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