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         { "save", cmd_save},
  84         { "enable-consumer", cmd_enable_consumer}, /* OBSOLETE */
  85         { "disable-consumer", cmd_disable_consumer}, /* OBSOLETE */
  86         { NULL, NULL}   /* Array closure */
  87 };
  88
  89 static void usage(FILE *ofp)
  90 {
  91         fprintf(ofp, "LTTng Trace Control " VERSION" - " VERSION_NAME"\n\n");
  92         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND> [<ARGS>]\n");
  93         fprintf(ofp, "\n");
  94         fprintf(ofp, "Options:\n");
  95         fprintf(ofp, "  -V, --version              Show version\n");
  96         fprintf(ofp, "  -h, --help                 Show this help\n");
  97         fprintf(ofp, "      --list-options         Simple listing of lttng options\n");
  98         fprintf(ofp, "      --list-commands        Simple listing of lttng commands\n");
  99         fprintf(ofp, "  -v, --verbose              Increase verbosity\n");
 100         fprintf(ofp, "  -q, --quiet                Quiet mode\n");
 101         fprintf(ofp, "  -g, --group NAME           Unix tracing group name. (default: tracing)\n");
 102         fprintf(ofp, "  -n, --no-sessiond          Don't spawn a session daemon\n");
 103         fprintf(ofp, "      --sessiond-path PATH   Session daemon full path\n");
 104         fprintf(ofp, "      --relayd-path PATH     Relayd daemon full path\n");
 105         fprintf(ofp, "\n");
 106         fprintf(ofp, "Commands:\n");
 107         fprintf(ofp, "    add-context       Add context to event and/or channel\n");
 108         fprintf(ofp, "    calibrate         Quantify LTTng overhead\n");
 109         fprintf(ofp, "    create            Create tracing session\n");
 110         fprintf(ofp, "    destroy           Tear down tracing session\n");
 111         fprintf(ofp, "    enable-channel    Enable tracing channel\n");
 112         fprintf(ofp, "    enable-event      Enable tracing event\n");
 113         fprintf(ofp, "    disable-channel   Disable tracing channel\n");
 114         fprintf(ofp, "    disable-event     Disable tracing event\n");
 115         fprintf(ofp, "    list              List possible tracing options\n");
 116         fprintf(ofp, "    set-session       Set current session name\n");
 117         fprintf(ofp, "    snapshot          Snapshot buffers of current session name\n");
 118         fprintf(ofp, "    start             Start tracing\n");
 119         fprintf(ofp, "    stop              Stop tracing\n");
 120         fprintf(ofp, "    version           Show version information\n");
 121         fprintf(ofp, "    view              Start trace viewer\n");
 122         fprintf(ofp, "    save              Save session configuration\n");
 123         fprintf(ofp, "\n");
 124         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 125         fprintf(ofp, "\n");
 126         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 127         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 128 }
 129
 130 static void version(FILE *ofp)
 131 {
 132         fprintf(ofp, "%s (LTTng Trace Control) " VERSION" - " VERSION_NAME"\n",
 133                         progname);
 134 }
 135
 136 /*
 137  *  list_options
 138  *
 139  *  List options line by line. This is mostly for bash auto completion and to
 140  *  avoid difficult parsing.
 141  */
 142 static void list_options(FILE *ofp)
 143 {
 144         int i = 0;
 145         struct option *option = NULL;
 146
 147         option = &long_options[i];
 148         while (option->name != NULL) {
 149                 fprintf(ofp, "--%s\n", option->name);
 150
 151                 if (isprint(option->val)) {
 152                         fprintf(ofp, "-%c\n", option->val);
 153                 }
 154
 155                 i++;
 156                 option = &long_options[i];
 157         }
 158 }
 159
 160 /*
 161  * clean_exit
 162  */
 163 static void clean_exit(int code)
 164 {
 165         DBG("Clean exit");
 166         exit(code);
 167 }
 168
 169 /*
 170  *  sighandler
 171  *
 172  *  Signal handler for the daemon
 173  */
 174 static void sighandler(int sig)
 175 {
 176         int status;
 177
 178         switch (sig) {
 179                 case SIGTERM:
 180                         DBG("SIGTERM caught");
 181                         clean_exit(EXIT_FAILURE);
 182                         break;
 183                 case SIGCHLD:
 184                         DBG("SIGCHLD caught");
 185                         waitpid(sessiond_pid, &status, 0);
 186                         recv_child_signal = 1;
 187                         /* Indicate that the session daemon died */
 188                         sessiond_pid = 0;
 189                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 190                         break;
 191                 case SIGUSR1:
 192                         /* Notify is done */
 193                         recv_child_signal = 1;
 194                         DBG("SIGUSR1 caught");
 195                         break;
 196                 default:
 197                         DBG("Unknown signal %d caught", sig);
 198                         break;
 199         }
 200
 201         return;
 202 }
 203
 204 /*
 205  *  set_signal_handler
 206  *
 207  *  Setup signal handler for SIGCHLD and SIGTERM.
 208  */
 209 static int set_signal_handler(void)
 210 {
 211         int ret = 0;
 212         struct sigaction sa;
 213         sigset_t sigset;
 214
 215         if ((ret = sigemptyset(&sigset)) < 0) {
 216                 perror("sigemptyset");
 217                 goto end;
 218         }
 219
 220         sa.sa_handler = sighandler;
 221         sa.sa_mask = sigset;
 222         sa.sa_flags = 0;
 223         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 224                 perror("sigaction");
 225                 goto end;
 226         }
 227
 228         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 229                 perror("sigaction");
 230                 goto end;
 231         }
 232
 233         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 234                 perror("sigaction");
 235                 goto end;
 236         }
 237
 238 end:
 239         return ret;
 240 }
 241
 242 /*
 243  *  handle_command
 244  *
 245  *  Handle the full argv list of a first level command. Will find the command
 246  *  in the global commands array and call the function callback associated.
 247  *
 248  *  If command not found, return -1
 249  *  else, return function command error code.
 250  */
 251 static int handle_command(int argc, char **argv)
 252 {
 253         int i = 0, ret;
 254         struct cmd_struct *cmd;
 255
 256         if (*argv == NULL) {
 257                 ret = CMD_SUCCESS;
 258                 goto end;
 259         }
 260
 261         cmd = &commands[i];
 262         while (cmd->func != NULL) {
 263                 /* Find command */
 264                 if (strcmp(argv[0], cmd->name) == 0) {
 265                         ret = cmd->func(argc, (const char**) argv);
 266                         goto end;
 267                 }
 268                 i++;
 269                 cmd = &commands[i];
 270         }
 271
 272         /* Command not found */
 273         ret = CMD_UNDEFINED;
 274
 275 end:
 276         return ret;
 277 }
 278
 279 /*
 280  *  spawn_sessiond
 281  *
 282  *  Spawn a session daemon by forking and execv.
 283  */
 284 static int spawn_sessiond(char *pathname)
 285 {
 286         int ret = 0;
 287         pid_t pid;
 288
 289         MSG("Spawning a session daemon");
 290         recv_child_signal = 0;
 291         pid = fork();
 292         if (pid == 0) {
 293                 /*
 294                  * Spawn session daemon and tell
 295                  * it to signal us when ready.
 296                  */
 297                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 298                 /* execlp only returns if error happened */
 299                 if (errno == ENOENT) {
 300                         ERR("No session daemon found. Use --sessiond-path.");
 301                 } else {
 302                         perror("execlp");
 303                 }
 304                 kill(getppid(), SIGTERM);       /* wake parent */
 305                 exit(EXIT_FAILURE);
 306         } else if (pid > 0) {
 307                 sessiond_pid = pid;
 308                 /*
 309                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 310                  * the signal has been sent to us, because the child can be scheduled
 311                  * before the parent, and thus send the signal before this check. In
 312                  * the signal handler, we set the recv_child_signal flag, so anytime we
 313                  * check it after the fork is fine. Note that sleep() is interrupted
 314                  * before the 1 second delay as soon as the signal is received, so it
 315                  * will not cause visible delay for the user.
 316                  */
 317                 while (!recv_child_signal) {
 318                         sleep(1);
 319                 }
 320                 /*
 321                  * The signal handler will nullify sessiond_pid on SIGCHLD
 322                  */
 323                 if (!sessiond_pid) {
 324                         exit(EXIT_FAILURE);
 325                 }
 326                 goto end;
 327         } else {
 328                 perror("fork");
 329                 ret = -1;
 330                 goto end;
 331         }
 332
 333 end:
 334         return ret;
 335 }
 336
 337 /*
 338  *  check_sessiond
 339  *
 340  *  Check if the session daemon is available using
 341  *  the liblttngctl API for the check. If not, try to
 342  *  spawn a daemon.
 343  */
 344 static int check_sessiond(void)
 345 {
 346         int ret;
 347         char *pathname = NULL;
 348
 349         ret = lttng_session_daemon_alive();
 350         if (ret == 0) { /* not alive */
 351                 /* Try command line option path */
 352                 pathname = opt_sessiond_path;
 353
 354                 /* Try LTTNG_SESSIOND_PATH env variable */
 355                 if (pathname == NULL) {
 356                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 357                 }
 358
 359                 /* Try with configured path */
 360                 if (pathname == NULL) {
 361                         if (CONFIG_SESSIOND_BIN[0] != '\0') {
 362                                 pathname = CONFIG_SESSIOND_BIN;
 363                         }
 364                 }
 365
 366                 /* Let's rock and roll while trying the default path */
 367                 if (pathname == NULL) {
 368                         pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 369                 }
 370
 371                 DBG("Session daemon at: %s", pathname);
 372
 373                 /* Check existence and permissions */
 374                 ret = access(pathname, F_OK | X_OK);
 375                 if (ret < 0) {
 376                         ERR("No such file or access denied: %s", pathname);
 377                         goto end;
 378                 }
 379
 380                 ret = spawn_sessiond(pathname);
 381                 if (ret < 0) {
 382                         ERR("Problem occurred when starting %s", pathname);
 383                 }
 384         }
 385 end:
 386         return ret;
 387 }
 388
 389 /*
 390  * Check args for specific options that *must* not trigger a session daemon
 391  * execution.
 392  *
 393  * Return 1 if match else 0.
 394  */
 395 static int check_args_no_sessiond(int argc, char **argv)
 396 {
 397         int i;
 398
 399         for (i = 0; i < argc; i++) {
 400                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 401                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 402                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 403                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 404                                 strncmp(argv[i], "version", sizeof("version")) == 0 ||
 405                                 strncmp(argv[i], "view", sizeof("view")) == 0) {
 406                         return 1;
 407                 }
 408         }
 409
 410         return 0;
 411 }
 412
 413 /*
 414  * Parse command line arguments.
 415  *
 416  * Return 0 if OK, else -1
 417  */
 418 static int parse_args(int argc, char **argv)
 419 {
 420         int opt, ret;
 421
 422         if (argc < 2) {
 423                 usage(stderr);
 424                 clean_exit(EXIT_FAILURE);
 425         }
 426
 427         while ((opt = getopt_long(argc, argv, "+Vhnvqg:", long_options, NULL)) != -1) {
 428                 switch (opt) {
 429                 case 'V':
 430                         version(stdout);
 431                         ret = 0;
 432                         goto end;
 433                 case 'h':
 434                         usage(stdout);
 435                         ret = 0;
 436                         goto end;
 437                 case 'v':
 438                         lttng_opt_verbose += 1;
 439                         break;
 440                 case 'q':
 441                         lttng_opt_quiet = 1;
 442                         break;
 443                 case 'g':
 444                         lttng_set_tracing_group(optarg);
 445                         break;
 446                 case 'n':
 447                         opt_no_sessiond = 1;
 448                         break;
 449                 case OPT_SESSION_PATH:
 450                         opt_sessiond_path = strdup(optarg);
 451                         break;
 452                 case OPT_RELAYD_PATH:
 453                         opt_relayd_path = strdup(optarg);
 454                         break;
 455                 case OPT_DUMP_OPTIONS:
 456                         list_options(stdout);
 457                         ret = 0;
 458                         goto end;
 459                 case OPT_DUMP_COMMANDS:
 460                         list_commands(commands, stdout);
 461                         ret = 0;
 462                         goto end;
 463                 default:
 464                         usage(stderr);
 465                         ret = 1;
 466                         goto error;
 467                 }
 468         }
 469
 470         /* If both options are specified, quiet wins */
 471         if (lttng_opt_verbose && lttng_opt_quiet) {
 472                 lttng_opt_verbose = 0;
 473         }
 474
 475         /* Spawn session daemon if needed */
 476         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 477                         (check_sessiond() < 0)) {
 478                 ret = 1;
 479                 goto error;
 480         }
 481
 482         /* No leftovers, print usage and quit */
 483         if ((argc - optind) == 0) {
 484                 usage(stderr);
 485                 ret = 1;
 486                 goto error;
 487         }
 488
 489         /*
 490          * Handle leftovers which is a first level command with the trailing
 491          * options.
 492          */
 493         ret = handle_command(argc - optind, argv + optind);
 494         switch (ret) {
 495         case CMD_WARNING:
 496                 WARN("Some command(s) went wrong");
 497                 break;
 498         case CMD_ERROR:
 499                 ERR("Command error");
 500                 break;
 501         case CMD_UNDEFINED:
 502                 ERR("Undefined command");
 503                 break;
 504         case CMD_FATAL:
 505                 ERR("Fatal error");
 506                 break;
 507         case CMD_UNSUPPORTED:
 508                 ERR("Unsupported command");
 509                 break;
 510         case -1:
 511                 usage(stderr);
 512                 ret = 1;
 513                 break;
 514         case 0:
 515                 break;
 516         default:
 517                 if (ret < 0) {
 518                         ret = -ret;
 519                 }
 520                 break;
 521         }
 522
 523 end:
 524 error:
 525         return ret;
 526 }
 527
 528
 529 /*
 530  *  main
 531  */
 532 int main(int argc, char *argv[])
 533 {
 534         int ret;
 535         char *user;
 536
 537         progname = argv[0] ? argv[0] : "lttng";
 538
 539         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 540         user = getenv("USER");
 541         if (user != NULL && ((strncmp(progname, "drtrace", 7) == 0 ||
 542                                 strncmp("compudj", user, 7) == 0))) {
 543                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 544         }
 545         /* Thanks Mathieu */
 546
 547         ret = set_signal_handler();
 548         if (ret < 0) {
 549                 clean_exit(ret);
 550         }
 551
 552         ret = parse_args(argc, argv);
 553         if (ret != 0) {
 554                 clean_exit(ret);
 555         }
 556
 557         return 0;
 558 }