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 char *opt_relayd_path;
  43
  44 enum {
  45         OPT_RELAYD_PATH,
  46         OPT_SESSION_PATH,
  47         OPT_DUMP_OPTIONS,
  48         OPT_DUMP_COMMANDS,
  49 };
  50
  51 /* Getopt options. No first level command. */
  52 static struct option long_options[] = {
  53         {"version",          0, NULL, 'V'},
  54         {"help",             0, NULL, 'h'},
  55         {"group",            1, NULL, 'g'},
  56         {"verbose",          0, NULL, 'v'},
  57         {"quiet",            0, NULL, 'q'},
  58         {"no-sessiond",      0, NULL, 'n'},
  59         {"sessiond-path",    1, NULL, OPT_SESSION_PATH},
  60         {"relayd-path",      1, NULL, OPT_RELAYD_PATH},
  61         {"list-options",     0, NULL, OPT_DUMP_OPTIONS},
  62         {"list-commands",    0, NULL, OPT_DUMP_COMMANDS},
  63         {NULL, 0, NULL, 0}
  64 };
  65
  66 /* First level command */
  67 static struct cmd_struct commands[] =  {
  68         { "list", cmd_list},
  69         { "create", cmd_create},
  70         { "destroy", cmd_destroy},
  71         { "start", cmd_start},
  72         { "stop", cmd_stop},
  73         { "enable-event", cmd_enable_events},
  74         { "disable-event", cmd_disable_events},
  75         { "enable-channel", cmd_enable_channels},
  76         { "disable-channel", cmd_disable_channels},
  77         { "add-context", cmd_add_context},
  78         { "set-session", cmd_set_session},
  79         { "version", cmd_version},
  80         { "calibrate", cmd_calibrate},
  81         { "view", cmd_view},
  82         { "snapshot", cmd_snapshot},
  83         { "enable-consumer", cmd_enable_consumer}, /* OBSOLETE */
  84         { "disable-consumer", cmd_disable_consumer}, /* OBSOLETE */
  85         { NULL, NULL}   /* Array closure */
  86 };
  87
  88 static void usage(FILE *ofp)
  89 {
  90         fprintf(ofp, "LTTng Trace Control " VERSION" - " VERSION_NAME"\n\n");
  91         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND> [<ARGS>]\n");
  92         fprintf(ofp, "\n");
  93         fprintf(ofp, "Options:\n");
  94         fprintf(ofp, "  -V, --version              Show version\n");
  95         fprintf(ofp, "  -h, --help                 Show this help\n");
  96         fprintf(ofp, "      --list-options         Simple listing of lttng options\n");
  97         fprintf(ofp, "      --list-commands        Simple listing of lttng commands\n");
  98         fprintf(ofp, "  -v, --verbose              Increase verbosity\n");
  99         fprintf(ofp, "  -q, --quiet                Quiet mode\n");
 100         fprintf(ofp, "  -g, --group NAME           Unix tracing group name. (default: tracing)\n");
 101         fprintf(ofp, "  -n, --no-sessiond          Don't spawn a session daemon\n");
 102         fprintf(ofp, "      --sessiond-path PATH   Session daemon full path\n");
 103         fprintf(ofp, "      --relayd-path PATH     Relayd daemon full path\n");
 104         fprintf(ofp, "\n");
 105         fprintf(ofp, "Commands:\n");
 106         fprintf(ofp, "    add-context       Add context to event and/or channel\n");
 107         fprintf(ofp, "    calibrate         Quantify LTTng overhead\n");
 108         fprintf(ofp, "    create            Create tracing session\n");
 109         fprintf(ofp, "    destroy           Tear down tracing session\n");
 110         fprintf(ofp, "    enable-channel    Enable tracing channel\n");
 111         fprintf(ofp, "    enable-event      Enable tracing event\n");
 112         fprintf(ofp, "    disable-channel   Disable tracing channel\n");
 113         fprintf(ofp, "    disable-event     Disable tracing event\n");
 114         fprintf(ofp, "    list              List possible tracing options\n");
 115         fprintf(ofp, "    set-session       Set current session name\n");
 116         fprintf(ofp, "    snapshot          Snapshot buffers of current session name\n");
 117         fprintf(ofp, "    start             Start tracing\n");
 118         fprintf(ofp, "    stop              Stop tracing\n");
 119         fprintf(ofp, "    version           Show version information\n");
 120         fprintf(ofp, "    view              Start trace viewer\n");
 121         fprintf(ofp, "\n");
 122         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 123         fprintf(ofp, "\n");
 124         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 125         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 126 }
 127
 128 static void version(FILE *ofp)
 129 {
 130         fprintf(ofp, "%s (LTTng Trace Control) " VERSION" - " VERSION_NAME"\n",
 131                         progname);
 132 }
 133
 134 /*
 135  *  list_options
 136  *
 137  *  List options line by line. This is mostly for bash auto completion and to
 138  *  avoid difficult parsing.
 139  */
 140 static void list_options(FILE *ofp)
 141 {
 142         int i = 0;
 143         struct option *option = NULL;
 144
 145         option = &long_options[i];
 146         while (option->name != NULL) {
 147                 fprintf(ofp, "--%s\n", option->name);
 148
 149                 if (isprint(option->val)) {
 150                         fprintf(ofp, "-%c\n", option->val);
 151                 }
 152
 153                 i++;
 154                 option = &long_options[i];
 155         }
 156 }
 157
 158 /*
 159  * clean_exit
 160  */
 161 static void clean_exit(int code)
 162 {
 163         DBG("Clean exit");
 164         exit(code);
 165 }
 166
 167 /*
 168  *  sighandler
 169  *
 170  *  Signal handler for the daemon
 171  */
 172 static void sighandler(int sig)
 173 {
 174         int status;
 175
 176         switch (sig) {
 177                 case SIGTERM:
 178                         DBG("SIGTERM caught");
 179                         clean_exit(EXIT_FAILURE);
 180                         break;
 181                 case SIGCHLD:
 182                         DBG("SIGCHLD caught");
 183                         waitpid(sessiond_pid, &status, 0);
 184                         recv_child_signal = 1;
 185                         /* Indicate that the session daemon died */
 186                         sessiond_pid = 0;
 187                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 188                         break;
 189                 case SIGUSR1:
 190                         /* Notify is done */
 191                         recv_child_signal = 1;
 192                         DBG("SIGUSR1 caught");
 193                         break;
 194                 default:
 195                         DBG("Unknown signal %d caught", sig);
 196                         break;
 197         }
 198
 199         return;
 200 }
 201
 202 /*
 203  *  set_signal_handler
 204  *
 205  *  Setup signal handler for SIGCHLD and SIGTERM.
 206  */
 207 static int set_signal_handler(void)
 208 {
 209         int ret = 0;
 210         struct sigaction sa;
 211         sigset_t sigset;
 212
 213         if ((ret = sigemptyset(&sigset)) < 0) {
 214                 perror("sigemptyset");
 215                 goto end;
 216         }
 217
 218         sa.sa_handler = sighandler;
 219         sa.sa_mask = sigset;
 220         sa.sa_flags = 0;
 221         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 222                 perror("sigaction");
 223                 goto end;
 224         }
 225
 226         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 227                 perror("sigaction");
 228                 goto end;
 229         }
 230
 231         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 232                 perror("sigaction");
 233                 goto end;
 234         }
 235
 236 end:
 237         return ret;
 238 }
 239
 240 /*
 241  *  handle_command
 242  *
 243  *  Handle the full argv list of a first level command. Will find the command
 244  *  in the global commands array and call the function callback associated.
 245  *
 246  *  If command not found, return -1
 247  *  else, return function command error code.
 248  */
 249 static int handle_command(int argc, char **argv)
 250 {
 251         int i = 0, ret;
 252         struct cmd_struct *cmd;
 253
 254         if (*argv == NULL) {
 255                 ret = CMD_SUCCESS;
 256                 goto end;
 257         }
 258
 259         cmd = &commands[i];
 260         while (cmd->func != NULL) {
 261                 /* Find command */
 262                 if (strcmp(argv[0], cmd->name) == 0) {
 263                         ret = cmd->func(argc, (const char**) argv);
 264                         goto end;
 265                 }
 266                 i++;
 267                 cmd = &commands[i];
 268         }
 269
 270         /* Command not found */
 271         ret = CMD_UNDEFINED;
 272
 273 end:
 274         return ret;
 275 }
 276
 277 /*
 278  *  spawn_sessiond
 279  *
 280  *  Spawn a session daemon by forking and execv.
 281  */
 282 static int spawn_sessiond(char *pathname)
 283 {
 284         int ret = 0;
 285         pid_t pid;
 286
 287         MSG("Spawning a session daemon");
 288         recv_child_signal = 0;
 289         pid = fork();
 290         if (pid == 0) {
 291                 /*
 292                  * Spawn session daemon and tell
 293                  * it to signal us when ready.
 294                  */
 295                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 296                 /* execlp only returns if error happened */
 297                 if (errno == ENOENT) {
 298                         ERR("No session daemon found. Use --sessiond-path.");
 299                 } else {
 300                         perror("execlp");
 301                 }
 302                 kill(getppid(), SIGTERM);       /* wake parent */
 303                 exit(EXIT_FAILURE);
 304         } else if (pid > 0) {
 305                 sessiond_pid = pid;
 306                 /*
 307                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 308                  * the signal has been sent to us, because the child can be scheduled
 309                  * before the parent, and thus send the signal before this check. In
 310                  * the signal handler, we set the recv_child_signal flag, so anytime we
 311                  * check it after the fork is fine. Note that sleep() is interrupted
 312                  * before the 1 second delay as soon as the signal is received, so it
 313                  * will not cause visible delay for the user.
 314                  */
 315                 while (!recv_child_signal) {
 316                         sleep(1);
 317                 }
 318                 /*
 319                  * The signal handler will nullify sessiond_pid on SIGCHLD
 320                  */
 321                 if (!sessiond_pid) {
 322                         exit(EXIT_FAILURE);
 323                 }
 324                 goto end;
 325         } else {
 326                 perror("fork");
 327                 ret = -1;
 328                 goto end;
 329         }
 330
 331 end:
 332         return ret;
 333 }
 334
 335 /*
 336  *  check_sessiond
 337  *
 338  *  Check if the session daemon is available using
 339  *  the liblttngctl API for the check. If not, try to
 340  *  spawn a daemon.
 341  */
 342 static int check_sessiond(void)
 343 {
 344         int ret;
 345         char *pathname = NULL;
 346
 347         ret = lttng_session_daemon_alive();
 348         if (ret == 0) { /* not alive */
 349                 /* Try command line option path */
 350                 pathname = opt_sessiond_path;
 351
 352                 /* Try LTTNG_SESSIOND_PATH env variable */
 353                 if (pathname == NULL) {
 354                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 355                 }
 356
 357                 /* Try with configured path */
 358                 if (pathname == NULL) {
 359                         if (CONFIG_SESSIOND_BIN[0] != '\0') {
 360                                 pathname = CONFIG_SESSIOND_BIN;
 361                         }
 362                 }
 363
 364                 /* Let's rock and roll while trying the default path */
 365                 if (pathname == NULL) {
 366                         pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 367                 }
 368
 369                 DBG("Session daemon at: %s", pathname);
 370
 371                 /* Check existence and permissions */
 372                 ret = access(pathname, F_OK | X_OK);
 373                 if (ret < 0) {
 374                         ERR("No such file or access denied: %s", pathname);
 375                         goto end;
 376                 }
 377
 378                 ret = spawn_sessiond(pathname);
 379                 if (ret < 0) {
 380                         ERR("Problem occurred when starting %s", pathname);
 381                 }
 382         }
 383 end:
 384         return ret;
 385 }
 386
 387 /*
 388  * Check args for specific options that *must* not trigger a session daemon
 389  * execution.
 390  *
 391  * Return 1 if match else 0.
 392  */
 393 static int check_args_no_sessiond(int argc, char **argv)
 394 {
 395         int i;
 396
 397         for (i = 0; i < argc; i++) {
 398                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 399                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 400                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 401                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 402                                 strncmp(argv[i], "version", sizeof("version")) == 0 ||
 403                                 strncmp(argv[i], "view", sizeof("view")) == 0) {
 404                         return 1;
 405                 }
 406         }
 407
 408         return 0;
 409 }
 410
 411 /*
 412  * Parse command line arguments.
 413  *
 414  * Return 0 if OK, else -1
 415  */
 416 static int parse_args(int argc, char **argv)
 417 {
 418         int opt, ret;
 419
 420         if (argc < 2) {
 421                 usage(stderr);
 422                 clean_exit(EXIT_FAILURE);
 423         }
 424
 425         while ((opt = getopt_long(argc, argv, "+Vhnvqg:", long_options, NULL)) != -1) {
 426                 switch (opt) {
 427                 case 'V':
 428                         version(stdout);
 429                         ret = 0;
 430                         goto end;
 431                 case 'h':
 432                         usage(stdout);
 433                         ret = 0;
 434                         goto end;
 435                 case 'v':
 436                         lttng_opt_verbose += 1;
 437                         break;
 438                 case 'q':
 439                         lttng_opt_quiet = 1;
 440                         break;
 441                 case 'g':
 442                         lttng_set_tracing_group(optarg);
 443                         break;
 444                 case 'n':
 445                         opt_no_sessiond = 1;
 446                         break;
 447                 case OPT_SESSION_PATH:
 448                         opt_sessiond_path = strdup(optarg);
 449                         break;
 450                 case OPT_RELAYD_PATH:
 451                         opt_relayd_path = strdup(optarg);
 452                         break;
 453                 case OPT_DUMP_OPTIONS:
 454                         list_options(stdout);
 455                         ret = 0;
 456                         goto end;
 457                 case OPT_DUMP_COMMANDS:
 458                         list_commands(commands, stdout);
 459                         ret = 0;
 460                         goto end;
 461                 default:
 462                         usage(stderr);
 463                         ret = 1;
 464                         goto error;
 465                 }
 466         }
 467
 468         /* If both options are specified, quiet wins */
 469         if (lttng_opt_verbose && lttng_opt_quiet) {
 470                 lttng_opt_verbose = 0;
 471         }
 472
 473         /* Spawn session daemon if needed */
 474         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 475                         (check_sessiond() < 0)) {
 476                 ret = 1;
 477                 goto error;
 478         }
 479
 480         /* No leftovers, print usage and quit */
 481         if ((argc - optind) == 0) {
 482                 usage(stderr);
 483                 ret = 1;
 484                 goto error;
 485         }
 486
 487         /*
 488          * Handle leftovers which is a first level command with the trailing
 489          * options.
 490          */
 491         ret = handle_command(argc - optind, argv + optind);
 492         switch (ret) {
 493         case CMD_WARNING:
 494                 WARN("Some command(s) went wrong");
 495                 break;
 496         case CMD_ERROR:
 497                 ERR("Command error");
 498                 break;
 499         case CMD_UNDEFINED:
 500                 ERR("Undefined command");
 501                 break;
 502         case CMD_FATAL:
 503                 ERR("Fatal error");
 504                 break;
 505         case CMD_UNSUPPORTED:
 506                 ERR("Unsupported command");
 507                 break;
 508         case -1:
 509                 usage(stderr);
 510                 ret = 1;
 511                 break;
 512         case 0:
 513                 break;
 514         default:
 515                 if (ret < 0) {
 516                         ret = -ret;
 517                 }
 518                 break;
 519         }
 520
 521 end:
 522 error:
 523         return ret;
 524 }
 525
 526
 527 /*
 528  *  main
 529  */
 530 int main(int argc, char *argv[])
 531 {
 532         int ret;
 533         char *user;
 534
 535         progname = argv[0] ? argv[0] : "lttng";
 536
 537         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 538         user = getenv("USER");
 539         if (user != NULL && ((strncmp(progname, "drtrace", 7) == 0 ||
 540                                 strncmp("compudj", user, 7) == 0))) {
 541                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 542         }
 543         /* Thanks Mathieu */
 544
 545         ret = set_signal_handler();
 546         if (ret < 0) {
 547                 clean_exit(ret);
 548         }
 549
 550         ret = parse_args(argc, argv);
 551         if (ret != 0) {
 552                 clean_exit(ret);
 553         }
 554
 555         return 0;
 556 }