src/lib/lttng-ctl/lttng-ctl.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 <common/common.h>
  32 #include <common/defaults.h>
  33 #include <common/sessiond-comm/sessiond-comm.h>
  34 #include <lttng/lttng.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                         /*
  70                         case LTTNG_DOMAIN_UST_EXEC_NAME:
  71                         case LTTNG_DOMAIN_UST_PID:
  72                         case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
  73                         */
  74                                 memcpy(dst, src, sizeof(struct lttng_domain));
  75                                 break;
  76                         default:
  77                                 memset(dst, 0, sizeof(struct lttng_domain));
  78                                 dst->type = LTTNG_DOMAIN_KERNEL;
  79                                 break;
  80                 }
  81         }
  82 }
  83
  84 /*
  85  * Send lttcomm_session_msg to the session daemon.
  86  *
  87  * On success, returns the number of bytes sent (>=0)
  88  * On error, returns -1
  89  */
  90 static int send_session_msg(struct lttcomm_session_msg *lsm)
  91 {
  92         int ret;
  93
  94         if (!connected) {
  95                 ret = -ENOTCONN;
  96                 goto end;
  97         }
  98
  99         ret = lttcomm_send_creds_unix_sock(sessiond_socket, lsm,
 100                         sizeof(struct lttcomm_session_msg));
 101
 102 end:
 103         return ret;
 104 }
 105
 106 /*
 107  * Receive data from the sessiond socket.
 108  *
 109  * On success, returns the number of bytes received (>=0)
 110  * On error, returns -1 (recvmsg() error) or -ENOTCONN
 111  */
 112 static int recv_data_sessiond(void *buf, size_t len)
 113 {
 114         int ret;
 115
 116         if (!connected) {
 117                 ret = -ENOTCONN;
 118                 goto end;
 119         }
 120
 121         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
 122
 123 end:
 124         return ret;
 125 }
 126
 127 /*
 128  *  Check if we are in the specified group.
 129  *
 130  *  If yes return 1, else return -1.
 131  */
 132 static int check_tracing_group(const char *grp_name)
 133 {
 134         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 135         gid_t *grp_list;
 136         int grp_list_size, grp_id, i;
 137         int ret = -1;
 138
 139         /* Get GID of group 'tracing' */
 140         grp_tracing = getgrnam(grp_name);
 141         if (grp_tracing == NULL) {
 142                 /* NULL means not found also. getgrnam(3) */
 143                 if (errno != 0) {
 144                         perror("getgrnam");
 145                 }
 146                 goto end;
 147         }
 148
 149         /* Get number of supplementary group IDs */
 150         grp_list_size = getgroups(0, NULL);
 151         if (grp_list_size < 0) {
 152                 perror("getgroups");
 153                 goto end;
 154         }
 155
 156         /* Alloc group list of the right size */
 157         grp_list = malloc(grp_list_size * sizeof(gid_t));
 158         if (!grp_list) {
 159                 perror("malloc");
 160                 goto end;
 161         }
 162         grp_id = getgroups(grp_list_size, grp_list);
 163         if (grp_id < 0) {
 164                 perror("getgroups");
 165                 goto free_list;
 166         }
 167
 168         for (i = 0; i < grp_list_size; i++) {
 169                 if (grp_list[i] == grp_tracing->gr_gid) {
 170                         ret = 1;
 171                         break;
 172                 }
 173         }
 174
 175 free_list:
 176         free(grp_list);
 177
 178 end:
 179         return ret;
 180 }
 181
 182 /*
 183  * Try connect to session daemon with sock_path.
 184  *
 185  * Return 0 on success, else -1
 186  */
 187 static int try_connect_sessiond(const char *sock_path)
 188 {
 189         int ret;
 190
 191         /* If socket exist, we check if the daemon listens for connect. */
 192         ret = access(sock_path, F_OK);
 193         if (ret < 0) {
 194                 /* Not alive */
 195                 return -1;
 196         }
 197
 198         ret = lttcomm_connect_unix_sock(sock_path);
 199         if (ret < 0) {
 200                 /* Not alive */
 201                 return -1;
 202         }
 203
 204         ret = lttcomm_close_unix_sock(ret);
 205         if (ret < 0) {
 206                 perror("lttcomm_close_unix_sock");
 207         }
 208
 209         return 0;
 210 }
 211
 212 /*
 213  * Set sessiond socket path by putting it in the global
 214  * sessiond_sock_path variable.
 215  * Returns 0 on success,
 216  * -ENOMEM on failure (the sessiond socket path is somehow too long)
 217  */
 218 static int set_session_daemon_path(void)
 219 {
 220         int ret;
 221         int in_tgroup = 0;      /* In tracing group */
 222         uid_t uid;
 223
 224         uid = getuid();
 225
 226         if (uid != 0) {
 227                 /* Are we in the tracing group ? */
 228                 in_tgroup = check_tracing_group(tracing_group);
 229         }
 230
 231         if ((uid == 0) || in_tgroup) {
 232                 copy_string(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 233                                 sizeof(sessiond_sock_path));
 234         }
 235
 236         if (uid != 0) {
 237                 if (in_tgroup) {
 238                         /* Tracing group */
 239                         ret = try_connect_sessiond(sessiond_sock_path);
 240                         if (ret >= 0) {
 241                                 goto end;
 242                         }
 243                         /* Global session daemon not available... */
 244                 }
 245                 /* ...or not in tracing group (and not root), default */
 246
 247                 /*
 248                  * With GNU C <  2.1, snprintf returns -1 if the target buffer is too small;
 249                  * With GNU C >= 2.1, snprintf returns the required size (excluding closing null)
 250                  */
 251                 ret = snprintf(sessiond_sock_path, sizeof(sessiond_sock_path),
 252                                 DEFAULT_HOME_CLIENT_UNIX_SOCK, getenv("HOME"));
 253                 if ((ret < 0) || (ret >= sizeof(sessiond_sock_path))) {
 254                         return -ENOMEM;
 255                 }
 256         }
 257 end:
 258         return 0;
 259 }
 260
 261 /*
 262  *  Connect to the LTTng session daemon.
 263  *
 264  *  On success, return 0. On error, return -1.
 265  */
 266 static int connect_sessiond(void)
 267 {
 268         int ret;
 269
 270         ret = set_session_daemon_path();
 271         if (ret < 0) {
 272                 return -1; /* set_session_daemon_path() returns -ENOMEM */
 273         }
 274
 275         /* Connect to the sesssion daemon */
 276         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 277         if (ret < 0) {
 278                 return ret;
 279         }
 280
 281         sessiond_socket = ret;
 282         connected = 1;
 283
 284         return 0;
 285 }
 286
 287 /*
 288  *  Clean disconnect from the session daemon.
 289  *  On success, return 0. On error, return -1.
 290  */
 291 static int disconnect_sessiond(void)
 292 {
 293         int ret = 0;
 294
 295         if (connected) {
 296                 ret = lttcomm_close_unix_sock(sessiond_socket);
 297                 sessiond_socket = 0;
 298                 connected = 0;
 299         }
 300
 301         return ret;
 302 }
 303
 304 /*
 305  * Ask the session daemon a specific command and put the data into buf.
 306  *
 307  * Return size of data (only payload, not header) or a negative error code.
 308  */
 309 static int ask_sessiond(struct lttcomm_session_msg *lsm, void **buf)
 310 {
 311         int ret;
 312         size_t size;
 313         void *data = NULL;
 314         struct lttcomm_lttng_msg llm;
 315
 316         ret = connect_sessiond();
 317         if (ret < 0) {
 318                 goto end;
 319         }
 320
 321         /* Send command to session daemon */
 322         ret = send_session_msg(lsm);
 323         if (ret < 0) {
 324                 goto end;
 325         }
 326
 327         /* Get header from data transmission */
 328         ret = recv_data_sessiond(&llm, sizeof(llm));
 329         if (ret < 0) {
 330                 goto end;
 331         }
 332
 333         /* Check error code if OK */
 334         if (llm.ret_code != LTTCOMM_OK) {
 335                 ret = -llm.ret_code;
 336                 goto end;
 337         }
 338
 339         size = llm.data_size;
 340         if (size == 0) {
 341                 /* If client free with size 0 */
 342                 if (buf != NULL) {
 343                         *buf = NULL;
 344                 }
 345                 ret = 0;
 346                 goto end;
 347         }
 348
 349         data = (void*) malloc(size);
 350
 351         /* Get payload data */
 352         ret = recv_data_sessiond(data, size);
 353         if (ret < 0) {
 354                 free(data);
 355                 goto end;
 356         }
 357
 358         /*
 359          * Extra protection not to dereference a NULL pointer. If buf is NULL at
 360          * this point, an error is returned and data is freed.
 361          */
 362         if (buf == NULL) {
 363                 ret = -1;
 364                 free(data);
 365                 goto end;
 366         }
 367
 368         *buf = data;
 369         ret = size;
 370
 371 end:
 372         disconnect_sessiond();
 373         return ret;
 374 }
 375
 376 /*
 377  * Create lttng handle and return pointer.
 378  * The returned pointer will be NULL in case of malloc() error.
 379  */
 380 struct lttng_handle *lttng_create_handle(const char *session_name,
 381                 struct lttng_domain *domain)
 382 {
 383         struct lttng_handle *handle;
 384
 385         handle = malloc(sizeof(struct lttng_handle));
 386         if (handle == NULL) {
 387                 perror("malloc handle");
 388                 goto end;
 389         }
 390
 391         /* Copy session name */
 392         copy_string(handle->session_name, session_name,
 393                         sizeof(handle->session_name));
 394
 395         /* Copy lttng domain */
 396         copy_lttng_domain(&handle->domain, domain);
 397
 398 end:
 399         return handle;
 400 }
 401
 402 /*
 403  * Destroy handle by free(3) the pointer.
 404  */
 405 void lttng_destroy_handle(struct lttng_handle *handle)
 406 {
 407         if (handle) {
 408                 free(handle);
 409         }
 410 }
 411
 412 /*
 413  * Register an outside consumer.
 414  * Returns size of returned session payload data or a negative error code.
 415  */
 416 int lttng_register_consumer(struct lttng_handle *handle,
 417                 const char *socket_path)
 418 {
 419         struct lttcomm_session_msg lsm;
 420
 421         lsm.cmd_type = LTTNG_REGISTER_CONSUMER;
 422         copy_string(lsm.session.name, handle->session_name,
 423                         sizeof(lsm.session.name));
 424         copy_lttng_domain(&lsm.domain, &handle->domain);
 425
 426         copy_string(lsm.u.reg.path, socket_path, sizeof(lsm.u.reg.path));
 427
 428         return ask_sessiond(&lsm, NULL);
 429 }
 430
 431 /*
 432  *  Start tracing for all traces of the session.
 433  *  Returns size of returned session payload data or a negative error code.
 434  */
 435 int lttng_start_tracing(const char *session_name)
 436 {
 437         struct lttcomm_session_msg lsm;
 438
 439         if (session_name == NULL) {
 440                 return -1;
 441         }
 442
 443         lsm.cmd_type = LTTNG_START_TRACE;
 444
 445         copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
 446
 447         return ask_sessiond(&lsm, NULL);
 448 }
 449
 450 /*
 451  *  Stop tracing for all traces of the session.
 452  *  Returns size of returned session payload data or a negative error code.
 453  */
 454 int lttng_stop_tracing(const char *session_name)
 455 {
 456         struct lttcomm_session_msg lsm;
 457
 458         if (session_name == NULL) {
 459                 return -1;
 460         }
 461
 462         lsm.cmd_type = LTTNG_STOP_TRACE;
 463
 464         copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
 465
 466         return ask_sessiond(&lsm, NULL);
 467 }
 468
 469 /*
 470  * Add context to event and/or channel.
 471  * If event_name is NULL, the context is applied to all events of the channel.
 472  * If channel_name is NULL, a lookup of the event's channel is done.
 473  * If both are NULL, the context is applied to all events of all channels.
 474  *
 475  * Returns the size of the returned payload data or a negative error code.
 476  */
 477 int lttng_add_context(struct lttng_handle *handle,
 478                 struct lttng_event_context *ctx, const char *event_name,
 479                 const char *channel_name)
 480 {
 481         struct lttcomm_session_msg lsm;
 482
 483         /* Safety check. Both are mandatory */
 484         if (handle == NULL || ctx == NULL) {
 485                 return -1;
 486         }
 487
 488         memset(&lsm, 0, sizeof(lsm));
 489
 490         lsm.cmd_type = LTTNG_ADD_CONTEXT;
 491
 492         /* Copy channel name */
 493         copy_string(lsm.u.context.channel_name, channel_name,
 494                         sizeof(lsm.u.context.channel_name));
 495         /* Copy event name */
 496         copy_string(lsm.u.context.event_name, event_name,
 497                         sizeof(lsm.u.context.event_name));
 498
 499         copy_lttng_domain(&lsm.domain, &handle->domain);
 500
 501         memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 502
 503         copy_string(lsm.session.name, handle->session_name,
 504                         sizeof(lsm.session.name));
 505
 506         return ask_sessiond(&lsm, NULL);
 507 }
 508
 509 /*
 510  *  Enable event(s) for a channel.
 511  *  If no event name is specified, all events are enabled.
 512  *  If no channel name is specified, the default 'channel0' is used.
 513  *  Returns size of returned session payload data or a negative error code.
 514  */
 515 int lttng_enable_event(struct lttng_handle *handle,
 516                 struct lttng_event *ev, const char *channel_name)
 517 {
 518         struct lttcomm_session_msg lsm;
 519
 520         if (handle == NULL || ev == NULL) {
 521                 return -1;
 522         }
 523
 524         memset(&lsm, 0, sizeof(lsm));
 525
 526         /* If no channel name, we put the default name */
 527         if (channel_name == NULL) {
 528                 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME,
 529                                 sizeof(lsm.u.enable.channel_name));
 530         } else {
 531                 copy_string(lsm.u.enable.channel_name, channel_name,
 532                                 sizeof(lsm.u.enable.channel_name));
 533         }
 534
 535         copy_lttng_domain(&lsm.domain, &handle->domain);
 536
 537         if (ev->name[0] != '\0') {
 538                 lsm.cmd_type = LTTNG_ENABLE_EVENT;
 539         } else {
 540                 lsm.cmd_type = LTTNG_ENABLE_ALL_EVENT;
 541         }
 542         memcpy(&lsm.u.enable.event, ev, sizeof(lsm.u.enable.event));
 543
 544         copy_string(lsm.session.name, handle->session_name,
 545                         sizeof(lsm.session.name));
 546
 547         return ask_sessiond(&lsm, NULL);
 548 }
 549
 550 /*
 551  *  Disable event(s) of a channel and domain.
 552  *  If no event name is specified, all events are disabled.
 553  *  If no channel name is specified, the default 'channel0' is used.
 554  *  Returns size of returned session payload data or a negative error code.
 555  */
 556 int lttng_disable_event(struct lttng_handle *handle, const char *name,
 557                 const char *channel_name)
 558 {
 559         struct lttcomm_session_msg lsm;
 560
 561         if (handle == NULL) {
 562                 return -1;
 563         }
 564
 565         memset(&lsm, 0, sizeof(lsm));
 566
 567         if (channel_name) {
 568                 copy_string(lsm.u.disable.channel_name, channel_name,
 569                                 sizeof(lsm.u.disable.channel_name));
 570         } else {
 571                 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME,
 572                                 sizeof(lsm.u.disable.channel_name));
 573         }
 574
 575         copy_lttng_domain(&lsm.domain, &handle->domain);
 576
 577         if (name != NULL) {
 578                 copy_string(lsm.u.disable.name, name, sizeof(lsm.u.disable.name));
 579                 lsm.cmd_type = LTTNG_DISABLE_EVENT;
 580         } else {
 581                 lsm.cmd_type = LTTNG_DISABLE_ALL_EVENT;
 582         }
 583
 584         copy_string(lsm.session.name, handle->session_name,
 585                         sizeof(lsm.session.name));
 586
 587         return ask_sessiond(&lsm, NULL);
 588 }
 589
 590 /*
 591  *  Enable channel per domain
 592  *  Returns size of returned session payload data or a negative error code.
 593  */
 594 int lttng_enable_channel(struct lttng_handle *handle,
 595                 struct lttng_channel *chan)
 596 {
 597         struct lttcomm_session_msg lsm;
 598
 599         /*
 600          * NULL arguments are forbidden. No default values.
 601          */
 602         if (handle == NULL || chan == NULL) {
 603                 return -1;
 604         }
 605
 606         memset(&lsm, 0, sizeof(lsm));
 607
 608         memcpy(&lsm.u.channel.chan, chan, sizeof(lsm.u.channel.chan));
 609
 610         lsm.cmd_type = LTTNG_ENABLE_CHANNEL;
 611
 612         copy_lttng_domain(&lsm.domain, &handle->domain);
 613
 614         copy_string(lsm.session.name, handle->session_name,
 615                         sizeof(lsm.session.name));
 616
 617         return ask_sessiond(&lsm, NULL);
 618 }
 619
 620 /*
 621  *  All tracing will be stopped for registered events of the channel.
 622  *  Returns size of returned session payload data or a negative error code.
 623  */
 624 int lttng_disable_channel(struct lttng_handle *handle, const char *name)
 625 {
 626         struct lttcomm_session_msg lsm;
 627
 628         /* Safety check. Both are mandatory */
 629         if (handle == NULL || name == NULL) {
 630                 return -1;
 631         }
 632
 633         memset(&lsm, 0, sizeof(lsm));
 634
 635         lsm.cmd_type = LTTNG_DISABLE_CHANNEL;
 636
 637         copy_string(lsm.u.disable.channel_name, name,
 638                         sizeof(lsm.u.disable.channel_name));
 639
 640         copy_lttng_domain(&lsm.domain, &handle->domain);
 641
 642         copy_string(lsm.session.name, handle->session_name,
 643                         sizeof(lsm.session.name));
 644
 645         return ask_sessiond(&lsm, NULL);
 646 }
 647
 648 /*
 649  *  Lists all available tracepoints of domain.
 650  *  Sets the contents of the events array.
 651  *  Returns the number of lttng_event entries in events;
 652  *  on error, returns a negative value.
 653  */
 654 int lttng_list_tracepoints(struct lttng_handle *handle,
 655                 struct lttng_event **events)
 656 {
 657         int ret;
 658         struct lttcomm_session_msg lsm;
 659
 660         if (handle == NULL) {
 661                 return -1;
 662         }
 663
 664         lsm.cmd_type = LTTNG_LIST_TRACEPOINTS;
 665         copy_lttng_domain(&lsm.domain, &handle->domain);
 666
 667         ret = ask_sessiond(&lsm, (void **) events);
 668         if (ret < 0) {
 669                 return ret;
 670         }
 671
 672         return ret / sizeof(struct lttng_event);
 673 }
 674
 675 /*
 676  *  Returns a human readable string describing
 677  *  the error code (a negative value).
 678  */
 679 const char *lttng_strerror(int code)
 680 {
 681         /* lttcomm error codes range from -LTTCOMM_OK down to -LTTCOMM_NR */
 682         if (code > -LTTCOMM_OK) {
 683                 return "Ended with errors";
 684         }
 685
 686         return lttcomm_get_readable_code(code);
 687 }
 688
 689 /*
 690  *  Create a brand new session using name and path.
 691  *  Returns size of returned session payload data or a negative error code.
 692  */
 693 int lttng_create_session(const char *name, const char *path)
 694 {
 695         struct lttcomm_session_msg lsm;
 696
 697         lsm.cmd_type = LTTNG_CREATE_SESSION;
 698         copy_string(lsm.session.name, name, sizeof(lsm.session.name));
 699         copy_string(lsm.session.path, path, sizeof(lsm.session.path));
 700
 701         return ask_sessiond(&lsm, NULL);
 702 }
 703
 704 /*
 705  *  Destroy session using name.
 706  *  Returns size of returned session payload data or a negative error code.
 707  */
 708 int lttng_destroy_session(const char *session_name)
 709 {
 710         struct lttcomm_session_msg lsm;
 711
 712         if (session_name == NULL) {
 713                 return -1;
 714         }
 715
 716         lsm.cmd_type = LTTNG_DESTROY_SESSION;
 717
 718         copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
 719
 720         return ask_sessiond(&lsm, NULL);
 721 }
 722
 723 /*
 724  *  Ask the session daemon for all available sessions.
 725  *  Sets the contents of the sessions array.
 726  *  Returns the number of lttng_session entries in sessions;
 727  *  on error, returns a negative value.
 728  */
 729 int lttng_list_sessions(struct lttng_session **sessions)
 730 {
 731         int ret;
 732         struct lttcomm_session_msg lsm;
 733
 734         lsm.cmd_type = LTTNG_LIST_SESSIONS;
 735         ret = ask_sessiond(&lsm, (void**) sessions);
 736         if (ret < 0) {
 737                 return ret;
 738         }
 739
 740         return ret / sizeof(struct lttng_session);
 741 }
 742
 743 /*
 744  *  Ask the session daemon for all available domains of a session.
 745  *  Sets the contents of the domains array.
 746  *  Returns the number of lttng_domain entries in domains;
 747  *  on error, returns a negative value.
 748  */
 749 int lttng_list_domains(const char *session_name,
 750                 struct lttng_domain **domains)
 751 {
 752         int ret;
 753         struct lttcomm_session_msg lsm;
 754
 755         if (session_name == NULL) {
 756                 return -1;
 757         }
 758
 759         lsm.cmd_type = LTTNG_LIST_DOMAINS;
 760
 761         copy_string(lsm.session.name, session_name, sizeof(lsm.session.name));
 762
 763         ret = ask_sessiond(&lsm, (void**) domains);
 764         if (ret < 0) {
 765                 return ret;
 766         }
 767
 768         return ret / sizeof(struct lttng_domain);
 769 }
 770
 771 /*
 772  *  Ask the session daemon for all available channels of a session.
 773  *  Sets the contents of the channels array.
 774  *  Returns the number of lttng_channel entries in channels;
 775  *  on error, returns a negative value.
 776  */
 777 int lttng_list_channels(struct lttng_handle *handle,
 778                 struct lttng_channel **channels)
 779 {
 780         int ret;
 781         struct lttcomm_session_msg lsm;
 782
 783         if (handle == NULL) {
 784                 return -1;
 785         }
 786
 787         lsm.cmd_type = LTTNG_LIST_CHANNELS;
 788         copy_string(lsm.session.name, handle->session_name,
 789                         sizeof(lsm.session.name));
 790
 791         copy_lttng_domain(&lsm.domain, &handle->domain);
 792
 793         ret = ask_sessiond(&lsm, (void**) channels);
 794         if (ret < 0) {
 795                 return ret;
 796         }
 797
 798         return ret / sizeof(struct lttng_channel);
 799 }
 800
 801 /*
 802  *  Ask the session daemon for all available events of a session channel.
 803  *  Sets the contents of the events array.
 804  *  Returns the number of lttng_event entries in events;
 805  *  on error, returns a negative value.
 806  */
 807 int lttng_list_events(struct lttng_handle *handle,
 808                 const char *channel_name, struct lttng_event **events)
 809 {
 810         int ret;
 811         struct lttcomm_session_msg lsm;
 812
 813         /* Safety check. An handle and channel name are mandatory */
 814         if (handle == NULL || channel_name == NULL) {
 815                 return -1;
 816         }
 817
 818         lsm.cmd_type = LTTNG_LIST_EVENTS;
 819         copy_string(lsm.session.name, handle->session_name,
 820                         sizeof(lsm.session.name));
 821         copy_string(lsm.u.list.channel_name, channel_name,
 822                         sizeof(lsm.u.list.channel_name));
 823
 824         copy_lttng_domain(&lsm.domain, &handle->domain);
 825
 826         ret = ask_sessiond(&lsm, (void**) events);
 827         if (ret < 0) {
 828                 return ret;
 829         }
 830
 831         return ret / sizeof(struct lttng_event);
 832 }
 833
 834 /*
 835  * Sets the tracing_group variable with name.
 836  * This function allocates memory pointed to by tracing_group.
 837  * On success, returns 0, on error, returns -1 (null name) or -ENOMEM.
 838  */
 839 int lttng_set_tracing_group(const char *name)
 840 {
 841         if (name == NULL) {
 842                 return -1;
 843         }
 844
 845         if (asprintf(&tracing_group, "%s", name) < 0) {
 846                 return -ENOMEM;
 847         }
 848
 849         return 0;
 850 }
 851
 852 /*
 853  * Returns size of returned session payload data or a negative error code.
 854  */
 855 int lttng_calibrate(struct lttng_handle *handle,
 856                 struct lttng_calibrate *calibrate)
 857 {
 858         struct lttcomm_session_msg lsm;
 859
 860         /* Safety check. NULL pointer are forbidden */
 861         if (handle == NULL || calibrate == NULL) {
 862                 return -1;
 863         }
 864
 865         lsm.cmd_type = LTTNG_CALIBRATE;
 866         copy_lttng_domain(&lsm.domain, &handle->domain);
 867
 868         memcpy(&lsm.u.calibrate, calibrate, sizeof(lsm.u.calibrate));
 869
 870         return ask_sessiond(&lsm, NULL);
 871 }
 872
 873 /*
 874  * Set default channel attributes.
 875  * If either or both of the arguments are null, attr content is zeroe'd.
 876  */
 877 void lttng_channel_set_default_attr(struct lttng_domain *domain,
 878                 struct lttng_channel_attr *attr)
 879 {
 880         memset(attr, 0, sizeof(struct lttng_channel_attr));
 881
 882         /* Safety check */
 883         if (attr == NULL || domain == NULL) {
 884                 return;
 885         }
 886
 887         switch (domain->type) {
 888         case LTTNG_DOMAIN_KERNEL:
 889                 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
 890                 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
 891                 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
 892
 893                 attr->subbuf_size = DEFAULT_KERNEL_CHANNEL_SUBBUF_SIZE;
 894                 attr->num_subbuf = DEFAULT_KERNEL_CHANNEL_SUBBUF_NUM;
 895                 attr->output = DEFAULT_KERNEL_CHANNEL_OUTPUT;
 896                 break;
 897         case LTTNG_DOMAIN_UST:
 898 #if 0
 899         case LTTNG_DOMAIN_UST_EXEC_NAME:
 900         case LTTNG_DOMAIN_UST_PID:
 901         case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
 902 #endif
 903                 attr->overwrite = DEFAULT_CHANNEL_OVERWRITE;
 904                 attr->switch_timer_interval = DEFAULT_CHANNEL_SWITCH_TIMER;
 905                 attr->read_timer_interval = DEFAULT_CHANNEL_READ_TIMER;
 906
 907                 attr->subbuf_size = DEFAULT_UST_CHANNEL_SUBBUF_SIZE;
 908                 attr->num_subbuf = DEFAULT_UST_CHANNEL_SUBBUF_NUM;
 909                 attr->output = DEFAULT_UST_CHANNEL_OUTPUT;
 910                 break;
 911         default:
 912                 /* Default behavior: leave set to 0. */
 913                 break;
 914         }
 915 }
 916
 917 /*
 918  * Check if session daemon is alive.
 919  *
 920  * Return 1 if alive or 0 if not.
 921  * On error returns a negative value.
 922  */
 923 int lttng_session_daemon_alive(void)
 924 {
 925         int ret;
 926
 927         ret = set_session_daemon_path();
 928         if (ret < 0) {
 929                 /* Error */
 930                 return ret;
 931         }
 932
 933         if (strlen(sessiond_sock_path) == 0) {
 934                 /* No socket path set. Weird error */
 935                 return -1;
 936         }
 937
 938         ret = try_connect_sessiond(sessiond_sock_path);
 939         if (ret < 0) {
 940                 /* Not alive */
 941                 return 0;
 942         }
 943
 944         /* Is alive */
 945         return 1;
 946 }
 947
 948 /*
 949  * lib constructor
 950  */
 951 static void __attribute__((constructor)) init()
 952 {
 953         /* Set default session group */
 954         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 955 }