lttng/lttng.c

   1 /*
   2  * Copyright (c)  2011 David Goulet <david.goulet@polymtl.ca>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <getopt.h>
  23 #include <grp.h>
  24 #include <limits.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <sys/stat.h>
  29 #include <sys/types.h>
  30 #include <sys/wait.h>
  31 #include <unistd.h>
  32
  33 #include <lttng/lttng.h>
  34
  35 #include "lttng.h"
  36 #include "lttngerr.h"
  37
  38 /* Variables */
  39 static char *progname;
  40 static char *session_name;
  41 static uuid_t current_uuid;
  42 static int auto_session;
  43 static int auto_trace;
  44
  45 /* Prototypes */
  46 static int process_client_opt(void);
  47 static int process_opt_list_apps(void);
  48 static int process_opt_list_sessions(void);
  49 static int process_opt_list_traces(void);
  50 static int process_opt_create_session(void);
  51 static int process_kernel_create_trace(void);
  52 static int process_opt_kernel_event(void);
  53 static int set_session_uuid(void);
  54 static void sighandler(int sig);
  55 static int set_signal_handler(void);
  56 static int validate_options(void);
  57 static char *get_cmdline_by_pid(pid_t pid);
  58 static void set_opt_session_info(void);
  59
  60 /*
  61  *  start_client
  62  *
  63  *  Process client request from the command line
  64  *  options. Every tracing action is done by the
  65  *  liblttngctl API.
  66  */
  67 static int process_client_opt(void)
  68 {
  69         int ret;
  70
  71         set_opt_session_info();
  72
  73         if (opt_list_apps) {
  74                 ret = process_opt_list_apps();
  75                 if (ret < 0) {
  76                         goto end;
  77                 }
  78                 goto error;
  79         }
  80
  81         if (opt_list_session) {
  82                 ret = process_opt_list_sessions();
  83                 if (ret < 0) {
  84                         goto end;
  85                 }
  86                 goto error;
  87         }
  88
  89         /* Session creation or auto session set on */
  90         if (auto_session || opt_create_session) {
  91                 DBG("Creating a new session");
  92                 ret = process_opt_create_session();
  93                 if (ret < 0) {
  94                         goto end;
  95                 }
  96         }
  97
  98         ret = set_session_uuid();
  99         if (ret < 0) {
 100                 ERR("Session %s not found", opt_session_name);
 101                 goto error;
 102         }
 103
 104         if (opt_destroy_session) {
 105                 ret = lttng_destroy_session(&current_uuid);
 106                 if (ret < 0) {
 107                         goto end;
 108                 }
 109                 MSG("Session %s destroyed.", opt_session_name);
 110         }
 111
 112         if (opt_list_traces) {
 113                 ret = process_opt_list_traces();
 114                 if (ret < 0) {
 115                         goto end;
 116                 }
 117         }
 118
 119         /*
 120          * Action on traces (kernel or/and userspace).
 121          */
 122
 123         if (opt_trace_kernel) {
 124                 if (auto_trace || opt_create_trace) {
 125                         DBG("Creating a kernel trace");
 126                         ret = process_kernel_create_trace();
 127                         if (ret < 0) {
 128                                 goto end;
 129                         }
 130                 }
 131
 132                 if (opt_event_list != NULL) {
 133                         ret = process_opt_kernel_event();
 134                         if (ret < 0) {
 135                                 goto end;
 136                         }
 137                 } else {
 138                         // Enable all events
 139                 }
 140         }
 141
 142         if (opt_trace_pid != 0) {
 143                 if (auto_trace || opt_create_trace) {
 144                         DBG("Create a userspace trace for pid %d", opt_trace_pid);
 145                         ret = lttng_ust_create_trace(opt_trace_pid);
 146                         if (ret < 0) {
 147                                 goto end;
 148                         }
 149                         MSG("Trace created successfully!");
 150                 }
 151
 152                 if (auto_trace || opt_start_trace) {
 153                         DBG("Start trace for pid %d", opt_trace_pid);
 154                         ret = lttng_ust_start_trace(opt_trace_pid);
 155                         if (ret < 0) {
 156                                 goto end;
 157                         }
 158                         MSG("Trace started successfully!");
 159                 } else if (opt_stop_trace) {
 160                         DBG("Stop trace for pid %d", opt_trace_pid);
 161                         ret = lttng_ust_stop_trace(opt_trace_pid);
 162                         if (ret < 0) {
 163                                 goto end;
 164                         }
 165                         MSG("Trace stopped successfully!");
 166                 }
 167
 168         }
 169
 170         return 0;
 171
 172 end:
 173         ERR("%s", lttng_get_readable_code(ret));
 174 error:  /* fall through */
 175         return ret;
 176 }
 177
 178 /*
 179  *  process_kernel_create_trace
 180  *
 181  *  Create a kernel trace.
 182  */
 183 static int process_kernel_create_trace(void)
 184 {
 185         int ret;
 186
 187         /* Setup kernel session */
 188         ret = lttng_kernel_create_session();
 189         if (ret < 0) {
 190                 goto error;
 191         }
 192
 193         /* Create an empty channel (with no event) */
 194         ret = lttng_kernel_create_channel();
 195         if (ret < 0) {
 196                 goto error;
 197         }
 198
 199         return 0;
 200
 201 error:
 202         return ret;
 203 }
 204
 205 /*
 206  *  process_kernel_event
 207  *
 208  *  Enable kernel event from the command line list given.
 209  */
 210 static int process_opt_kernel_event(void)
 211 {
 212         int ret;
 213         char *event_name;
 214
 215         event_name = strtok(opt_event_list, ",");
 216         while (event_name != NULL) {
 217                 DBG("Enabling kernel event %s", event_name);
 218                 ret = lttng_kernel_enable_event(event_name);
 219                 if (ret < 0) {
 220                         ERR("%s %s", lttng_get_readable_code(ret), event_name);
 221                 } else {
 222                         MSG("Kernel event %s enabled.", event_name);
 223                 }
 224                 /* Next event */
 225                 event_name = strtok(NULL, ",");
 226         }
 227
 228         return 0;
 229 }
 230
 231 /*
 232  *  set_opt_session_info
 233  *
 234  *  Setup session_name, current_uuid, short_str_uuid and
 235  *  long_str_uuid using the command line options.
 236  */
 237 static void set_opt_session_info(void)
 238 {
 239         if (opt_session_name != NULL) {
 240                 session_name = strndup(opt_session_name, NAME_MAX);
 241                 DBG("Session name set to %s", session_name);
 242         }
 243 }
 244
 245 /*
 246  *  set_session_uuid
 247  *
 248  *  Set current session uuid to the current flow of command(s) using the
 249  *  session_name.
 250  */
 251 static int set_session_uuid(void)
 252 {
 253         int ret, count, i, found = 0;
 254         struct lttng_session *sessions;
 255
 256         if (!uuid_is_null(current_uuid)) {
 257                 lttng_set_current_session_uuid(&current_uuid);
 258                 goto end;
 259         }
 260
 261         count = lttng_list_sessions(&sessions);
 262         if (count < 0) {
 263                 ret = count;
 264                 goto error;
 265         }
 266
 267         for (i = 0; i < count; i++) {
 268                 if (strncmp(sessions[i].name, session_name, NAME_MAX) == 0) {
 269                         lttng_set_current_session_uuid(&sessions[i].uuid);
 270                         uuid_copy(current_uuid, sessions[i].uuid);
 271                         found = 1;
 272                         break;
 273                 }
 274         }
 275
 276         free(sessions);
 277
 278         if (!found) {
 279                 return -1;
 280         }
 281
 282 end:
 283         DBG("Session UUID set");
 284         return 0;
 285
 286 error:
 287         return ret;
 288 }
 289
 290 /*
 291  *  process_opt_list_traces
 292  *
 293  *  Get list of all traces for a specific session uuid.
 294  */
 295 static int process_opt_list_traces(void)
 296 {
 297         int ret, i;
 298         struct lttng_trace *traces;
 299
 300         ret = lttng_list_traces(&current_uuid, &traces);
 301         DBG("Number of traces to list %d", ret);
 302         if (ret < 0) {
 303                 goto error;
 304         }
 305
 306         /* No traces */
 307         if (ret == 0) {
 308                 MSG("No traces found.");
 309                 goto error;
 310         }
 311
 312         MSG("Userspace traces:");
 313         for (i = 0; i < ret; i++) {
 314                 if (traces[i].type == USERSPACE) {
 315                         MSG("\t%d) %s (pid: %d): %s",
 316                                         i, traces[i].name, traces[i].pid,
 317                                         get_cmdline_by_pid(traces[i].pid));
 318                 } else {
 319                         break;
 320                 }
 321         }
 322
 323         MSG("Kernel traces:");
 324         for (;i < ret; i++) {
 325                 if (traces[i].type == KERNEL) {
 326                         MSG("\t%d) %s", i, traces[i].name);
 327                 }
 328         }
 329
 330         free(traces);
 331
 332 error:
 333         return ret;
 334 }
 335
 336 /*
 337  *  process_opt_create_session
 338  *
 339  *  Create a new session using the name pass
 340  *  to the command line.
 341  */
 342 static int process_opt_create_session(void)
 343 {
 344         int ret;
 345         char name[NAME_MAX];
 346         time_t rawtime;
 347         struct tm *timeinfo;
 348
 349         /* Auto session name creation */
 350         if (opt_session_name == NULL) {
 351                 time(&rawtime);
 352                 timeinfo = localtime(&rawtime);
 353                 strftime(name, sizeof(name), "auto-%Y%m%d-%H%M%S", timeinfo);
 354                 session_name = strndup(name, sizeof(name));
 355                 DBG("Auto session name set to %s", session_name);
 356         }
 357
 358         ret = lttng_create_session(session_name);
 359         if (ret < 0) {
 360                 goto error;
 361         }
 362
 363         MSG("Session created: %s", session_name);
 364
 365 error:
 366         return ret;
 367 }
 368
 369 /*
 370  *  process_opt_list_sessions
 371  *
 372  *  Get the list of available sessions from
 373  *  the session daemon and print it to user.
 374  */
 375 static int process_opt_list_sessions(void)
 376 {
 377         int ret, count, i;
 378         struct lttng_session *sessions;
 379
 380         count = lttng_list_sessions(&sessions);
 381         DBG("Session count %d", count);
 382         if (count < 0) {
 383                 ret = count;
 384                 goto error;
 385         }
 386
 387         MSG("Available sessions (UUIDs):");
 388         for (i = 0; i < count; i++) {
 389                 MSG("    %d) %s", i+1, sessions[i].name);
 390         }
 391
 392         free(sessions);
 393         MSG("\nTo select a session, use -s, --session UUID.");
 394
 395         return 0;
 396
 397 error:
 398         return ret;
 399 }
 400
 401 /*
 402  *  process_opt_list_apps
 403  *
 404  *  Get the UST traceable pid list and print
 405  *  them to the user.
 406  */
 407 static int process_opt_list_apps(void)
 408 {
 409         int i, ret, count;
 410         pid_t *pids;
 411         char *cmdline;
 412
 413         count = lttng_ust_list_apps(&pids);
 414         if (count < 0) {
 415                 ret = count;
 416                 goto error;
 417         }
 418
 419         MSG("LTTng UST traceable application [name (pid)]:");
 420         for (i=0; i < count; i++) {
 421                 cmdline = get_cmdline_by_pid(pids[i]);
 422                 if (cmdline == NULL) {
 423                         MSG("\t(not running) (%d)", pids[i]);
 424                         continue;
 425                 }
 426                 MSG("\t%s (%d)", cmdline, pids[i]);
 427                 free(cmdline);
 428         }
 429
 430         /* Allocated by lttng_ust_list_apps() */
 431         free(pids);
 432
 433         return 0;
 434
 435 error:
 436         return ret;
 437 }
 438
 439 /*
 440  *  get_cmdline_by_pid
 441  *
 442  *  Get command line from /proc for a specific pid.
 443  *
 444  *  On success, return an allocated string pointer pointing to
 445  *  the proc cmdline.
 446  *  On error, return NULL.
 447  */
 448 static char *get_cmdline_by_pid(pid_t pid)
 449 {
 450         int ret;
 451         FILE *fp;
 452         char *cmdline = NULL;
 453         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 454
 455         snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
 456         fp = fopen(path, "r");
 457         if (fp == NULL) {
 458                 goto end;
 459         }
 460
 461         /* Caller must free() *cmdline */
 462         cmdline = malloc(PATH_MAX);
 463         ret = fread(cmdline, 1, PATH_MAX, fp);
 464         fclose(fp);
 465
 466 end:
 467         return cmdline;
 468 }
 469
 470 /*
 471  *  validate_options
 472  *
 473  *  Make sure that all options passed to the command line are compatible with
 474  *  each others.
 475  *
 476  *  On error, return -1
 477  *  On success, return 0
 478  */
 479 static int validate_options(void)
 480 {
 481         /* If listing options, jump validation */
 482         if (opt_list_apps || opt_list_session) {
 483                 goto end;
 484         }
 485         /* Conflicting command */
 486         if (opt_start_trace && opt_stop_trace) {
 487                 ERR("Can't use --start and --stop together.");
 488                 goto error;
 489         /* If no PID specified and trace_kernel is off */
 490         } else if ((opt_trace_pid == 0 && !opt_trace_kernel) &&
 491                         (opt_create_trace || opt_start_trace || opt_stop_trace || opt_destroy_trace)) {
 492                 ERR("Please specify for which tracer (-k or -p PID).");
 493                 goto error;
 494         /* List traces, we need a session name */
 495         } else if (opt_list_traces && opt_session_name == NULL) {
 496                 ERR("Can't use -t without -s, --session option.");
 497                 goto error;
 498         /* Can't set event for both kernel and userspace at the same time */
 499         } else if (opt_event_list != NULL && (opt_trace_kernel && opt_trace_pid)) {
 500                 ERR("Please don't use --event for both kernel and userspace.\nOne at a time to enable events.");
 501                 goto error;
 502         /* Don't need a trace name for kernel tracig */
 503         } else if (opt_trace_name != NULL && opt_trace_kernel) {
 504                 ERR("For action on a kernel trace, please don't specify a trace name.");
 505                 goto error;
 506         } else if (opt_destroy_trace && opt_session_name == NULL) {
 507                 ERR("Please specify a session in order to destroy a trace");
 508                 goto error;
 509         } else if (opt_create_trace || opt_destroy_trace) {
 510                 /* Both kernel and user-space are denied for these options */
 511                 if (opt_trace_pid != 0 && opt_trace_kernel) {
 512                         ERR("Kernel and user-space trace creation and destruction can't be used together.");
 513                         goto error;
 514                 /* Need a trace name for user-space tracing */
 515                 } else if (opt_trace_name == NULL && opt_trace_pid != 0) {
 516                         ERR("Please specify a trace name for user-space tracing");
 517                         goto error;
 518                 }
 519         } else if (opt_stop_trace && opt_trace_pid != 0 && opt_trace_name == NULL) {
 520                 ERR("Please specify a trace name for user-space tracing");
 521                 goto error;
 522         }
 523
 524         /* If start trace, auto start tracing */
 525         if (opt_start_trace || opt_event_list != NULL) {
 526                 DBG("Requesting auto tracing");
 527                 auto_trace = 1;
 528         }
 529
 530         /* If no session, auto create one */
 531         if (opt_session_name == NULL) {
 532                 DBG("Requesting an auto session creation");
 533                 auto_session = 1;
 534         }
 535
 536 end:
 537         return 0;
 538
 539 error:
 540         return -1;
 541 }
 542
 543 /*
 544  *  spawn_sessiond
 545  *
 546  *  Spawn a session daemon by forking and execv.
 547  */
 548 static int spawn_sessiond(char *pathname)
 549 {
 550         int ret = 0;
 551         pid_t pid;
 552
 553         MSG("Spawning session daemon");
 554         pid = fork();
 555         if (pid == 0) {
 556                 /*
 557                  * Spawn session daemon and tell
 558                  * it to signal us when ready.
 559                  */
 560                 execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 561                 /* execlp only returns if error happened */
 562                 if (errno == ENOENT) {
 563                         ERR("No session daemon found. Use --sessiond-path.");
 564                 } else {
 565                         perror("execlp");
 566                 }
 567                 kill(getppid(), SIGTERM);       /* unpause parent */
 568                 exit(EXIT_FAILURE);
 569         } else if (pid > 0) {
 570                 /* Wait for ltt-sessiond to start */
 571                 pause();
 572                 goto end;
 573         } else {
 574                 perror("fork");
 575                 ret = -1;
 576                 goto end;
 577         }
 578
 579 end:
 580         return ret;
 581 }
 582
 583 /*
 584  *  check_ltt_sessiond
 585  *
 586  *  Check if the session daemon is available using
 587  *  the liblttngctl API for the check. If not, try to
 588  *  spawn a daemon.
 589  */
 590 static int check_ltt_sessiond(void)
 591 {
 592         int ret;
 593         char *pathname = NULL, *alloc_pathname = NULL;
 594
 595         ret = lttng_check_session_daemon();
 596         if (ret < 0) {
 597                 /* Try command line option path */
 598                 if (opt_sessiond_path != NULL) {
 599                         ret = access(opt_sessiond_path, F_OK | X_OK);
 600                         if (ret < 0) {
 601                                 ERR("No such file: %s", opt_sessiond_path);
 602                                 goto end;
 603                         }
 604                         pathname = opt_sessiond_path;
 605                 } else {
 606                         /* Try LTTNG_SESSIOND_PATH env variable */
 607                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 608                 }
 609
 610                 /* Let's rock and roll */
 611                 if (pathname == NULL) {
 612                         ret = asprintf(&alloc_pathname, "ltt-sessiond");
 613                         if (ret < 0) {
 614                                 goto end;
 615                         }
 616                         pathname = alloc_pathname;
 617                 }
 618
 619                 ret = spawn_sessiond(pathname);
 620                 free(alloc_pathname);
 621                 if (ret < 0) {
 622                         ERR("Problem occurs when starting %s", pathname);
 623                         goto end;
 624                 }
 625         }
 626
 627 end:
 628         return ret;
 629 }
 630
 631 /*
 632  *  set_signal_handler
 633  *
 634  *  Setup signal handler for SIGCHLD and SIGTERM.
 635  */
 636 static int set_signal_handler(void)
 637 {
 638         int ret = 0;
 639         struct sigaction sa;
 640         sigset_t sigset;
 641
 642         if ((ret = sigemptyset(&sigset)) < 0) {
 643                 perror("sigemptyset");
 644                 goto end;
 645         }
 646
 647         sa.sa_handler = sighandler;
 648         sa.sa_mask = sigset;
 649         sa.sa_flags = 0;
 650         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 651                 perror("sigaction");
 652                 goto end;
 653         }
 654
 655         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 656                 perror("sigaction");
 657                 goto end;
 658         }
 659
 660 end:
 661         return ret;
 662 }
 663
 664 /*
 665  *  sighandler
 666  *
 667  *  Signal handler for the daemon
 668  */
 669 static void sighandler(int sig)
 670 {
 671         switch (sig) {
 672                 case SIGTERM:
 673                         DBG("SIGTERM catched");
 674                         clean_exit(EXIT_FAILURE);
 675                         break;
 676                 case SIGCHLD:
 677                         /* Notify is done */
 678                         DBG("SIGCHLD catched");
 679                         break;
 680                 default:
 681                         DBG("Unknown signal %d catched", sig);
 682                         break;
 683         }
 684
 685         return;
 686 }
 687
 688 /*
 689  * clean_exit
 690  */
 691 void clean_exit(int code)
 692 {
 693         DBG("Clean exit");
 694         if (session_name) {
 695                 free(session_name);
 696         }
 697
 698         exit(code);
 699 }
 700
 701 /*
 702  *  main
 703  */
 704 int main(int argc, char *argv[])
 705 {
 706         int ret;
 707
 708         progname = argv[0] ? argv[0] : "lttng";
 709
 710         /* For Mathieu Desnoyers aka Dr Tracing */
 711         if (strncmp(progname, "drtrace", 7) == 0) {
 712                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 713         }
 714
 715         ret = parse_args(argc, (const char **) argv);
 716         if (ret < 0) {
 717                 clean_exit(EXIT_FAILURE);
 718         }
 719
 720         ret = validate_options();
 721         if (ret < 0) {
 722                 return EXIT_FAILURE;
 723         }
 724
 725         ret = set_signal_handler();
 726         if (ret < 0) {
 727                 clean_exit(ret);
 728         }
 729
 730         if (opt_tracing_group != NULL) {
 731                 DBG("Set tracing group to '%s'", opt_tracing_group);
 732                 lttng_set_tracing_group(opt_tracing_group);
 733         }
 734
 735         /* If ask for kernel tracing, need root perms */
 736         if (opt_trace_kernel) {
 737                 DBG("Kernel tracing activated");
 738                 if (getuid() != 0) {
 739                         ERR("%s must be setuid root", progname);
 740                         clean_exit(-EPERM);
 741                 }
 742         }
 743
 744         /* Check if the lttng session daemon is running.
 745          * If no, a daemon will be spawned.
 746          */
 747         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 748                 clean_exit(EXIT_FAILURE);
 749         }
 750
 751         ret = process_client_opt();
 752         if (ret < 0) {
 753                 clean_exit(ret);
 754         }
 755
 756         clean_exit(0);
 757
 758         return 0;
 759 }