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