArg(pc);
541 v = strtoull(opt_arg, NULL, 0);
542 if (errno != 0 || !isdigit(opt_arg[0])) {
543 ERR("Wrong value in --monitor-timer parameter: %s", opt_arg);
544 ret = CMD_ERROR;
545 goto end;
546 }
547 opt_monitor_timer.interval = (uint64_t) v;
548 opt_monitor_timer.set = true;
549 DBG("Channel monitor timer interval set to %" PRIu64" (µs)", opt_monitor_timer.interval);
550 break;
551 }
552 case OPT_BLOCKING_TIMEOUT:
553 {
554 long long v; /* in usec */
555 long long v_msec;
556
557 errno = 0;
558 opt_arg = poptGetOptArg(pc);
559
560 if (strcmp(opt_arg, "inf") == 0) {
561 opt_blocking_timeout.value = (int64_t) -1;
562 opt_blocking_timeout.set = true;
563 DBG("Channel blocking timeout set to infinity");
564 break;
565 }
566
567 v = strtoll(opt_arg, NULL, 0);
568 if (errno != 0 || (!isdigit(opt_arg[0]) && opt_arg[0] != '-')
569 || v < 0) {
570 ERR("Wrong value in --blocking-timeout parameter: %s", opt_arg);
571 ret = CMD_ERROR;
572 goto end;
573 }
574
575 /*
576 * While LTTng-UST and LTTng-tools will accept a
577 * blocking timeout expressed in µs, the current
578 * tracer implementation relies on poll() which
579 * takes an "int timeout" parameter expressed in
580 * msec.
581 *
582 * Since the error reporting from the tracer is
583 * not precise, we perform this check here to
584 * provide a helpful error message in case of
585 * overflow.
586 *
587 * The setter (liblttng-ctl) also performs an
588 * equivalent check.
589 */
590 v_msec = v / 1000;
591 if (v_msec != (int32_t) v_msec) {
592 ERR("32-bit milliseconds overflow in --blocking-timeout parameter: %s", opt_arg);
593 ret = CMD_ERROR;
594 goto end;
595 }
596
597 opt_blocking_timeout.value = (int64_t) v;
598 opt_blocking_timeout.set = true;
599 DBG("Channel blocking timeout set to %" PRId64 " µs%s",
600 opt_blocking_timeout.value,
601 opt_blocking_timeout.value == 0 ?
602 " (non-blocking)" : "");
603 break;
604 }
605 case OPT_USERSPACE:
606 opt_userspace = 1;
607 break;
608 case OPT_TRACEFILE_SIZE:
609 opt_arg = poptGetOptArg(pc);
610 if (utils_parse_size_suffix(opt_arg, &chan_opts.attr.tracefile_size) < 0) {
611 ERR("Wrong value in --tracefile-size parameter: %s", opt_arg);
612 ret = CMD_ERROR;
613 goto end;
614 }
615 DBG("Maximum tracefile size set to %" PRIu64,
616 chan_opts.attr.tracefile_size);
617 break;
618 case OPT_TRACEFILE_COUNT:
619 {
620 unsigned long v;
621
622 errno = 0;
623 opt_arg = poptGetOptArg(pc);
624 v = strtoul(opt_arg, NULL, 0);
625 if (errno != 0 || !isdigit(opt_arg[0])) {
626 ERR("Wrong value in --tracefile-count parameter: %s", opt_arg);
627 ret = CMD_ERROR;
628 goto end;
629 }
630 if (v != (uint32_t) v) {
631 ERR("32-bit overflow in --tracefile-count parameter: %s", opt_arg);
632 ret = CMD_ERROR;
633 goto end;
634 }
635 chan_opts.attr.tracefile_count = (uint32_t) v;
636 DBG("Maximum tracefile count set to %" PRIu64,
637 chan_opts.attr.tracefile_count);
638 break;
639 }
640 case OPT_LIST_OPTIONS:
641 list_cmd_options(stdout, long_options);
642 goto end;
643 default:
644 ret = CMD_UNDEFINED;
645 goto end;
646 }
647 }
648
649 ret = print_missing_or_multiple_domains(opt_kernel + opt_userspace);
650 if (ret) {
651 ret = CMD_ERROR;
652 goto end;
653 }
654
655 if (chan_opts.attr.overwrite == 1 && opt_blocking_timeout.set &&
656 opt_blocking_timeout.value != 0) {
657 ERR("You cannot specify --overwrite and --blocking-timeout=N, "
658 "where N is different than 0");
659 ret = CMD_ERROR;
660 goto end;
661 }
662
663 /* Mi check */
664 if (lttng_opt_mi) {
665 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
666 if (!writer) {
667 ret = -LTTNG_ERR_NOMEM;
668 goto end;
669 }
670
671 /* Open command element */
672 ret = mi_lttng_writer_command_open(writer,
673 mi_lttng_element_command_enable_channels);
674 if (ret) {
675 ret = CMD_ERROR;
676 goto end;
677 }
678
679 /* Open output element */
680 ret = mi_lttng_writer_open_element(writer,
681 mi_lttng_element_command_output);
682 if (ret) {
683 ret = CMD_ERROR;
684 goto end;
685 }
686 }
687
688 opt_channels = (char*) poptGetArg(pc);
689 if (opt_channels == NULL) {
690 ERR("Missing channel name.\n");
691 ret = CMD_ERROR;
692 success = 0;
693 goto mi_closing;
694 }
695
696 if (!opt_session_name) {
697 session_name = get_session_name();
698 if (session_name == NULL) {
699 command_ret = CMD_ERROR;
700 success = 0;
701 goto mi_closing;
702 }
703 } else {
704 session_name = opt_session_name;
705 }
706
707 command_ret = enable_channel(session_name);
708 if (command_ret) {
709 success = 0;
710 }
711
712 mi_closing:
713 /* Mi closing */
714 if (lttng_opt_mi) {
715 /* Close output element */
716 ret = mi_lttng_writer_close_element(writer);
717 if (ret) {
718 goto end;
719 }
720
721 /* Success ? */
722 ret = mi_lttng_writer_write_element_bool(writer,
723 mi_lttng_element_command_success, success);
724 if (ret) {
725 goto end;
726 }
727
728 /* Command element close */
729 ret = mi_lttng_writer_command_close(writer);
730 if (ret) {
731 goto end;
732 }
733 }
734
735 end:
736 /* Mi clean-up */
737 if (writer && mi_lttng_writer_destroy(writer)) {
738 /* Preserve original error code */
739 ret = ret ? ret : LTTNG_ERR_MI_IO_FAIL;
740 }
741
742 if (!opt_session_name && session_name) {
743 free(session_name);
744 }
745
746 /* Overwrite ret if an error occurred when enable_channel */
747 ret = command_ret ? command_ret : ret;
748 poptFreeContext(pc);
749 return ret;
750 }
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