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         { "enable-consumer", cmd_enable_consumer}, /* OBSOLETE */
  79         { "disable-consumer", cmd_disable_consumer}, /* OBSOLETE */
  80         { NULL, NULL}   /* Array closure */
  81 };
  82
  83 static void usage(FILE *ofp)
  84 {
  85         fprintf(ofp, "LTTng Trace Control " VERSION" - " VERSION_NAME"\n\n");
  86         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND> [<ARGS>]\n");
  87         fprintf(ofp, "\n");
  88         fprintf(ofp, "Options:\n");
  89         fprintf(ofp, "  -V, --version              Show version\n");
  90         fprintf(ofp, "  -h, --help                 Show this help\n");
  91         fprintf(ofp, "      --list-options         Simple listing of lttng options\n");
  92         fprintf(ofp, "      --list-commands        Simple listing of lttng commands\n");
  93         fprintf(ofp, "  -v, --verbose              Increase verbosity\n");
  94         fprintf(ofp, "  -q, --quiet                Quiet mode\n");
  95         fprintf(ofp, "  -g, --group NAME           Unix tracing group name. (default: tracing)\n");
  96         fprintf(ofp, "  -n, --no-sessiond          Don't spawn a session daemon\n");
  97         fprintf(ofp, "      --sessiond-path PATH   Session daemon full path\n");
  98         fprintf(ofp, "\n");
  99         fprintf(ofp, "Commands:\n");
 100         fprintf(ofp, "    add-context       Add context to event and/or channel\n");
 101         fprintf(ofp, "    calibrate         Quantify LTTng overhead\n");
 102         fprintf(ofp, "    create            Create tracing session\n");
 103         fprintf(ofp, "    destroy           Tear down tracing session\n");
 104         fprintf(ofp, "    enable-channel    Enable tracing channel\n");
 105         fprintf(ofp, "    enable-event      Enable tracing event\n");
 106         fprintf(ofp, "    disable-channel   Disable tracing channel\n");
 107         fprintf(ofp, "    disable-event     Disable tracing event\n");
 108         fprintf(ofp, "    list              List possible tracing options\n");
 109         fprintf(ofp, "    set-session       Set current session name\n");
 110         fprintf(ofp, "    start             Start tracing\n");
 111         fprintf(ofp, "    stop              Stop tracing\n");
 112         fprintf(ofp, "    version           Show version information\n");
 113         fprintf(ofp, "    view              Start trace viewer\n");
 114         fprintf(ofp, "\n");
 115         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 116         fprintf(ofp, "\n");
 117         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 118         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 119 }
 120
 121 static void version(FILE *ofp)
 122 {
 123         fprintf(ofp, "%s (LTTng Trace Control) " VERSION" - " VERSION_NAME"\n",
 124                         progname);
 125 }
 126
 127 /*
 128  *  list_options
 129  *
 130  *  List options line by line. This is mostly for bash auto completion and to
 131  *  avoid difficult parsing.
 132  */
 133 static void list_options(FILE *ofp)
 134 {
 135         int i = 0;
 136         struct option *option = NULL;
 137
 138         option = &long_options[i];
 139         while (option->name != NULL) {
 140                 fprintf(ofp, "--%s\n", option->name);
 141
 142                 if (isprint(option->val)) {
 143                         fprintf(ofp, "-%c\n", option->val);
 144                 }
 145
 146                 i++;
 147                 option = &long_options[i];
 148         }
 149 }
 150
 151 /*
 152  *  list_commands
 153  *
 154  *  List commands line by line. This is mostly for bash auto completion and to
 155  *  avoid difficult parsing.
 156  */
 157 static void list_commands(FILE *ofp)
 158 {
 159         int i = 0;
 160         struct cmd_struct *cmd = NULL;
 161
 162         cmd = &commands[i];
 163         while (cmd->name != NULL) {
 164                 fprintf(ofp, "%s\n", cmd->name);
 165                 i++;
 166                 cmd = &commands[i];
 167         }
 168 }
 169
 170 /*
 171  * clean_exit
 172  */
 173 static void clean_exit(int code)
 174 {
 175         DBG("Clean exit");
 176         exit(code);
 177 }
 178
 179 /*
 180  *  sighandler
 181  *
 182  *  Signal handler for the daemon
 183  */
 184 static void sighandler(int sig)
 185 {
 186         int status;
 187
 188         switch (sig) {
 189                 case SIGTERM:
 190                         DBG("SIGTERM caught");
 191                         clean_exit(EXIT_FAILURE);
 192                         break;
 193                 case SIGCHLD:
 194                         DBG("SIGCHLD caught");
 195                         waitpid(sessiond_pid, &status, 0);
 196                         recv_child_signal = 1;
 197                         /* Indicate that the session daemon died */
 198                         sessiond_pid = 0;
 199                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 200                         break;
 201                 case SIGUSR1:
 202                         /* Notify is done */
 203                         recv_child_signal = 1;
 204                         DBG("SIGUSR1 caught");
 205                         break;
 206                 default:
 207                         DBG("Unknown signal %d caught", sig);
 208                         break;
 209         }
 210
 211         return;
 212 }
 213
 214 /*
 215  *  set_signal_handler
 216  *
 217  *  Setup signal handler for SIGCHLD and SIGTERM.
 218  */
 219 static int set_signal_handler(void)
 220 {
 221         int ret = 0;
 222         struct sigaction sa;
 223         sigset_t sigset;
 224
 225         if ((ret = sigemptyset(&sigset)) < 0) {
 226                 perror("sigemptyset");
 227                 goto end;
 228         }
 229
 230         sa.sa_handler = sighandler;
 231         sa.sa_mask = sigset;
 232         sa.sa_flags = 0;
 233         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 234                 perror("sigaction");
 235                 goto end;
 236         }
 237
 238         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 239                 perror("sigaction");
 240                 goto end;
 241         }
 242
 243         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 244                 perror("sigaction");
 245                 goto end;
 246         }
 247
 248 end:
 249         return ret;
 250 }
 251
 252 /*
 253  *  handle_command
 254  *
 255  *  Handle the full argv list of a first level command. Will find the command
 256  *  in the global commands array and call the function callback associated.
 257  *
 258  *  If command not found, return -1
 259  *  else, return function command error code.
 260  */
 261 static int handle_command(int argc, char **argv)
 262 {
 263         int i = 0, ret;
 264         struct cmd_struct *cmd;
 265
 266         if (*argv == NULL) {
 267                 ret = CMD_SUCCESS;
 268                 goto end;
 269         }
 270
 271         cmd = &commands[i];
 272         while (cmd->func != NULL) {
 273                 /* Find command */
 274                 if (strcmp(argv[0], cmd->name) == 0) {
 275                         ret = cmd->func(argc, (const char**) argv);
 276                         goto end;
 277                 }
 278                 i++;
 279                 cmd = &commands[i];
 280         }
 281
 282         /* Command not found */
 283         ret = CMD_UNDEFINED;
 284
 285 end:
 286         return ret;
 287 }
 288
 289 /*
 290  *  spawn_sessiond
 291  *
 292  *  Spawn a session daemon by forking and execv.
 293  */
 294 static int spawn_sessiond(char *pathname)
 295 {
 296         int ret = 0;
 297         pid_t pid;
 298
 299         MSG("Spawning a session daemon");
 300         recv_child_signal = 0;
 301         pid = fork();
 302         if (pid == 0) {
 303                 /*
 304                  * Spawn session daemon and tell
 305                  * it to signal us when ready.
 306                  */
 307                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 308                 /* execlp only returns if error happened */
 309                 if (errno == ENOENT) {
 310                         ERR("No session daemon found. Use --sessiond-path.");
 311                 } else {
 312                         perror("execlp");
 313                 }
 314                 kill(getppid(), SIGTERM);       /* wake parent */
 315                 exit(EXIT_FAILURE);
 316         } else if (pid > 0) {
 317                 sessiond_pid = pid;
 318                 /*
 319                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 320                  * the signal has been sent to us, because the child can be scheduled
 321                  * before the parent, and thus send the signal before this check. In
 322                  * the signal handler, we set the recv_child_signal flag, so anytime we
 323                  * check it after the fork is fine. Note that sleep() is interrupted
 324                  * before the 1 second delay as soon as the signal is received, so it
 325                  * will not cause visible delay for the user.
 326                  */
 327                 while (!recv_child_signal) {
 328                         sleep(1);
 329                 }
 330                 /*
 331                  * The signal handler will nullify sessiond_pid on SIGCHLD
 332                  */
 333                 if (!sessiond_pid) {
 334                         exit(EXIT_FAILURE);
 335                 }
 336                 goto end;
 337         } else {
 338                 perror("fork");
 339                 ret = -1;
 340                 goto end;
 341         }
 342
 343 end:
 344         return ret;
 345 }
 346
 347 /*
 348  *  check_sessiond
 349  *
 350  *  Check if the session daemon is available using
 351  *  the liblttngctl API for the check. If not, try to
 352  *  spawn a daemon.
 353  */
 354 static int check_sessiond(void)
 355 {
 356         int ret;
 357         char *pathname = NULL;
 358
 359         ret = lttng_session_daemon_alive();
 360         if (ret == 0) { /* not alive */
 361                 /* Try command line option path */
 362                 pathname = opt_sessiond_path;
 363
 364                 /* Try LTTNG_SESSIOND_PATH env variable */
 365                 if (pathname == NULL) {
 366                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 367                 }
 368
 369                 /* Try with configured path */
 370                 if (pathname == NULL) {
 371                         if (CONFIG_SESSIOND_BIN[0] != '\0') {
 372                                 pathname = CONFIG_SESSIOND_BIN;
 373                         }
 374                 }
 375
 376                 /* Let's rock and roll while trying the default path */
 377                 if (pathname == NULL) {
 378                         pathname = INSTALL_BIN_PATH "/lttng-sessiond";
 379                 }
 380
 381                 DBG("Session daemon at: %s", pathname);
 382
 383                 /* Check existence and permissions */
 384                 ret = access(pathname, F_OK | X_OK);
 385                 if (ret < 0) {
 386                         ERR("No such file or access denied: %s", pathname);
 387                         goto end;
 388                 }
 389
 390                 ret = spawn_sessiond(pathname);
 391                 if (ret < 0) {
 392                         ERR("Problem occurred when starting %s", pathname);
 393                 }
 394         }
 395 end:
 396         return ret;
 397 }
 398
 399 /*
 400  * Check args for specific options that *must* not trigger a session daemon
 401  * execution.
 402  *
 403  * Return 1 if match else 0.
 404  */
 405 static int check_args_no_sessiond(int argc, char **argv)
 406 {
 407         int i;
 408
 409         for (i = 0; i < argc; i++) {
 410                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 411                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 412                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 413                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 414                                 strncmp(argv[i], "version", sizeof("version")) == 0 ||
 415                                 strncmp(argv[i], "view", sizeof("view")) == 0) {
 416                         return 1;
 417                 }
 418         }
 419
 420         return 0;
 421 }
 422
 423 /*
 424  * Parse command line arguments.
 425  *
 426  * Return 0 if OK, else -1
 427  */
 428 static int parse_args(int argc, char **argv)
 429 {
 430         int opt, ret;
 431
 432         if (argc < 2) {
 433                 usage(stderr);
 434                 clean_exit(EXIT_FAILURE);
 435         }
 436
 437         while ((opt = getopt_long(argc, argv, "+Vhnvqg:", long_options, NULL)) != -1) {
 438                 switch (opt) {
 439                 case 'V':
 440                         version(stdout);
 441                         ret = 0;
 442                         goto end;
 443                 case 'h':
 444                         usage(stdout);
 445                         ret = 0;
 446                         goto end;
 447                 case 'v':
 448                         lttng_opt_verbose += 1;
 449                         break;
 450                 case 'q':
 451                         lttng_opt_quiet = 1;
 452                         break;
 453                 case 'g':
 454                         lttng_set_tracing_group(optarg);
 455                         break;
 456                 case 'n':
 457                         opt_no_sessiond = 1;
 458                         break;
 459                 case OPT_SESSION_PATH:
 460                         opt_sessiond_path = strdup(optarg);
 461                         break;
 462                 case OPT_DUMP_OPTIONS:
 463                         list_options(stdout);
 464                         ret = 0;
 465                         goto end;
 466                 case OPT_DUMP_COMMANDS:
 467                         list_commands(stdout);
 468                         ret = 0;
 469                         goto end;
 470                 default:
 471                         usage(stderr);
 472                         ret = 1;
 473                         goto error;
 474                 }
 475         }
 476
 477         /* If both options are specified, quiet wins */
 478         if (lttng_opt_verbose && lttng_opt_quiet) {
 479                 lttng_opt_verbose = 0;
 480         }
 481
 482         /* Spawn session daemon if needed */
 483         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 484                         (check_sessiond() < 0)) {
 485                 ret = 1;
 486                 goto error;
 487         }
 488
 489         /* No leftovers, print usage and quit */
 490         if ((argc - optind) == 0) {
 491                 usage(stderr);
 492                 ret = 1;
 493                 goto error;
 494         }
 495
 496         /*
 497          * Handle leftovers which is a first level command with the trailing
 498          * options.
 499          */
 500         ret = handle_command(argc - optind, argv + optind);
 501         switch (ret) {
 502         case CMD_WARNING:
 503                 WARN("Some command(s) went wrong");
 504                 break;
 505         case CMD_ERROR:
 506                 ERR("Command error");
 507                 break;
 508         case CMD_UNDEFINED:
 509                 ERR("Undefined command");
 510                 break;
 511         case CMD_FATAL:
 512                 ERR("Fatal error");
 513                 break;
 514         case CMD_UNSUPPORTED:
 515                 ERR("Unsupported command");
 516                 break;
 517         case -1:
 518                 usage(stderr);
 519                 ret = 1;
 520                 break;
 521         case 0:
 522                 break;
 523         default:
 524                 if (ret < 0) {
 525                         ret = -ret;
 526                 }
 527                 break;
 528         }
 529
 530 end:
 531 error:
 532         return ret;
 533 }
 534
 535
 536 /*
 537  *  main
 538  */
 539 int main(int argc, char *argv[])
 540 {
 541         int ret;
 542         char *user;
 543
 544         progname = argv[0] ? argv[0] : "lttng";
 545
 546         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 547         user = getenv("USER");
 548         if (user != NULL && ((strncmp(progname, "drtrace", 7) == 0 ||
 549                                 strncmp("compudj", user, 7) == 0))) {
 550                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 551         }
 552         /* Thanks Mathieu */
 553
 554         ret = set_signal_handler();
 555         if (ret < 0) {
 556                 clean_exit(ret);
 557         }
 558
 559         ret = parse_args(argc, argv);
 560         if (ret != 0) {
 561                 clean_exit(ret);
 562         }
 563
 564         return 0;
 565 }