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
  27 #include <lttng/lttng.h>
  28
  29 #include "cmd.h"
  30 #include "conf.h"
  31 #include "lttngerr.h"
  32
  33 /* Variables */
  34 static char *progname;
  35
  36 int opt_quiet;
  37 int opt_verbose;
  38 static int opt_no_sessiond;
  39 static char *opt_sessiond_path;
  40
  41 enum {
  42         OPT_SESSION_PATH,
  43         OPT_DUMP_OPTIONS,
  44         OPT_DUMP_COMMANDS,
  45 };
  46
  47 /* Getopt options. No first level command. */
  48 static struct option long_options[] = {
  49         {"help",             0, NULL, 'h'},
  50         {"group",            1, NULL, 'g'},
  51         {"verbose",          0, NULL, 'v'},
  52         {"quiet",            0, NULL, 'q'},
  53         {"no-sessiond",      0, NULL, 'n'},
  54         {"sessiond-path",    1, NULL, OPT_SESSION_PATH},
  55         {"list-options",     0, NULL, OPT_DUMP_OPTIONS},
  56         {"list-commands",    0, NULL, OPT_DUMP_COMMANDS},
  57         {NULL, 0, NULL, 0}
  58 };
  59
  60 /* First level command */
  61 static struct cmd_struct commands[] =  {
  62         { "list", cmd_list},
  63         { "create", cmd_create},
  64         { "destroy", cmd_destroy},
  65         { "start", cmd_start},
  66         { "stop", cmd_stop},
  67         { "enable-event", cmd_enable_events},
  68         { "disable-event", cmd_disable_events},
  69         { "enable-channel", cmd_enable_channels},
  70         { "disable-channel", cmd_disable_channels},
  71         { "add-context", cmd_add_context},
  72         { "set-session", cmd_set_session},
  73         { "version", cmd_version},
  74         { NULL, NULL}   /* Array closure */
  75 };
  76
  77 static void usage(FILE *ofp)
  78 {
  79         fprintf(ofp, "LTTng Trace Control " VERSION"\n\n");
  80         fprintf(ofp, "usage: lttng [options] <command>\n");
  81         fprintf(ofp, "\n");
  82         fprintf(ofp, "Options:\n");
  83         fprintf(ofp, "  -h, --help             Show this help\n");
  84         fprintf(ofp, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
  85         fprintf(ofp, "  -v, --verbose          Verbose mode\n");
  86         fprintf(ofp, "  -q, --quiet            Quiet mode\n");
  87         fprintf(ofp, "  -n, --no-sessiond      Don't spawn a session daemon\n");
  88         fprintf(ofp, "      --sessiond-path    Session daemon full path\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, "\n");
  92         fprintf(ofp, "Commands:\n");
  93         fprintf(ofp, "    add-context     Add context to event or/and channel\n");
  94         fprintf(ofp, "    create          Create tracing session\n");
  95         fprintf(ofp, "    destroy         Teardown tracing session\n");
  96         fprintf(ofp, "    enable-channel  Enable tracing channel\n");
  97         fprintf(ofp, "    enable-event    Enable tracing event\n");
  98         fprintf(ofp, "    disable-channel Disable tracing channel\n");
  99         fprintf(ofp, "    disable-event   Disable tracing event\n");
 100         fprintf(ofp, "    list            List possible tracing options\n");
 101         fprintf(ofp, "    set-session     Set current session name\n");
 102         fprintf(ofp, "    start           Start tracing\n");
 103         fprintf(ofp, "    stop            Stop tracing\n");
 104         fprintf(ofp, "    version         Show version information\n");
 105         fprintf(ofp, "\n");
 106         fprintf(ofp, "Please see the lttng(1) man page for full documentation.\n");
 107         fprintf(ofp, "See http://lttng.org for updates, bug reports and news.\n");
 108 }
 109
 110 /*
 111  *  list_options
 112  *
 113  *  List options line by line. This is mostly for bash auto completion and to
 114  *  avoid difficult parsing.
 115  */
 116 static void list_options(FILE *ofp)
 117 {
 118         int i = 0;
 119         struct option *option = NULL;
 120
 121         option = &long_options[i];
 122         while (option->name != NULL) {
 123                 fprintf(ofp, "--%s\n", option->name);
 124
 125                 if (isprint(option->val)) {
 126                         fprintf(ofp, "-%c\n", option->val);
 127                 }
 128
 129                 i++;
 130                 option = &long_options[i];
 131         }
 132 }
 133
 134 /*
 135  *  list_commands
 136  *
 137  *  List commands line by line. This is mostly for bash auto completion and to
 138  *  avoid difficult parsing.
 139  */
 140 static void list_commands(FILE *ofp)
 141 {
 142         int i = 0;
 143         struct cmd_struct *cmd = NULL;
 144
 145         cmd = &commands[i];
 146         while (cmd->name != NULL) {
 147                 fprintf(ofp, "%s\n", cmd->name);
 148                 i++;
 149                 cmd = &commands[i];
 150         }
 151 }
 152
 153 /*
 154  * clean_exit
 155  */
 156 static void clean_exit(int code)
 157 {
 158         DBG("Clean exit");
 159         exit(code);
 160 }
 161
 162 /*
 163  *  sighandler
 164  *
 165  *  Signal handler for the daemon
 166  */
 167 static void sighandler(int sig)
 168 {
 169         switch (sig) {
 170                 case SIGTERM:
 171                         DBG("SIGTERM catched");
 172                         clean_exit(EXIT_FAILURE);
 173                         break;
 174                 case SIGCHLD:
 175                         /* Notify is done */
 176                         DBG("SIGCHLD catched");
 177                         break;
 178                 default:
 179                         DBG("Unknown signal %d catched", sig);
 180                         break;
 181         }
 182
 183         return;
 184 }
 185
 186 /*
 187  *  set_signal_handler
 188  *
 189  *  Setup signal handler for SIGCHLD and SIGTERM.
 190  */
 191 static int set_signal_handler(void)
 192 {
 193         int ret = 0;
 194         struct sigaction sa;
 195         sigset_t sigset;
 196
 197         if ((ret = sigemptyset(&sigset)) < 0) {
 198                 perror("sigemptyset");
 199                 goto end;
 200         }
 201
 202         sa.sa_handler = sighandler;
 203         sa.sa_mask = sigset;
 204         sa.sa_flags = 0;
 205         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 206                 perror("sigaction");
 207                 goto end;
 208         }
 209
 210         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 211                 perror("sigaction");
 212                 goto end;
 213         }
 214
 215 end:
 216         return ret;
 217 }
 218
 219 /*
 220  *  handle_command
 221  *
 222  *  Handle the full argv list of a first level command. Will find the command
 223  *  in the global commands array and call the function callback associated.
 224  *
 225  *  If command not found, return -1
 226  *  else, return function command error code.
 227  */
 228 static int handle_command(int argc, char **argv)
 229 {
 230         int i = 0, ret;
 231         struct cmd_struct *cmd;
 232
 233         if (*argv == NULL) {
 234                 ret = CMD_SUCCESS;
 235                 goto end;
 236         }
 237
 238         cmd = &commands[i];
 239         while (cmd->func != NULL) {
 240                 /* Find command */
 241                 if (strcmp(argv[0], cmd->name) == 0) {
 242                         ret = cmd->func(argc, (const char**) argv);
 243                         switch (ret) {
 244                         case CMD_ERROR:
 245                                 ERR("Command error");
 246                                 break;
 247                         case CMD_NOT_IMPLEMENTED:
 248                                 ERR("Options not implemented");
 249                                 break;
 250                         case CMD_UNDEFINED:
 251                                 ERR("Undefined command");
 252                                 break;
 253                         case CMD_FATAL:
 254                                 ERR("Fatal error");
 255                                 break;
 256                         }
 257                         goto end;
 258                 }
 259                 i++;
 260                 cmd = &commands[i];
 261         }
 262
 263         /* Command not found */
 264         ret = -1;
 265
 266 end:
 267         return ret;
 268 }
 269
 270 /*
 271  *  spawn_sessiond
 272  *
 273  *  Spawn a session daemon by forking and execv.
 274  */
 275 static int spawn_sessiond(char *pathname)
 276 {
 277         int ret = 0;
 278         pid_t pid;
 279
 280         MSG("Spawning a session daemon");
 281         pid = fork();
 282         if (pid == 0) {
 283                 /*
 284                  * Spawn session daemon and tell
 285                  * it to signal us when ready.
 286                  */
 287                 execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 288                 /* execlp only returns if error happened */
 289                 if (errno == ENOENT) {
 290                         ERR("No session daemon found. Use --sessiond-path.");
 291                 } else {
 292                         perror("execlp");
 293                 }
 294                 kill(getppid(), SIGTERM);       /* unpause parent */
 295                 exit(EXIT_FAILURE);
 296         } else if (pid > 0) {
 297                 /* Wait for ltt-sessiond to start */
 298                 pause();
 299                 goto end;
 300         } else {
 301                 perror("fork");
 302                 ret = -1;
 303                 goto end;
 304         }
 305
 306 end:
 307         return ret;
 308 }
 309
 310 /*
 311  *  check_sessiond
 312  *
 313  *  Check if the session daemon is available using
 314  *  the liblttngctl API for the check. If not, try to
 315  *  spawn a daemon.
 316  */
 317 static int check_sessiond(void)
 318 {
 319         int ret;
 320         char *pathname = NULL, *alloc_pathname = NULL;
 321
 322         ret = lttng_session_daemon_alive();
 323         if (ret == 0) { /* not alive */
 324                 /* Try command line option path */
 325                 if (opt_sessiond_path != NULL) {
 326                         ret = access(opt_sessiond_path, F_OK | X_OK);
 327                         if (ret < 0) {
 328                                 ERR("No such file: %s", opt_sessiond_path);
 329                                 goto end;
 330                         }
 331                         pathname = opt_sessiond_path;
 332                 } else {
 333                         /* Try LTTNG_SESSIOND_PATH env variable */
 334                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 335                 }
 336
 337                 /* Let's rock and roll */
 338                 if (pathname == NULL) {
 339                         ret = asprintf(&alloc_pathname, INSTALL_PATH "/ltt-sessiond");
 340                         if (ret < 0) {
 341                                 perror("asprintf spawn sessiond");
 342                                 goto end;
 343                         }
 344                         pathname = alloc_pathname;
 345                 }
 346
 347                 ret = spawn_sessiond(pathname);
 348                 free(alloc_pathname);
 349                 if (ret < 0) {
 350                         ERR("Problem occurs when starting %s", pathname);
 351                         goto end;
 352                 }
 353         }
 354
 355 end:
 356         return ret;
 357 }
 358
 359 /*
 360  *  parse_args
 361  *
 362  *  Parse command line arguments.
 363  *  Return 0 if OK, else -1
 364  */
 365 static int parse_args(int argc, char **argv)
 366 {
 367         int opt, ret;
 368
 369         if (argc < 2) {
 370                 usage(stderr);
 371                 clean_exit(EXIT_FAILURE);
 372         }
 373
 374         while ((opt = getopt_long(argc, argv, "+hnvqg:", long_options, NULL)) != -1) {
 375                 switch (opt) {
 376                 case 'h':
 377                         usage(stderr);
 378                         goto error;
 379                 case 'v':
 380                         opt_verbose = 1;
 381                         break;
 382                 case 'q':
 383                         opt_quiet = 1;
 384                         break;
 385                 case 'g':
 386                         lttng_set_tracing_group(optarg);
 387                         break;
 388                 case 'n':
 389                         opt_no_sessiond = 1;
 390                         break;
 391                 case OPT_SESSION_PATH:
 392                         opt_sessiond_path = strdup(optarg);
 393                         break;
 394                 case OPT_DUMP_OPTIONS:
 395                         list_options(stdout);
 396                         ret = 0;
 397                         goto error;
 398                 case OPT_DUMP_COMMANDS:
 399                         list_commands(stdout);
 400                         ret = 0;
 401                         goto error;
 402                 default:
 403                         usage(stderr);
 404                         goto error;
 405                 }
 406         }
 407
 408         /* If both options are specified, quiet wins */
 409         if (opt_verbose && opt_quiet) {
 410                 opt_verbose = 0;
 411         }
 412
 413         /* Spawn session daemon if needed */
 414         if (opt_no_sessiond == 0 && (check_sessiond() < 0)) {
 415                 goto error;
 416         }
 417
 418         /* No leftovers, print usage and quit */
 419         if ((argc - optind) == 0) {
 420                 usage(stderr);
 421                 goto error;
 422         }
 423
 424         /*
 425          * Handle leftovers which is a first level command with the trailing
 426          * options.
 427          */
 428         ret = handle_command(argc - optind, argv + optind);
 429         if (ret < 0) {
 430                 if (ret == -1) {
 431                         usage(stderr);
 432                 } else {
 433                         ERR("%s", lttng_get_readable_code(ret));
 434                 }
 435                 goto error;
 436         }
 437
 438         return 0;
 439
 440 error:
 441         return -1;
 442 }
 443
 444
 445 /*
 446  *  main
 447  */
 448 int main(int argc, char *argv[])
 449 {
 450         int ret;
 451
 452         progname = argv[0] ? argv[0] : "lttng";
 453
 454         /* For Mathieu Desnoyers aka Dr Tracing */
 455         if (strncmp(progname, "drtrace", 7) == 0) {
 456                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 457         }
 458
 459         ret = set_signal_handler();
 460         if (ret < 0) {
 461                 clean_exit(ret);
 462         }
 463
 464         ret = parse_args(argc, argv);
 465         if (ret < 0) {
 466                 clean_exit(EXIT_FAILURE);
 467         }
 468
 469         return 0;
 470 }