liblttngctl/liblttngctl.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 <errno.h>
  25 #include <grp.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <lttng/lttng.h>
  32
  33 #include "liblttsessiondcomm.h"
  34 #include "lttngerr.h"
  35 #include "lttng-share.h"
  36
  37 /* Socket to session daemon for communication */
  38 static int sessiond_socket;
  39 static char sessiond_sock_path[PATH_MAX];
  40
  41 /* Communication structure to ltt-sessiond */
  42 static struct lttcomm_session_msg lsm;
  43 static struct lttcomm_lttng_msg llm;
  44
  45 /* Variables */
  46 static char *tracing_group;
  47 static int connected;
  48
  49 /*
  50  *  send_data_sessiond
  51  *
  52  *  Send lttcomm_session_msg to the session daemon.
  53  *
  54  *  On success, return 0
  55  *  On error, return error code
  56  */
  57 static int send_data_sessiond(void)
  58 {
  59         int ret;
  60
  61         if (!connected) {
  62                 ret = -ENOTCONN;
  63                 goto end;
  64         }
  65
  66         ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
  67
  68 end:
  69         return ret;
  70 }
  71
  72 /*
  73  *  recv_data_sessiond
  74  *
  75  *  Receive data from the sessiond socket.
  76  *
  77  *  On success, return 0
  78  *  On error, return recv() error code
  79  */
  80 static int recv_data_sessiond(void *buf, size_t len)
  81 {
  82         int ret;
  83
  84         if (!connected) {
  85                 ret = -ENOTCONN;
  86                 goto end;
  87         }
  88
  89         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
  90
  91 end:
  92         return ret;
  93 }
  94
  95 /*
  96  *  Check if the specified group name exist.
  97  *
  98  *  If yes return 0, else return -1.
  99  */
 100 static int check_tracing_group(const char *grp_name)
 101 {
 102         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 103         gid_t *grp_list;
 104         int grp_list_size, grp_id, i;
 105         int ret = -1;
 106
 107         /* Get GID of group 'tracing' */
 108         grp_tracing = getgrnam(grp_name);
 109         if (grp_tracing == NULL) {
 110                 /* NULL means not found also. getgrnam(3) */
 111                 if (errno != 0) {
 112                         perror("getgrnam");
 113                 }
 114                 goto end;
 115         }
 116
 117         /* Get number of supplementary group IDs */
 118         grp_list_size = getgroups(0, NULL);
 119         if (grp_list_size < 0) {
 120                 perror("getgroups");
 121                 goto end;
 122         }
 123
 124         /* Alloc group list of the right size */
 125         grp_list = malloc(grp_list_size * sizeof(gid_t));
 126         grp_id = getgroups(grp_list_size, grp_list);
 127         if (grp_id < -1) {
 128                 perror("getgroups");
 129                 goto free_list;
 130         }
 131
 132         for (i = 0; i < grp_list_size; i++) {
 133                 if (grp_list[i] == grp_tracing->gr_gid) {
 134                         ret = 0;
 135                         break;
 136                 }
 137         }
 138
 139 free_list:
 140         free(grp_list);
 141
 142 end:
 143         return ret;
 144 }
 145
 146 /*
 147  *  Set sessiond socket path by putting it in the global sessiond_sock_path
 148  *  variable.
 149  */
 150 static int set_session_daemon_path(void)
 151 {
 152         int ret;
 153
 154         /* Are we in the tracing group ? */
 155         ret = check_tracing_group(tracing_group);
 156         if (ret < 0 && getuid() != 0) {
 157                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 158                                         getenv("HOME")) < 0) {
 159                         return -ENOMEM;
 160                 }
 161         } else {
 162                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 163                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 164         }
 165
 166         return 0;
 167 }
 168
 169 /*
 170  *  Connect to the LTTng session daemon.
 171  *
 172  *  On success, return 0. On error, return -1.
 173  */
 174 static int connect_sessiond(void)
 175 {
 176         int ret;
 177
 178         ret = set_session_daemon_path();
 179         if (ret < 0) {
 180                 return ret;
 181         }
 182
 183         /* Connect to the sesssion daemon */
 184         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 185         if (ret < 0) {
 186                 return ret;
 187         }
 188
 189         sessiond_socket = ret;
 190         connected = 1;
 191
 192         return 0;
 193 }
 194
 195 /*
 196  *  Clean disconnect the session daemon.
 197  */
 198 static int disconnect_sessiond(void)
 199 {
 200         int ret = 0;
 201
 202         if (connected) {
 203                 ret = lttcomm_close_unix_sock(sessiond_socket);
 204                 sessiond_socket = 0;
 205                 connected = 0;
 206         }
 207
 208         return ret;
 209 }
 210
 211 /*
 212  * Reset the session message structure.
 213  */
 214 static void reset_session_msg(void)
 215 {
 216         memset(&lsm, 0, sizeof(struct lttcomm_session_msg));
 217 }
 218
 219 /*
 220  *  ask_sessiond
 221  *
 222  *  Ask the session daemon a specific command and put the data into buf.
 223  *
 224  *  Return size of data (only payload, not header).
 225  */
 226 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf)
 227 {
 228         int ret;
 229         size_t size;
 230         void *data = NULL;
 231
 232         ret = connect_sessiond();
 233         if (ret < 0) {
 234                 goto end;
 235         }
 236
 237         lsm.cmd_type = lct;
 238
 239         /* Send command to session daemon */
 240         ret = send_data_sessiond();
 241         if (ret < 0) {
 242                 goto end;
 243         }
 244
 245         /* Get header from data transmission */
 246         ret = recv_data_sessiond(&llm, sizeof(llm));
 247         if (ret < 0) {
 248                 goto end;
 249         }
 250
 251         /* Check error code if OK */
 252         if (llm.ret_code != LTTCOMM_OK) {
 253                 ret = -llm.ret_code;
 254                 goto end;
 255         }
 256
 257         size = llm.data_size;
 258         if (size == 0) {
 259                 ret = 0;
 260                 goto end;
 261         }
 262
 263         data = (void*) malloc(size);
 264
 265         /* Get payload data */
 266         ret = recv_data_sessiond(data, size);
 267         if (ret < 0) {
 268                 free(data);
 269                 goto end;
 270         }
 271
 272         *buf = data;
 273         ret = size;
 274
 275 end:
 276         disconnect_sessiond();
 277         reset_session_msg();
 278         return ret;
 279 }
 280
 281 /*
 282  * Copy domain to lttcomm_session_msg domain. If unknown domain, default domain
 283  * will be the kernel.
 284  */
 285 static void copy_lttng_domain(struct lttng_domain *dom)
 286 {
 287         if (dom) {
 288                 switch (dom->type) {
 289                 case LTTNG_DOMAIN_KERNEL:
 290                 case LTTNG_DOMAIN_UST:
 291                 case LTTNG_DOMAIN_UST_EXEC_NAME:
 292                 case LTTNG_DOMAIN_UST_PID:
 293                 case LTTNG_DOMAIN_UST_PID_FOLLOW_CHILDREN:
 294                         memcpy(&lsm.domain, dom, sizeof(struct lttng_domain));
 295                         break;
 296                 default:
 297                         lsm.domain.type = LTTNG_DOMAIN_KERNEL;
 298                         break;
 299                 }
 300         }
 301 }
 302
 303 /*
 304  * Copy string from src to dst and enforce null terminated byte.
 305  */
 306 static void copy_string(char *dst, const char *src, size_t len)
 307 {
 308         if (src && dst) {
 309                 strncpy(dst, src, len);
 310                 /* Enforce the NULL terminated byte */
 311                 dst[len - 1] = '\0';
 312         }
 313 }
 314
 315 /*
 316  *  Start tracing for all trace of the session.
 317  */
 318 int lttng_start_tracing(const char *session_name)
 319 {
 320         copy_string(lsm.session.name, session_name, NAME_MAX);
 321         return ask_sessiond(LTTNG_START_TRACE, NULL);
 322 }
 323
 324 /*
 325  *  Stop tracing for all trace of the session.
 326  */
 327 int lttng_stop_tracing(const char *session_name)
 328 {
 329         copy_string(lsm.session.name, session_name, NAME_MAX);
 330         return ask_sessiond(LTTNG_STOP_TRACE, NULL);
 331 }
 332
 333 /*
 334  *  lttng_add_context
 335  */
 336 int lttng_add_context(struct lttng_domain *domain,
 337                 struct lttng_event_context *ctx, const char *event_name,
 338                 const char *channel_name)
 339 {
 340         copy_string(lsm.u.context.channel_name, channel_name, NAME_MAX);
 341         copy_string(lsm.u.context.event_name, event_name, NAME_MAX);
 342         copy_lttng_domain(domain);
 343
 344         if (ctx) {
 345                 memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 346         }
 347
 348         return ask_sessiond(LTTNG_ADD_CONTEXT, NULL);
 349 }
 350
 351 /*
 352  *  lttng_enable_event
 353  */
 354 int lttng_enable_event(struct lttng_domain *domain,
 355                 struct lttng_event *ev, const char *channel_name)
 356 {
 357         int ret = -1;
 358
 359         if (channel_name == NULL) {
 360                 copy_string(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 361         } else {
 362                 copy_string(lsm.u.enable.channel_name, channel_name, NAME_MAX);
 363         }
 364
 365         if (domain) {
 366                 switch (domain->type) {
 367                         case LTTNG_DOMAIN_KERNEL:
 368                                 if (ev == NULL) {
 369                                         ret = ask_sessiond(LTTNG_KERNEL_ENABLE_ALL_EVENT, NULL);
 370                                 } else {
 371                                         memcpy(&lsm.u.enable.event, ev, sizeof(struct lttng_event));
 372                                         ret = ask_sessiond(LTTNG_KERNEL_ENABLE_EVENT, NULL);
 373                                 }
 374                                 break;
 375                         case LTTNG_DOMAIN_UST:
 376                                 ret = LTTCOMM_NOT_IMPLEMENTED;
 377                                 break;
 378                         default:
 379                                 ret = LTTCOMM_UNKNOWN_DOMAIN;
 380                                 break;
 381                 };
 382         }
 383
 384         return ret;
 385 }
 386
 387 /*
 388  * Disable event of a channel and domain.
 389  */
 390 int lttng_disable_event(struct lttng_domain *domain, const char *name,
 391                 const char *channel_name)
 392 {
 393         int ret = -1;
 394
 395         if (channel_name == NULL) {
 396                 copy_string(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 397         } else {
 398                 copy_string(lsm.u.disable.channel_name, channel_name, NAME_MAX);
 399         }
 400
 401         copy_lttng_domain(domain);
 402
 403         if (name == NULL) {
 404                 ret = ask_sessiond(LTTNG_DISABLE_ALL_EVENT, NULL);
 405         } else {
 406                 copy_string(lsm.u.disable.name, name, NAME_MAX);
 407                 ret = ask_sessiond(LTTNG_DISABLE_EVENT, NULL);
 408         }
 409
 410         return ret;
 411 }
 412
 413 /*
 414  * Enable recording for a channel for the kernel tracer.
 415  */
 416 int lttng_enable_channel(struct lttng_domain *domain,
 417                 struct lttng_channel *chan)
 418 {
 419         int ret = -1;
 420
 421         if (chan) {
 422                 memcpy(&lsm.u.channel.chan, chan, sizeof(struct lttng_channel));
 423         }
 424
 425         if (domain) {
 426                 switch (domain->type) {
 427                         case LTTNG_DOMAIN_KERNEL:
 428                                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_CHANNEL, NULL);
 429                                 break;
 430                         case LTTNG_DOMAIN_UST:
 431                                 ret = LTTCOMM_NOT_IMPLEMENTED;
 432                                 break;
 433                         default:
 434                                 ret = LTTCOMM_UNKNOWN_DOMAIN;
 435                                 break;
 436                 };
 437         }
 438
 439         return ret;
 440 }
 441
 442 /*
 443  * Disable channel.
 444  *
 445  * All tracing will be stopped for registered events of the channel.
 446  */
 447 int lttng_disable_channel(struct lttng_domain *domain, const char *name)
 448 {
 449         copy_string(lsm.u.disable.channel_name, name, NAME_MAX);
 450         copy_lttng_domain(domain);
 451
 452         return ask_sessiond(LTTNG_DISABLE_CHANNEL, NULL);
 453 }
 454
 455 /*
 456  * List all available tracepoints of domain.
 457  *
 458  * Return the size (bytes) of the list and set the events array.
 459  * On error, return negative value.
 460  */
 461 int lttng_list_tracepoints(struct lttng_domain *domain,
 462                 struct lttng_event **events)
 463 {
 464         int ret;
 465
 466         copy_lttng_domain(domain);
 467
 468         ret = ask_sessiond(LTTNG_LIST_TRACEPOINTS, (void **) events);
 469         if (ret < 0) {
 470                 return ret;
 471         }
 472
 473         return ret / sizeof(struct lttng_event);
 474 }
 475
 476 /*
 477  *  Return a human readable string of code
 478  */
 479 const char *lttng_get_readable_code(int code)
 480 {
 481         if (code > -LTTCOMM_OK) {
 482                 return "Ended with errors";
 483         }
 484
 485         return lttcomm_get_readable_code(code);
 486 }
 487
 488 /*
 489  *  Create a brand new session using name.
 490  */
 491 int lttng_create_session(const char *name, const char *path)
 492 {
 493         copy_string(lsm.session.name, name, NAME_MAX);
 494         copy_string(lsm.session.path, path, PATH_MAX);
 495         return ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 496 }
 497
 498 /*
 499  *  Destroy session using name.
 500  */
 501 int lttng_destroy_session(const char *name)
 502 {
 503         copy_string(lsm.session.name, name, NAME_MAX);
 504         return ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 505 }
 506
 507 /*
 508  *  Ask the session daemon for all available sessions.
 509  *
 510  *  Return number of session.
 511  *  On error, return negative value.
 512  */
 513 int lttng_list_sessions(struct lttng_session **sessions)
 514 {
 515         int ret;
 516
 517         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 518         if (ret < 0) {
 519                 return ret;
 520         }
 521
 522         return ret / sizeof(struct lttng_session);
 523 }
 524
 525 /*
 526  * List domain of a session.
 527  */
 528 int lttng_list_domains(const char *session_name, struct lttng_domain **domains)
 529 {
 530         int ret;
 531
 532         copy_string(lsm.session.name, session_name, NAME_MAX);
 533         ret = ask_sessiond(LTTNG_LIST_DOMAINS, (void**) domains);
 534         if (ret < 0) {
 535                 return ret;
 536         }
 537
 538         return ret / sizeof(struct lttng_domain);
 539 }
 540
 541 /*
 542  * List channels of a session
 543  */
 544 int lttng_list_channels(struct lttng_domain *domain,
 545                 const char *session_name, struct lttng_channel **channels)
 546 {
 547         int ret;
 548
 549         copy_string(lsm.session.name, session_name, NAME_MAX);
 550         copy_lttng_domain(domain);
 551
 552         ret = ask_sessiond(LTTNG_LIST_CHANNELS, (void**) channels);
 553         if (ret < 0) {
 554                 return ret;
 555         }
 556
 557         return ret / sizeof(struct lttng_channel);
 558 }
 559
 560 /*
 561  * List events of a session channel.
 562  */
 563 int lttng_list_events(struct lttng_domain *domain,
 564                 const char *session_name, const char *channel_name,
 565                 struct lttng_event **events)
 566 {
 567         int ret;
 568
 569         copy_string(lsm.session.name, session_name, NAME_MAX);
 570         copy_string(lsm.u.list.channel_name, channel_name, NAME_MAX);
 571         copy_lttng_domain(domain);
 572
 573         ret = ask_sessiond(LTTNG_LIST_EVENTS, (void**) events);
 574         if (ret < 0) {
 575                 return ret;
 576         }
 577
 578         return ret / sizeof(struct lttng_event);
 579 }
 580
 581 /*
 582  * Set session name for the current lsm.
 583  */
 584 void lttng_set_session_name(const char *name)
 585 {
 586         copy_string(lsm.session.name, name, NAME_MAX);
 587 }
 588
 589 /*
 590  *  lttng_set_tracing_group
 591  *
 592  *  Set tracing group variable with name. This function
 593  *  allocate memory pointed by tracing_group.
 594  */
 595 int lttng_set_tracing_group(const char *name)
 596 {
 597         if (asprintf(&tracing_group, "%s", name) < 0) {
 598                 return -ENOMEM;
 599         }
 600
 601         return 0;
 602 }
 603
 604 /*
 605  *  lttng_check_session_daemon
 606  *
 607  *  Yes, return 1
 608  *  No, return 0
 609  *  Error, return negative value
 610  */
 611 int lttng_session_daemon_alive(void)
 612 {
 613         int ret;
 614
 615         ret = set_session_daemon_path();
 616         if (ret < 0) {
 617                 /* Error */
 618                 return ret;
 619         }
 620
 621         /* If socket exist, we consider the daemon started */
 622         ret = access(sessiond_sock_path, F_OK);
 623         if (ret < 0) {
 624                 /* Not alive */
 625                 return 0;
 626         }
 627
 628         /* Is alive */
 629         return 1;
 630 }
 631
 632 /*
 633  * lib constructor
 634  */
 635 static void __attribute__((constructor)) init()
 636 {
 637         /* Set default session group */
 638         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 639 }