src/bin/lttng/commands/create.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 <assert.h>
  20 #include <ctype.h>
  21 #include <popt.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/stat.h>
  26 #include <sys/types.h>
  27 #include <time.h>
  28 #include <unistd.h>
  29 #include <signal.h>
  30 #include <sys/wait.h>
  31
  32 #include <common/mi-lttng.h>
  33
  34 #include "../command.h"
  35 #include "../utils.h"
  36
  37 #include <common/defaults.h>
  38 #include <common/sessiond-comm/sessiond-comm.h>
  39 #include <common/uri.h>
  40 #include <common/utils.h>
  41 #include <lttng/snapshot.h>
  42
  43 static char *opt_output_path;
  44 static char *opt_session_name;
  45 static char *opt_url;
  46 static char *opt_ctrl_url;
  47 static char *opt_data_url;
  48 static char *opt_shm_path;
  49 static int opt_no_consumer;
  50 static int opt_no_output;
  51 static int opt_snapshot;
  52 static unsigned int opt_live_timer;
  53
  54 enum {
  55         OPT_HELP = 1,
  56         OPT_LIST_OPTIONS,
  57         OPT_LIVE_TIMER,
  58 };
  59
  60 static struct mi_writer *writer;
  61
  62 static struct poptOption long_options[] = {
  63         /* longName, shortName, argInfo, argPtr, value, descrip, argDesc */
  64         {"help", 'h', POPT_ARG_NONE, NULL, OPT_HELP, NULL, NULL},
  65         {"output", 'o', POPT_ARG_STRING, &opt_output_path, 0, NULL, NULL},
  66         {"list-options", 0, POPT_ARG_NONE, NULL, OPT_LIST_OPTIONS, NULL, NULL},
  67         {"set-url",        'U', POPT_ARG_STRING, &opt_url, 0, 0, 0},
  68         {"ctrl-url",       'C', POPT_ARG_STRING, &opt_ctrl_url, 0, 0, 0},
  69         {"data-url",       'D', POPT_ARG_STRING, &opt_data_url, 0, 0, 0},
  70         {"no-output",       0, POPT_ARG_VAL, &opt_no_output, 1, 0, 0},
  71         {"no-consumer",     0, POPT_ARG_VAL, &opt_no_consumer, 1, 0, 0},
  72         {"snapshot",        0, POPT_ARG_VAL, &opt_snapshot, 1, 0, 0},
  73         {"live",            0, POPT_ARG_INT | POPT_ARGFLAG_OPTIONAL, 0, OPT_LIVE_TIMER, 0, 0},
  74         {"shm-path",        0, POPT_ARG_STRING, &opt_shm_path, 0, 0, 0},
  75         {0, 0, 0, 0, 0, 0, 0}
  76 };
  77
  78 /*
  79  * Please have a look at src/lib/lttng-ctl/lttng-ctl.c for more information on
  80  * why this declaration exists and used ONLY in for this command.
  81  */
  82 extern int _lttng_create_session_ext(const char *name, const char *url,
  83                 const char *datetime);
  84
  85 /*
  86  * usage
  87  */
  88 static void usage(FILE *ofp)
  89 {
  90         fprintf(ofp, "usage: lttng create [NAME] [OPTIONS] \n");
  91         fprintf(ofp, "\n");
  92         fprintf(ofp, "Without a given NAME, the default is 'auto-<yyyymmdd>-<hhmmss>'\n");
  93         fprintf(ofp, "\n");
  94         fprintf(ofp, "Options:\n");
  95         fprintf(ofp, "  -h, --help           Show this help\n");
  96         fprintf(ofp, "      --list-options   Simple listing of options\n");
  97         fprintf(ofp, "  -o, --output PATH    Specify output path for traces\n");
  98         fprintf(ofp, "      --no-output      Traces will not be outputted\n");
  99         fprintf(ofp, "      --snapshot       Set the session in snapshot mode.\n");
 100         fprintf(ofp, "                       Created in no-output mode and uses the URL,\n");
 101         fprintf(ofp, "                       if one, as the default snapshot output.\n");
 102         fprintf(ofp, "                       Every channel will be set in overwrite mode\n");
 103         fprintf(ofp, "                       and with mmap output (splice not supported).\n");
 104         fprintf(ofp, "      --live [USEC]    Set the session in live-reading mode.\n");
 105         fprintf(ofp, "                       The delay parameter in micro-seconds is the\n");
 106         fprintf(ofp, "                       maximum time the user can wait for the data\n");
 107         fprintf(ofp, "                       to be flushed. Can be set with a network\n");
 108         fprintf(ofp, "                       URL (-U or -C/-D) and must have a relayd listening.\n");
 109         fprintf(ofp, "                       By default, %u is used for the timer and the\n",
 110                                                                                         DEFAULT_LTTNG_LIVE_TIMER);
 111         fprintf(ofp, "                       network URL is set to net://127.0.0.1.\n");
 112         fprintf(ofp, "      --shm-path PATH  Path where shared memory holding buffers\n");
 113         fprintf(ofp, "                       should be created. Useful when used with pramfs\n");
 114         fprintf(ofp, "                       to extract trace data after crash.\n");
 115         fprintf(ofp, "\n");
 116         fprintf(ofp, "Extended Options:\n");
 117         fprintf(ofp, "\n");
 118         fprintf(ofp, "Using these options, each API call can be controlled individually.\n");
 119         fprintf(ofp, "\n");
 120         fprintf(ofp, "  -U, --set-url=URL    Set URL destination of the trace data.\n");
 121         fprintf(ofp, "                       It is persistent for the session lifetime.\n");
 122         fprintf(ofp, "                       This will set both data and control URL.\n");
 123         fprintf(ofp, "  -C, --ctrl-url=URL   Set control path URL. (Must use -D also)\n");
 124         fprintf(ofp, "  -D, --data-url=URL   Set data path URL. (Must use -C also)\n");
 125         fprintf(ofp, "\n");
 126         fprintf(ofp, "Please refer to the man page (lttng(1)) for more information on network\n");
 127         fprintf(ofp, "streaming mechanisms and explanation of the control and data port\n");
 128         fprintf(ofp, "You must have a running remote lttng-relayd for network streaming\n");
 129         fprintf(ofp, "\n");
 130         fprintf(ofp, "URL format is has followed:\n");
 131         fprintf(ofp, "\n");
 132         fprintf(ofp, "  proto://[HOST|IP][:PORT1[:PORT2]][/TRACE_PATH]\n");
 133         fprintf(ofp, "\n");
 134         fprintf(ofp, "  Supported protocols are (proto):\n");
 135         fprintf(ofp, "  > file://...\n");
 136         fprintf(ofp, "    Local filesystem full path.\n");
 137         fprintf(ofp, "\n");
 138         fprintf(ofp, "  > net[6]://...\n");
 139         fprintf(ofp, "    This will use the default network transport layer which is\n");
 140         fprintf(ofp, "    TCP for both control (PORT1) and data port (PORT2).\n");
 141         fprintf(ofp, "    The default ports are respectively 5342 and 5343.\n");
 142         fprintf(ofp, "\n");
 143         fprintf(ofp, "  > tcp[6]://...\n");
 144         fprintf(ofp, "    Can only be used with -C and -D together\n");
 145         fprintf(ofp, "\n");
 146         fprintf(ofp, "NOTE: IPv6 address MUST be enclosed in brackets '[]' (rfc2732)\n");
 147         fprintf(ofp, "\n");
 148         fprintf(ofp, "Examples:\n");
 149         fprintf(ofp, "    # lttng create -U net://192.168.1.42\n");
 150         fprintf(ofp, "    Uses TCP and default ports for the given destination.\n");
 151         fprintf(ofp, "    # lttng create -U net6://[fe80::f66d:4ff:fe53:d220]\n");
 152         fprintf(ofp, "    Uses TCP, default ports and IPv6.\n");
 153         fprintf(ofp, "    # lttng create s1 -U net://myhost.com:3229\n");
 154         fprintf(ofp, "    Set the consumer to the remote HOST on port 3229 for control.\n");
 155         fprintf(ofp, "\n");
 156 }
 157
 158 /*
 159  * Retrieve the created session and mi output it based on provided argument
 160  * This is currently a summary of what was pretty printed and is subject to
 161  * enhancements.
 162  */
 163 static int mi_created_session(const char *session_name)
 164 {
 165         int ret, i, count, found;
 166         struct lttng_session *sessions;
 167
 168         /* session_name should not be null */
 169         assert(session_name);
 170         assert(writer);
 171
 172         count = lttng_list_sessions(&sessions);
 173         if (count < 0) {
 174                 ret = count;
 175                 ERR("%s", lttng_strerror(ret));
 176                 goto error;
 177         }
 178
 179         if (count == 0) {
 180                 ERR("Error session creation failed: session %s not found", session_name);
 181                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 182                 goto end;
 183         }
 184
 185         found = 0;
 186         for (i = 0; i < count; i++) {
 187                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 188                         found = 1;
 189                         ret = mi_lttng_session(writer, &sessions[i], 0);
 190                         if (ret) {
 191                                 goto error;
 192                         }
 193                         break;
 194                 }
 195         }
 196
 197         if (!found) {
 198                 ret = -LTTNG_ERR_SESS_NOT_FOUND;
 199         } else {
 200                 ret = CMD_SUCCESS;
 201         }
 202
 203 error:
 204         free(sessions);
 205 end:
 206         return ret;
 207 }
 208
 209 /*
 210  * For a session name, set the consumer URLs.
 211  */
 212 static int set_consumer_url(const char *session_name, const char *ctrl_url,
 213                 const char *data_url)
 214 {
 215         int ret;
 216         struct lttng_handle *handle;
 217         struct lttng_domain dom;
 218
 219         assert(session_name);
 220
 221         /*
 222          * Set handle with the session name and the domain set to 0. This means to
 223          * the session daemon that the next action applies on the tracing session
 224          * rather then the domain specific session.
 225          */
 226         memset(&dom, 0, sizeof(dom));
 227
 228         handle = lttng_create_handle(session_name, &dom);
 229         if (handle == NULL) {
 230                 ret = CMD_FATAL;
 231                 goto error;
 232         }
 233
 234         ret = lttng_set_consumer_url(handle, ctrl_url, data_url);
 235         if (ret < 0) {
 236                 goto error;
 237         }
 238
 239         if (ctrl_url) {
 240                 MSG("Control URL %s set for session %s", ctrl_url, session_name);
 241         }
 242
 243         if (data_url) {
 244                 MSG("Data URL %s set for session %s", data_url, session_name);
 245         }
 246
 247 error:
 248         lttng_destroy_handle(handle);
 249         return ret;
 250 }
 251
 252 static int add_snapshot_output(const char *session_name, const char *ctrl_url,
 253                 const char *data_url)
 254 {
 255         int ret;
 256         struct lttng_snapshot_output *output = NULL;
 257
 258         assert(session_name);
 259
 260         output = lttng_snapshot_output_create();
 261         if (!output) {
 262                 ret = CMD_FATAL;
 263                 goto error_create;
 264         }
 265
 266         if (ctrl_url) {
 267                 ret = lttng_snapshot_output_set_ctrl_url(ctrl_url, output);
 268                 if (ret < 0) {
 269                         goto error;
 270                 }
 271         }
 272
 273         if (data_url) {
 274                 ret = lttng_snapshot_output_set_data_url(data_url, output);
 275                 if (ret < 0) {
 276                         goto error;
 277                 }
 278         }
 279
 280         /* This call, if successful, populates the id of the output object. */
 281         ret = lttng_snapshot_add_output(session_name, output);
 282         if (ret < 0) {
 283                 goto error;
 284         }
 285
 286 error:
 287         lttng_snapshot_output_destroy(output);
 288 error_create:
 289         return ret;
 290 }
 291
 292 /*
 293  *  Create a tracing session.
 294  *  If no name is specified, a default name is generated.
 295  *
 296  *  Returns one of the CMD_* result constants.
 297  */
 298 static int create_session(void)
 299 {
 300         int ret;
 301         char *session_name = NULL, *traces_path = NULL, *alloc_path = NULL;
 302         char *alloc_url = NULL, *url = NULL, datetime[16];
 303         char session_name_date[NAME_MAX + 17], *print_str_url = NULL;
 304         time_t rawtime;
 305         struct tm *timeinfo;
 306         char shm_path[PATH_MAX] = "";
 307
 308         /* Get date and time for automatic session name/path */
 309         time(&rawtime);
 310         timeinfo = localtime(&rawtime);
 311         strftime(datetime, sizeof(datetime), "%Y%m%d-%H%M%S", timeinfo);
 312
 313         /* Auto session name creation */
 314         if (opt_session_name == NULL) {
 315                 ret = snprintf(session_name_date, sizeof(session_name_date),
 316                                 DEFAULT_SESSION_NAME "-%s", datetime);
 317                 if (ret < 0) {
 318                         PERROR("snprintf session name");
 319                         goto error;
 320                 }
 321                 session_name = session_name_date;
 322                 DBG("Auto session name set to %s", session_name_date);
 323         } else {
 324                 if (strlen(opt_session_name) > NAME_MAX) {
 325                         ERR("Session name too long. Length must be lower or equal to %d",
 326                                         NAME_MAX);
 327                         ret = LTTNG_ERR_SESSION_FAIL;
 328                         goto error;
 329                 }
 330                 /*
 331                  * Check if the session name begins with "auto-" or is exactly "auto".
 332                  * Both are reserved for the default session name. See bug #449 to
 333                  * understand why we need to check both here.
 334                  */
 335                 if ((strncmp(opt_session_name, DEFAULT_SESSION_NAME "-",
 336                                         strlen(DEFAULT_SESSION_NAME) + 1) == 0) ||
 337                                 (strncmp(opt_session_name, DEFAULT_SESSION_NAME,
 338                                         strlen(DEFAULT_SESSION_NAME)) == 0 &&
 339                                 strlen(opt_session_name) == strlen(DEFAULT_SESSION_NAME))) {
 340                         ERR("%s is a reserved keyword for default session(s)",
 341                                         DEFAULT_SESSION_NAME);
 342                         ret = CMD_ERROR;
 343                         goto error;
 344                 }
 345                 session_name = opt_session_name;
 346                 ret = snprintf(session_name_date, sizeof(session_name_date),
 347                                 "%s-%s", session_name, datetime);
 348                 if (ret < 0) {
 349                         PERROR("snprintf session name");
 350                         goto error;
 351                 }
 352         }
 353
 354         if ((!opt_ctrl_url && opt_data_url) || (opt_ctrl_url && !opt_data_url)) {
 355                 ERR("You need both control and data URL.");
 356                 ret = CMD_ERROR;
 357                 goto error;
 358         }
 359
 360         if (opt_output_path != NULL) {
 361                 traces_path = utils_expand_path(opt_output_path);
 362                 if (traces_path == NULL) {
 363                         ret = CMD_ERROR;
 364                         goto error;
 365                 }
 366
 367                 /* Create URL string from the local file system path */
 368                 ret = asprintf(&alloc_url, "file://%s", traces_path);
 369                 if (ret < 0) {
 370                         PERROR("asprintf url path");
 371                         ret = CMD_FATAL;
 372                         goto error;
 373                 }
 374                 /* URL to use in the lttng_create_session() call */
 375                 url = alloc_url;
 376                 print_str_url = traces_path;
 377         } else if (opt_url) { /* Handling URL (-U opt) */
 378                 url = opt_url;
 379                 print_str_url = url;
 380         } else if (opt_data_url && opt_ctrl_url) {
 381                 /*
 382                  * With both control and data, we'll be setting the consumer URL after
 383                  * session creation thus use no URL.
 384                  */
 385                 url = NULL;
 386         } else if (!opt_no_output) {
 387                 char *tmp_path;
 388
 389                 /* Auto output path */
 390                 tmp_path = utils_get_home_dir();
 391                 if (tmp_path == NULL) {
 392                         ERR("HOME path not found.\n \
 393                                         Please specify an output path using -o, --output PATH");
 394                         ret = CMD_FATAL;
 395                         goto error;
 396                 }
 397                 alloc_path = strdup(tmp_path);
 398                 if (!alloc_path) {
 399                         PERROR("allocating alloc_path");
 400                         ret = CMD_FATAL;
 401                         goto error;
 402                 }
 403                 ret = asprintf(&alloc_url,
 404                                 "file://%s/" DEFAULT_TRACE_DIR_NAME "/%s",
 405                                 alloc_path, session_name_date);
 406                 if (ret < 0) {
 407                         PERROR("asprintf trace dir name");
 408                         ret = CMD_FATAL;
 409                         goto error;
 410                 }
 411
 412                 url = alloc_url;
 413                 print_str_url = alloc_url + strlen("file://");
 414         } else {
 415                 /* No output means --no-output or --snapshot mode. */
 416                 url = NULL;
 417         }
 418
 419         /* Use default live URL if NO url is/are found. */
 420         if ((opt_live_timer && !opt_url) && (opt_live_timer && !opt_data_url)) {
 421                 ret = asprintf(&alloc_url, "net://127.0.0.1");
 422                 if (ret < 0) {
 423                         PERROR("asprintf default live URL");
 424                         ret = CMD_FATAL;
 425                         goto error;
 426                 }
 427                 url = alloc_url;
 428                 print_str_url = url;
 429         }
 430
 431         if (opt_snapshot && opt_live_timer) {
 432                 ERR("Snapshot and live modes are mutually exclusive.");
 433                 ret = CMD_ERROR;
 434                 goto error;
 435         }
 436
 437         if (opt_snapshot) {
 438                 /* No output by default. */
 439                 const char *snapshot_url = NULL;
 440
 441                 if (opt_url) {
 442                         snapshot_url = url;
 443                 } else if (!opt_data_url && !opt_ctrl_url) {
 444                         /* This is the session path that we need to use as output. */
 445                         snapshot_url = url;
 446                 }
 447                 ret = lttng_create_session_snapshot(session_name, snapshot_url);
 448         } else if (opt_live_timer) {
 449                 const char *pathname;
 450
 451                 if (opt_relayd_path) {
 452                         pathname = opt_relayd_path;
 453                 } else {
 454                         pathname = INSTALL_BIN_PATH "/lttng-relayd";
 455                 }
 456                 if (!opt_url && !opt_data_url && !check_relayd() &&
 457                                 spawn_relayd(pathname, 0) < 0) {
 458                         goto error;
 459                 }
 460                 ret = lttng_create_session_live(session_name, url, opt_live_timer);
 461         } else {
 462                 ret = _lttng_create_session_ext(session_name, url, datetime);
 463         }
 464         if (ret < 0) {
 465                 /* Don't set ret so lttng can interpret the sessiond error. */
 466                 switch (-ret) {
 467                 case LTTNG_ERR_EXIST_SESS:
 468                         WARN("Session %s already exists", session_name);
 469                         break;
 470                 default:
 471                         break;
 472                 }
 473                 goto error;
 474         }
 475
 476         if (opt_ctrl_url && opt_data_url) {
 477                 if (opt_snapshot) {
 478                         ret = add_snapshot_output(session_name, opt_ctrl_url,
 479                                         opt_data_url);
 480                 } else {
 481                         /* Setting up control URI (-C or/and -D opt) */
 482                         ret = set_consumer_url(session_name, opt_ctrl_url, opt_data_url);
 483                 }
 484                 if (ret < 0) {
 485                         /* Destroy created session because the URL are not valid. */
 486                         lttng_destroy_session(session_name);
 487                         goto error;
 488                 }
 489         }
 490
 491         if (opt_shm_path) {
 492                 ret = snprintf(shm_path, sizeof(shm_path),
 493                                 "%s/%s", opt_shm_path, session_name_date);
 494                 if (ret < 0) {
 495                         PERROR("snprintf shm_path");
 496                         goto error;
 497                 }
 498
 499                 ret = lttng_set_session_shm_path(session_name, shm_path);
 500                 if (ret < 0) {
 501                         lttng_destroy_session(session_name);
 502                         goto error;
 503                 }
 504         }
 505
 506         MSG("Session %s created.", session_name);
 507         if (print_str_url && !opt_snapshot) {
 508                 MSG("Traces will be written in %s", print_str_url);
 509
 510                 if (opt_live_timer) {
 511                         MSG("Live timer set to %u usec", opt_live_timer);
 512                 }
 513         } else if (opt_snapshot) {
 514                 if (print_str_url) {
 515                         MSG("Default snapshot output set to: %s", print_str_url);
 516                 }
 517                 MSG("Snapshot mode set. Every channel enabled for that session will "
 518                                 "be set in overwrite mode and mmap output.");
 519         }
 520         if (opt_shm_path) {
 521                 MSG("Session %s set to shm_path: %s.", session_name,
 522                         shm_path);
 523         }
 524
 525         /* Mi output */
 526         if (lttng_opt_mi) {
 527                 ret = mi_created_session(session_name);
 528                 if (ret) {
 529                         ret = CMD_ERROR;
 530                         goto error;
 531                 }
 532         }
 533
 534         /* Init lttng session config */
 535         ret = config_init(session_name);
 536         if (ret < 0) {
 537                 ret = CMD_ERROR;
 538                 goto error;
 539         }
 540
 541         ret = CMD_SUCCESS;
 542
 543 error:
 544         free(alloc_url);
 545         free(traces_path);
 546         free(alloc_path);
 547
 548         if (ret < 0) {
 549                 ERR("%s", lttng_strerror(ret));
 550         }
 551         return ret;
 552 }
 553
 554 /*
 555  *  spawn_sessiond
 556  *
 557  *  Spawn a session daemon by forking and execv.
 558  */
 559 static int spawn_sessiond(char *pathname)
 560 {
 561         int ret = 0;
 562         pid_t pid;
 563
 564         MSG("Spawning a session daemon");
 565         pid = fork();
 566         if (pid == 0) {
 567                 /*
 568                  * Spawn session daemon in daemon mode.
 569                  */
 570                 execlp(pathname, "lttng-sessiond",
 571                                 "--daemonize", NULL);
 572                 /* execlp only returns if error happened */
 573                 if (errno == ENOENT) {
 574                         ERR("No session daemon found. Use --sessiond-path.");
 575                 } else {
 576                         PERROR("execlp");
 577                 }
 578                 kill(getppid(), SIGTERM);       /* wake parent */
 579                 exit(EXIT_FAILURE);
 580         } else if (pid > 0) {
 581                 /*
 582                  * In daemon mode (--daemonize), sessiond only exits when
 583                  * it's ready to accept commands.
 584                  */
 585                 for (;;) {
 586                         int status;
 587                         pid_t wait_pid_ret = waitpid(pid, &status, 0);
 588
 589                         if (wait_pid_ret < 0) {
 590                                 if (errno == EINTR) {
 591                                         continue;
 592                                 }
 593                                 PERROR("waitpid");
 594                                 ret = -errno;
 595                                 goto end;
 596                         }
 597
 598                         if (WIFSIGNALED(status)) {
 599                                 ERR("Session daemon was killed by signal %d",
 600                                                 WTERMSIG(status));
 601                                 ret = -1;
 602                                 goto end;
 603                         } else if (WIFEXITED(status)) {
 604                                 DBG("Session daemon terminated normally (exit status: %d)",
 605                                                 WEXITSTATUS(status));
 606
 607                                 if (WEXITSTATUS(status) != 0) {
 608                                         ERR("Session daemon terminated with an error (exit status: %d)",
 609                                                         WEXITSTATUS(status));
 610                                         ret = -1;
 611                                         goto end;
 612                                 }
 613                                 break;
 614                         }
 615                 }
 616
 617                 goto end;
 618         } else {
 619                 PERROR("fork");
 620                 ret = -1;
 621                 goto end;
 622         }
 623
 624 end:
 625         return ret;
 626 }
 627
 628 /*
 629  *  launch_sessiond
 630  *
 631  *  Check if the session daemon is available using
 632  *  the liblttngctl API for the check. If not, try to
 633  *  spawn a daemon.
 634  */
 635 static int launch_sessiond(void)
 636 {
 637         int ret;
 638         char *pathname = NULL;
 639
 640         ret = lttng_session_daemon_alive();
 641         if (ret) {
 642                 /* Sessiond is alive, not an error */
 643                 ret = 0;
 644                 goto end;
 645         }
 646
 647         /* Try command line option path */
 648         pathname = opt_sessiond_path;
 649
 650         /* Try LTTNG_SESSIOND_PATH env variable */
 651         if (pathname == NULL) {
 652                 pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 653         }
 654
 655         /* Try with configured path */
 656         if (pathname == NULL) {
 657                 if (CONFIG_SESSIOND_BIN[0] != '\0') {
 658                         pathname = CONFIG_SESSIOND_BIN;
 659                 }
 660         }
 661
 662         /* Try the default path */
 663         if (pathname == NULL) {
 664                 pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 665         }
 666
 667         DBG("Session daemon binary path: %s", pathname);
 668
 669         /* Check existence and permissions */
 670         ret = access(pathname, F_OK | X_OK);
 671         if (ret < 0) {
 672                 ERR("No such file or access denied: %s", pathname);
 673                 goto end;
 674         }
 675
 676         ret = spawn_sessiond(pathname);
 677 end:
 678         if (ret) {
 679                 ERR("Problem occurred while launching session daemon (%s)",
 680                                 pathname);
 681         }
 682         return ret;
 683 }
 684
 685 /*
 686  *  The 'create <options>' first level command
 687  *
 688  *  Returns one of the CMD_* result constants.
 689  */
 690 int cmd_create(int argc, const char **argv)
 691 {
 692         int opt, ret = CMD_SUCCESS, command_ret = CMD_SUCCESS, success = 1;
 693         char *opt_arg = NULL;
 694         static poptContext pc;
 695
 696         pc = poptGetContext(NULL, argc, argv, long_options, 0);
 697         poptReadDefaultConfig(pc, 0);
 698
 699         while ((opt = poptGetNextOpt(pc)) != -1) {
 700                 switch (opt) {
 701                 case OPT_HELP:
 702                         usage(stdout);
 703                         goto end;
 704                 case OPT_LIST_OPTIONS:
 705                         list_cmd_options(stdout, long_options);
 706                         goto end;
 707                 case OPT_LIVE_TIMER:
 708                 {
 709                         unsigned long v;
 710
 711                         errno = 0;
 712                         opt_arg = poptGetOptArg(pc);
 713                         if (!opt_arg) {
 714                                 /* Set up default values. */
 715                                 opt_live_timer = (uint32_t) DEFAULT_LTTNG_LIVE_TIMER;
 716                                 DBG("Session live timer interval set to default value %d",
 717                                                 opt_live_timer);
 718                                 break;
 719                         }
 720
 721                         v = strtoul(opt_arg, NULL, 0);
 722                         if (errno != 0 || !isdigit(opt_arg[0])) {
 723                                 ERR("Wrong value in --live parameter: %s", opt_arg);
 724                                 ret = CMD_ERROR;
 725                                 goto end;
 726                         }
 727                         if (v != (uint32_t) v) {
 728                                 ERR("32-bit overflow in --live parameter: %s", opt_arg);
 729                                 ret = CMD_ERROR;
 730                                 goto end;
 731                         }
 732                         if (v == 0) {
 733                                 ERR("Live timer interval must be greater than zero");
 734                                 ret = CMD_ERROR;
 735                                 goto end;
 736                         }
 737                         opt_live_timer = (uint32_t) v;
 738                         DBG("Session live timer interval set to %d", opt_live_timer);
 739                         break;
 740                 }
 741                 default:
 742                         usage(stderr);
 743                         ret = CMD_UNDEFINED;
 744                         goto end;
 745                 }
 746         }
 747
 748         if (opt_no_consumer) {
 749                 MSG("The option --no-consumer is obsolete. Use --no-output now.");
 750                 ret = CMD_WARNING;
 751                 goto end;
 752         }
 753
 754         /* Spawn a session daemon if needed */
 755         if (!opt_no_sessiond) {
 756                 ret = launch_sessiond();
 757                 if (ret) {
 758                         ret = CMD_ERROR;
 759                         goto end;
 760                 }
 761         }
 762
 763         /* MI initialization */
 764         if (lttng_opt_mi) {
 765                 writer = mi_lttng_writer_create(fileno(stdout), lttng_opt_mi);
 766                 if (!writer) {
 767                         ret = -LTTNG_ERR_NOMEM;
 768                         goto end;
 769                 }
 770
 771                 /* Open command element */
 772                 ret = mi_lttng_writer_command_open(writer,
 773                                 mi_lttng_element_command_create);
 774                 if (ret) {
 775                         ret = CMD_ERROR;
 776                         goto end;
 777                 }
 778
 779                 /* Open output element */
 780                 ret = mi_lttng_writer_open_element(writer,
 781                                 mi_lttng_element_command_output);
 782                 if (ret) {
 783                         ret = CMD_ERROR;
 784                         goto end;
 785                 }
 786         }
 787         opt_session_name = (char*) poptGetArg(pc);
 788
 789         command_ret = create_session();
 790         if (command_ret) {
 791                 success = 0;
 792         }
 793
 794         if (lttng_opt_mi) {
 795                 /* Close  output element */
 796                 ret = mi_lttng_writer_close_element(writer);
 797                 if (ret) {
 798                         ret = CMD_ERROR;
 799                         goto end;
 800                 }
 801
 802                 /* Success ? */
 803                 ret = mi_lttng_writer_write_element_bool(writer,
 804                                 mi_lttng_element_command_success, success);
 805                 if (ret) {
 806                         ret = CMD_ERROR;
 807                         goto end;
 808                 }
 809
 810                 /* Command element close */
 811                 ret = mi_lttng_writer_command_close(writer);
 812                 if (ret) {
 813                         ret = CMD_ERROR;
 814                         goto end;
 815                 }
 816         }
 817
 818 end:
 819         /* Mi clean-up */
 820         if (writer && mi_lttng_writer_destroy(writer)) {
 821                 /* Preserve original error code */
 822                 ret = ret ? ret : -LTTNG_ERR_MI_IO_FAIL;
 823         }
 824
 825         /* Overwrite ret if an error occurred in create_session() */
 826         ret = command_ret ? command_ret : ret;
 827
 828         poptFreeContext(pc);
 829         return ret;
 830 }