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