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