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 <errno.h>
  21 #include <fcntl.h>
  22 #include <getopt.h>
  23 #include <grp.h>
  24 #include <limits.h>
  25 #include <stdio.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <sys/stat.h>
  29 #include <sys/types.h>
  30 #include <sys/wait.h>
  31 #include <unistd.h>
  32
  33 #include <lttng/liblttngctl.h>
  34
  35 #include "lttng.h"
  36 #include "lttngerr.h"
  37
  38 /* Variables */
  39 static char *progname;
  40
  41 /* Prototypes */
  42 static int process_client_opt(void);
  43 static int process_opt_list_apps(void);
  44 static int process_opt_list_sessions(void);
  45 static int process_opt_create_session(void);
  46 static void sighandler(int sig);
  47 static int set_signal_handler(void);
  48
  49 /*
  50  *  start_client
  51  *
  52  *  Process client request from the command line
  53  *  options. Every tracing action is done by the
  54  *  liblttngctl API.
  55  */
  56 static int process_client_opt(void)
  57 {
  58         int ret;
  59         uuid_t uuid;
  60
  61         /* Connect to the session daemon */
  62         ret = lttng_connect_sessiond();
  63         if (ret < 0) {
  64                 goto end;
  65         }
  66
  67         if (opt_list_apps) {
  68                 ret = process_opt_list_apps();
  69                 if (ret < 0) {
  70                         goto end;
  71                 }
  72         }
  73
  74         if (opt_list_session) {
  75                 ret = process_opt_list_sessions();
  76                 if (ret < 0) {
  77                         goto end;
  78                 }
  79         }
  80
  81         if (opt_create_session != NULL) {
  82                 ret = process_opt_create_session();
  83                 if (ret < 0) {
  84                         goto end;
  85                 }
  86         }
  87
  88         if (opt_destroy_session != NULL) {
  89                 uuid_parse(opt_destroy_session, uuid);
  90                 ret = lttng_destroy_session(&uuid);
  91                 if (ret < 0) {
  92                         goto end;
  93                 }
  94         }
  95
  96         if (opt_session_uuid != NULL) {
  97                 lttng_set_current_session_uuid(opt_session_uuid);
  98         }
  99
 100         return 0;
 101
 102 end:
 103         ERR("%s", lttng_get_readable_code(ret));
 104         return ret;
 105 }
 106
 107 /*
 108  *  process_opt_create_session
 109  *
 110  *  Create a new session using the name pass
 111  *  to the command line.
 112  */
 113 static int process_opt_create_session(void)
 114 {
 115         int ret;
 116         uuid_t session_id;
 117         char str_uuid[37];
 118
 119         ret = lttng_create_session(opt_create_session, &session_id);
 120         if (ret < 0) {
 121                 goto error;
 122         }
 123
 124         uuid_unparse(session_id, str_uuid);
 125
 126         MSG("Session created:");
 127         MSG("    %s (%s)", opt_create_session, str_uuid);
 128
 129 error:
 130         return ret;
 131 }
 132
 133 /*
 134  *  process_opt_list_sessions
 135  *
 136  *  Get the list of available sessions from
 137  *  the session daemon and print it to user.
 138  */
 139 static int process_opt_list_sessions(void)
 140 {
 141         int ret, count, i;
 142         struct lttng_session *sess;
 143
 144         count = lttng_list_sessions(&sess);
 145         if (count < 0) {
 146                 ret = count;
 147                 goto error;
 148         }
 149
 150         MSG("Available sessions [Name (uuid)]:");
 151         for (i = 0; i < count; i++) {
 152                 MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
 153         }
 154
 155         free(sess);
 156         MSG("\nTo select a session, use --session UUID.");
 157
 158         return 0;
 159
 160 error:
 161         return ret;
 162 }
 163
 164 /*
 165  *  process_opt_list_apps
 166  *
 167  *  Get the UST traceable pid list and print
 168  *  them to the user.
 169  */
 170 static int process_opt_list_apps(void)
 171 {
 172         int i, ret, count;
 173         pid_t *pids;
 174         FILE *fp;
 175         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 176         char cmdline[PATH_MAX];
 177
 178         count = lttng_ust_list_apps(&pids);
 179         if (count < 0) {
 180                 ret = count;
 181                 goto error;
 182         }
 183
 184         MSG("LTTng UST traceable application [name (pid)]:");
 185         for (i=0; i < count; i++) {
 186                 snprintf(path, sizeof(path), "/proc/%d/cmdline", pids[i]);
 187                 fp = fopen(path, "r");
 188                 if (fp == NULL) {
 189                         MSG("\t(not running) (%d)", pids[i]);
 190                         continue;
 191                 }
 192                 ret = fread(cmdline, 1, sizeof(cmdline), fp);
 193                 MSG("\t%s (%d)", cmdline, pids[i]);
 194                 fclose(fp);
 195         }
 196
 197         /* Allocated by lttng_ust_list_apps() */
 198         free(pids);
 199
 200         return 0;
 201
 202 error:
 203         return ret;
 204 }
 205
 206 /*
 207  *  spawn_sessiond
 208  *
 209  *  Spawn a session daemon by forking and execv.
 210  */
 211 static int spawn_sessiond(char *pathname)
 212 {
 213         int ret = 0;
 214         pid_t pid;
 215
 216         MSG("Spawning session daemon");
 217         pid = fork();
 218         if (pid == 0) {
 219                 /* Spawn session daemon and tell
 220                  * it to signal us when ready.
 221                  */
 222                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 223                 if (ret < 0) {
 224                         if (errno == ENOENT) {
 225                                 ERR("No session daemon found. Use --sessiond-path.");
 226                         } else {
 227                                 perror("execlp");
 228                         }
 229                         kill(getppid(), SIGTERM);
 230                         exit(EXIT_FAILURE);
 231                 }
 232                 exit(EXIT_SUCCESS);
 233         } else if (pid > 0) {
 234                 /* Wait for ltt-sessiond to start */
 235                 pause();
 236                 goto end;
 237         } else {
 238                 perror("fork");
 239                 ret = -1;
 240                 goto end;
 241         }
 242
 243 end:
 244         return ret;
 245 }
 246
 247 /*
 248  *  check_ltt_sessiond
 249  *
 250  *  Check if the session daemon is available using
 251  *  the liblttngctl API for the check. If not, try to
 252  *  spawn a daemon.
 253  */
 254 static int check_ltt_sessiond(void)
 255 {
 256         int ret;
 257         char *pathname = NULL;
 258
 259         ret = lttng_check_session_daemon();
 260         if (ret < 0) {
 261                 /* Try command line option path */
 262                 if (opt_sessiond_path != NULL) {
 263                         ret = access(opt_sessiond_path, F_OK | X_OK);
 264                         if (ret < 0) {
 265                                 ERR("No such file: %s", opt_sessiond_path);
 266                                 goto end;
 267                         }
 268                         pathname = opt_sessiond_path;
 269                 } else {
 270                         /* Try LTTNG_SESSIOND_PATH env variable */
 271                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 272                         if (pathname != NULL) {
 273                                 /* strdup here in order to make the free()
 274                                  * not fail later on.
 275                                  */
 276                                 pathname = strdup(pathname);
 277                         }
 278                 }
 279
 280                 /* Let's rock and roll */
 281                 if (pathname == NULL) {
 282                         ret = asprintf(&pathname, "ltt-sessiond");
 283                         if (ret < 0) {
 284                                 goto end;
 285                         }
 286                 }
 287
 288                 ret = spawn_sessiond(pathname);
 289                 free(pathname);
 290                 if (ret < 0) {
 291                         ERR("Problem occurs when starting %s", pathname);
 292                         goto end;
 293                 }
 294         }
 295
 296 end:
 297         return ret;
 298 }
 299
 300 /*
 301  *  set_signal_handler
 302  *
 303  *  Setup signal handler for SIGCHLD and SIGTERM.
 304  */
 305 static int set_signal_handler(void)
 306 {
 307         int ret = 0;
 308         struct sigaction sa;
 309         sigset_t sigset;
 310
 311         if ((ret = sigemptyset(&sigset)) < 0) {
 312                 perror("sigemptyset");
 313                 goto end;
 314         }
 315
 316         sa.sa_handler = sighandler;
 317         sa.sa_mask = sigset;
 318         sa.sa_flags = 0;
 319         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 320                 perror("sigaction");
 321                 goto end;
 322         }
 323
 324         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 325                 perror("sigaction");
 326                 goto end;
 327         }
 328
 329 end:
 330         return ret;
 331 }
 332
 333 /*
 334  *  sighandler
 335  *
 336  *  Signal handler for the daemon
 337  */
 338 static void sighandler(int sig)
 339 {
 340         DBG("%d received", sig);
 341         switch (sig) {
 342                 case SIGTERM:
 343                         clean_exit(EXIT_FAILURE);
 344                         break;
 345                 case SIGCHLD:
 346                         /* Notify is done */
 347                         break;
 348                 default:
 349                         break;
 350         }
 351
 352         return;
 353 }
 354 /*
 355  * clean_exit
 356  */
 357 void clean_exit(int code)
 358 {
 359         DBG("Clean exit");
 360         if (lttng_disconnect_sessiond() < 0) {
 361                 ERR("Session daemon disconnect failed.");
 362         }
 363         exit(code);
 364 }
 365
 366 /*
 367  *  main
 368  */
 369 int main(int argc, char *argv[])
 370 {
 371         int ret;
 372
 373         progname = argv[0] ? argv[0] : "lttng";
 374
 375         /* For Mathieu Desnoyers aka Dr Tracing */
 376         if (strncmp(progname, "drtrace", 7) == 0) {
 377                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 378         }
 379
 380         ret = parse_args(argc, (const char **) argv);
 381         if (ret < 0) {
 382                 clean_exit(EXIT_FAILURE);
 383         }
 384
 385         ret = set_signal_handler();
 386         if (ret < 0) {
 387                 clean_exit(ret);
 388         }
 389
 390         if (opt_tracing_group != NULL) {
 391                 DBG("Set tracing group to '%s'", opt_tracing_group);
 392                 lttng_set_tracing_group(opt_tracing_group);
 393         }
 394
 395         /* If ask for kernel tracing, need root perms */
 396         if (opt_trace_kernel) {
 397                 DBG("Kernel tracing activated");
 398                 if (getuid() != 0) {
 399                         ERR("%s must be setuid root", progname);
 400                         clean_exit(-EPERM);
 401                 }
 402         }
 403
 404         /* Check if the lttng session daemon is running.
 405          * If no, a daemon will be spawned.
 406          */
 407         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 408                 clean_exit(EXIT_FAILURE);
 409         }
 410
 411         ret = process_client_opt();
 412         if (ret < 0) {
 413                 clean_exit(ret);
 414         }
 415
 416         clean_exit(0);
 417
 418         return 0;
 419 }