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 static int get_cmdline_by_pid(pid_t pid, char **cmdline);
  49 static int validate_options(void);
  50
  51 /*
  52  *  start_client
  53  *
  54  *  Process client request from the command line
  55  *  options. Every tracing action is done by the
  56  *  liblttngctl API.
  57  */
  58 static int process_client_opt(void)
  59 {
  60         int ret;
  61         uuid_t uuid;
  62
  63         /* Connect to the session daemon */
  64         ret = lttng_connect_sessiond();
  65         if (ret < 0) {
  66                 goto end;
  67         }
  68
  69         if (opt_list_apps) {
  70                 ret = process_opt_list_apps();
  71                 if (ret < 0) {
  72                         goto end;
  73                 }
  74         }
  75
  76         if (opt_list_session) {
  77                 ret = process_opt_list_sessions();
  78                 if (ret < 0) {
  79                         goto end;
  80                 }
  81         }
  82
  83         if (opt_create_session != NULL) {
  84                 ret = process_opt_create_session();
  85                 if (ret < 0) {
  86                         goto end;
  87                 }
  88         }
  89
  90         if (opt_destroy_session != NULL) {
  91                 uuid_parse(opt_destroy_session, uuid);
  92                 ret = lttng_destroy_session(&uuid);
  93                 if (ret < 0) {
  94                         goto end;
  95                 }
  96         }
  97
  98         if (opt_session_uuid != NULL) {
  99                 lttng_set_current_session_uuid(opt_session_uuid);
 100         }
 101
 102         if (opt_create_trace) {
 103                 DBG("Create trace for pid %d", opt_create_trace);
 104                 ret = lttng_ust_create_trace(opt_create_trace);
 105                 if (ret < 0) {
 106                         goto end;
 107                 }
 108                 MSG("Trace created successfully!\nUse --start PID to start tracing.");
 109         }
 110
 111         return 0;
 112
 113 end:
 114         ERR("%s", lttng_get_readable_code(ret));
 115         return ret;
 116 }
 117
 118 /*
 119  *  process_opt_create_session
 120  *
 121  *  Create a new session using the name pass
 122  *  to the command line.
 123  */
 124 static int process_opt_create_session(void)
 125 {
 126         int ret;
 127         uuid_t session_id;
 128         char str_uuid[37];
 129
 130         ret = lttng_create_session(opt_create_session, &session_id);
 131         if (ret < 0) {
 132                 goto error;
 133         }
 134
 135         uuid_unparse(session_id, str_uuid);
 136
 137         MSG("Session created:");
 138         MSG("    %s (%s)", opt_create_session, str_uuid);
 139
 140 error:
 141         return ret;
 142 }
 143
 144 /*
 145  *  process_opt_list_sessions
 146  *
 147  *  Get the list of available sessions from
 148  *  the session daemon and print it to user.
 149  */
 150 static int process_opt_list_sessions(void)
 151 {
 152         int ret, count, i;
 153         struct lttng_session *sess;
 154
 155         count = lttng_list_sessions(&sess);
 156         if (count < 0) {
 157                 ret = count;
 158                 goto error;
 159         }
 160
 161         MSG("Available sessions [Name (uuid)]:");
 162         for (i = 0; i < count; i++) {
 163                 MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
 164         }
 165
 166         free(sess);
 167         MSG("\nTo select a session, use --session UUID.");
 168
 169         return 0;
 170
 171 error:
 172         return ret;
 173 }
 174
 175 /*
 176  *  process_opt_list_apps
 177  *
 178  *  Get the UST traceable pid list and print
 179  *  them to the user.
 180  */
 181 static int process_opt_list_apps(void)
 182 {
 183         int i, ret, count;
 184         pid_t *pids;
 185         char *cmdline;
 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                 ret = get_cmdline_by_pid(pids[i], &cmdline);
 196                 if (!ret) {
 197                         MSG("\t(not running) (%d)", pids[i]);
 198                         continue;
 199                 }
 200                 MSG("\t%s (%d)", cmdline, pids[i]);
 201                 free(cmdline);
 202         }
 203
 204         /* Allocated by lttng_ust_list_apps() */
 205         free(pids);
 206
 207         return 0;
 208
 209 error:
 210         return ret;
 211 }
 212
 213 /*
 214  *  get_cmdline_by_pid
 215  *
 216  *  Get command line from /proc for a
 217  *  specific pid. Allocate cmdline so the
 218  *  user must free() that pointer.
 219  *
 220  *  On success, return 1
 221  *  On error (not found), return 0
 222  */
 223 static int get_cmdline_by_pid(pid_t pid, char **cmdline)
 224 {
 225         int ret;
 226         FILE *fp;
 227         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 228
 229         snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
 230         fp = fopen(path, "r");
 231         if (fp == NULL) {
 232                 goto not_running;
 233         }
 234
 235         /* Caller must free() *cmdline */
 236         *cmdline = malloc(PATH_MAX);
 237         ret = fread(*cmdline, 1, PATH_MAX, fp);
 238         fclose(fp);
 239
 240         return 1;
 241
 242 not_running:
 243         return 0;
 244 }
 245
 246 /*
 247  *  validate_options
 248  *
 249  *  Make sure that all options passed to the command line
 250  *  are compatible with each others.
 251  *
 252  *  On error, return -1
 253  *  On success, return 0
 254  */
 255 static int validate_options(void)
 256 {
 257         if ((opt_session_uuid == NULL) &&
 258                         (opt_create_trace)) {
 259                 ERR("Can't create trace without a session ID.\nPlease specify using --session UUID");
 260                 goto error;
 261         }
 262
 263         return 0;
 264
 265 error:
 266         return -1;
 267 }
 268
 269 /*
 270  *  spawn_sessiond
 271  *
 272  *  Spawn a session daemon by forking and execv.
 273  */
 274 static int spawn_sessiond(char *pathname)
 275 {
 276         int ret = 0;
 277         pid_t pid;
 278
 279         MSG("Spawning session daemon");
 280         pid = fork();
 281         if (pid == 0) {
 282                 /* Spawn session daemon and tell
 283                  * it to signal us when ready.
 284                  */
 285                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 286                 if (ret < 0) {
 287                         if (errno == ENOENT) {
 288                                 ERR("No session daemon found. Use --sessiond-path.");
 289                         } else {
 290                                 perror("execlp");
 291                         }
 292                         kill(getppid(), SIGTERM);
 293                         exit(EXIT_FAILURE);
 294                 }
 295                 exit(EXIT_SUCCESS);
 296         } else if (pid > 0) {
 297                 /* Wait for ltt-sessiond to start */
 298                 pause();
 299                 goto end;
 300         } else {
 301                 perror("fork");
 302                 ret = -1;
 303                 goto end;
 304         }
 305
 306 end:
 307         return ret;
 308 }
 309
 310 /*
 311  *  check_ltt_sessiond
 312  *
 313  *  Check if the session daemon is available using
 314  *  the liblttngctl API for the check. If not, try to
 315  *  spawn a daemon.
 316  */
 317 static int check_ltt_sessiond(void)
 318 {
 319         int ret;
 320         char *pathname = NULL;
 321
 322         ret = lttng_check_session_daemon();
 323         if (ret < 0) {
 324                 /* Try command line option path */
 325                 if (opt_sessiond_path != NULL) {
 326                         ret = access(opt_sessiond_path, F_OK | X_OK);
 327                         if (ret < 0) {
 328                                 ERR("No such file: %s", opt_sessiond_path);
 329                                 goto end;
 330                         }
 331                         pathname = opt_sessiond_path;
 332                 } else {
 333                         /* Try LTTNG_SESSIOND_PATH env variable */
 334                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 335                         if (pathname != NULL) {
 336                                 /* strdup here in order to make the free()
 337                                  * not fail later on.
 338                                  */
 339                                 pathname = strdup(pathname);
 340                         }
 341                 }
 342
 343                 /* Let's rock and roll */
 344                 if (pathname == NULL) {
 345                         ret = asprintf(&pathname, "ltt-sessiond");
 346                         if (ret < 0) {
 347                                 goto end;
 348                         }
 349                 }
 350
 351                 ret = spawn_sessiond(pathname);
 352                 free(pathname);
 353                 if (ret < 0) {
 354                         ERR("Problem occurs when starting %s", pathname);
 355                         goto end;
 356                 }
 357         }
 358
 359 end:
 360         return ret;
 361 }
 362
 363 /*
 364  *  set_signal_handler
 365  *
 366  *  Setup signal handler for SIGCHLD and SIGTERM.
 367  */
 368 static int set_signal_handler(void)
 369 {
 370         int ret = 0;
 371         struct sigaction sa;
 372         sigset_t sigset;
 373
 374         if ((ret = sigemptyset(&sigset)) < 0) {
 375                 perror("sigemptyset");
 376                 goto end;
 377         }
 378
 379         sa.sa_handler = sighandler;
 380         sa.sa_mask = sigset;
 381         sa.sa_flags = 0;
 382         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 383                 perror("sigaction");
 384                 goto end;
 385         }
 386
 387         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 388                 perror("sigaction");
 389                 goto end;
 390         }
 391
 392 end:
 393         return ret;
 394 }
 395
 396 /*
 397  *  sighandler
 398  *
 399  *  Signal handler for the daemon
 400  */
 401 static void sighandler(int sig)
 402 {
 403         DBG("%d received", sig);
 404         switch (sig) {
 405                 case SIGTERM:
 406                         clean_exit(EXIT_FAILURE);
 407                         break;
 408                 case SIGCHLD:
 409                         /* Notify is done */
 410                         break;
 411                 default:
 412                         break;
 413         }
 414
 415         return;
 416 }
 417 /*
 418  * clean_exit
 419  */
 420 void clean_exit(int code)
 421 {
 422         DBG("Clean exit");
 423         if (lttng_disconnect_sessiond() < 0) {
 424                 ERR("Session daemon disconnect failed.");
 425         }
 426         exit(code);
 427 }
 428
 429 /*
 430  *  main
 431  */
 432 int main(int argc, char *argv[])
 433 {
 434         int ret;
 435
 436         progname = argv[0] ? argv[0] : "lttng";
 437
 438         /* For Mathieu Desnoyers aka Dr Tracing */
 439         if (strncmp(progname, "drtrace", 7) == 0) {
 440                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 441         }
 442
 443         ret = parse_args(argc, (const char **) argv);
 444         if (ret < 0) {
 445                 clean_exit(EXIT_FAILURE);
 446         }
 447
 448         ret = validate_options();
 449         if (ret < 0) {
 450                 return EXIT_FAILURE;
 451         }
 452
 453         ret = set_signal_handler();
 454         if (ret < 0) {
 455                 clean_exit(ret);
 456         }
 457
 458         if (opt_tracing_group != NULL) {
 459                 DBG("Set tracing group to '%s'", opt_tracing_group);
 460                 lttng_set_tracing_group(opt_tracing_group);
 461         }
 462
 463         /* If ask for kernel tracing, need root perms */
 464         if (opt_trace_kernel) {
 465                 DBG("Kernel tracing activated");
 466                 if (getuid() != 0) {
 467                         ERR("%s must be setuid root", progname);
 468                         clean_exit(-EPERM);
 469                 }
 470         }
 471
 472         /* Check if the lttng session daemon is running.
 473          * If no, a daemon will be spawned.
 474          */
 475         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 476                 clean_exit(EXIT_FAILURE);
 477         }
 478
 479         ret = process_client_opt();
 480         if (ret < 0) {
 481                 clean_exit(ret);
 482         }
 483
 484         clean_exit(0);
 485
 486         return 0;
 487 }