liblttngctl/lttngctl.c

   1 /*
   2  * liblttngctl.c
   3  *
   4  * Linux Trace Toolkit Control Library
   5  *
   6  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #define _GNU_SOURCE
  24 #include <grp.h>
  25 #include <errno.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <lttng-sessiond-comm.h>
  32 #include <lttng-share.h>
  33 #include <lttng/lttng.h>
  34 #include <lttngerr.h>
  35
  36 /* Socket to session daemon for communication */
  37 static int sessiond_socket;
  38 static char sessiond_sock_path[PATH_MAX];
  39
  40 /* Variables */
  41 static char *tracing_group;
  42 static int connected;
  43
  44 /*
  45  * Copy string from src to dst and enforce null terminated byte.
  46  */
  47 static void copy_string(char *dst, const char *src, size_t len)
  48 {
  49         if (src && dst) {
  50                 strncpy(dst, src, len);
  51                 /* Enforce the NULL terminated byte */
  52                 dst[len - 1] = '\0';
  53         } else if (dst) {
  54                 dst[0] = '\0';
  55         }
  56 }
  57
  58 /*
  59  * Copy domain to lttcomm_session_msg domain.
  60  *
  61  * If domain is unknown, default domain will be the kernel.
  62  */
  63 static void copy_lttng_domain(struct lttng_domain *dst, struct lttng_domain *src)
  64 {
  65         if (src && dst) {
  66                 switch (src->type) {
  67                         case LTTNG_DOMAIN_KERNEL:
  68                         case LTTNG_DOMAIN_UST:
  69                         case LTTNG_DOMAIN_UST_EXEC_NAME:
  70                         case LTTNG_DOMAIN_UST_PID:
  71                         case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
  72                                 memcpy(dst, src, sizeof(struct lttng_domain));
  73                                 break;
  74                         default:
  75                                 dst->type = LTTNG_DOMAIN_KERNEL;
  76                                 break;
  77                 }
  78         }
  79 }
  80
  81 /*
  82  * Send lttcomm_session_msg to the session daemon.
  83  *
  84  * On success, return 0
  85  * On error, return error code
  86  */
  87 static int send_session_msg(struct lttcomm_session_msg *lsm)
  88 {
  89         int ret;
  90
  91         if (!connected) {
  92                 ret = -ENOTCONN;
  93                 goto end;
  94         }
  95
  96         ret = lttcomm_send_unix_sock(sessiond_socket, lsm,
  97                         sizeof(struct lttcomm_session_msg));
  98
  99 end:
 100         return ret;
 101 }
 102
 103 /*
 104  * Receive data from the sessiond socket.
 105  *
 106  * On success, return 0
 107  * On error, return recv() error code
 108  */
 109 static int recv_data_sessiond(void *buf, size_t len)
 110 {
 111         int ret;
 112
 113         if (!connected) {
 114                 ret = -ENOTCONN;
 115                 goto end;
 116         }
 117
 118         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
 119
 120 end:
 121         return ret;
 122 }
 123
 124 /*
 125  *  Check if the specified group name exist.
 126  *
 127  *  If yes return 1, else return -1.
 128  */
 129 static int check_tracing_group(const char *grp_name)
 130 {
 131         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 132         gid_t *grp_list;
 133         int grp_list_size, grp_id, i;
 134         int ret = -1;
 135
 136         /* Get GID of group 'tracing' */
 137         grp_tracing = getgrnam(grp_name);
 138         if (grp_tracing == NULL) {
 139                 /* NULL means not found also. getgrnam(3) */
 140                 if (errno != 0) {
 141                         perror("getgrnam");
 142                 }
 143                 goto end;
 144         }
 145
 146         /* Get number of supplementary group IDs */
 147         grp_list_size = getgroups(0, NULL);
 148         if (grp_list_size < 0) {
 149                 perror("getgroups");
 150                 goto end;
 151         }
 152
 153         /* Alloc group list of the right size */
 154         grp_list = malloc(grp_list_size * sizeof(gid_t));
 155         grp_id = getgroups(grp_list_size, grp_list);
 156         if (grp_id < -1) {
 157                 perror("getgroups");
 158                 goto free_list;
 159         }
 160
 161         for (i = 0; i < grp_list_size; i++) {
 162                 if (grp_list[i] == grp_tracing->gr_gid) {
 163                         ret = 1;
 164                         break;
 165                 }
 166         }
 167
 168 free_list:
 169         free(grp_list);
 170
 171 end:
 172         return ret;
 173 }
 174
 175 /*
 176  * Try connect to session daemon with sock_path.
 177  *
 178  * Return 0 on success, else -1
 179  */
 180 static int try_connect_sessiond(const char *sock_path)
 181 {
 182         int ret;
 183
 184         /* If socket exist, we check if the daemon listens for connect. */
 185         ret = access(sock_path, F_OK);
 186         if (ret < 0) {
 187                 /* Not alive */
 188                 return -1;
 189         }
 190
 191         ret = lttcomm_connect_unix_sock(sock_path);
 192         if (ret < 0) {
 193                 /* Not alive */
 194                 return -1;
 195         }
 196
 197         ret = lttcomm_close_unix_sock(ret);
 198         if (ret < 0) {
 199                 perror("lttcomm_close_unix_sock");
 200         }
 201
 202         return 0;
 203 }
 204
 205 /*
 206  * Set sessiond socket path by putting it in the global sessiond_sock_path
 207  * variable.
 208  */
 209 static int set_session_daemon_path(void)
 210 {
 211         int ret;
 212         int in_tgroup = 0;      /* In tracing group */
 213         uid_t uid;
 214
 215         uid = getuid();
 216
 217         if (uid != 0) {
 218                 /* Are we in the tracing group ? */
 219                 in_tgroup = check_tracing_group(tracing_group);
 220         }
 221
 222         if (uid == 0) {
 223                 /* Root */
 224                 copy_string(sessiond_sock_path,
 225                                 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 226                                 sizeof(sessiond_sock_path));
 227         } else if (in_tgroup) {
 228                 /* Tracing group */
 229                 copy_string(sessiond_sock_path,
 230                                 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 231                                 sizeof(sessiond_sock_path));
 232
 233                 ret = try_connect_sessiond(sessiond_sock_path);
 234                 if (ret < 0) {
 235                         /* Global session daemon not available */
 236                         if (snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
 237                                                 DEFAULT_HOME_CLIENT_UNIX_SOCK,
 238                                                 getenv("HOME")) < 0) {
 239                                 return -ENOMEM;
 240                         }
 241                 }
 242         } else {
 243                 /* Not in tracing group and not root, default */
 244                 if (snprintf(sessiond_sock_path, PATH_MAX,
 245                                         DEFAULT_HOME_CLIENT_UNIX_SOCK,
 246                                         getenv("HOME")) < 0) {
 247                         return -ENOMEM;
 248                 }
 249         }
 250
 251         return 0;
 252 }
 253
 254 /*
 255  *  Connect to the LTTng session daemon.
 256  *
 257  *  On success, return 0. On error, return -1.
 258  */
 259 static int connect_sessiond(void)
 260 {
 261         int ret;
 262
 263         ret = set_session_daemon_path();
 264         if (ret < 0) {
 265                 return ret;
 266         }
 267
 268         /* Connect to the sesssion daemon */
 269         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 270         if (ret < 0) {
 271                 return ret;
 272         }
 273
 274         sessiond_socket = ret;
 275         connected = 1;
 276
 277         return 0;
 278 }
 279
 280 /*
 281  *  Clean disconnect the session daemon.
 282  */
 283 static int disconnect_sessiond(void)
 284 {
 285         int ret = 0;
 286
 287         if (connected) {
 288                 ret = lttcomm_close_unix_sock(sessiond_socket);
 289                 sessiond_socket = 0;
 290                 connected = 0;
 291         }
 292
 293         return ret;
 294 }
 295
 296 /*
 297  * Ask the session daemon a specific command and put the data into buf.
 298  *
 299  * Return size of data (only payload, not header).
 300  */
 301 static int ask_sessiond(struct lttcomm_session_msg *lsm, void **buf)
 302 {
 303         int ret;
 304         size_t size;
 305         void *data = NULL;
 306         struct lttcomm_lttng_msg llm;
 307
 308         ret = connect_sessiond();
 309         if (ret < 0) {
 310                 goto end;
 311         }
 312
 313         /* Send command to session daemon */
 314         ret = send_session_msg(lsm);
 315         if (ret < 0) {
 316                 goto end;
 317         }
 318
 319         /* Get header from data transmission */
 320         ret = recv_data_sessiond(&llm, sizeof(llm));
 321         if (ret < 0) {
 322                 goto end;
 323         }
 324
 325         /* Check error code if OK */
 326         if (llm.ret_code != LTTCOMM_OK) {
 327                 ret = -llm.ret_code;
 328                 goto end;
 329         }
 330
 331         size = llm.data_size;
 332         if (size == 0) {
 333                 ret = 0;
 334                 goto end;
 335         }
 336
 337         data = (void*) malloc(size);
 338
 339         /* Get payload data */
 340         ret = recv_data_sessiond(data, size);
 341         if (ret < 0) {
 342                 free(data);
 343                 goto end;
 344         }
 345
 346         *buf = data;
 347         ret = size;
 348
 349 end:
 350         disconnect_sessiond();
 351         return ret;
 352 }
 353
 354 /*
 355  * Create lttng handle and return pointer.
 356  */
 357 struct lttng_handle *lttng_create_handle(const char *session_name,
 358                 struct lttng_domain *domain)
 359 {
 360         struct lttng_handle *handle;
 361
 362         handle = malloc(sizeof(struct lttng_handle));
 363         if (handle == NULL) {
 364                 perror("malloc handle");
 365                 goto end;
 366         }
 367
 368         /* Copy session name */
 369         copy_string(handle->session_name, session_name,
 370                         sizeof(handle->session_name));
 371
 372         /* Copy lttng domain */
 373         copy_lttng_domain(&handle->domain, domain);
 374
 375 end:
 376         return handle;
 377 }
 378
 379 /*
 380  * Destroy handle by free(3) the pointer.
 381  */
 382 void lttng_destroy_handle(struct lttng_handle *handle)
 383 {
 384         if (handle) {
 385                 free(handle);
 386         }
 387 }
 388
 389 /*
 390  * Register an outside consumer.
 391  */
 392 int lttng_register_consumer(struct lttng_handle *handle,
 393                 const char *socket_path)
 394 {
 395         struct lttcomm_session_msg lsm;
 396
 397         lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
 398         copy_string(lsm.session.name, handle->session_name,
 399                         sizeof(lsm.session.name));
 400         copy_lttng_domain(&lsm.domain, &handle->domain);
 401
 402         copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
 403
 404         return ask_sessiond(&lsm, NULL);
 405 }
 406
 407 /*
 408  *  Start tracing for all trace of the session.
 409  */
 410 int lttng_start_tracing(struct lttng_handle *handle)
 411 {
 412         struct lttcomm_session_msg lsm;
 413
 414         if (!handle) {
 415                 return -1;
 416         }
 417
 418         lsm.cmd_type = LTTNG_START_TRACE;
 419         copy_string(lsm.session.name, handle->session_name,
 420                         sizeof(lsm.session.name));
 421
 422         return ask_sessiond(&lsm, NULL);
 423 }
 424
 425 /*
 426  *  Stop tracing for all trace of the session.
 427  */
 428 int lttng_stop_tracing(struct lttng_handle *handle)
 429 {
 430         struct lttcomm_session_msg lsm;
 431
 432         lsm.cmd_type = LTTNG_STOP_TRACE;
 433         copy_string(lsm.session.name, handle->session_name,
 434                         sizeof(lsm.session.name));
 435
 436         return ask_sessiond(&lsm, NULL);
 437 }
 438
 439 /*
 440  * Add context to event or/and channel.
 441  */
 442 int lttng_add_context(struct lttng_handle *handle,
 443                 struct lttng_event_context *ctx, const char *event_name,
 444                 const char *channel_name)
 445 {
 446         struct lttcomm_session_msg lsm;
 447
 448         if (!handle) {
 449                 return -1;
 450         }
 451
 452         lsm.cmd_type = LTTNG_ADD_CONTEXT;
 453
 454         /* Copy channel name */
 455         copy_string(lsm.u.context.channel_name, channel_name,
 456                         sizeof(lsm.u.context.channel_name));
 457         /* Copy event name */
 458         copy_string(lsm.u.context.event_name, event_name,
 459                         sizeof(lsm.u.context.event_name));
 460
 461         copy_lttng_domain(&lsm.domain, &handle->domain);
 462
 463         if (ctx) {
 464                 memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 465         }
 466
 467         copy_string(lsm.session.name, handle->session_name,
 468                         sizeof(lsm.session.name));
 469
 470         return ask_sessiond(&lsm, NULL);
 471 }
 472
 473 /*
 474  * Enable event
 475  */
 476 int lttng_enable_event(struct lttng_handle *handle,
 477                 struct lttng_event *ev, const char *channel_name)
 478 {
 479         struct lttcomm_session_msg lsm;
 480
 481         if (!handle) {
 482                 return -1;
 483         }
 484
 485         if (channel_name == NULL) {
 486                 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME,
 487                                 sizeof(lsm.u.enable.channel_name));
 488         } else {
 489                 copy_string(lsm.u.enable.channel_name, channel_name,
 490                                 sizeof(lsm.u.enable.channel_name));
 491         }
 492
 493         copy_lttng_domain(&lsm.domain, &handle->domain);
 494
 495         if (ev) {
 496                 lsm.cmd_type = LTTNG_ENABLE_EVENT;
 497                 memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
 498         } else {
 499                 lsm.cmd_type = LTTNG_ENABLE_ALL_EVENT;
 500         }
 501
 502         copy_string(lsm.session.name, handle->session_name,
 503                         sizeof(lsm.session.name));
 504
 505         return ask_sessiond(&lsm, NULL);
 506 }
 507
 508 /*
 509  * Disable event of a channel and domain.
 510  */
 511 int lttng_disable_event(struct lttng_handle *handle, const char *name,
 512                 const char *channel_name)
 513 {
 514         struct lttcomm_session_msg lsm;
 515
 516         if (!handle) {
 517                 return -1;
 518         }
 519
 520         if (channel_name) {
 521                 copy_string(lsm.u.disable.channel_name, channel_name,
 522                                 sizeof(lsm.u.disable.channel_name));
 523         } else {
 524                 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME,
 525                                 sizeof(lsm.u.disable.channel_name));
 526         }
 527
 528         copy_lttng_domain(&lsm.domain, &handle->domain);
 529
 530         if (name == NULL) {
 531                 copy_string(lsm.u.disable.name, name, sizeof(lsm.u.disable.name));
 532                 lsm.cmd_type = LTTNG_DISABLE_EVENT;
 533         } else {
 534                 lsm.cmd_type = LTTNG_DISABLE_ALL_EVENT;
 535         }
 536
 537         copy_string(lsm.session.name, handle->session_name,
 538                         sizeof(lsm.session.name));
 539
 540         return ask_sessiond(&lsm, NULL);
 541 }
 542
 543 /*
 544  * Enable channel per domain
 545  */
 546 int lttng_enable_channel(struct lttng_handle *handle,
 547                 struct lttng_channel *chan)
 548 {
 549         struct lttcomm_session_msg lsm;
 550
 551         if (!handle) {
 552                 return -1;
 553         }
 554
 555         if (chan) {
 556                 memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
 557         }
 558
 559         lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
 560
 561         copy_lttng_domain(&lsm.domain, &handle->domain);
 562
 563         copy_string(lsm.session.name, handle->session_name,
 564                         sizeof(lsm.session.name));
 565
 566         return ask_sessiond(&lsm, NULL);
 567 }
 568
 569 /*
 570  * All tracing will be stopped for registered events of the channel.
 571  */
 572 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 573 {
 574         struct lttcomm_session_msg lsm;
 575
 576         if (!handle) {
 577                 return -1;
 578         }
 579
 580         if (name) {
 581                 copy_string(lsm.u.disable.channel_name, name,
 582                                 sizeof(lsm.u.disable.channel_name));
 583         }
 584
 585         lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
 586
 587         copy_lttng_domain(&lsm.domain, &handle->domain);
 588
 589         copy_string(lsm.session.name, handle->session_name,
 590                         sizeof(lsm.session.name));
 591
 592         return ask_sessiond(&lsm, NULL);
 593 }
 594
 595 /*
 596  * List all available tracepoints of domain.
 597  *
 598  * Return the size (bytes) of the list and set the events array.
 599  * On error, return negative value.
 600  */
 601 int lttng_list_tracepoints(struct lttng_handle *handle,
 602                 struct lttng_event **events)
 603 {
 604         int ret;
 605         struct lttcomm_session_msg lsm;
 606
 607         if (!handle) {
 608                 return -1;
 609         }
 610
 611         lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
 612         copy_lttng_domain(&lsm.domain, &handle->domain);
 613
 614         ret = ask_sessiond(&lsm, (void **) events);
 615         if (ret < 0) {
 616                 return ret;
 617         }
 618
 619         return ret / sizeof(struct lttng_event);
 620 }
 621
 622 /*
 623  *  Return a human readable string of code
 624  */
 625 const char *lttng_get_readable_code(int code)
 626 {
 627         if (code > -LTTCOMM_OK) {
 628                 return "Ended with errors";
 629         }
 630
 631         return lttcomm_get_readable_code(code);
 632 }
 633
 634 /*
 635  *  Create a brand new session using name.
 636  */
 637 int lttng_create_session(const char *name, const char *path)
 638 {
 639         struct lttcomm_session_msg lsm;
 640
 641         lsm.cmd_type = LTTNG_CREATE_SESSION;
 642         copy_string(lsm.session.name, name, sizeof(lsm.session.name));
 643         copy_string(lsm.session.path, path, sizeof(lsm.session.path));
 644
 645         return ask_sessiond(&lsm, NULL);
 646 }
 647
 648 /*
 649  *  Destroy session using name.
 650  */
 651 int lttng_destroy_session(struct lttng_handle *handle)
 652 {
 653         struct lttcomm_session_msg lsm;
 654
 655         if (!handle) {
 656                 return -1;
 657         }
 658
 659         lsm.cmd_type = LTTNG_DESTROY_SESSION;
 660         copy_string(lsm.session.name, handle->session_name,
 661                         sizeof(lsm.session.name));
 662
 663         return ask_sessiond(&lsm, NULL);
 664 }
 665
 666 /*
 667  *  Ask the session daemon for all available sessions.
 668  *
 669  *  Return number of session.
 670  *  On error, return negative value.
 671  */
 672 int lttng_list_sessions(struct lttng_session **sessions)
 673 {
 674         int ret;
 675         struct lttcomm_session_msg lsm;
 676
 677         lsm.cmd_type = LTTNG_LIST_SESSIONS;
 678         ret = ask_sessiond(&lsm, (void**) sessions);
 679         if (ret < 0) {
 680                 return ret;
 681         }
 682
 683         return ret / sizeof(struct lttng_session);
 684 }
 685
 686 /*
 687  * List domain of a session.
 688  */
 689 int lttng_list_domains(struct lttng_handle *handle,
 690                 struct lttng_domain **domains)
 691 {
 692         int ret;
 693         struct lttcomm_session_msg lsm;
 694
 695         if (!handle) {
 696                 return -1;
 697         }
 698
 699         lsm.cmd_type = LTTNG_LIST_DOMAINS;
 700
 701         copy_string(lsm.session.name, handle->session_name,
 702                         sizeof(lsm.session.name));
 703
 704         ret = ask_sessiond(&lsm, (void**) domains);
 705         if (ret < 0) {
 706                 return ret;
 707         }
 708
 709         return ret / sizeof(struct lttng_domain);
 710 }
 711
 712 /*
 713  * List channels of a session
 714  */
 715 int lttng_list_channels(struct lttng_handle *handle,
 716                 struct lttng_channel **channels)
 717 {
 718         int ret;
 719         struct lttcomm_session_msg lsm;
 720
 721         if (!handle) {
 722                 return -1;
 723         }
 724
 725         lsm.cmd_type = LTTNG_LIST_CHANNELS;
 726         copy_string(lsm.session.name, handle->session_name,
 727                         sizeof(lsm.session.name));
 728
 729         copy_lttng_domain(&lsm.domain, &handle->domain);
 730
 731         ret = ask_sessiond(&lsm, (void**) channels);
 732         if (ret < 0) {
 733                 return ret;
 734         }
 735
 736         return ret / sizeof(struct lttng_channel);
 737 }
 738
 739 /*
 740  * List events of a session channel.
 741  */
 742 int lttng_list_events(struct lttng_handle *handle,
 743                 const char *channel_name, struct lttng_event **events)
 744 {
 745         int ret;
 746         struct lttcomm_session_msg lsm;
 747
 748         if (!handle) {
 749                 return -1;
 750         }
 751
 752         lsm.cmd_type = LTTNG_LIST_EVENTS;
 753         copy_string(lsm.session.name, handle->session_name,
 754                         sizeof(lsm.session.name));
 755         copy_string(lsm.u.list.channel_name, channel_name,
 756                         sizeof(lsm.u.list.channel_name));
 757
 758         copy_lttng_domain(&lsm.domain, &handle->domain);
 759
 760         ret = ask_sessiond(&lsm, (void**) events);
 761         if (ret < 0) {
 762                 return ret;
 763         }
 764
 765         return ret / sizeof(struct lttng_event);
 766 }
 767
 768 /*
 769  *  lttng_set_tracing_group
 770  *
 771  *  Set tracing group variable with name. This function
 772  *  allocate memory pointed by tracing_group.
 773  */
 774 int lttng_set_tracing_group(const char *name)
 775 {
 776         if (asprintf(&tracing_group, "%s", name) < 0) {
 777                 return -ENOMEM;
 778         }
 779
 780         return 0;
 781 }
 782
 783 /*
 784  *  lttng_calibrate
 785  */
 786 int lttng_calibrate(struct lttng_handle *handle,
 787                 struct lttng_calibrate *calibrate)
 788 {
 789         struct lttcomm_session_msg lsm;
 790
 791         if (!handle) {
 792                 return -1;
 793         }
 794
 795         lsm.cmd_type = LTTNG_CALIBRATE;
 796         copy_lttng_domain(&lsm.domain, &handle->domain);
 797
 798         memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
 799
 800         return ask_sessiond(&lsm, NULL);
 801 }
 802
 803 /*
 804  * Check if session daemon is alive.
 805  *
 806  * Return 1 if alive or 0 if not.
 807  * On error return -1
 808  */
 809 int lttng_session_daemon_alive(void)
 810 {
 811         int ret;
 812
 813         ret = set_session_daemon_path();
 814         if (ret < 0) {
 815                 /* Error */
 816                 return ret;
 817         }
 818
 819         if (strlen(sessiond_sock_path) == 0) {
 820                 /* No socket path set. Weird error */
 821                 return -1;
 822         }
 823
 824         ret = try_connect_sessiond(sessiond_sock_path);
 825         if (ret < 0) {
 826                 /* Not alive */
 827                 return 0;
 828         }
 829
 830         /* Is alive */
 831         return 1;
 832 }
 833
 834 /*
 835  * lib constructor
 836  */
 837 static void __attribute__((constructor)) init()
 838 {
 839         /* Set default session group */
 840         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 841 }