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                         switch (ret) {
 268                         case CMD_WARNING:
 269                                 WARN("Some command(s) went wrong");
 270                                 break;
 271                         case CMD_ERROR:
 272                                 ERR("Command error");
 273                                 break;
 274                         case CMD_UNDEFINED:
 275                                 ERR("Undefined command");
 276                                 break;
 277                         case CMD_FATAL:
 278                                 ERR("Fatal error");
 279                                 break;
 280                         }
 281                         goto end;
 282                 }
 283                 i++;
 284                 cmd = &commands[i];
 285         }
 286
 287         /* Command not found */
 288         ret = -1;
 289
 290 end:
 291         return ret;
 292 }
 293
 294 /*
 295  *  spawn_sessiond
 296  *
 297  *  Spawn a session daemon by forking and execv.
 298  */
 299 static int spawn_sessiond(char *pathname)
 300 {
 301         int ret = 0;
 302         pid_t pid;
 303
 304         MSG("Spawning a session daemon");
 305         recv_child_signal = 0;
 306         pid = fork();
 307         if (pid == 0) {
 308                 /*
 309                  * Spawn session daemon and tell
 310                  * it to signal us when ready.
 311                  */
 312                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 313                 /* execlp only returns if error happened */
 314                 if (errno == ENOENT) {
 315                         ERR("No session daemon found. Use --sessiond-path.");
 316                 } else {
 317                         perror("execlp");
 318                 }
 319                 kill(getppid(), SIGTERM);       /* wake parent */
 320                 exit(EXIT_FAILURE);
 321         } else if (pid > 0) {
 322                 sessiond_pid = pid;
 323                 /*
 324                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 325                  * the signal has been sent to us, because the child can be scheduled
 326                  * before the parent, and thus send the signal before this check. In
 327                  * the signal handler, we set the recv_child_signal flag, so anytime we
 328                  * check it after the fork is fine. Note that sleep() is interrupted
 329                  * before the 1 second delay as soon as the signal is received, so it
 330                  * will not cause visible delay for the user.
 331                  */
 332                 while (!recv_child_signal) {
 333                         sleep(1);
 334                 }
 335                 /*
 336                  * The signal handler will nullify sessiond_pid on SIGCHLD
 337                  */
 338                 if (!sessiond_pid) {
 339                         exit(EXIT_FAILURE);
 340                 }
 341                 goto end;
 342         } else {
 343                 perror("fork");
 344                 ret = -1;
 345                 goto end;
 346         }
 347
 348 end:
 349         return ret;
 350 }
 351
 352 /*
 353  *  check_sessiond
 354  *
 355  *  Check if the session daemon is available using
 356  *  the liblttngctl API for the check. If not, try to
 357  *  spawn a daemon.
 358  */
 359 static int check_sessiond(void)
 360 {
 361         int ret;
 362         char *pathname = NULL, *alloc_pathname = NULL;
 363
 364         ret = lttng_session_daemon_alive();
 365         if (ret == 0) { /* not alive */
 366                 /* Try command line option path */
 367                 if (opt_sessiond_path != NULL) {
 368                         ret = access(opt_sessiond_path, F_OK | X_OK);
 369                         if (ret < 0) {
 370                                 ERR("No such file or access denied: %s", opt_sessiond_path);
 371                                 goto end;
 372                         }
 373                         pathname = opt_sessiond_path;
 374                 } else {
 375                         /* Try LTTNG_SESSIOND_PATH env variable */
 376                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 377                 }
 378
 379                 /* Let's rock and roll */
 380                 if (pathname == NULL) {
 381                         ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
 382                         if (ret < 0) {
 383                                 perror("asprintf spawn sessiond");
 384                                 goto end;
 385                         }
 386                         pathname = alloc_pathname;
 387                 }
 388
 389                 ret = spawn_sessiond(pathname);
 390                 free(alloc_pathname);
 391                 if (ret < 0) {
 392                         ERR("Problem occurred when starting %s", pathname);
 393                         goto end;
 394                 }
 395         }
 396
 397 end:
 398         return ret;
 399 }
 400
 401 /*
 402  * Check args for specific options that *must* not trigger a session daemon
 403  * execution.
 404  *
 405  * Return 1 if match else 0.
 406  */
 407 static int check_args_no_sessiond(int argc, char **argv)
 408 {
 409         int i;
 410
 411         for (i = 0; i < argc; i++) {
 412                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 413                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 414                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0 ||
 415                                 strncmp(argv[i], "--list-commands", sizeof("--list-commands")) == 0 ||
 416                                 strncmp(argv[i], "version", sizeof("version"))) {
 417                         return 1;
 418                 }
 419         }
 420
 421         return 0;
 422 }
 423
 424 /*
 425  * Parse command line arguments.
 426  *
 427  * Return 0 if OK, else -1
 428  */
 429 static int parse_args(int argc, char **argv)
 430 {
 431         int opt, ret;
 432
 433         if (argc < 2) {
 434                 usage(stderr);
 435                 clean_exit(EXIT_FAILURE);
 436         }
 437
 438         while ((opt = getopt_long(argc, argv, "+hnvqg:", long_options, NULL)) != -1) {
 439                 switch (opt) {
 440                 case 'h':
 441                         usage(stdout);
 442                         goto end;
 443                 case 'v':
 444                         opt_verbose += 1;
 445                         break;
 446                 case 'q':
 447                         opt_quiet = 1;
 448                         break;
 449                 case 'g':
 450                         lttng_set_tracing_group(optarg);
 451                         break;
 452                 case 'n':
 453                         opt_no_sessiond = 1;
 454                         break;
 455                 case OPT_SESSION_PATH:
 456                         opt_sessiond_path = strdup(optarg);
 457                         break;
 458                 case OPT_DUMP_OPTIONS:
 459                         list_options(stdout);
 460                         ret = 0;
 461                         goto end;
 462                 case OPT_DUMP_COMMANDS:
 463                         list_commands(stdout);
 464                         ret = 0;
 465                         goto end;
 466                 default:
 467                         usage(stderr);
 468                         goto error;
 469                 }
 470         }
 471
 472         /* If both options are specified, quiet wins */
 473         if (opt_verbose && opt_quiet) {
 474                 opt_verbose = 0;
 475         }
 476
 477         /* Spawn session daemon if needed */
 478         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 479                         (check_sessiond() < 0)) {
 480                 goto error;
 481         }
 482
 483         /* No leftovers, print usage and quit */
 484         if ((argc - optind) == 0) {
 485                 usage(stderr);
 486                 goto error;
 487         }
 488
 489         /*
 490          * Handle leftovers which is a first level command with the trailing
 491          * options.
 492          */
 493         ret = handle_command(argc - optind, argv + optind);
 494         if (ret < 0) {
 495                 if (ret == -1) {
 496                         usage(stderr);
 497                 } else {
 498                         ERR("%s", lttng_strerror(ret));
 499                 }
 500                 goto error;
 501         }
 502
 503 end:
 504         return 0;
 505
 506 error:
 507         return -1;
 508 }
 509
 510
 511 /*
 512  *  main
 513  */
 514 int main(int argc, char *argv[])
 515 {
 516         int ret;
 517
 518         progname = argv[0] ? argv[0] : "lttng";
 519
 520         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 521         if (strncmp(progname, "drtrace", 7) == 0 ||
 522                         strncmp("compudj", getenv("USER"), 7) == 0) {
 523                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 524         }
 525
 526         ret = set_signal_handler();
 527         if (ret < 0) {
 528                 clean_exit(ret);
 529         }
 530
 531         ret = parse_args(argc, argv);
 532         if (ret < 0) {
 533                 clean_exit(EXIT_FAILURE);
 534         }
 535
 536         return 0;
 537 }