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         {"help",             0, NULL, 'h'},
  51         {"group",            1, NULL, 'g'},
  52         {"verbose",          0, NULL, 'v'},
  53         {"quiet",            0, NULL, 'q'},
  54         {"no-sessiond",      0, NULL, 'n'},
  55         {"sessiond-path",    1, NULL, OPT_SESSION_PATH},
  56         {"list-options",     0, NULL, OPT_DUMP_OPTIONS},
  57         {"list-commands",    0, NULL, OPT_DUMP_COMMANDS},
  58         {NULL, 0, NULL, 0}
  59 };
  60
  61 /* First level command */
  62 static struct cmd_struct commands[] =  {
  63         { "list", cmd_list},
  64         { "create", cmd_create},
  65         { "destroy", cmd_destroy},
  66         { "start", cmd_start},
  67         { "stop", cmd_stop},
  68         { "enable-event", cmd_enable_events},
  69         { "disable-event", cmd_disable_events},
  70         { "enable-channel", cmd_enable_channels},
  71         { "disable-channel", cmd_disable_channels},
  72         { "add-context", cmd_add_context},
  73         { "set-session", cmd_set_session},
  74         { "version", cmd_version},
  75         { "calibrate", cmd_calibrate},
  76         { "view", cmd_view},
  77         { "enable-consumer", cmd_enable_consumer}, /* OBSELETE */
  78         { "disable-consumer", cmd_disable_consumer}, /*OBSELETE */
  79         { NULL, NULL}   /* Array closure */
  80 };
  81
  82 static void usage(FILE *ofp)
  83 {
  84         fprintf(ofp, "LTTng Trace Control " VERSION" - " VERSION_NAME"\n\n");
  85         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND> [<ARGS>]\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, "    view              Start trace viewer\n");
 112         fprintf(ofp, "\n");
 113         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 114         fprintf(ofp, "\n");
 115         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 116         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 117 }
 118
 119 /*
 120  *  list_options
 121  *
 122  *  List options line by line. This is mostly for bash auto completion and to
 123  *  avoid difficult parsing.
 124  */
 125 static void list_options(FILE *ofp)
 126 {
 127         int i = 0;
 128         struct option *option = NULL;
 129
 130         option = &long_options[i];
 131         while (option->name != NULL) {
 132                 fprintf(ofp, "--%s\n", option->name);
 133
 134                 if (isprint(option->val)) {
 135                         fprintf(ofp, "-%c\n", option->val);
 136                 }
 137
 138                 i++;
 139                 option = &long_options[i];
 140         }
 141 }
 142
 143 /*
 144  *  list_commands
 145  *
 146  *  List commands line by line. This is mostly for bash auto completion and to
 147  *  avoid difficult parsing.
 148  */
 149 static void list_commands(FILE *ofp)
 150 {
 151         int i = 0;
 152         struct cmd_struct *cmd = NULL;
 153
 154         cmd = &commands[i];
 155         while (cmd->name != NULL) {
 156                 fprintf(ofp, "%s\n", cmd->name);
 157                 i++;
 158                 cmd = &commands[i];
 159         }
 160 }
 161
 162 /*
 163  * clean_exit
 164  */
 165 static void clean_exit(int code)
 166 {
 167         DBG("Clean exit");
 168         exit(code);
 169 }
 170
 171 /*
 172  *  sighandler
 173  *
 174  *  Signal handler for the daemon
 175  */
 176 static void sighandler(int sig)
 177 {
 178         int status;
 179
 180         switch (sig) {
 181                 case SIGTERM:
 182                         DBG("SIGTERM caught");
 183                         clean_exit(EXIT_FAILURE);
 184                         break;
 185                 case SIGCHLD:
 186                         DBG("SIGCHLD caught");
 187                         waitpid(sessiond_pid, &status, 0);
 188                         recv_child_signal = 1;
 189                         /* Indicate that the session daemon died */
 190                         sessiond_pid = 0;
 191                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 192                         break;
 193                 case SIGUSR1:
 194                         /* Notify is done */
 195                         recv_child_signal = 1;
 196                         DBG("SIGUSR1 caught");
 197                         break;
 198                 default:
 199                         DBG("Unknown signal %d caught", sig);
 200                         break;
 201         }
 202
 203         return;
 204 }
 205
 206 /*
 207  *  set_signal_handler
 208  *
 209  *  Setup signal handler for SIGCHLD and SIGTERM.
 210  */
 211 static int set_signal_handler(void)
 212 {
 213         int ret = 0;
 214         struct sigaction sa;
 215         sigset_t sigset;
 216
 217         if ((ret = sigemptyset(&sigset)) < 0) {
 218                 perror("sigemptyset");
 219                 goto end;
 220         }
 221
 222         sa.sa_handler = sighandler;
 223         sa.sa_mask = sigset;
 224         sa.sa_flags = 0;
 225         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 226                 perror("sigaction");
 227                 goto end;
 228         }
 229
 230         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 231                 perror("sigaction");
 232                 goto end;
 233         }
 234
 235         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 236                 perror("sigaction");
 237                 goto end;
 238         }
 239
 240 end:
 241         return ret;
 242 }
 243
 244 /*
 245  *  handle_command
 246  *
 247  *  Handle the full argv list of a first level command. Will find the command
 248  *  in the global commands array and call the function callback associated.
 249  *
 250  *  If command not found, return -1
 251  *  else, return function command error code.
 252  */
 253 static int handle_command(int argc, char **argv)
 254 {
 255         int i = 0, ret;
 256         struct cmd_struct *cmd;
 257
 258         if (*argv == NULL) {
 259                 ret = CMD_SUCCESS;
 260                 goto end;
 261         }
 262
 263         cmd = &commands[i];
 264         while (cmd->func != NULL) {
 265                 /* Find command */
 266                 if (strcmp(argv[0], cmd->name) == 0) {
 267                         ret = cmd->func(argc, (const char**) argv);
 268                         goto end;
 269                 }
 270                 i++;
 271                 cmd = &commands[i];
 272         }
 273
 274         /* Command not found */
 275         ret = -1;
 276
 277 end:
 278         return ret;
 279 }
 280
 281 /*
 282  *  spawn_sessiond
 283  *
 284  *  Spawn a session daemon by forking and execv.
 285  */
 286 static int spawn_sessiond(char *pathname)
 287 {
 288         int ret = 0;
 289         pid_t pid;
 290
 291         MSG("Spawning a session daemon");
 292         recv_child_signal = 0;
 293         pid = fork();
 294         if (pid == 0) {
 295                 /*
 296                  * Spawn session daemon and tell
 297                  * it to signal us when ready.
 298                  */
 299                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 300                 /* execlp only returns if error happened */
 301                 if (errno == ENOENT) {
 302                         ERR("No session daemon found. Use --sessiond-path.");
 303                 } else {
 304                         perror("execlp");
 305                 }
 306                 kill(getppid(), SIGTERM);       /* wake parent */
 307                 exit(EXIT_FAILURE);
 308         } else if (pid > 0) {
 309                 sessiond_pid = pid;
 310                 /*
 311                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 312                  * the signal has been sent to us, because the child can be scheduled
 313                  * before the parent, and thus send the signal before this check. In
 314                  * the signal handler, we set the recv_child_signal flag, so anytime we
 315                  * check it after the fork is fine. Note that sleep() is interrupted
 316                  * before the 1 second delay as soon as the signal is received, so it
 317                  * will not cause visible delay for the user.
 318                  */
 319                 while (!recv_child_signal) {
 320                         sleep(1);
 321                 }
 322                 /*
 323                  * The signal handler will nullify sessiond_pid on SIGCHLD
 324                  */
 325                 if (!sessiond_pid) {
 326                         exit(EXIT_FAILURE);
 327                 }
 328                 goto end;
 329         } else {
 330                 perror("fork");
 331                 ret = -1;
 332                 goto end;
 333         }
 334
 335 end:
 336         return ret;
 337 }
 338
 339 /*
 340  *  check_sessiond
 341  *
 342  *  Check if the session daemon is available using
 343  *  the liblttngctl API for the check. If not, try to
 344  *  spawn a daemon.
 345  */
 346 static int check_sessiond(void)
 347 {
 348         int ret;
 349         char *pathname = NULL, *alloc_pathname = NULL;
 350
 351         ret = lttng_session_daemon_alive();
 352         if (ret == 0) { /* not alive */
 353                 /* Try command line option path */
 354                 if (opt_sessiond_path != NULL) {
 355                         ret = access(opt_sessiond_path, F_OK | X_OK);
 356                         if (ret < 0) {
 357                                 ERR("No such file or access denied: %s", opt_sessiond_path);
 358                                 goto end;
 359                         }
 360                         pathname = opt_sessiond_path;
 361                 } else {
 362                         /* Try LTTNG_SESSIOND_PATH env variable */
 363                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 364                 }
 365
 366                 /* Let's rock and roll */
 367                 if (pathname == NULL) {
 368                         ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
 369                         if (ret < 0) {
 370                                 perror("asprintf spawn sessiond");
 371                                 goto end;
 372                         }
 373                         pathname = alloc_pathname;
 374                 }
 375
 376                 ret = spawn_sessiond(pathname);
 377                 if (ret < 0) {
 378                         ERR("Problem occurred when starting %s", pathname);
 379                 }
 380
 381                 free(alloc_pathname);
 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                                 strncmp(argv[i], "view", sizeof("view")) == 0) {
 404                         return 1;
 405                 }
 406         }
 407
 408         return 0;
 409 }
 410
 411 /*
 412  * Parse command line arguments.
 413  *
 414  * Return 0 if OK, else -1
 415  */
 416 static int parse_args(int argc, char **argv)
 417 {
 418         int opt, ret;
 419
 420         if (argc < 2) {
 421                 usage(stderr);
 422                 clean_exit(EXIT_FAILURE);
 423         }
 424
 425         while ((opt = getopt_long(argc, argv, "+hnvqg:", long_options, NULL)) != -1) {
 426                 switch (opt) {
 427                 case 'h':
 428                         usage(stdout);
 429                         ret = 0;
 430                         goto end;
 431                 case 'v':
 432                         lttng_opt_verbose += 1;
 433                         break;
 434                 case 'q':
 435                         lttng_opt_quiet = 1;
 436                         break;
 437                 case 'g':
 438                         lttng_set_tracing_group(optarg);
 439                         break;
 440                 case 'n':
 441                         opt_no_sessiond = 1;
 442                         break;
 443                 case OPT_SESSION_PATH:
 444                         opt_sessiond_path = strdup(optarg);
 445                         break;
 446                 case OPT_DUMP_OPTIONS:
 447                         list_options(stdout);
 448                         ret = 0;
 449                         goto end;
 450                 case OPT_DUMP_COMMANDS:
 451                         list_commands(stdout);
 452                         ret = 0;
 453                         goto end;
 454                 default:
 455                         usage(stderr);
 456                         ret = 1;
 457                         goto error;
 458                 }
 459         }
 460
 461         /* If both options are specified, quiet wins */
 462         if (lttng_opt_verbose && lttng_opt_quiet) {
 463                 lttng_opt_verbose = 0;
 464         }
 465
 466         /* Spawn session daemon if needed */
 467         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 468                         (check_sessiond() < 0)) {
 469                 ret = 1;
 470                 goto error;
 471         }
 472
 473         /* No leftovers, print usage and quit */
 474         if ((argc - optind) == 0) {
 475                 usage(stderr);
 476                 ret = 1;
 477                 goto error;
 478         }
 479
 480         /*
 481          * Handle leftovers which is a first level command with the trailing
 482          * options.
 483          */
 484         ret = handle_command(argc - optind, argv + optind);
 485         switch (ret) {
 486         case CMD_WARNING:
 487                 WARN("Some command(s) went wrong");
 488                 break;
 489         case CMD_ERROR:
 490                 ERR("Command error");
 491                 break;
 492         case CMD_UNDEFINED:
 493                 ERR("Undefined command");
 494                 break;
 495         case CMD_FATAL:
 496                 ERR("Fatal error");
 497                 break;
 498         case -1:
 499                 usage(stderr);
 500                 ret = 1;
 501                 break;
 502         case 0:
 503                 break;
 504         default:
 505                 if (ret < 0) {
 506                         ret = -ret;
 507                 }
 508                 break;
 509         }
 510
 511 end:
 512 error:
 513         return ret;
 514 }
 515
 516
 517 /*
 518  *  main
 519  */
 520 int main(int argc, char *argv[])
 521 {
 522         int ret;
 523         char *user;
 524
 525         progname = argv[0] ? argv[0] : "lttng";
 526
 527         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 528         user = getenv("USER");
 529         if (user != NULL && ((strncmp(progname, "drtrace", 7) == 0 ||
 530                                 strncmp("compudj", user, 7) == 0))) {
 531                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 532         }
 533         /* Thanks Mathieu */
 534
 535         ret = set_signal_handler();
 536         if (ret < 0) {
 537                 clean_exit(ret);
 538         }
 539
 540         ret = parse_args(argc, argv);
 541         if (ret != 0) {
 542                 clean_exit(ret);
 543         }
 544
 545         return 0;
 546 }