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         { NULL, NULL}   /* Array closure */
  78 };
  79
  80 static void usage(FILE *ofp)
  81 {
  82         fprintf(ofp, "LTTng Trace Control " VERSION" - " VERSION_NAME"\n\n");
  83         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND>\n");
  84         fprintf(ofp, "\n");
  85         fprintf(ofp, "Options:\n");
  86         fprintf(ofp, "  -h, --help                 Show this help\n");
  87         fprintf(ofp, "      --list-options         Simple listing of lttng options\n");
  88         fprintf(ofp, "      --list-commands        Simple listing of lttng commands\n");
  89         fprintf(ofp, "  -v, --verbose              Increase verbosity\n");
  90         fprintf(ofp, "  -q, --quiet                Quiet mode\n");
  91         fprintf(ofp, "  -g, --group NAME           Unix tracing group name. (default: tracing)\n");
  92         fprintf(ofp, "  -n, --no-sessiond          Don't spawn a session daemon\n");
  93         fprintf(ofp, "      --sessiond-path PATH   Session daemon full path\n");
  94         fprintf(ofp, "\n");
  95         fprintf(ofp, "Commands:\n");
  96         fprintf(ofp, "    add-context     Add context to event and/or channel\n");
  97         fprintf(ofp, "    calibrate       Quantify LTTng overhead\n");
  98         fprintf(ofp, "    create          Create tracing session\n");
  99         fprintf(ofp, "    destroy         Tear down tracing session\n");
 100         fprintf(ofp, "    enable-channel  Enable tracing channel\n");
 101         fprintf(ofp, "    enable-event    Enable tracing event\n");
 102         fprintf(ofp, "    disable-channel Disable tracing channel\n");
 103         fprintf(ofp, "    disable-event   Disable tracing event\n");
 104         fprintf(ofp, "    list            List possible tracing options\n");
 105         fprintf(ofp, "    set-session     Set current session name\n");
 106         fprintf(ofp, "    start           Start tracing\n");
 107         fprintf(ofp, "    stop            Stop tracing\n");
 108         fprintf(ofp, "    version         Show version information\n");
 109         fprintf(ofp, "    view            Start trace viewer\n");
 110         fprintf(ofp, "\n");
 111         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 112         fprintf(ofp, "\n");
 113         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 114         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 115 }
 116
 117 /*
 118  *  list_options
 119  *
 120  *  List options line by line. This is mostly for bash auto completion and to
 121  *  avoid difficult parsing.
 122  */
 123 static void list_options(FILE *ofp)
 124 {
 125         int i = 0;
 126         struct option *option = NULL;
 127
 128         option = &long_options[i];
 129         while (option->name != NULL) {
 130                 fprintf(ofp, "--%s\n", option->name);
 131
 132                 if (isprint(option->val)) {
 133                         fprintf(ofp, "-%c\n", option->val);
 134                 }
 135
 136                 i++;
 137                 option = &long_options[i];
 138         }
 139 }
 140
 141 /*
 142  *  list_commands
 143  *
 144  *  List commands line by line. This is mostly for bash auto completion and to
 145  *  avoid difficult parsing.
 146  */
 147 static void list_commands(FILE *ofp)
 148 {
 149         int i = 0;
 150         struct cmd_struct *cmd = NULL;
 151
 152         cmd = &commands[i];
 153         while (cmd->name != NULL) {
 154                 fprintf(ofp, "%s\n", cmd->name);
 155                 i++;
 156                 cmd = &commands[i];
 157         }
 158 }
 159
 160 /*
 161  * clean_exit
 162  */
 163 static void clean_exit(int code)
 164 {
 165         DBG("Clean exit");
 166         exit(code);
 167 }
 168
 169 /*
 170  *  sighandler
 171  *
 172  *  Signal handler for the daemon
 173  */
 174 static void sighandler(int sig)
 175 {
 176         int status;
 177
 178         switch (sig) {
 179                 case SIGTERM:
 180                         DBG("SIGTERM caught");
 181                         clean_exit(EXIT_FAILURE);
 182                         break;
 183                 case SIGCHLD:
 184                         DBG("SIGCHLD caught");
 185                         waitpid(sessiond_pid, &status, 0);
 186                         recv_child_signal = 1;
 187                         /* Indicate that the session daemon died */
 188                         sessiond_pid = 0;
 189                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 190                         break;
 191                 case SIGUSR1:
 192                         /* Notify is done */
 193                         recv_child_signal = 1;
 194                         DBG("SIGUSR1 caught");
 195                         break;
 196                 default:
 197                         DBG("Unknown signal %d caught", sig);
 198                         break;
 199         }
 200
 201         return;
 202 }
 203
 204 /*
 205  *  set_signal_handler
 206  *
 207  *  Setup signal handler for SIGCHLD and SIGTERM.
 208  */
 209 static int set_signal_handler(void)
 210 {
 211         int ret = 0;
 212         struct sigaction sa;
 213         sigset_t sigset;
 214
 215         if ((ret = sigemptyset(&sigset)) < 0) {
 216                 perror("sigemptyset");
 217                 goto end;
 218         }
 219
 220         sa.sa_handler = sighandler;
 221         sa.sa_mask = sigset;
 222         sa.sa_flags = 0;
 223         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 224                 perror("sigaction");
 225                 goto end;
 226         }
 227
 228         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 229                 perror("sigaction");
 230                 goto end;
 231         }
 232
 233         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 234                 perror("sigaction");
 235                 goto end;
 236         }
 237
 238 end:
 239         return ret;
 240 }
 241
 242 /*
 243  *  handle_command
 244  *
 245  *  Handle the full argv list of a first level command. Will find the command
 246  *  in the global commands array and call the function callback associated.
 247  *
 248  *  If command not found, return -1
 249  *  else, return function command error code.
 250  */
 251 static int handle_command(int argc, char **argv)
 252 {
 253         int i = 0, ret;
 254         struct cmd_struct *cmd;
 255
 256         if (*argv == NULL) {
 257                 ret = CMD_SUCCESS;
 258                 goto end;
 259         }
 260
 261         cmd = &commands[i];
 262         while (cmd->func != NULL) {
 263                 /* Find command */
 264                 if (strcmp(argv[0], cmd->name) == 0) {
 265                         ret = cmd->func(argc, (const char**) argv);
 266                         goto end;
 267                 }
 268                 i++;
 269                 cmd = &commands[i];
 270         }
 271
 272         /* Command not found */
 273         ret = -1;
 274
 275 end:
 276         return ret;
 277 }
 278
 279 /*
 280  *  spawn_sessiond
 281  *
 282  *  Spawn a session daemon by forking and execv.
 283  */
 284 static int spawn_sessiond(char *pathname)
 285 {
 286         int ret = 0;
 287         pid_t pid;
 288
 289         MSG("Spawning a session daemon");
 290         recv_child_signal = 0;
 291         pid = fork();
 292         if (pid == 0) {
 293                 /*
 294                  * Spawn session daemon and tell
 295                  * it to signal us when ready.
 296                  */
 297                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 298                 /* execlp only returns if error happened */
 299                 if (errno == ENOENT) {
 300                         ERR("No session daemon found. Use --sessiond-path.");
 301                 } else {
 302                         perror("execlp");
 303                 }
 304                 kill(getppid(), SIGTERM);       /* wake parent */
 305                 exit(EXIT_FAILURE);
 306         } else if (pid > 0) {
 307                 sessiond_pid = pid;
 308                 /*
 309                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 310                  * the signal has been sent to us, because the child can be scheduled
 311                  * before the parent, and thus send the signal before this check. In
 312                  * the signal handler, we set the recv_child_signal flag, so anytime we
 313                  * check it after the fork is fine. Note that sleep() is interrupted
 314                  * before the 1 second delay as soon as the signal is received, so it
 315                  * will not cause visible delay for the user.
 316                  */
 317                 while (!recv_child_signal) {
 318                         sleep(1);
 319                 }
 320                 /*
 321                  * The signal handler will nullify sessiond_pid on SIGCHLD
 322                  */
 323                 if (!sessiond_pid) {
 324                         exit(EXIT_FAILURE);
 325                 }
 326                 goto end;
 327         } else {
 328                 perror("fork");
 329                 ret = -1;
 330                 goto end;
 331         }
 332
 333 end:
 334         return ret;
 335 }
 336
 337 /*
 338  *  check_sessiond
 339  *
 340  *  Check if the session daemon is available using
 341  *  the liblttngctl API for the check. If not, try to
 342  *  spawn a daemon.
 343  */
 344 static int check_sessiond(void)
 345 {
 346         int ret;
 347         char *pathname = NULL, *alloc_pathname = NULL;
 348
 349         ret = lttng_session_daemon_alive();
 350         if (ret == 0) { /* not alive */
 351                 /* Try command line option path */
 352                 if (opt_sessiond_path != NULL) {
 353                         ret = access(opt_sessiond_path, F_OK | X_OK);
 354                         if (ret < 0) {
 355                                 ERR("No such file or access denied: %s", opt_sessiond_path);
 356                                 goto end;
 357                         }
 358                         pathname = opt_sessiond_path;
 359                 } else {
 360                         /* Try LTTNG_SESSIOND_PATH env variable */
 361                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 362                 }
 363
 364                 /* Let's rock and roll */
 365                 if (pathname == NULL) {
 366                         ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
 367                         if (ret < 0) {
 368                                 perror("asprintf spawn sessiond");
 369                                 goto end;
 370                         }
 371                         pathname = alloc_pathname;
 372                 }
 373
 374                 ret = spawn_sessiond(pathname);
 375                 free(alloc_pathname);
 376                 if (ret < 0) {
 377                         ERR("Problem occurred when starting %s", pathname);
 378                         goto end;
 379                 }
 380         }
 381
 382 end:
 383         return ret;
 384 }
 385
 386 /*
 387  * Check args for specific options that *must* not trigger a session daemon
 388  * execution.
 389  *
 390  * Return 1 if match else 0.
 391  */
 392 static int check_args_no_sessiond(int argc, char **argv)
 393 {
 394         int i;
 395
 396         for (i = 0; i < argc; i++) {
 397                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 398                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 399                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 400                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 401                                 strncmp(argv[i], "version", sizeof("version")) == 0 ||
 402                                 strncmp(argv[i], "view", sizeof("view")) == 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                         lttng_opt_verbose += 1;
 432                         break;
 433                 case 'q':
 434                         lttng_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 (lttng_opt_verbose && lttng_opt_quiet) {
 462                 lttng_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                 if (ret < 0) {
 505                         ret = -ret;
 506                 }
 507                 break;
 508         }
 509
 510 end:
 511 error:
 512         return ret;
 513 }
 514
 515
 516 /*
 517  *  main
 518  */
 519 int main(int argc, char *argv[])
 520 {
 521         int ret;
 522
 523         progname = argv[0] ? argv[0] : "lttng";
 524
 525         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 526         if (strncmp(progname, "drtrace", 7) == 0 ||
 527                         strncmp("compudj", getenv("USER"), 7) == 0) {
 528                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 529         }
 530
 531         ret = set_signal_handler();
 532         if (ret < 0) {
 533                 clean_exit(ret);
 534         }
 535
 536         ret = parse_args(argc, argv);
 537         if (ret != 0) {
 538                 clean_exit(ret);
 539         }
 540
 541         return 0;
 542 }