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