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