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         { "view", cmd_view},
  80         { NULL, NULL}   /* Array closure */
  81 };
  82
  83 static void usage(FILE *ofp)
  84 {
  85         fprintf(ofp, "LTTng Trace Control " VERSION"\n\n");
  86         fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND>\n");
  87         fprintf(ofp, "\n");
  88         fprintf(ofp, "Options:\n");
  89         fprintf(ofp, "  -h, --help                 Show this help\n");
  90         fprintf(ofp, "      --list-options         Simple listing of lttng options\n");
  91         fprintf(ofp, "      --list-commands        Simple listing of lttng commands\n");
  92         fprintf(ofp, "  -v, --verbose              Increase verbosity\n");
  93         fprintf(ofp, "  -q, --quiet                Quiet mode\n");
  94         fprintf(ofp, "  -g, --group NAME           Unix tracing group name. (default: tracing)\n");
  95         fprintf(ofp, "  -n, --no-sessiond          Don't spawn a session daemon\n");
  96         fprintf(ofp, "      --sessiond-path PATH   Session daemon full path\n");
  97         fprintf(ofp, "\n");
  98         fprintf(ofp, "Commands:\n");
  99         fprintf(ofp, "    add-context     Add context to event and/or channel\n");
 100         fprintf(ofp, "    calibrate       Quantify LTTng overhead\n");
 101         fprintf(ofp, "    create          Create tracing session\n");
 102         fprintf(ofp, "    destroy         Tear down tracing session\n");
 103         fprintf(ofp, "    enable-channel  Enable tracing channel\n");
 104         fprintf(ofp, "    enable-event    Enable tracing event\n");
 105         fprintf(ofp, "    disable-channel Disable tracing channel\n");
 106         fprintf(ofp, "    disable-event   Disable tracing event\n");
 107         fprintf(ofp, "    list            List possible tracing options\n");
 108         fprintf(ofp, "    set-session     Set current session name\n");
 109         fprintf(ofp, "    start           Start tracing\n");
 110         fprintf(ofp, "    stop            Stop tracing\n");
 111         fprintf(ofp, "    version         Show version information\n");
 112         fprintf(ofp, "    view            Start trace viewer\n");
 113         fprintf(ofp, "\n");
 114         fprintf(ofp, "Each command also has its own -h, --help option.\n");
 115         fprintf(ofp, "\n");
 116         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 117         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 118 }
 119
 120 /*
 121  *  list_options
 122  *
 123  *  List options line by line. This is mostly for bash auto completion and to
 124  *  avoid difficult parsing.
 125  */
 126 static void list_options(FILE *ofp)
 127 {
 128         int i = 0;
 129         struct option *option = NULL;
 130
 131         option = &long_options[i];
 132         while (option->name != NULL) {
 133                 fprintf(ofp, "--%s\n", option->name);
 134
 135                 if (isprint(option->val)) {
 136                         fprintf(ofp, "-%c\n", option->val);
 137                 }
 138
 139                 i++;
 140                 option = &long_options[i];
 141         }
 142 }
 143
 144 /*
 145  *  list_commands
 146  *
 147  *  List commands line by line. This is mostly for bash auto completion and to
 148  *  avoid difficult parsing.
 149  */
 150 static void list_commands(FILE *ofp)
 151 {
 152         int i = 0;
 153         struct cmd_struct *cmd = NULL;
 154
 155         cmd = &commands[i];
 156         while (cmd->name != NULL) {
 157                 fprintf(ofp, "%s\n", cmd->name);
 158                 i++;
 159                 cmd = &commands[i];
 160         }
 161 }
 162
 163 /*
 164  * clean_exit
 165  */
 166 static void clean_exit(int code)
 167 {
 168         DBG("Clean exit");
 169         exit(code);
 170 }
 171
 172 /*
 173  *  sighandler
 174  *
 175  *  Signal handler for the daemon
 176  */
 177 static void sighandler(int sig)
 178 {
 179         int status;
 180
 181         switch (sig) {
 182                 case SIGTERM:
 183                         DBG("SIGTERM caught");
 184                         clean_exit(EXIT_FAILURE);
 185                         break;
 186                 case SIGCHLD:
 187                         DBG("SIGCHLD caught");
 188                         waitpid(sessiond_pid, &status, 0);
 189                         recv_child_signal = 1;
 190                         /* Indicate that the session daemon died */
 191                         sessiond_pid = 0;
 192                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 193                         break;
 194                 case SIGUSR1:
 195                         /* Notify is done */
 196                         recv_child_signal = 1;
 197                         DBG("SIGUSR1 caught");
 198                         break;
 199                 default:
 200                         DBG("Unknown signal %d caught", sig);
 201                         break;
 202         }
 203
 204         return;
 205 }
 206
 207 /*
 208  *  set_signal_handler
 209  *
 210  *  Setup signal handler for SIGCHLD and SIGTERM.
 211  */
 212 static int set_signal_handler(void)
 213 {
 214         int ret = 0;
 215         struct sigaction sa;
 216         sigset_t sigset;
 217
 218         if ((ret = sigemptyset(&sigset)) < 0) {
 219                 perror("sigemptyset");
 220                 goto end;
 221         }
 222
 223         sa.sa_handler = sighandler;
 224         sa.sa_mask = sigset;
 225         sa.sa_flags = 0;
 226         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 227                 perror("sigaction");
 228                 goto end;
 229         }
 230
 231         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 232                 perror("sigaction");
 233                 goto end;
 234         }
 235
 236         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 237                 perror("sigaction");
 238                 goto end;
 239         }
 240
 241 end:
 242         return ret;
 243 }
 244
 245 /*
 246  *  handle_command
 247  *
 248  *  Handle the full argv list of a first level command. Will find the command
 249  *  in the global commands array and call the function callback associated.
 250  *
 251  *  If command not found, return -1
 252  *  else, return function command error code.
 253  */
 254 static int handle_command(int argc, char **argv)
 255 {
 256         int i = 0, ret;
 257         struct cmd_struct *cmd;
 258
 259         if (*argv == NULL) {
 260                 ret = CMD_SUCCESS;
 261                 goto end;
 262         }
 263
 264         cmd = &commands[i];
 265         while (cmd->func != NULL) {
 266                 /* Find command */
 267                 if (strcmp(argv[0], cmd->name) == 0) {
 268                         ret = cmd->func(argc, (const char**) argv);
 269                         goto end;
 270                 }
 271                 i++;
 272                 cmd = &commands[i];
 273         }
 274
 275         /* Command not found */
 276         ret = -1;
 277
 278 end:
 279         return ret;
 280 }
 281
 282 /*
 283  *  spawn_sessiond
 284  *
 285  *  Spawn a session daemon by forking and execv.
 286  */
 287 static int spawn_sessiond(char *pathname)
 288 {
 289         int ret = 0;
 290         pid_t pid;
 291
 292         MSG("Spawning a session daemon");
 293         recv_child_signal = 0;
 294         pid = fork();
 295         if (pid == 0) {
 296                 /*
 297                  * Spawn session daemon and tell
 298                  * it to signal us when ready.
 299                  */
 300                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 301                 /* execlp only returns if error happened */
 302                 if (errno == ENOENT) {
 303                         ERR("No session daemon found. Use --sessiond-path.");
 304                 } else {
 305                         perror("execlp");
 306                 }
 307                 kill(getppid(), SIGTERM);       /* wake parent */
 308                 exit(EXIT_FAILURE);
 309         } else if (pid > 0) {
 310                 sessiond_pid = pid;
 311                 /*
 312                  * Wait for lttng-sessiond to start. We need to use a flag to check if
 313                  * the signal has been sent to us, because the child can be scheduled
 314                  * before the parent, and thus send the signal before this check. In
 315                  * the signal handler, we set the recv_child_signal flag, so anytime we
 316                  * check it after the fork is fine. Note that sleep() is interrupted
 317                  * before the 1 second delay as soon as the signal is received, so it
 318                  * will not cause visible delay for the user.
 319                  */
 320                 while (!recv_child_signal) {
 321                         sleep(1);
 322                 }
 323                 /*
 324                  * The signal handler will nullify sessiond_pid on SIGCHLD
 325                  */
 326                 if (!sessiond_pid) {
 327                         exit(EXIT_FAILURE);
 328                 }
 329                 goto end;
 330         } else {
 331                 perror("fork");
 332                 ret = -1;
 333                 goto end;
 334         }
 335
 336 end:
 337         return ret;
 338 }
 339
 340 /*
 341  *  check_sessiond
 342  *
 343  *  Check if the session daemon is available using
 344  *  the liblttngctl API for the check. If not, try to
 345  *  spawn a daemon.
 346  */
 347 static int check_sessiond(void)
 348 {
 349         int ret;
 350         char *pathname = NULL, *alloc_pathname = NULL;
 351
 352         ret = lttng_session_daemon_alive();
 353         if (ret == 0) { /* not alive */
 354                 /* Try command line option path */
 355                 if (opt_sessiond_path != NULL) {
 356                         ret = access(opt_sessiond_path, F_OK | X_OK);
 357                         if (ret < 0) {
 358                                 ERR("No such file or access denied: %s", opt_sessiond_path);
 359                                 goto end;
 360                         }
 361                         pathname = opt_sessiond_path;
 362                 } else {
 363                         /* Try LTTNG_SESSIOND_PATH env variable */
 364                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 365                 }
 366
 367                 /* Let's rock and roll */
 368                 if (pathname == NULL) {
 369                         ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
 370                         if (ret < 0) {
 371                                 perror("asprintf spawn sessiond");
 372                                 goto end;
 373                         }
 374                         pathname = alloc_pathname;
 375                 }
 376
 377                 ret = spawn_sessiond(pathname);
 378                 free(alloc_pathname);
 379                 if (ret < 0) {
 380                         ERR("Problem occurred when starting %s", pathname);
 381                         goto end;
 382                 }
 383         }
 384
 385 end:
 386         printf("HIT essiond %d\n", ret);
 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                         opt_verbose += 1;
 436                         break;
 437                 case 'q':
 438                         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 (opt_verbose && opt_quiet) {
 466                 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                 ERR("%s", lttng_strerror(ret));
 509                 break;
 510         }
 511
 512 end:
 513 error:
 514         return ret;
 515 }
 516
 517
 518 /*
 519  *  main
 520  */
 521 int main(int argc, char *argv[])
 522 {
 523         int ret;
 524
 525         progname = argv[0] ? argv[0] : "lttng";
 526
 527         /* For Mathieu Desnoyers a.k.a. Dr. Tracing */
 528         if (strncmp(progname, "drtrace", 7) == 0 ||
 529                         strncmp("compudj", getenv("USER"), 7) == 0) {
 530                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 531         }
 532
 533         ret = set_signal_handler();
 534         if (ret < 0) {
 535                 clean_exit(ret);
 536         }
 537
 538         ret = parse_args(argc, argv);
 539         if (ret != 0) {
 540                 clean_exit(ret);
 541         }
 542
 543         return 0;
 544 }