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         if (!grp_list) {
 156                 ret = -1;
 157                 goto end;
 158         }
 159         grp_id = getgroups(grp_list_size, grp_list);
 160         if (grp_id < -1) {
 161                 perror("getgroups");
 162                 goto free_list;
 163         }
 164
 165         for (i = 0; i < grp_list_size; i++) {
 166                 if (grp_list[i] == grp_tracing->gr_gid) {
 167                         ret = 1;
 168                         break;
 169                 }
 170         }
 171
 172 free_list:
 173         free(grp_list);
 174
 175 end:
 176         return ret;
 177 }
 178
 179 /*
 180  * Try connect to session daemon with sock_path.
 181  *
 182  * Return 0 on success, else -1
 183  */
 184 static int try_connect_sessiond(const char *sock_path)
 185 {
 186         int ret;
 187
 188         /* If socket exist, we check if the daemon listens for connect. */
 189         ret = access(sock_path, F_OK);
 190         if (ret < 0) {
 191                 /* Not alive */
 192                 return -1;
 193         }
 194
 195         ret = lttcomm_connect_unix_sock(sock_path);
 196         if (ret < 0) {
 197                 /* Not alive */
 198                 return -1;
 199         }
 200
 201         ret = lttcomm_close_unix_sock(ret);
 202         if (ret < 0) {
 203                 perror("lttcomm_close_unix_sock");
 204         }
 205
 206         return 0;
 207 }
 208
 209 /*
 210  * Set sessiond socket path by putting it in the global sessiond_sock_path
 211  * variable.
 212  */
 213 static int set_session_daemon_path(void)
 214 {
 215         int ret;
 216         int in_tgroup = 0;      /* In tracing group */
 217         uid_t uid;
 218
 219         uid = getuid();
 220
 221         if (uid != 0) {
 222                 /* Are we in the tracing group ? */
 223                 in_tgroup = check_tracing_group(tracing_group);
 224         }
 225
 226         if (uid == 0) {
 227                 /* Root */
 228                 copy_string(sessiond_sock_path,
 229                                 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 230                                 sizeof(sessiond_sock_path));
 231         } else if (in_tgroup) {
 232                 /* Tracing group */
 233                 copy_string(sessiond_sock_path,
 234                                 DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 235                                 sizeof(sessiond_sock_path));
 236
 237                 ret = try_connect_sessiond(sessiond_sock_path);
 238                 if (ret < 0) {
 239                         /* Global session daemon not available */
 240                         if (snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
 241                                                 DEFAULT_HOME_CLIENT_UNIX_SOCK,
 242                                                 getenv("HOME")) < 0) {
 243                                 return -ENOMEM;
 244                         }
 245                 }
 246         } else {
 247                 /* Not in tracing group and not root, default */
 248                 if (snprintf(sessiond_sock_path, PATH_MAX,
 249                                         DEFAULT_HOME_CLIENT_UNIX_SOCK,
 250                                         getenv("HOME")) < 0) {
 251                         return -ENOMEM;
 252                 }
 253         }
 254
 255         return 0;
 256 }
 257
 258 /*
 259  *  Connect to the LTTng session daemon.
 260  *
 261  *  On success, return 0. On error, return -1.
 262  */
 263 static int connect_sessiond(void)
 264 {
 265         int ret;
 266
 267         ret = set_session_daemon_path();
 268         if (ret < 0) {
 269                 return ret;
 270         }
 271
 272         /* Connect to the sesssion daemon */
 273         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 274         if (ret < 0) {
 275                 return ret;
 276         }
 277
 278         sessiond_socket = ret;
 279         connected = 1;
 280
 281         return 0;
 282 }
 283
 284 /*
 285  *  Clean disconnect the session daemon.
 286  */
 287 static int disconnect_sessiond(void)
 288 {
 289         int ret = 0;
 290
 291         if (connected) {
 292                 ret = lttcomm_close_unix_sock(sessiond_socket);
 293                 sessiond_socket = 0;
 294                 connected = 0;
 295         }
 296
 297         return ret;
 298 }
 299
 300 /*
 301  * Ask the session daemon a specific command and put the data into buf.
 302  *
 303  * Return size of data (only payload, not header).
 304  */
 305 static int ask_sessiond(struct lttcomm_session_msg *lsm, void **buf)
 306 {
 307         int ret;
 308         size_t size;
 309         void *data = NULL;
 310         struct lttcomm_lttng_msg llm;
 311
 312         ret = connect_sessiond();
 313         if (ret < 0) {
 314                 goto end;
 315         }
 316
 317         /* Send command to session daemon */
 318         ret = send_session_msg(lsm);
 319         if (ret < 0) {
 320                 goto end;
 321         }
 322
 323         /* Get header from data transmission */
 324         ret = recv_data_sessiond(&llm, sizeof(llm));
 325         if (ret < 0) {
 326                 goto end;
 327         }
 328
 329         /* Check error code if OK */
 330         if (llm.ret_code != LTTCOMM_OK) {
 331                 ret = -llm.ret_code;
 332                 goto end;
 333         }
 334
 335         size = llm.data_size;
 336         if (size == 0) {
 337                 /* If client free with size 0 */
 338                 if (buf != NULL) {
 339                         *buf = NULL;
 340                 }
 341                 ret = 0;
 342                 goto end;
 343         }
 344
 345         data = (void*) malloc(size);
 346
 347         /* Get payload data */
 348         ret = recv_data_sessiond(data, size);
 349         if (ret < 0) {
 350                 free(data);
 351                 goto end;
 352         }
 353
 354         /*
 355          * Extra protection not to dereference a NULL pointer. If buf is NULL at
 356          * this point, an error is returned and data is freed.
 357          */
 358         if (buf == NULL) {
 359                 ret = -1;
 360                 free(data);
 361                 goto end;
 362         }
 363
 364         *buf = data;
 365         ret = size;
 366
 367 end:
 368         disconnect_sessiond();
 369         return ret;
 370 }
 371
 372 /*
 373  * Create lttng handle and return pointer.
 374  */
 375 struct lttng_handle *lttng_create_handle(const char *session_name,
 376                 struct lttng_domain *domain)
 377 {
 378         struct lttng_handle *handle;
 379
 380         handle = malloc(sizeof(struct lttng_handle));
 381         if (handle == NULL) {
 382                 perror("malloc handle");
 383                 goto end;
 384         }
 385
 386         /* Copy session name */
 387         copy_string(handle->session_name, session_name,
 388                         sizeof(handle->session_name));
 389
 390         /* Copy lttng domain */
 391         copy_lttng_domain(&handle->domain, domain);
 392
 393 end:
 394         return handle;
 395 }
 396
 397 /*
 398  * Destroy handle by free(3) the pointer.
 399  */
 400 void lttng_destroy_handle(struct lttng_handle *handle)
 401 {
 402         if (handle) {
 403                 free(handle);
 404         }
 405 }
 406
 407 /*
 408  * Register an outside consumer.
 409  */
 410 int lttng_register_consumer(struct lttng_handle *handle,
 411                 const char *socket_path)
 412 {
 413         struct lttcomm_session_msg lsm;
 414
 415         lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
 416         copy_string(lsm.session.name, handle->session_name,
 417                         sizeof(lsm.session.name));
 418         copy_lttng_domain(&lsm.domain, &handle->domain);
 419
 420         copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
 421
 422         return ask_sessiond(&lsm, NULL);
 423 }
 424
 425 /*
 426  *  Start tracing for all trace of the session.
 427  */
 428 int lttng_start_tracing(struct lttng_handle *handle)
 429 {
 430         struct lttcomm_session_msg lsm;
 431
 432         if (handle == NULL) {
 433                 return -1;
 434         }
 435
 436         lsm.cmd_type = LTTNG_START_TRACE;
 437         copy_string(lsm.session.name, handle->session_name,
 438                         sizeof(lsm.session.name));
 439
 440         return ask_sessiond(&lsm, NULL);
 441 }
 442
 443 /*
 444  *  Stop tracing for all trace of the session.
 445  */
 446 int lttng_stop_tracing(struct lttng_handle *handle)
 447 {
 448         struct lttcomm_session_msg lsm;
 449
 450         lsm.cmd_type = LTTNG_STOP_TRACE;
 451         copy_string(lsm.session.name, handle->session_name,
 452                         sizeof(lsm.session.name));
 453
 454         return ask_sessiond(&lsm, NULL);
 455 }
 456
 457 /*
 458  * Add context to event or/and channel.
 459  */
 460 int lttng_add_context(struct lttng_handle *handle,
 461                 struct lttng_event_context *ctx, const char *event_name,
 462                 const char *channel_name)
 463 {
 464         struct lttcomm_session_msg lsm;
 465
 466         /* Safety check. Both are mandatory */
 467         if (handle == NULL || ctx == NULL) {
 468                 return -1;
 469         }
 470
 471         lsm.cmd_type = LTTNG_ADD_CONTEXT;
 472
 473         /* Copy channel name */
 474         copy_string(lsm.u.context.channel_name, channel_name,
 475                         sizeof(lsm.u.context.channel_name));
 476         /* Copy event name */
 477         copy_string(lsm.u.context.event_name, event_name,
 478                         sizeof(lsm.u.context.event_name));
 479
 480         copy_lttng_domain(&lsm.domain, &handle->domain);
 481
 482         memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 483
 484         copy_string(lsm.session.name, handle->session_name,
 485                         sizeof(lsm.session.name));
 486
 487         return ask_sessiond(&lsm, NULL);
 488 }
 489
 490 /*
 491  * Enable event
 492  */
 493 int lttng_enable_event(struct lttng_handle *handle,
 494                 struct lttng_event *ev, const char *channel_name)
 495 {
 496         struct lttcomm_session_msg lsm;
 497
 498         if (handle == NULL || ev == NULL) {
 499                 return -1;
 500         }
 501
 502         /* If no channel name, we put the default name */
 503         if (channel_name == NULL) {
 504                 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME,
 505                                 sizeof(lsm.u.enable.channel_name));
 506         } else {
 507                 copy_string(lsm.u.enable.channel_name, channel_name,
 508                                 sizeof(lsm.u.enable.channel_name));
 509         }
 510
 511         copy_lttng_domain(&lsm.domain, &handle->domain);
 512
 513         if (ev->name[0] != '\0') {
 514                 lsm.cmd_type = LTTNG_ENABLE_EVENT;
 515         } else {
 516                 lsm.cmd_type = LTTNG_ENABLE_ALL_EVENT;
 517         }
 518         memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
 519
 520         copy_string(lsm.session.name, handle->session_name,
 521                         sizeof(lsm.session.name));
 522
 523         return ask_sessiond(&lsm, NULL);
 524 }
 525
 526 /*
 527  * Disable event of a channel and domain.
 528  */
 529 int lttng_disable_event(struct lttng_handle *handle, const char *name,
 530                 const char *channel_name)
 531 {
 532         struct lttcomm_session_msg lsm;
 533
 534         if (handle == NULL) {
 535                 return -1;
 536         }
 537
 538         if (channel_name) {
 539                 copy_string(lsm.u.disable.channel_name, channel_name,
 540                                 sizeof(lsm.u.disable.channel_name));
 541         } else {
 542                 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME,
 543                                 sizeof(lsm.u.disable.channel_name));
 544         }
 545
 546         copy_lttng_domain(&lsm.domain, &handle->domain);
 547
 548         if (name != NULL) {
 549                 copy_string(lsm.u.disable.name, name, sizeof(lsm.u.disable.name));
 550                 lsm.cmd_type = LTTNG_DISABLE_EVENT;
 551         } else {
 552                 lsm.cmd_type = LTTNG_DISABLE_ALL_EVENT;
 553         }
 554
 555         copy_string(lsm.session.name, handle->session_name,
 556                         sizeof(lsm.session.name));
 557
 558         return ask_sessiond(&lsm, NULL);
 559 }
 560
 561 /*
 562  * Enable channel per domain
 563  */
 564 int lttng_enable_channel(struct lttng_handle *handle,
 565                 struct lttng_channel *chan)
 566 {
 567         struct lttcomm_session_msg lsm;
 568
 569         /*
 570          * NULL arguments are forbidden. No default values.
 571          */
 572         if (handle == NULL || chan == NULL) {
 573                 return -1;
 574         }
 575
 576         memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
 577
 578         lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
 579
 580         copy_lttng_domain(&lsm.domain, &handle->domain);
 581
 582         copy_string(lsm.session.name, handle->session_name,
 583                         sizeof(lsm.session.name));
 584
 585         return ask_sessiond(&lsm, NULL);
 586 }
 587
 588 /*
 589  * All tracing will be stopped for registered events of the channel.
 590  */
 591 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 592 {
 593         struct lttcomm_session_msg lsm;
 594
 595         /* Safety check. Both are mandatory */
 596         if (handle == NULL || name == NULL) {
 597                 return -1;
 598         }
 599
 600         lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
 601
 602         copy_string(lsm.u.disable.channel_name, name,
 603                         sizeof(lsm.u.disable.channel_name));
 604
 605         copy_lttng_domain(&lsm.domain, &handle->domain);
 606
 607         copy_string(lsm.session.name, handle->session_name,
 608                         sizeof(lsm.session.name));
 609
 610         return ask_sessiond(&lsm, NULL);
 611 }
 612
 613 /*
 614  * List all available tracepoints of domain.
 615  *
 616  * Return the size (bytes) of the list and set the events array.
 617  * On error, return negative value.
 618  */
 619 int lttng_list_tracepoints(struct lttng_handle *handle,
 620                 struct lttng_event **events)
 621 {
 622         int ret;
 623         struct lttcomm_session_msg lsm;
 624
 625         if (handle == NULL) {
 626                 return -1;
 627         }
 628
 629         lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
 630         copy_lttng_domain(&lsm.domain, &handle->domain);
 631
 632         ret = ask_sessiond(&lsm, (void **) events);
 633         if (ret < 0) {
 634                 return ret;
 635         }
 636
 637         return ret / sizeof(struct lttng_event);
 638 }
 639
 640 /*
 641  *  Return a human readable string of code
 642  */
 643 const char *lttng_strerror(int code)
 644 {
 645         if (code > -LTTCOMM_OK) {
 646                 return "Ended with errors";
 647         }
 648
 649         return lttcomm_get_readable_code(code);
 650 }
 651
 652 /*
 653  *  Create a brand new session using name.
 654  */
 655 int lttng_create_session(const char *name, const char *path)
 656 {
 657         struct lttcomm_session_msg lsm;
 658
 659         lsm.cmd_type = LTTNG_CREATE_SESSION;
 660         copy_string(lsm.session.name, name, sizeof(lsm.session.name));
 661         copy_string(lsm.session.path, path, sizeof(lsm.session.path));
 662
 663         return ask_sessiond(&lsm, NULL);
 664 }
 665
 666 /*
 667  *  Destroy session using name.
 668  */
 669 int lttng_destroy_session(const char *session_name)
 670 {
 671         struct lttcomm_session_msg lsm;
 672
 673         if (session_name == NULL) {
 674                 return -1;
 675         }
 676
 677         lsm.cmd_type = LTTNG_DESTROY_SESSION;
 678
 679         copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
 680
 681         return ask_sessiond(&lsm, NULL);
 682 }
 683
 684 /*
 685  *  Ask the session daemon for all available sessions.
 686  *
 687  *  Return number of session.
 688  *  On error, return negative value.
 689  */
 690 int lttng_list_sessions(struct lttng_session **sessions)
 691 {
 692         int ret;
 693         struct lttcomm_session_msg lsm;
 694
 695         lsm.cmd_type = LTTNG_LIST_SESSIONS;
 696         ret = ask_sessiond(&lsm, (void**) sessions);
 697         if (ret < 0) {
 698                 return ret;
 699         }
 700
 701         return ret / sizeof(struct lttng_session);
 702 }
 703
 704 /*
 705  * List domain of a session.
 706  */
 707 int lttng_list_domains(struct lttng_handle *handle,
 708                 struct lttng_domain **domains)
 709 {
 710         int ret;
 711         struct lttcomm_session_msg lsm;
 712
 713         if (handle == NULL) {
 714                 return -1;
 715         }
 716
 717         lsm.cmd_type = LTTNG_LIST_DOMAINS;
 718
 719         copy_string(lsm.session.name, handle->session_name,
 720                         sizeof(lsm.session.name));
 721
 722         ret = ask_sessiond(&lsm, (void**) domains);
 723         if (ret < 0) {
 724                 return ret;
 725         }
 726
 727         return ret / sizeof(struct lttng_domain);
 728 }
 729
 730 /*
 731  * List channels of a session
 732  */
 733 int lttng_list_channels(struct lttng_handle *handle,
 734                 struct lttng_channel **channels)
 735 {
 736         int ret;
 737         struct lttcomm_session_msg lsm;
 738
 739         if (handle == NULL) {
 740                 return -1;
 741         }
 742
 743         lsm.cmd_type = LTTNG_LIST_CHANNELS;
 744         copy_string(lsm.session.name, handle->session_name,
 745                         sizeof(lsm.session.name));
 746
 747         copy_lttng_domain(&lsm.domain, &handle->domain);
 748
 749         ret = ask_sessiond(&lsm, (void**) channels);
 750         if (ret < 0) {
 751                 return ret;
 752         }
 753
 754         return ret / sizeof(struct lttng_channel);
 755 }
 756
 757 /*
 758  * List events of a session channel.
 759  */
 760 int lttng_list_events(struct lttng_handle *handle,
 761                 const char *channel_name, struct lttng_event **events)
 762 {
 763         int ret;
 764         struct lttcomm_session_msg lsm;
 765
 766         /* Safety check. An handle and channel name are mandatory */
 767         if (handle == NULL || channel_name == NULL) {
 768                 return -1;
 769         }
 770
 771         lsm.cmd_type = LTTNG_LIST_EVENTS;
 772         copy_string(lsm.session.name, handle->session_name,
 773                         sizeof(lsm.session.name));
 774         copy_string(lsm.u.list.channel_name, channel_name,
 775                         sizeof(lsm.u.list.channel_name));
 776
 777         copy_lttng_domain(&lsm.domain, &handle->domain);
 778
 779         ret = ask_sessiond(&lsm, (void**) events);
 780         if (ret < 0) {
 781                 return ret;
 782         }
 783
 784         return ret / sizeof(struct lttng_event);
 785 }
 786
 787 /*
 788  * Set tracing group variable with name. This function allocate memory pointed
 789  * by tracing_group.
 790  */
 791 int lttng_set_tracing_group(const char *name)
 792 {
 793         if (name == NULL) {
 794                 return -1;
 795         }
 796
 797         if (asprintf(&tracing_group, "%s", name) < 0) {
 798                 return -ENOMEM;
 799         }
 800
 801         return 0;
 802 }
 803
 804 /*
 805  *  lttng_calibrate
 806  */
 807 int lttng_calibrate(struct lttng_handle *handle,
 808                 struct lttng_calibrate *calibrate)
 809 {
 810         struct lttcomm_session_msg lsm;
 811
 812         /* Safety check. NULL pointer are forbidden */
 813         if (handle == NULL || calibrate == NULL) {
 814                 return -1;
 815         }
 816
 817         lsm.cmd_type = LTTNG_CALIBRATE;
 818         copy_lttng_domain(&lsm.domain, &handle->domain);
 819
 820         memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
 821
 822         return ask_sessiond(&lsm, NULL);
 823 }
 824
 825 /*
 826  * Set default channel attributes.
 827  */
 828 void lttng_channel_set_default_attr(struct lttng_domain *domain,
 829                 struct lttng_channel_attr *attr)
 830 {
 831         /* Safety check */
 832         if (attr == NULL || domain == NULL) {
 833                 return;
 834         }
 835
 836         switch (domain->type) {
 837         case LTTNG_DOMAIN_KERNEL:
 838                 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
 839                 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
 840                 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
 841
 842                 attr->subbuf_size = DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE;
 843                 attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
 844                 attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
 845                 break;
 846         case LTTNG_DOMAIN_UST:
 847         case LTTNG_DOMAIN_UST_EXEC_NAME:
 848         case LTTNG_DOMAIN_UST_PID:
 849         case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
 850                 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
 851                 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
 852                 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
 853
 854                 attr->subbuf_size = DEFAULT_UST_CHANNEL_SUBBUF_SIZE;
 855                 attr->num_subbuf = DEFAULT_UST_CHANNEL_SUBBUF_NUM;
 856                 attr->output = DEFAULT_UST_CHANNEL_OUTPUT;
 857                 break;
 858         default:
 859                 /* Default behavior */
 860                 memset(attr, 0, sizeof(struct lttng_channel_attr));
 861                 break;
 862         }
 863 }
 864
 865 /*
 866  * Check if session daemon is alive.
 867  *
 868  * Return 1 if alive or 0 if not.
 869  * On error return -1
 870  */
 871 int lttng_session_daemon_alive(void)
 872 {
 873         int ret;
 874
 875         ret = set_session_daemon_path();
 876         if (ret < 0) {
 877                 /* Error */
 878                 return ret;
 879         }
 880
 881         if (strlen(sessiond_sock_path) == 0) {
 882                 /* No socket path set. Weird error */
 883                 return -1;
 884         }
 885
 886         ret = try_connect_sessiond(sessiond_sock_path);
 887         if (ret < 0) {
 888                 /* Not alive */
 889                 return 0;
 890         }
 891
 892         /* Is alive */
 893         return 1;
 894 }
 895
 896 /*
 897  * lib constructor
 898  */
 899 static void __attribute__((constructor)) init()
 900 {
 901         /* Set default session group */
 902         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 903 }