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 <unistd.h>
  26 #include <config.h>
  27
  28 #include <lttng/lttng.h>
  29
  30 #include "cmd.h"
  31 #include "conf.h"
  32 #include "lttngerr.h"
  33
  34 /* Variables */
  35 static char *progname;
  36
  37 int opt_quiet;
  38 int opt_verbose;
  39 static int opt_no_sessiond;
  40 static char *opt_sessiond_path;
  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         { NULL, NULL}   /* Array closure */
  77 };
  78
  79 static void usage(FILE *ofp)
  80 {
  81         fprintf(ofp, "LTTng Trace Control " VERSION"\n\n");
  82         fprintf(ofp, "usage: lttng [options] <command>\n");
  83         fprintf(ofp, "\n");
  84         fprintf(ofp, "Options:\n");
  85         fprintf(ofp, "  -h, --help             Show this help\n");
  86         fprintf(ofp, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
  87         fprintf(ofp, "  -v, --verbose          Verbose mode\n");
  88         fprintf(ofp, "  -q, --quiet            Quiet mode\n");
  89         fprintf(ofp, "  -n, --no-sessiond      Don't spawn a session daemon\n");
  90         fprintf(ofp, "      --sessiond-path    Session daemon full path\n");
  91         fprintf(ofp, "      --list-options     Simple listing of lttng options\n");
  92         fprintf(ofp, "      --list-commands    Simple listing of lttng commands\n");
  93         fprintf(ofp, "\n");
  94         fprintf(ofp, "Commands:\n");
  95         fprintf(ofp, "    add-context     Add context to event or/and channel\n");
  96         fprintf(ofp, "    calibrate       Quantify LTTng overhead\n");
  97         fprintf(ofp, "    create          Create tracing session\n");
  98         fprintf(ofp, "    destroy         Teardown tracing session\n");
  99         fprintf(ofp, "    enable-channel  Enable tracing channel\n");
 100         fprintf(ofp, "    enable-event    Enable tracing event\n");
 101         fprintf(ofp, "    disable-channel Disable tracing channel\n");
 102         fprintf(ofp, "    disable-event   Disable tracing event\n");
 103         fprintf(ofp, "    list            List possible tracing options\n");
 104         fprintf(ofp, "    set-session     Set current session name\n");
 105         fprintf(ofp, "    start           Start tracing\n");
 106         fprintf(ofp, "    stop            Stop tracing\n");
 107         fprintf(ofp, "    version         Show version information\n");
 108         fprintf(ofp, "\n");
 109         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 110         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 111 }
 112
 113 /*
 114  *  list_options
 115  *
 116  *  List options line by line. This is mostly for bash auto completion and to
 117  *  avoid difficult parsing.
 118  */
 119 static void list_options(FILE *ofp)
 120 {
 121         int i = 0;
 122         struct option *option = NULL;
 123
 124         option = &long_options[i];
 125         while (option->name != NULL) {
 126                 fprintf(ofp, "--%s\n", option->name);
 127
 128                 if (isprint(option->val)) {
 129                         fprintf(ofp, "-%c\n", option->val);
 130                 }
 131
 132                 i++;
 133                 option = &long_options[i];
 134         }
 135 }
 136
 137 /*
 138  *  list_commands
 139  *
 140  *  List commands line by line. This is mostly for bash auto completion and to
 141  *  avoid difficult parsing.
 142  */
 143 static void list_commands(FILE *ofp)
 144 {
 145         int i = 0;
 146         struct cmd_struct *cmd = NULL;
 147
 148         cmd = &commands[i];
 149         while (cmd->name != NULL) {
 150                 fprintf(ofp, "%s\n", cmd->name);
 151                 i++;
 152                 cmd = &commands[i];
 153         }
 154 }
 155
 156 /*
 157  * clean_exit
 158  */
 159 static void clean_exit(int code)
 160 {
 161         DBG("Clean exit");
 162         exit(code);
 163 }
 164
 165 /*
 166  *  sighandler
 167  *
 168  *  Signal handler for the daemon
 169  */
 170 static void sighandler(int sig)
 171 {
 172         switch (sig) {
 173                 case SIGTERM:
 174                         DBG("SIGTERM catched");
 175                         clean_exit(EXIT_FAILURE);
 176                         break;
 177                 case SIGCHLD:
 178                         /* Notify is done */
 179                         DBG("SIGCHLD catched");
 180                         break;
 181                 default:
 182                         DBG("Unknown signal %d catched", sig);
 183                         break;
 184         }
 185
 186         return;
 187 }
 188
 189 /*
 190  *  set_signal_handler
 191  *
 192  *  Setup signal handler for SIGCHLD and SIGTERM.
 193  */
 194 static int set_signal_handler(void)
 195 {
 196         int ret = 0;
 197         struct sigaction sa;
 198         sigset_t sigset;
 199
 200         if ((ret = sigemptyset(&sigset)) < 0) {
 201                 perror("sigemptyset");
 202                 goto end;
 203         }
 204
 205         sa.sa_handler = sighandler;
 206         sa.sa_mask = sigset;
 207         sa.sa_flags = 0;
 208         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 209                 perror("sigaction");
 210                 goto end;
 211         }
 212
 213         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 214                 perror("sigaction");
 215                 goto end;
 216         }
 217
 218 end:
 219         return ret;
 220 }
 221
 222 /*
 223  *  handle_command
 224  *
 225  *  Handle the full argv list of a first level command. Will find the command
 226  *  in the global commands array and call the function callback associated.
 227  *
 228  *  If command not found, return -1
 229  *  else, return function command error code.
 230  */
 231 static int handle_command(int argc, char **argv)
 232 {
 233         int i = 0, ret;
 234         struct cmd_struct *cmd;
 235
 236         if (*argv == NULL) {
 237                 ret = CMD_SUCCESS;
 238                 goto end;
 239         }
 240
 241         cmd = &commands[i];
 242         while (cmd->func != NULL) {
 243                 /* Find command */
 244                 if (strcmp(argv[0], cmd->name) == 0) {
 245                         ret = cmd->func(argc, (const char**) argv);
 246                         switch (ret) {
 247                         case CMD_ERROR:
 248                                 ERR("Command error");
 249                                 break;
 250                         case CMD_NOT_IMPLEMENTED:
 251                                 ERR("Options not implemented");
 252                                 break;
 253                         case CMD_UNDEFINED:
 254                                 ERR("Undefined command");
 255                                 break;
 256                         case CMD_FATAL:
 257                                 ERR("Fatal error");
 258                                 break;
 259                         }
 260                         goto end;
 261                 }
 262                 i++;
 263                 cmd = &commands[i];
 264         }
 265
 266         /* Command not found */
 267         ret = -1;
 268
 269 end:
 270         return ret;
 271 }
 272
 273 /*
 274  *  spawn_sessiond
 275  *
 276  *  Spawn a session daemon by forking and execv.
 277  */
 278 static int spawn_sessiond(char *pathname)
 279 {
 280         int ret = 0;
 281         pid_t pid;
 282
 283         MSG("Spawning a session daemon");
 284         pid = fork();
 285         if (pid == 0) {
 286                 /*
 287                  * Spawn session daemon and tell
 288                  * it to signal us when ready.
 289                  */
 290                 execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
 291                 /* execlp only returns if error happened */
 292                 if (errno == ENOENT) {
 293                         ERR("No session daemon found. Use --sessiond-path.");
 294                 } else {
 295                         perror("execlp");
 296                 }
 297                 kill(getppid(), SIGTERM);       /* unpause parent */
 298                 exit(EXIT_FAILURE);
 299         } else if (pid > 0) {
 300                 /* Wait for lttng-sessiond to start */
 301                 pause();
 302                 goto end;
 303         } else {
 304                 perror("fork");
 305                 ret = -1;
 306                 goto end;
 307         }
 308
 309 end:
 310         return ret;
 311 }
 312
 313 /*
 314  *  check_sessiond
 315  *
 316  *  Check if the session daemon is available using
 317  *  the liblttngctl API for the check. If not, try to
 318  *  spawn a daemon.
 319  */
 320 static int check_sessiond(void)
 321 {
 322         int ret;
 323         char *pathname = NULL, *alloc_pathname = NULL;
 324
 325         ret = lttng_session_daemon_alive();
 326         if (ret == 0) { /* not alive */
 327                 /* Try command line option path */
 328                 if (opt_sessiond_path != NULL) {
 329                         ret = access(opt_sessiond_path, F_OK | X_OK);
 330                         if (ret < 0) {
 331                                 ERR("No such file: %s", opt_sessiond_path);
 332                                 goto end;
 333                         }
 334                         pathname = opt_sessiond_path;
 335                 } else {
 336                         /* Try LTTNG_SESSIOND_PATH env variable */
 337                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 338                 }
 339
 340                 /* Let's rock and roll */
 341                 if (pathname == NULL) {
 342                         ret = asprintf(&alloc_pathname, INSTALL_BIN_PATH "/lttng-sessiond");
 343                         if (ret < 0) {
 344                                 perror("asprintf spawn sessiond");
 345                                 goto end;
 346                         }
 347                         pathname = alloc_pathname;
 348                 }
 349
 350                 ret = spawn_sessiond(pathname);
 351                 free(alloc_pathname);
 352                 if (ret < 0) {
 353                         ERR("Problem occurs when starting %s", pathname);
 354                         goto end;
 355                 }
 356         }
 357
 358 end:
 359         return ret;
 360 }
 361
 362 /*
 363  *  parse_args
 364  *
 365  *  Parse command line arguments.
 366  *  Return 0 if OK, else -1
 367  */
 368 static int parse_args(int argc, char **argv)
 369 {
 370         int opt, ret;
 371
 372         if (argc < 2) {
 373                 usage(stderr);
 374                 clean_exit(EXIT_FAILURE);
 375         }
 376
 377         while ((opt = getopt_long(argc, argv, "+hnvqg:", long_options, NULL)) != -1) {
 378                 switch (opt) {
 379                 case 'h':
 380                         usage(stderr);
 381                         goto error;
 382                 case 'v':
 383                         opt_verbose += 1;
 384                         break;
 385                 case 'q':
 386                         opt_quiet = 1;
 387                         break;
 388                 case 'g':
 389                         lttng_set_tracing_group(optarg);
 390                         break;
 391                 case 'n':
 392                         opt_no_sessiond = 1;
 393                         break;
 394                 case OPT_SESSION_PATH:
 395                         opt_sessiond_path = strdup(optarg);
 396                         break;
 397                 case OPT_DUMP_OPTIONS:
 398                         list_options(stdout);
 399                         ret = 0;
 400                         goto error;
 401                 case OPT_DUMP_COMMANDS:
 402                         list_commands(stdout);
 403                         ret = 0;
 404                         goto error;
 405                 default:
 406                         usage(stderr);
 407                         goto error;
 408                 }
 409         }
 410
 411         /* If both options are specified, quiet wins */
 412         if (opt_verbose && opt_quiet) {
 413                 opt_verbose = 0;
 414         }
 415
 416         /* Spawn session daemon if needed */
 417         if (opt_no_sessiond == 0 && (check_sessiond() < 0)) {
 418                 goto error;
 419         }
 420
 421         /* No leftovers, print usage and quit */
 422         if ((argc - optind) == 0) {
 423                 usage(stderr);
 424                 goto error;
 425         }
 426
 427         /*
 428          * Handle leftovers which is a first level command with the trailing
 429          * options.
 430          */
 431         ret = handle_command(argc - optind, argv + optind);
 432         if (ret < 0) {
 433                 if (ret == -1) {
 434                         usage(stderr);
 435                 } else {
 436                         ERR("%s", lttng_strerror(ret));
 437                 }
 438                 goto error;
 439         }
 440
 441         return 0;
 442
 443 error:
 444         return -1;
 445 }
 446
 447
 448 /*
 449  *  main
 450  */
 451 int main(int argc, char *argv[])
 452 {
 453         int ret;
 454
 455         progname = argv[0] ? argv[0] : "lttng";
 456
 457         /* For Mathieu Desnoyers aka Dr Tracing */
 458         if (strncmp(progname, "drtrace", 7) == 0) {
 459                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 460         }
 461
 462         ret = set_signal_handler();
 463         if (ret < 0) {
 464                 clean_exit(ret);
 465         }
 466
 467         ret = parse_args(argc, argv);
 468         if (ret < 0) {
 469                 clean_exit(EXIT_FAILURE);
 470         }
 471
 472         return 0;
 473 }