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