src/bin/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, version 2 only,
   6  * as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #include <getopt.h>
  20 #include <signal.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <sys/types.h>
  25 #include <sys/wait.h>
  26 #include <unistd.h>
  27 #include <config.h>
  28 #include <ctype.h>
  29
  30 #include <lttng/lttng.h>
  31 #include <common/error.h>
  32
  33 #include "command.h"
  34
  35 /* Variables */
  36 static char *progname;
  37 static int opt_no_sessiond;
  38 static char *opt_sessiond_path;
  39 static pid_t sessiond_pid;
  40 static volatile int recv_child_signal;
  41
  42 enum {
  43         OPT_SESSION_PATH,
  44         OPT_DUMP_OPTIONS,
  45         OPT_DUMP_COMMANDS,
  46 };
  47
  48 /* Getopt options. No first level command. */
  49 static struct option long_options[] = {
  50         {"version",          0, NULL, 'V'},
  51         {"help",             0, NULL, 'h'},
  52         {"group",            1, NULL, 'g'},
  53         {"verbose",          0, NULL, 'v'},
  54         {"quiet",            0, NULL, 'q'},
  55         {"no-sessiond",      0, NULL, 'n'},
  56         {"sessiond-path",    1, NULL, OPT_SESSION_PATH},
  57         {"list-options",     0, NULL, OPT_DUMP_OPTIONS},
  58         {"list-commands",    0, NULL, OPT_DUMP_COMMANDS},
  59         {NULL, 0, NULL, 0}
  60 };
  61
  62 /* First level command */
  63 static struct cmd_struct commands[] =  {
  64         { "list", cmd_list},
  65         { "create", cmd_create},
  66         { "destroy", cmd_destroy},
  67         { "start", cmd_start},
  68         { "stop", cmd_stop},
  69         { "enable-event", cmd_enable_events},
  70         { "disable-event", cmd_disable_events},
  71         { "enable-channel", cmd_enable_channels},
  72         { "disable-channel", cmd_disable_channels},
  73         { "add-context", cmd_add_context},
  74         { "set-session", cmd_set_session},
  75         { "version", cmd_version},
  76         { "calibrate", cmd_calibrate},
  77         { "view", cmd_view},
  78         { "snapshot", cmd_snapshot},
  79         { "enable-consumer", cmd_enable_consumer}, /* OBSOLETE */
  80         { "disable-consumer", cmd_disable_consumer}, /* OBSOLETE */
  81         { NULL, NULL}   /* Array closure */
  82 };
  83
  84 static void usage(FILE *ofp)
  85 {
  86         fprintf(ofp, "LTTng Trace Control " VERSION" - " VERSION_NAME"\n\n");
  87         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND> [<ARGS>]\n");
  88         fprintf(ofp, "\n");
  89         fprintf(ofp, "Options:\n");
  90         fprintf(ofp, "  -V, --version              Show version\n");
  91         fprintf(ofp, "  -h, --help                 Show this help\n");
  92         fprintf(ofp, "      --list-options         Simple listing of lttng options\n");
  93         fprintf(ofp, "      --list-commands        Simple listing of lttng commands\n");
  94         fprintf(ofp, "  -v, --verbose              Increase verbosity\n");
  95         fprintf(ofp, "  -q, --quiet                Quiet mode\n");
  96         fprintf(ofp, "  -g, --group NAME           Unix tracing group name. (default: tracing)\n");
  97         fprintf(ofp, "  -n, --no-sessiond          Don't spawn a session daemon\n");
  98         fprintf(ofp, "      --sessiond-path PATH   Session daemon full path\n");
  99         fprintf(ofp, "\n");
 100         fprintf(ofp, "Commands:\n");
 101         fprintf(ofp, "    add-context       Add context to event and/or channel\n");
 102         fprintf(ofp, "    calibrate         Quantify LTTng overhead\n");
 103         fprintf(ofp, "    create            Create tracing session\n");
 104         fprintf(ofp, "    destroy           Tear down tracing session\n");
 105         fprintf(ofp, "    enable-channel    Enable tracing channel\n");
 106         fprintf(ofp, "    enable-event      Enable tracing event\n");
 107         fprintf(ofp, "    disable-channel   Disable tracing channel\n");
 108         fprintf(ofp, "    disable-event     Disable tracing event\n");
 109         fprintf(ofp, "    list              List possible tracing options\n");
 110         fprintf(ofp, "    set-session       Set current session name\n");
 111         fprintf(ofp, "    snapshot          Snapshot buffers of current session name\n");
 112         fprintf(ofp, "    start             Start tracing\n");
 113         fprintf(ofp, "    stop              Stop tracing\n");
 114         fprintf(ofp, "    version           Show version information\n");
 115         fprintf(ofp, "    view              Start trace viewer\n");
 116         fprintf(ofp, "\n");
 117         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 118         fprintf(ofp, "\n");
 119         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 120         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 121 }
 122
 123 static void version(FILE *ofp)
 124 {
 125         fprintf(ofp, "%s (LTTng Trace Control) " VERSION" - " VERSION_NAME"\n",
 126                         progname);
 127 }
 128
 129 /*
 130  *  list_options
 131  *
 132  *  List options line by line. This is mostly for bash auto completion and to
 133  *  avoid difficult parsing.
 134  */
 135 static void list_options(FILE *ofp)
 136 {
 137         int i = 0;
 138         struct option *option = NULL;
 139
 140         option = &long_options[i];
 141         while (option->name != NULL) {
 142                 fprintf(ofp, "--%s\n", option->name);
 143
 144                 if (isprint(option->val)) {
 145                         fprintf(ofp, "-%c\n", option->val);
 146                 }
 147
 148                 i++;
 149                 option = &long_options[i];
 150         }
 151 }
 152
 153 /*
 154  * clean_exit
 155  */
 156 static void clean_exit(int code)
 157 {
 158         DBG("Clean exit");
 159         exit(code);
 160 }
 161
 162 /*
 163  *  sighandler
 164  *
 165  *  Signal handler for the daemon
 166  */
 167 static void sighandler(int sig)
 168 {
 169         int status;
 170
 171         switch (sig) {
 172                 case SIGTERM:
 173                         DBG("SIGTERM caught");
 174                         clean_exit(EXIT_FAILURE);
 175                         break;
 176                 case SIGCHLD:
 177                         DBG("SIGCHLD caught");
 178                         waitpid(sessiond_pid, &status, 0);
 179                         recv_child_signal = 1;
 180                         /* Indicate that the session daemon died */
 181                         sessiond_pid = 0;
 182                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 183                         break;
 184                 case SIGUSR1:
 185                         /* Notify is done */
 186                         recv_child_signal = 1;
 187                         DBG("SIGUSR1 caught");
 188                         break;
 189                 default:
 190                         DBG("Unknown signal %d caught", sig);
 191                         break;
 192         }
 193
 194         return;
 195 }
 196
 197 /*
 198  *  set_signal_handler
 199  *
 200  *  Setup signal handler for SIGCHLD and SIGTERM.
 201  */
 202 static int set_signal_handler(void)
 203 {
 204         int ret = 0;
 205         struct sigaction sa;
 206         sigset_t sigset;
 207
 208         if ((ret = sigemptyset(&sigset)) < 0) {
 209                 perror("sigemptyset");
 210                 goto end;
 211         }
 212
 213         sa.sa_handler = sighandler;
 214         sa.sa_mask = sigset;
 215         sa.sa_flags = 0;
 216         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 217                 perror("sigaction");
 218                 goto end;
 219         }
 220
 221         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 222                 perror("sigaction");
 223                 goto end;
 224         }
 225
 226         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 227                 perror("sigaction");
 228                 goto end;
 229         }
 230
 231 end:
 232         return ret;
 233 }
 234
 235 /*
 236  *  handle_command
 237  *
 238  *  Handle the full argv list of a first level command. Will find the command
 239  *  in the global commands array and call the function callback associated.
 240  *
 241  *  If command not found, return -1
 242  *  else, return function command error code.
 243  */
 244 static int handle_command(int argc, char **argv)
 245 {
 246         int i = 0, ret;
 247         struct cmd_struct *cmd;
 248
 249         if (*argv == NULL) {
 250                 ret = CMD_SUCCESS;
 251                 goto end;
 252         }
 253
 254         cmd = &commands[i];
 255         while (cmd->func != NULL) {
 256                 /* Find command */
 257                 if (strcmp(argv[0], cmd->name) == 0) {
 258                         ret = cmd->func(argc, (const char**) argv);
 259                         goto end;
 260                 }
 261                 i++;
 262                 cmd = &commands[i];
 263         }
 264
 265         /* Command not found */
 266         ret = CMD_UNDEFINED;
 267
 268 end:
 269         return ret;
 270 }
 271
 272 /*
 273  *  spawn_sessiond
 274  *
 275  *  Spawn a session daemon by forking and execv.
 276  */
 277 static int spawn_sessiond(char *pathname)
 278 {
 279         int ret = 0;
 280         pid_t pid;
 281
 282         MSG("Spawning a session daemon");
 283         recv_child_signal = 0;
 284         pid = fork();
 285         if (pid == 0) {
 286                 /*
 287                  * Spawn session daemon and tell
 288                  * it to signal us when ready.
 289                  */
 290                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 291                 /* execlp only returns if error happened */
 292                 if (errno == ENOENT) {
 293                         ERR("No session daemon found. Use --sessiond-path.");
 294                 } else {
 295                         perror("execlp");
 296                 }
 297                 kill(getppid(), SIGTERM);       /* wake parent */
 298                 exit(EXIT_FAILURE);
 299         } else if (pid > 0) {
 300                 sessiond_pid = pid;
 301                 /*
 302                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 303                  * the signal has been sent to us, because the child can be scheduled
 304                  * before the parent, and thus send the signal before this check. In
 305                  * the signal handler, we set the recv_child_signal flag, so anytime we
 306                  * check it after the fork is fine. Note that sleep() is interrupted
 307                  * before the 1 second delay as soon as the signal is received, so it
 308                  * will not cause visible delay for the user.
 309                  */
 310                 while (!recv_child_signal) {
 311                         sleep(1);
 312                 }
 313                 /*
 314                  * The signal handler will nullify sessiond_pid on SIGCHLD
 315                  */
 316                 if (!sessiond_pid) {
 317                         exit(EXIT_FAILURE);
 318                 }
 319                 goto end;
 320         } else {
 321                 perror("fork");
 322                 ret = -1;
 323                 goto end;
 324         }
 325
 326 end:
 327         return ret;
 328 }
 329
 330 /*
 331  *  check_sessiond
 332  *
 333  *  Check if the session daemon is available using
 334  *  the liblttngctl API for the check. If not, try to
 335  *  spawn a daemon.
 336  */
 337 static int check_sessiond(void)
 338 {
 339         int ret;
 340         char *pathname = NULL;
 341
 342         ret = lttng_session_daemon_alive();
 343         if (ret == 0) { /* not alive */
 344                 /* Try command line option path */
 345                 pathname = opt_sessiond_path;
 346
 347                 /* Try LTTNG_SESSIOND_PATH env variable */
 348                 if (pathname == NULL) {
 349                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 350                 }
 351
 352                 /* Try with configured path */
 353                 if (pathname == NULL) {
 354                         if (CONFIG_SESSIOND_BIN[0] != '\0') {
 355                                 pathname = CONFIG_SESSIOND_BIN;
 356                         }
 357                 }
 358
 359                 /* Let's rock and roll while trying the default path */
 360                 if (pathname == NULL) {
 361                         pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 362                 }
 363
 364                 DBG("Session daemon at: %s", pathname);
 365
 366                 /* Check existence and permissions */
 367                 ret = access(pathname, F_OK | X_OK);
 368                 if (ret < 0) {
 369                         ERR("No such file or access denied: %s", pathname);
 370                         goto end;
 371                 }
 372
 373                 ret = spawn_sessiond(pathname);
 374                 if (ret < 0) {
 375                         ERR("Problem occurred when starting %s", pathname);
 376                 }
 377         }
 378 end:
 379         return ret;
 380 }
 381
 382 /*
 383  * Check args for specific options that *must* not trigger a session daemon
 384  * execution.
 385  *
 386  * Return 1 if match else 0.
 387  */
 388 static int check_args_no_sessiond(int argc, char **argv)
 389 {
 390         int i;
 391
 392         for (i = 0; i < argc; i++) {
 393                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 394                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 395                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 396                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 397                                 strncmp(argv[i], "version", sizeof("version")) == 0 ||
 398                                 strncmp(argv[i], "view", sizeof("view")) == 0) {
 399                         return 1;
 400                 }
 401         }
 402
 403         return 0;
 404 }
 405
 406 /*
 407  * Parse command line arguments.
 408  *
 409  * Return 0 if OK, else -1
 410  */
 411 static int parse_args(int argc, char **argv)
 412 {
 413         int opt, ret;
 414
 415         if (argc < 2) {
 416                 usage(stderr);
 417                 clean_exit(EXIT_FAILURE);
 418         }
 419
 420         while ((opt = getopt_long(argc, argv, "+Vhnvqg:", long_options, NULL)) != -1) {
 421                 switch (opt) {
 422                 case 'V':
 423                         version(stdout);
 424                         ret = 0;
 425                         goto end;
 426                 case 'h':
 427                         usage(stdout);
 428                         ret = 0;
 429                         goto end;
 430                 case 'v':
 431                         lttng_opt_verbose += 1;
 432                         break;
 433                 case 'q':
 434                         lttng_opt_quiet = 1;
 435                         break;
 436                 case 'g':
 437                         lttng_set_tracing_group(optarg);
 438                         break;
 439                 case 'n':
 440                         opt_no_sessiond = 1;
 441                         break;
 442                 case OPT_SESSION_PATH:
 443                         opt_sessiond_path = strdup(optarg);
 444                         break;
 445                 case OPT_DUMP_OPTIONS:
 446                         list_options(stdout);
 447                         ret = 0;
 448                         goto end;
 449                 case OPT_DUMP_COMMANDS:
 450                         list_commands(commands, stdout);
 451                         ret = 0;
 452                         goto end;
 453                 default:
 454                         usage(stderr);
 455                         ret = 1;
 456                         goto error;
 457                 }
 458         }
 459
 460         /* If both options are specified, quiet wins */
 461         if (lttng_opt_verbose && lttng_opt_quiet) {
 462                 lttng_opt_verbose = 0;
 463         }
 464
 465         /* Spawn session daemon if needed */
 466         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 467                         (check_sessiond() < 0)) {
 468                 ret = 1;
 469                 goto error;
 470         }
 471
 472         /* No leftovers, print usage and quit */
 473         if ((argc - optind) == 0) {
 474                 usage(stderr);
 475                 ret = 1;
 476                 goto error;
 477         }
 478
 479         /*
 480          * Handle leftovers which is a first level command with the trailing
 481          * options.
 482          */
 483         ret = handle_command(argc - optind, argv + optind);
 484         switch (ret) {
 485         case CMD_WARNING:
 486                 WARN("Some command(s) went wrong");
 487                 break;
 488         case CMD_ERROR:
 489                 ERR("Command error");
 490                 break;
 491         case CMD_UNDEFINED:
 492                 ERR("Undefined command");
 493                 break;
 494         case CMD_FATAL:
 495                 ERR("Fatal error");
 496                 break;
 497         case CMD_UNSUPPORTED:
 498                 ERR("Unsupported command");
 499                 break;
 500         case -1:
 501                 usage(stderr);
 502                 ret = 1;
 503                 break;
 504         case 0:
 505                 break;
 506         default:
 507                 if (ret < 0) {
 508                         ret = -ret;
 509                 }
 510                 break;
 511         }
 512
 513 end:
 514 error:
 515         return ret;
 516 }
 517
 518
 519 /*
 520  *  main
 521  */
 522 int main(int argc, char *argv[])
 523 {
 524         int ret;
 525         char *user;
 526
 527         progname = argv[0] ? argv[0] : "lttng";
 528
 529         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 530         user = getenv("USER");
 531         if (user != NULL && ((strncmp(progname, "drtrace", 7) == 0 ||
 532                                 strncmp("compudj", user, 7) == 0))) {
 533                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 534         }
 535         /* Thanks Mathieu */
 536
 537         ret = set_signal_handler();
 538         if (ret < 0) {
 539                 clean_exit(ret);
 540         }
 541
 542         ret = parse_args(argc, argv);
 543         if (ret != 0) {
 544                 clean_exit(ret);
 545         }
 546
 547         return 0;
 548 }