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         if (opt_create_trace) {
 101                 DBG("Create trace for pid %d", opt_create_trace);
 102                 ret = lttng_ust_create_trace(opt_create_trace);
 103                 if (ret < 0) {
 104                         goto end;
 105                 }
 106                 MSG("Trace created successfully!\nUse --start PID to start tracing");
 107         }
 108
 109         return 0;
 110
 111 end:
 112         ERR("%s", lttng_get_readable_code(ret));
 113         return ret;
 114 }
 115
 116 /*
 117  *  process_opt_create_session
 118  *
 119  *  Create a new session using the name pass
 120  *  to the command line.
 121  */
 122 static int process_opt_create_session(void)
 123 {
 124         int ret;
 125         uuid_t session_id;
 126         char str_uuid[37];
 127
 128         ret = lttng_create_session(opt_create_session, &session_id);
 129         if (ret < 0) {
 130                 goto error;
 131         }
 132
 133         uuid_unparse(session_id, str_uuid);
 134
 135         MSG("Session created:");
 136         MSG("    %s (%s)", opt_create_session, str_uuid);
 137
 138 error:
 139         return ret;
 140 }
 141
 142 /*
 143  *  process_opt_list_sessions
 144  *
 145  *  Get the list of available sessions from
 146  *  the session daemon and print it to user.
 147  */
 148 static int process_opt_list_sessions(void)
 149 {
 150         int ret, count, i;
 151         struct lttng_session *sess;
 152
 153         count = lttng_list_sessions(&sess);
 154         if (count < 0) {
 155                 ret = count;
 156                 goto error;
 157         }
 158
 159         MSG("Available sessions [Name (uuid)]:");
 160         for (i = 0; i < count; i++) {
 161                 MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
 162         }
 163
 164         free(sess);
 165         MSG("\nTo select a session, use --session UUID.");
 166
 167         return 0;
 168
 169 error:
 170         return ret;
 171 }
 172
 173 /*
 174  *  process_opt_list_apps
 175  *
 176  *  Get the UST traceable pid list and print
 177  *  them to the user.
 178  */
 179 static int process_opt_list_apps(void)
 180 {
 181         int i, ret, count;
 182         pid_t *pids;
 183         FILE *fp;
 184         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 185         char cmdline[PATH_MAX];
 186
 187         count = lttng_ust_list_apps(&pids);
 188         if (count < 0) {
 189                 ret = count;
 190                 goto error;
 191         }
 192
 193         MSG("LTTng UST traceable application [name (pid)]:");
 194         for (i=0; i < count; i++) {
 195                 snprintf(path, sizeof(path), "/proc/%d/cmdline", pids[i]);
 196                 fp = fopen(path, "r");
 197                 if (fp == NULL) {
 198                         MSG("\t(not running) (%d)", pids[i]);
 199                         continue;
 200                 }
 201                 ret = fread(cmdline, 1, sizeof(cmdline), fp);
 202                 MSG("\t%s (%d)", cmdline, pids[i]);
 203                 fclose(fp);
 204         }
 205
 206         /* Allocated by lttng_ust_list_apps() */
 207         free(pids);
 208
 209         return 0;
 210
 211 error:
 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 session daemon");
 226         pid = fork();
 227         if (pid == 0) {
 228                 /* Spawn session daemon and tell
 229                  * it to signal us when ready.
 230                  */
 231                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 232                 if (ret < 0) {
 233                         if (errno == ENOENT) {
 234                                 ERR("No session daemon found. Use --sessiond-path.");
 235                         } else {
 236                                 perror("execlp");
 237                         }
 238                         kill(getppid(), SIGTERM);
 239                         exit(EXIT_FAILURE);
 240                 }
 241                 exit(EXIT_SUCCESS);
 242         } else if (pid > 0) {
 243                 /* Wait for ltt-sessiond to start */
 244                 pause();
 245                 goto end;
 246         } else {
 247                 perror("fork");
 248                 ret = -1;
 249                 goto end;
 250         }
 251
 252 end:
 253         return ret;
 254 }
 255
 256 /*
 257  *  check_ltt_sessiond
 258  *
 259  *  Check if the session daemon is available using
 260  *  the liblttngctl API for the check. If not, try to
 261  *  spawn a daemon.
 262  */
 263 static int check_ltt_sessiond(void)
 264 {
 265         int ret;
 266         char *pathname = NULL;
 267
 268         ret = lttng_check_session_daemon();
 269         if (ret < 0) {
 270                 /* Try command line option path */
 271                 if (opt_sessiond_path != NULL) {
 272                         ret = access(opt_sessiond_path, F_OK | X_OK);
 273                         if (ret < 0) {
 274                                 ERR("No such file: %s", opt_sessiond_path);
 275                                 goto end;
 276                         }
 277                         pathname = opt_sessiond_path;
 278                 } else {
 279                         /* Try LTTNG_SESSIOND_PATH env variable */
 280                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 281                         if (pathname != NULL) {
 282                                 /* strdup here in order to make the free()
 283                                  * not fail later on.
 284                                  */
 285                                 pathname = strdup(pathname);
 286                         }
 287                 }
 288
 289                 /* Let's rock and roll */
 290                 if (pathname == NULL) {
 291                         ret = asprintf(&pathname, "ltt-sessiond");
 292                         if (ret < 0) {
 293                                 goto end;
 294                         }
 295                 }
 296
 297                 ret = spawn_sessiond(pathname);
 298                 free(pathname);
 299                 if (ret < 0) {
 300                         ERR("Problem occurs when starting %s", pathname);
 301                         goto end;
 302                 }
 303         }
 304
 305 end:
 306         return ret;
 307 }
 308
 309 /*
 310  *  set_signal_handler
 311  *
 312  *  Setup signal handler for SIGCHLD and SIGTERM.
 313  */
 314 static int set_signal_handler(void)
 315 {
 316         int ret = 0;
 317         struct sigaction sa;
 318         sigset_t sigset;
 319
 320         if ((ret = sigemptyset(&sigset)) < 0) {
 321                 perror("sigemptyset");
 322                 goto end;
 323         }
 324
 325         sa.sa_handler = sighandler;
 326         sa.sa_mask = sigset;
 327         sa.sa_flags = 0;
 328         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 329                 perror("sigaction");
 330                 goto end;
 331         }
 332
 333         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 334                 perror("sigaction");
 335                 goto end;
 336         }
 337
 338 end:
 339         return ret;
 340 }
 341
 342 /*
 343  *  sighandler
 344  *
 345  *  Signal handler for the daemon
 346  */
 347 static void sighandler(int sig)
 348 {
 349         DBG("%d received", sig);
 350         switch (sig) {
 351                 case SIGTERM:
 352                         clean_exit(EXIT_FAILURE);
 353                         break;
 354                 case SIGCHLD:
 355                         /* Notify is done */
 356                         break;
 357                 default:
 358                         break;
 359         }
 360
 361         return;
 362 }
 363 /*
 364  * clean_exit
 365  */
 366 void clean_exit(int code)
 367 {
 368         DBG("Clean exit");
 369         if (lttng_disconnect_sessiond() < 0) {
 370                 ERR("Session daemon disconnect failed.");
 371         }
 372         exit(code);
 373 }
 374
 375 /*
 376  *  main
 377  */
 378 int main(int argc, char *argv[])
 379 {
 380         int ret;
 381
 382         progname = argv[0] ? argv[0] : "lttng";
 383
 384         /* For Mathieu Desnoyers aka Dr Tracing */
 385         if (strncmp(progname, "drtrace", 7) == 0) {
 386                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 387         }
 388
 389         ret = parse_args(argc, (const char **) argv);
 390         if (ret < 0) {
 391                 clean_exit(EXIT_FAILURE);
 392         }
 393
 394         ret = set_signal_handler();
 395         if (ret < 0) {
 396                 clean_exit(ret);
 397         }
 398
 399         if (opt_tracing_group != NULL) {
 400                 DBG("Set tracing group to '%s'", opt_tracing_group);
 401                 lttng_set_tracing_group(opt_tracing_group);
 402         }
 403
 404         /* If ask for kernel tracing, need root perms */
 405         if (opt_trace_kernel) {
 406                 DBG("Kernel tracing activated");
 407                 if (getuid() != 0) {
 408                         ERR("%s must be setuid root", progname);
 409                         clean_exit(-EPERM);
 410                 }
 411         }
 412
 413         /* Check if the lttng session daemon is running.
 414          * If no, a daemon will be spawned.
 415          */
 416         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 417                 clean_exit(EXIT_FAILURE);
 418         }
 419
 420         ret = process_client_opt();
 421         if (ret < 0) {
 422                 clean_exit(ret);
 423         }
 424
 425         clean_exit(0);
 426
 427         return 0;
 428 }