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, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
  90         fprintf(ofp, "  -v, --verbose          Verbose mode\n");
  91         fprintf(ofp, "  -q, --quiet            Quiet mode\n");
  92         fprintf(ofp, "  -n, --no-sessiond      Don't spawn a session daemon\n");
  93         fprintf(ofp, "      --sessiond-path    Session daemon full path\n");
  94         fprintf(ofp, "      --list-options     Simple listing of lttng options\n");
  95         fprintf(ofp, "      --list-commands    Simple listing of lttng commands\n");
  96         fprintf(ofp, "\n");
  97         fprintf(ofp, "Commands:\n");
  98         fprintf(ofp, "    add-context     Add context to event or/and channel\n");
  99         fprintf(ofp, "    calibrate       Quantify LTTng overhead\n");
 100         fprintf(ofp, "    create          Create tracing session\n");
 101         fprintf(ofp, "    destroy         Teardown 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, "Please see the lttng(1) man page for full documentation.\n");
 113         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 114 }
 115
 116 /*
 117  *  list_options
 118  *
 119  *  List options line by line. This is mostly for bash auto completion and to
 120  *  avoid difficult parsing.
 121  */
 122 static void list_options(FILE *ofp)
 123 {
 124         int i = 0;
 125         struct option *option = NULL;
 126
 127         option = &long_options[i];
 128         while (option->name != NULL) {
 129                 fprintf(ofp, "--%s\n", option->name);
 130
 131                 if (isprint(option->val)) {
 132                         fprintf(ofp, "-%c\n", option->val);
 133                 }
 134
 135                 i++;
 136                 option = &long_options[i];
 137         }
 138 }
 139
 140 /*
 141  *  list_commands
 142  *
 143  *  List commands line by line. This is mostly for bash auto completion and to
 144  *  avoid difficult parsing.
 145  */
 146 static void list_commands(FILE *ofp)
 147 {
 148         int i = 0;
 149         struct cmd_struct *cmd = NULL;
 150
 151         cmd = &commands[i];
 152         while (cmd->name != NULL) {
 153                 fprintf(ofp, "%s\n", cmd->name);
 154                 i++;
 155                 cmd = &commands[i];
 156         }
 157 }
 158
 159 /*
 160  * clean_exit
 161  */
 162 static void clean_exit(int code)
 163 {
 164         DBG("Clean exit");
 165         exit(code);
 166 }
 167
 168 /*
 169  *  sighandler
 170  *
 171  *  Signal handler for the daemon
 172  */
 173 static void sighandler(int sig)
 174 {
 175         int status;
 176
 177         switch (sig) {
 178                 case SIGTERM:
 179                         DBG("SIGTERM caugth");
 180                         clean_exit(EXIT_FAILURE);
 181                         break;
 182                 case SIGCHLD:
 183                         DBG("SIGCHLD caugth");
 184                         waitpid(sessiond_pid, &status, 0);
 185                         recv_child_signal = 1;
 186                         /* Indicate that the session daemon died */
 187                         sessiond_pid = 0;
 188                         ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 189                         break;
 190                 case SIGUSR1:
 191                         /* Notify is done */
 192                         recv_child_signal = 1;
 193                         DBG("SIGUSR1 caugth");
 194                         break;
 195                 default:
 196                         DBG("Unknown signal %d caugth", sig);
 197                         break;
 198         }
 199
 200         return;
 201 }
 202
 203 /*
 204  *  set_signal_handler
 205  *
 206  *  Setup signal handler for SIGCHLD and SIGTERM.
 207  */
 208 static int set_signal_handler(void)
 209 {
 210         int ret = 0;
 211         struct sigaction sa;
 212         sigset_t sigset;
 213
 214         if ((ret = sigemptyset(&sigset)) < 0) {
 215                 perror("sigemptyset");
 216                 goto end;
 217         }
 218
 219         sa.sa_handler = sighandler;
 220         sa.sa_mask = sigset;
 221         sa.sa_flags = 0;
 222         if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
 223                 perror("sigaction");
 224                 goto end;
 225         }
 226
 227         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 228                 perror("sigaction");
 229                 goto end;
 230         }
 231
 232         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 233                 perror("sigaction");
 234                 goto end;
 235         }
 236
 237 end:
 238         return ret;
 239 }
 240
 241 /*
 242  *  handle_command
 243  *
 244  *  Handle the full argv list of a first level command. Will find the command
 245  *  in the global commands array and call the function callback associated.
 246  *
 247  *  If command not found, return -1
 248  *  else, return function command error code.
 249  */
 250 static int handle_command(int argc, char **argv)
 251 {
 252         int i = 0, ret;
 253         struct cmd_struct *cmd;
 254
 255         if (*argv == NULL) {
 256                 ret = CMD_SUCCESS;
 257                 goto end;
 258         }
 259
 260         cmd = &commands[i];
 261         while (cmd->func != NULL) {
 262                 /* Find command */
 263                 if (strcmp(argv[0], cmd->name) == 0) {
 264                         ret = cmd->func(argc, (const char**) argv);
 265                         switch (ret) {
 266                         case CMD_ERROR:
 267                                 ERR("Command error");
 268                                 break;
 269                         case CMD_UNDEFINED:
 270                                 ERR("Undefined command");
 271                                 break;
 272                         case CMD_FATAL:
 273                                 ERR("Fatal error");
 274                                 break;
 275                         }
 276                         goto end;
 277                 }
 278                 i++;
 279                 cmd = &commands[i];
 280         }
 281
 282         /* Command not found */
 283         ret = -1;
 284
 285 end:
 286         return ret;
 287 }
 288
 289 /*
 290  *  spawn_sessiond
 291  *
 292  *  Spawn a session daemon by forking and execv.
 293  */
 294 static int spawn_sessiond(char *pathname)
 295 {
 296         int ret = 0;
 297         pid_t pid;
 298
 299         MSG("Spawning a session daemon");
 300         recv_child_signal = 0;
 301         pid = fork();
 302         if (pid == 0) {
 303                 /*
 304                  * Spawn session daemon and tell
 305                  * it to signal us when ready.
 306                  */
 307                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 308                 /* execlp only returns if error happened */
 309                 if (errno == ENOENT) {
 310                         ERR("No session daemon found. Use --sessiond-path.");
 311                 } else {
 312                         perror("execlp");
 313                 }
 314                 kill(getppid(), SIGTERM);       /* wake parent */
 315                 exit(EXIT_FAILURE);
 316         } else if (pid > 0) {
 317                 sessiond_pid = pid;
 318                 /*
 319                  * Wait for lttng-sessiond to start. We need to use a
 320                  * flag to check if the signal has been sent to us,
 321                  * because the child can be scheduled before the parent,
 322                  * and thus send the signal before this check. In the
 323                  * signal handler, we set the recv_child_signal flag, so
 324                  * anytime we check it after the fork is fine. Note that
 325                  * sleep() is interrupted before the 1 second delay as
 326                  * soon as the signal is received, so it will not cause
 327                  * visible delay for the user.
 328                  */
 329                 while (!recv_child_signal) {
 330                         sleep(1);
 331                 }
 332                 if (!sessiond_pid) {
 333                         exit(EXIT_FAILURE);
 334                 }
 335                 goto end;
 336         } else {
 337                 perror("fork");
 338                 ret = -1;
 339                 goto end;
 340         }
 341
 342 end:
 343         return ret;
 344 }
 345
 346 /*
 347  *  check_sessiond
 348  *
 349  *  Check if the session daemon is available using
 350  *  the liblttngctl API for the check. If not, try to
 351  *  spawn a daemon.
 352  */
 353 static int check_sessiond(void)
 354 {
 355         int ret;
 356         char *pathname = NULL, *alloc_pathname = NULL;
 357
 358         ret = lttng_session_daemon_alive();
 359         if (ret == 0) { /* not alive */
 360                 /* Try command line option path */
 361                 if (opt_sessiond_path != NULL) {
 362                         ret = access(opt_sessiond_path, F_OK | X_OK);
 363                         if (ret < 0) {
 364                                 ERR("No such file: %s", opt_sessiond_path);
 365                                 goto end;
 366                         }
 367                         pathname = opt_sessiond_path;
 368                 } else {
 369                         /* Try LTTNG_SESSIOND_PATH env variable */
 370                         pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 371                 }
 372
 373                 /* Let's rock and roll */
 374                 if (pathname == NULL) {
 375                         ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
 376                         if (ret < 0) {
 377                                 perror("asprintf spawn sessiond");
 378                                 goto end;
 379                         }
 380                         pathname = alloc_pathname;
 381                 }
 382
 383                 ret = spawn_sessiond(pathname);
 384                 free(alloc_pathname);
 385                 if (ret < 0) {
 386                         ERR("Problem occurs when starting %s", pathname);
 387                         goto end;
 388                 }
 389         }
 390
 391 end:
 392         return ret;
 393 }
 394
 395 /*
 396  * Check args for specific options that *must* not trigger a session daemon
 397  * execution.
 398  *
 399  * Return 1 if match else 0.
 400  */
 401 static int check_args_no_sessiond(int argc, char **argv)
 402 {
 403         int i;
 404
 405         for (i = 0; i < argc; i++) {
 406                 if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
 407                                 strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
 408                                 strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0) {
 409                         return 1;
 410                 }
 411         }
 412
 413         return 0;
 414 }
 415
 416 /*
 417  *  parse_args
 418  *
 419  *  Parse command line arguments.
 420  *  Return 0 if OK, else -1
 421  */
 422 static int parse_args(int argc, char **argv)
 423 {
 424         int opt, ret;
 425
 426         if (argc < 2) {
 427                 usage(stderr);
 428                 clean_exit(EXIT_FAILURE);
 429         }
 430
 431         while ((opt = getopt_long(argc, argv, "+hnvqg:", long_options, NULL)) != -1) {
 432                 switch (opt) {
 433                 case 'h':
 434                         usage(stderr);
 435                         goto error;
 436                 case 'v':
 437                         opt_verbose += 1;
 438                         break;
 439                 case 'q':
 440                         opt_quiet = 1;
 441                         break;
 442                 case 'g':
 443                         lttng_set_tracing_group(optarg);
 444                         break;
 445                 case 'n':
 446                         opt_no_sessiond = 1;
 447                         break;
 448                 case OPT_SESSION_PATH:
 449                         opt_sessiond_path = strdup(optarg);
 450                         break;
 451                 case OPT_DUMP_OPTIONS:
 452                         list_options(stdout);
 453                         ret = 0;
 454                         goto error;
 455                 case OPT_DUMP_COMMANDS:
 456                         list_commands(stdout);
 457                         ret = 0;
 458                         goto error;
 459                 default:
 460                         usage(stderr);
 461                         goto error;
 462                 }
 463         }
 464
 465         /* If both options are specified, quiet wins */
 466         if (opt_verbose && opt_quiet) {
 467                 opt_verbose = 0;
 468         }
 469
 470         /* Spawn session daemon if needed */
 471         if (opt_no_sessiond == 0 && check_args_no_sessiond(argc, argv) == 0 &&
 472                         (check_sessiond() < 0)) {
 473                 goto error;
 474         }
 475
 476         /* No leftovers, print usage and quit */
 477         if ((argc - optind) == 0) {
 478                 usage(stderr);
 479                 goto error;
 480         }
 481
 482         /*
 483          * Handle leftovers which is a first level command with the trailing
 484          * options.
 485          */
 486         ret = handle_command(argc - optind, argv + optind);
 487         if (ret < 0) {
 488                 if (ret == -1) {
 489                         usage(stderr);
 490                 } else {
 491                         ERR("%s", lttng_strerror(ret));
 492                 }
 493                 goto error;
 494         }
 495
 496         return 0;
 497
 498 error:
 499         return -1;
 500 }
 501
 502
 503 /*
 504  *  main
 505  */
 506 int main(int argc, char *argv[])
 507 {
 508         int ret;
 509
 510         progname = argv[0] ? argv[0] : "lttng";
 511
 512         /* For Mathieu Desnoyers aka Dr Tracing */
 513         if (strncmp(progname, "drtrace", 7) == 0 ||
 514                         strncmp("compudj", getenv("USER"), 7) == 0) {
 515                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n", 27,1,33,27,0);
 516         }
 517
 518         ret = set_signal_handler();
 519         if (ret < 0) {
 520                 clean_exit(ret);
 521         }
 522
 523         ret = parse_args(argc, argv);
 524         if (ret < 0) {
 525                 clean_exit(EXIT_FAILURE);
 526         }
 527
 528         return 0;
 529 }