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.
 283  *
 284  * Return -1 if the domain is unkown.
 285  */
 286 static int copy_lttng_domain(struct lttng_domain *dom)
 287 {
 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                 return 0;
 296         default:
 297                 return -1;
 298         }
 299 }
 300
 301 /*
 302  *  Start tracing for all trace of the session.
 303  */
 304 int lttng_start_tracing(const char *session_name)
 305 {
 306         strncpy(lsm.session_name, session_name, NAME_MAX);
 307         return ask_sessiond(LTTNG_START_TRACE, NULL);
 308 }
 309
 310 /*
 311  *  Stop tracing for all trace of the session.
 312  */
 313 int lttng_stop_tracing(const char *session_name)
 314 {
 315         strncpy(lsm.session_name, session_name, NAME_MAX);
 316         return ask_sessiond(LTTNG_STOP_TRACE, NULL);
 317 }
 318
 319 /*
 320  *  lttng_add_context
 321  */
 322 int lttng_add_context(struct lttng_domain *domain,
 323                 struct lttng_event_context *ctx, const char *event_name,
 324                 const char *channel_name)
 325 {
 326         int ret;
 327
 328         if (channel_name != NULL) {
 329                 strncpy(lsm.u.context.channel_name, channel_name, NAME_MAX);
 330         }
 331
 332         if (event_name != NULL) {
 333                 strncpy(lsm.u.context.event_name, event_name, NAME_MAX);
 334         }
 335
 336         memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_event_context));
 337
 338         switch (domain->type) {
 339         case LTTNG_DOMAIN_KERNEL:
 340                 ret = ask_sessiond(LTTNG_KERNEL_ADD_CONTEXT, NULL);
 341                 break;
 342         case LTTNG_DOMAIN_UST:
 343                 ret = LTTCOMM_NOT_IMPLEMENTED;
 344                 break;
 345         default:
 346                 ret = LTTCOMM_UNKNOWN_DOMAIN;
 347                 break;
 348         };
 349
 350         return ret;
 351 }
 352
 353 /*
 354  *  lttng_enable_event
 355  */
 356 int lttng_enable_event(struct lttng_domain *domain,
 357                 struct lttng_event *ev, const char *channel_name)
 358 {
 359         int ret;
 360
 361         if (channel_name == NULL) {
 362                 strncpy(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 363         } else {
 364                 strncpy(lsm.u.enable.channel_name, channel_name, NAME_MAX);
 365         }
 366
 367         switch (domain->type) {
 368                 case LTTNG_DOMAIN_KERNEL:
 369                         if (ev == NULL) {
 370                                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_ALL_EVENT, NULL);
 371                         } else {
 372                                 memcpy(&lsm.u.enable.event, ev, sizeof(struct lttng_event));
 373                                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_EVENT, NULL);
 374                         }
 375                         break;
 376                 case LTTNG_DOMAIN_UST:
 377                         ret = LTTCOMM_NOT_IMPLEMENTED;
 378                         break;
 379                 default:
 380                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 381                         break;
 382         };
 383
 384         return ret;
 385 }
 386
 387 /*
 388  * Disable an event in the kernel tracer.
 389  */
 390 int lttng_disable_event(struct lttng_domain *domain, const char *name,
 391                 const char *channel_name)
 392 {
 393         int ret;
 394
 395         if (channel_name == NULL) {
 396                 strncpy(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 397         } else {
 398                 strncpy(lsm.u.disable.channel_name, channel_name, NAME_MAX);
 399         }
 400
 401         switch (domain->type) {
 402                 case LTTNG_DOMAIN_KERNEL:
 403                         if (name == NULL) {
 404                                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_ALL_EVENT, NULL);
 405                         } else {
 406                                 strncpy(lsm.u.disable.name, name, NAME_MAX);
 407                                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_EVENT, NULL);
 408                         }
 409                         break;
 410                 case LTTNG_DOMAIN_UST:
 411                         ret = LTTCOMM_NOT_IMPLEMENTED;
 412                         break;
 413                 default:
 414                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 415                         break;
 416         };
 417
 418         return ret;
 419 }
 420
 421 /*
 422  * Enable recording for a channel for the kernel tracer.
 423  */
 424 int lttng_enable_channel(struct lttng_domain *domain,
 425                 struct lttng_channel *chan)
 426 {
 427         int ret;
 428
 429         memcpy(&lsm.u.channel.chan, chan, sizeof(struct lttng_channel));
 430
 431         switch (domain->type) {
 432                 case LTTNG_DOMAIN_KERNEL:
 433                         ret = ask_sessiond(LTTNG_KERNEL_ENABLE_CHANNEL, NULL);
 434                         break;
 435                 case LTTNG_DOMAIN_UST:
 436                         ret = LTTCOMM_NOT_IMPLEMENTED;
 437                         break;
 438                 default:
 439                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 440                         break;
 441         };
 442
 443         return ret;
 444 }
 445
 446 /*
 447  * Disable recording for the channel for the kernel tracer.
 448  */
 449 int lttng_disable_channel(struct lttng_domain *domain, const char *name)
 450 {
 451         int ret;
 452
 453         strncpy(lsm.u.disable.channel_name, name, NAME_MAX);
 454
 455         switch (domain->type) {
 456                 case LTTNG_DOMAIN_KERNEL:
 457                         ret = ask_sessiond(LTTNG_KERNEL_DISABLE_CHANNEL, NULL);
 458                         break;
 459                 case LTTNG_DOMAIN_UST:
 460                         ret = LTTCOMM_NOT_IMPLEMENTED;
 461                         break;
 462                 default:
 463                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 464                         break;
 465         };
 466
 467         return ret;
 468 }
 469
 470 /*
 471  * List all available kernel events.
 472  *
 473  * Return the size (bytes) of the list and set the event_list array.
 474  * On error, return negative value.
 475  */
 476 int lttng_list_kernel_events(struct lttng_event **events)
 477 {
 478         int ret;
 479
 480         ret = ask_sessiond(LTTNG_KERNEL_LIST_EVENTS, (void **) events);
 481
 482         return ret / sizeof(struct lttng_event);
 483 }
 484
 485 /*
 486  *  Return a human readable string of code
 487  */
 488 const char *lttng_get_readable_code(int code)
 489 {
 490         if (code > -LTTCOMM_OK) {
 491                 return "Ended with errors";
 492         }
 493
 494         return lttcomm_get_readable_code(code);
 495 }
 496
 497 /*
 498  *  Create a brand new session using name.
 499  */
 500 int lttng_create_session(const char *name, const char *path)
 501 {
 502         strncpy(lsm.session_name, name, NAME_MAX);
 503         strncpy(lsm.path, path, PATH_MAX);
 504         return ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 505 }
 506
 507 /*
 508  *  Destroy session using name.
 509  */
 510 int lttng_destroy_session(const char *name)
 511 {
 512         strncpy(lsm.session_name, name, NAME_MAX);
 513         return ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 514 }
 515
 516 /*
 517  *  Ask the session daemon for all available sessions.
 518  *
 519  *  Return number of session.
 520  *  On error, return negative value.
 521  */
 522 int lttng_list_sessions(struct lttng_session **sessions)
 523 {
 524         int ret;
 525
 526         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 527         if (ret < 0) {
 528                 return ret;
 529         }
 530
 531         return ret / sizeof(struct lttng_session);
 532 }
 533
 534 /*
 535  * List domain of a session.
 536  */
 537 int lttng_list_domains(const char *session_name, struct lttng_domain **domains)
 538 {
 539         int ret;
 540
 541         strncpy(lsm.session_name, session_name, NAME_MAX);
 542         ret = ask_sessiond(LTTNG_LIST_DOMAINS, (void**) domains);
 543         if (ret < 0) {
 544                 return ret;
 545         }
 546
 547         return ret / sizeof(struct lttng_domain);
 548 }
 549
 550 /*
 551  * List channels of a session
 552  */
 553 int lttng_list_channels(struct lttng_domain *domain,
 554                 const char *session_name, struct lttng_channel **channels)
 555 {
 556         int ret;
 557
 558         strncpy(lsm.session_name, session_name, NAME_MAX);
 559         ret = copy_lttng_domain(domain);
 560         if (ret < 0) {
 561                 return -LTTCOMM_UNKNOWN_DOMAIN;
 562         }
 563
 564         ret = ask_sessiond(LTTNG_LIST_CHANNELS, (void**) channels);
 565         if (ret < 0) {
 566                 return ret;
 567         }
 568
 569         return ret / sizeof(struct lttng_channel);
 570 }
 571
 572 /*
 573  * List events of a session channel.
 574  */
 575 int lttng_list_events(struct lttng_domain *domain,
 576                 const char *session_name, const char *channel_name,
 577                 struct lttng_event **events)
 578 {
 579         int ret;
 580
 581         strncpy(lsm.session_name, session_name, NAME_MAX);
 582         strncpy(lsm.u.list.channel_name, channel_name, NAME_MAX);
 583         ret = copy_lttng_domain(domain);
 584         if (ret < 0) {
 585                 return -LTTCOMM_UNKNOWN_DOMAIN;
 586         }
 587
 588         ret = ask_sessiond(LTTNG_LIST_EVENTS, (void**) events);
 589         if (ret < 0) {
 590                 return ret;
 591         }
 592
 593         return ret / sizeof(struct lttng_event);
 594 }
 595
 596 /*
 597  * Set session name for the current lsm.
 598  */
 599 void lttng_set_session_name(const char *name)
 600 {
 601         strncpy(lsm.session_name, name, NAME_MAX);
 602 }
 603
 604 /*
 605  *  lttng_set_tracing_group
 606  *
 607  *  Set tracing group variable with name. This function
 608  *  allocate memory pointed by tracing_group.
 609  */
 610 int lttng_set_tracing_group(const char *name)
 611 {
 612         if (asprintf(&tracing_group, "%s", name) < 0) {
 613                 return -ENOMEM;
 614         }
 615
 616         return 0;
 617 }
 618
 619 /*
 620  *  lttng_check_session_daemon
 621  *
 622  *  Yes, return 1
 623  *  No, return 0
 624  *  Error, return negative value
 625  */
 626 int lttng_session_daemon_alive(void)
 627 {
 628         int ret;
 629
 630         ret = set_session_daemon_path();
 631         if (ret < 0) {
 632                 /* Error */
 633                 return ret;
 634         }
 635
 636         /* If socket exist, we consider the daemon started */
 637         ret = access(sessiond_sock_path, F_OK);
 638         if (ret < 0) {
 639                 /* Not alive */
 640                 return 0;
 641         }
 642
 643         /* Is alive */
 644         return 1;
 645 }
 646
 647 /*
 648  * lib constructor
 649  */
 650 static void __attribute__((constructor)) init()
 651 {
 652         /* Set default session group */
 653         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 654 }