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