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  *  list_commands
 155  *
 156  *  List commands line by line. This is mostly for bash auto completion and to
 157  *  avoid difficult parsing.
 158  */
 159 static void list_commands(FILE *ofp)
 160 {
 161         int i = 0;
 162         struct cmd_struct *cmd = NULL;
 163
 164         cmd = &commands[i];
 165         while (cmd->name != NULL) {
 166                 fprintf(ofp, "%s\n", cmd->name);
 167                 i++;
 168                 cmd = &commands[i];
 169         }
 170 }
 171
 172 /*
 173  * clean_exit
 174  */
 175 static void clean_exit(int code)
 176 {
 177         DBG("Clean exit");
 178         exit(code);
 179 }
 180
 181 /*
 182  *  sighandler
 183  *
 184  *  Signal handler for the daemon
 185  */
 186 static void sighandler(int sig)
 187 {
 188         int status;
 189
 190         switch (sig) {
 191                 case SIGTERM:
 192                         DBG("SIGTERM caught");
 193                         clean_exit(EXIT_FAILURE);
 194                         break;
 195                 case SIGCHLD:
 196                         DBG("SIGCHLD caught");
 197                         waitpid(sessiond_pid, &status, 0);
 198                         recv_child_signal = 1;
 199                         /* Indicate that the session daemon died */
 200                         sessiond_pid = 0;
 201                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 202                         break;
 203                 case SIGUSR1:
 204                         /* Notify is done */
 205                         recv_child_signal = 1;
 206                         DBG("SIGUSR1 caught");
 207                         break;
 208                 default:
 209                         DBG("Unknown signal %d caught", sig);
 210                         break;
 211         }
 212
 213         return;
 214 }
 215
 216 /*
 217  *  set_signal_handler
 218  *
 219  *  Setup signal handler for SIGCHLD and SIGTERM.
 220  */
 221 static int set_signal_handler(void)
 222 {
 223         int ret = 0;
 224         struct sigaction sa;
 225         sigset_t sigset;
 226
 227         if ((ret = sigemptyset(&sigset)) < 0) {
 228                 perror("sigemptyset");
 229                 goto end;
 230         }
 231
 232         sa.sa_handler = sighandler;
 233         sa.sa_mask = sigset;
 234         sa.sa_flags = 0;
 235         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 236                 perror("sigaction");
 237                 goto end;
 238         }
 239
 240         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 241                 perror("sigaction");
 242                 goto end;
 243         }
 244
 245         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 246                 perror("sigaction");
 247                 goto end;
 248         }
 249
 250 end:
 251         return ret;
 252 }
 253
 254 /*
 255  *  handle_command
 256  *
 257  *  Handle the full argv list of a first level command. Will find the command
 258  *  in the global commands array and call the function callback associated.
 259  *
 260  *  If command not found, return -1
 261  *  else, return function command error code.
 262  */
 263 static int handle_command(int argc, char **argv)
 264 {
 265         int i = 0, ret;
 266         struct cmd_struct *cmd;
 267
 268         if (*argv == NULL) {
 269                 ret = CMD_SUCCESS;
 270                 goto end;
 271         }
 272
 273         cmd = &commands[i];
 274         while (cmd->func != NULL) {
 275                 /* Find command */
 276                 if (strcmp(argv[0], cmd->name) == 0) {
 277                         ret = cmd->func(argc, (const char**) argv);
 278                         goto end;
 279                 }
 280                 i++;
 281                 cmd = &commands[i];
 282         }
 283
 284         /* Command not found */
 285         ret = CMD_UNDEFINED;
 286
 287 end:
 288         return ret;
 289 }
 290
 291 /*
 292  *  spawn_sessiond
 293  *
 294  *  Spawn a session daemon by forking and execv.
 295  */
 296 static int spawn_sessiond(char *pathname)
 297 {
 298         int ret = 0;
 299         pid_t pid;
 300
 301         MSG("Spawning a session daemon");
 302         recv_child_signal = 0;
 303         pid = fork();
 304         if (pid == 0) {
 305                 /*
 306                  * Spawn session daemon and tell
 307                  * it to signal us when ready.
 308                  */
 309                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 310                 /* execlp only returns if error happened */
 311                 if (errno == ENOENT) {
 312                         ERR("No session daemon found. Use --sessiond-path.");
 313                 } else {
 314                         perror("execlp");
 315                 }
 316                 kill(getppid(), SIGTERM);       /* wake parent */
 317                 exit(EXIT_FAILURE);
 318         } else if (pid > 0) {
 319                 sessiond_pid = pid;
 320                 /*
 321                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 322                  * the signal has been sent to us, because the child can be scheduled
 323                  * before the parent, and thus send the signal before this check. In
 324                  * the signal handler, we set the recv_child_signal flag, so anytime we
 325                  * check it after the fork is fine. Note that sleep() is interrupted
 326                  * before the 1 second delay as soon as the signal is received, so it
 327                  * will not cause visible delay for the user.
 328                  */
 329                 while (!recv_child_signal) {
 330                         sleep(1);
 331                 }
 332                 /*
 333                  * The signal handler will nullify sessiond_pid on SIGCHLD
 334                  */
 335                 if (!sessiond_pid) {
 336                         exit(EXIT_FAILURE);
 337                 }
 338                 goto end;
 339         } else {
 340                 perror("fork");
 341                 ret = -1;
 342                 goto end;
 343         }
 344
 345 end:
 346         return ret;
 347 }
 348
 349 /*
 350  *  check_sessiond
 351  *
 352  *  Check if the session daemon is available using
 353  *  the liblttngctl API for the check. If not, try to
 354  *  spawn a daemon.
 355  */
 356 static int check_sessiond(void)
 357 {
 358         int ret;
 359         char *pathname = NULL;
 360
 361         ret = lttng_session_daemon_alive();
 362         if (ret == 0) { /* not alive */
 363                 /* Try command line option path */
 364                 pathname = opt_sessiond_path;
 365
 366                 /* Try LTTNG_SESSIOND_PATH env variable */
 367                 if (pathname == NULL) {
 368                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 369                 }
 370
 371                 /* Try with configured path */
 372                 if (pathname == NULL) {
 373                         if (CONFIG_SESSIOND_BIN[0] != '\0') {
 374                                 pathname = CONFIG_SESSIOND_BIN;
 375                         }
 376                 }
 377
 378                 /* Let's rock and roll while trying the default path */
 379                 if (pathname == NULL) {
 380                         pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 381                 }
 382
 383                 DBG("Session daemon at: %s", pathname);
 384
 385                 /* Check existence and permissions */
 386                 ret = access(pathname, F_OK | X_OK);
 387                 if (ret < 0) {
 388                         ERR("No such file or access denied: %s", pathname);
 389                         goto end;
 390                 }
 391
 392                 ret = spawn_sessiond(pathname);
 393                 if (ret < 0) {
 394                         ERR("Problem occurred when starting %s", pathname);
 395                 }
 396         }
 397 end:
 398         return ret;
 399 }
 400
 401 /*
 402  * Check args for specific options that *must* not trigger a session daemon
 403  * execution.
 404  *
 405  * Return 1 if match else 0.
 406  */
 407 static int check_args_no_sessiond(int argc, char **argv)
 408 {
 409         int i;
 410
 411         for (i = 0; i < argc; i++) {
 412                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 413                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 414                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 415                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 416                                 strncmp(argv[i], "version", sizeof("version")) == 0 ||
 417                                 strncmp(argv[i], "view", sizeof("view")) == 0) {
 418                         return 1;
 419                 }
 420         }
 421
 422         return 0;
 423 }
 424
 425 /*
 426  * Parse command line arguments.
 427  *
 428  * Return 0 if OK, else -1
 429  */
 430 static int parse_args(int argc, char **argv)
 431 {
 432         int opt, ret;
 433
 434         if (argc < 2) {
 435                 usage(stderr);
 436                 clean_exit(EXIT_FAILURE);
 437         }
 438
 439         while ((opt = getopt_long(argc, argv, "+Vhnvqg:", long_options, NULL)) != -1) {
 440                 switch (opt) {
 441                 case 'V':
 442                         version(stdout);
 443                         ret = 0;
 444                         goto end;
 445                 case 'h':
 446                         usage(stdout);
 447                         ret = 0;
 448                         goto end;
 449                 case 'v':
 450                         lttng_opt_verbose += 1;
 451                         break;
 452                 case 'q':
 453                         lttng_opt_quiet = 1;
 454                         break;
 455                 case 'g':
 456                         lttng_set_tracing_group(optarg);
 457                         break;
 458                 case 'n':
 459                         opt_no_sessiond = 1;
 460                         break;
 461                 case OPT_SESSION_PATH:
 462                         opt_sessiond_path = strdup(optarg);
 463                         break;
 464                 case OPT_DUMP_OPTIONS:
 465                         list_options(stdout);
 466                         ret = 0;
 467                         goto end;
 468                 case OPT_DUMP_COMMANDS:
 469                         list_commands(stdout);
 470                         ret = 0;
 471                         goto end;
 472                 default:
 473                         usage(stderr);
 474                         ret = 1;
 475                         goto error;
 476                 }
 477         }
 478
 479         /* If both options are specified, quiet wins */
 480         if (lttng_opt_verbose && lttng_opt_quiet) {
 481                 lttng_opt_verbose = 0;
 482         }
 483
 484         /* Spawn session daemon if needed */
 485         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 486                         (check_sessiond() < 0)) {
 487                 ret = 1;
 488                 goto error;
 489         }
 490
 491         /* No leftovers, print usage and quit */
 492         if ((argc - optind) == 0) {
 493                 usage(stderr);
 494                 ret = 1;
 495                 goto error;
 496         }
 497
 498         /*
 499          * Handle leftovers which is a first level command with the trailing
 500          * options.
 501          */
 502         ret = handle_command(argc - optind, argv + optind);
 503         switch (ret) {
 504         case CMD_WARNING:
 505                 WARN("Some command(s) went wrong");
 506                 break;
 507         case CMD_ERROR:
 508                 ERR("Command error");
 509                 break;
 510         case CMD_UNDEFINED:
 511                 ERR("Undefined command");
 512                 break;
 513         case CMD_FATAL:
 514                 ERR("Fatal error");
 515                 break;
 516         case CMD_UNSUPPORTED:
 517                 ERR("Unsupported command");
 518                 break;
 519         case -1:
 520                 usage(stderr);
 521                 ret = 1;
 522                 break;
 523         case 0:
 524                 break;
 525         default:
 526                 if (ret < 0) {
 527                         ret = -ret;
 528                 }
 529                 break;
 530         }
 531
 532 end:
 533 error:
 534         return ret;
 535 }
 536
 537
 538 /*
 539  *  main
 540  */
 541 int main(int argc, char *argv[])
 542 {
 543         int ret;
 544         char *user;
 545
 546         progname = argv[0] ? argv[0] : "lttng";
 547
 548         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 549         user = getenv("USER");
 550         if (user != NULL && ((strncmp(progname, "drtrace", 7) == 0 ||
 551                                 strncmp("compudj", user, 7) == 0))) {
 552                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 553         }
 554         /* Thanks Mathieu */
 555
 556         ret = set_signal_handler();
 557         if (ret < 0) {
 558                 clean_exit(ret);
 559         }
 560
 561         ret = parse_args(argc, argv);
 562         if (ret != 0) {
 563                 clean_exit(ret);
 564         }
 565
 566         return 0;
 567 }