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