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