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                 DBG("Set session uuid to %s", opt_session_uuid);
 100                 lttng_set_current_session_uuid(opt_session_uuid);
 101         }
 102
 103         if (opt_create_trace) {
 104                 DBG("Create trace for pid %d", opt_create_trace);
 105                 ret = lttng_ust_create_trace(opt_create_trace);
 106                 if (ret < 0) {
 107                         goto end;
 108                 }
 109                 MSG("Trace created successfully!\nUse --start PID to start tracing.");
 110         }
 111
 112         if (opt_start_trace) {
 113                 DBG("Start trace for pid %d", opt_start_trace);
 114                 ret = lttng_ust_start_trace(opt_start_trace);
 115                 if (ret < 0) {
 116                         goto end;
 117                 }
 118                 MSG("Trace started successfully!");
 119         }
 120
 121         return 0;
 122
 123 end:
 124         ERR("%s", lttng_get_readable_code(ret));
 125         return ret;
 126 }
 127
 128 /*
 129  *  process_opt_create_session
 130  *
 131  *  Create a new session using the name pass
 132  *  to the command line.
 133  */
 134 static int process_opt_create_session(void)
 135 {
 136         int ret;
 137         uuid_t session_id;
 138         char str_uuid[37];
 139
 140         ret = lttng_create_session(opt_create_session, &session_id);
 141         if (ret < 0) {
 142                 goto error;
 143         }
 144
 145         uuid_unparse(session_id, str_uuid);
 146
 147         MSG("Session created:");
 148         MSG("    %s (%s)", opt_create_session, str_uuid);
 149
 150 error:
 151         return ret;
 152 }
 153
 154 /*
 155  *  process_opt_list_sessions
 156  *
 157  *  Get the list of available sessions from
 158  *  the session daemon and print it to user.
 159  */
 160 static int process_opt_list_sessions(void)
 161 {
 162         int ret, count, i;
 163         struct lttng_session *sess;
 164
 165         count = lttng_list_sessions(&sess);
 166         if (count < 0) {
 167                 ret = count;
 168                 goto error;
 169         }
 170
 171         MSG("Available sessions [Name (uuid)]:");
 172         for (i = 0; i < count; i++) {
 173                 MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
 174         }
 175
 176         free(sess);
 177         MSG("\nTo select a session, use --session UUID.");
 178
 179         return 0;
 180
 181 error:
 182         return ret;
 183 }
 184
 185 /*
 186  *  process_opt_list_apps
 187  *
 188  *  Get the UST traceable pid list and print
 189  *  them to the user.
 190  */
 191 static int process_opt_list_apps(void)
 192 {
 193         int i, ret, count;
 194         pid_t *pids;
 195         char *cmdline;
 196
 197         count = lttng_ust_list_apps(&pids);
 198         if (count < 0) {
 199                 ret = count;
 200                 goto error;
 201         }
 202
 203         MSG("LTTng UST traceable application [name (pid)]:");
 204         for (i=0; i < count; i++) {
 205                 ret = get_cmdline_by_pid(pids[i], &cmdline);
 206                 if (!ret) {
 207                         MSG("\t(not running) (%d)", pids[i]);
 208                         continue;
 209                 }
 210                 MSG("\t%s (%d)", cmdline, pids[i]);
 211                 free(cmdline);
 212         }
 213
 214         /* Allocated by lttng_ust_list_apps() */
 215         free(pids);
 216
 217         return 0;
 218
 219 error:
 220         return ret;
 221 }
 222
 223 /*
 224  *  get_cmdline_by_pid
 225  *
 226  *  Get command line from /proc for a
 227  *  specific pid. Allocate cmdline so the
 228  *  user must free() that pointer.
 229  *
 230  *  On success, return 1
 231  *  On error (not found), return 0
 232  */
 233 static int get_cmdline_by_pid(pid_t pid, char **cmdline)
 234 {
 235         int ret;
 236         FILE *fp;
 237         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 238
 239         snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
 240         fp = fopen(path, "r");
 241         if (fp == NULL) {
 242                 goto not_running;
 243         }
 244
 245         /* Caller must free() *cmdline */
 246         *cmdline = malloc(PATH_MAX);
 247         ret = fread(*cmdline, 1, PATH_MAX, fp);
 248         fclose(fp);
 249
 250         return 1;
 251
 252 not_running:
 253         return 0;
 254 }
 255
 256 /*
 257  *  validate_options
 258  *
 259  *  Make sure that all options passed to the command line
 260  *  are compatible with each others.
 261  *
 262  *  On error, return -1
 263  *  On success, return 0
 264  */
 265 static int validate_options(void)
 266 {
 267         if ((opt_session_uuid == NULL) &&
 268                         (opt_create_trace || opt_start_trace)) {
 269                 ERR("Can't act on trace without a session ID.\nPlease specify using --session UUID");
 270                 goto error;
 271         }
 272
 273         return 0;
 274
 275 error:
 276         return -1;
 277 }
 278
 279 /*
 280  *  spawn_sessiond
 281  *
 282  *  Spawn a session daemon by forking and execv.
 283  */
 284 static int spawn_sessiond(char *pathname)
 285 {
 286         int ret = 0;
 287         pid_t pid;
 288
 289         MSG("Spawning session daemon");
 290         pid = fork();
 291         if (pid == 0) {
 292                 /* Spawn session daemon and tell
 293                  * it to signal us when ready.
 294                  */
 295                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 296                 if (ret < 0) {
 297                         if (errno == ENOENT) {
 298                                 ERR("No session daemon found. Use --sessiond-path.");
 299                         } else {
 300                                 perror("execlp");
 301                         }
 302                         kill(getppid(), SIGTERM);
 303                         exit(EXIT_FAILURE);
 304                 }
 305                 exit(EXIT_SUCCESS);
 306         } else if (pid > 0) {
 307                 /* Wait for ltt-sessiond to start */
 308                 pause();
 309                 goto end;
 310         } else {
 311                 perror("fork");
 312                 ret = -1;
 313                 goto end;
 314         }
 315
 316 end:
 317         return ret;
 318 }
 319
 320 /*
 321  *  check_ltt_sessiond
 322  *
 323  *  Check if the session daemon is available using
 324  *  the liblttngctl API for the check. If not, try to
 325  *  spawn a daemon.
 326  */
 327 static int check_ltt_sessiond(void)
 328 {
 329         int ret;
 330         char *pathname = NULL;
 331
 332         ret = lttng_check_session_daemon();
 333         if (ret < 0) {
 334                 /* Try command line option path */
 335                 if (opt_sessiond_path != NULL) {
 336                         ret = access(opt_sessiond_path, F_OK | X_OK);
 337                         if (ret < 0) {
 338                                 ERR("No such file: %s", opt_sessiond_path);
 339                                 goto end;
 340                         }
 341                         pathname = opt_sessiond_path;
 342                 } else {
 343                         /* Try LTTNG_SESSIOND_PATH env variable */
 344                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 345                         if (pathname != NULL) {
 346                                 /* strdup here in order to make the free()
 347                                  * not fail later on.
 348                                  */
 349                                 pathname = strdup(pathname);
 350                         }
 351                 }
 352
 353                 /* Let's rock and roll */
 354                 if (pathname == NULL) {
 355                         ret = asprintf(&pathname, "ltt-sessiond");
 356                         if (ret < 0) {
 357                                 goto end;
 358                         }
 359                 }
 360
 361                 ret = spawn_sessiond(pathname);
 362                 free(pathname);
 363                 if (ret < 0) {
 364                         ERR("Problem occurs when starting %s", pathname);
 365                         goto end;
 366                 }
 367         }
 368
 369 end:
 370         return ret;
 371 }
 372
 373 /*
 374  *  set_signal_handler
 375  *
 376  *  Setup signal handler for SIGCHLD and SIGTERM.
 377  */
 378 static int set_signal_handler(void)
 379 {
 380         int ret = 0;
 381         struct sigaction sa;
 382         sigset_t sigset;
 383
 384         if ((ret = sigemptyset(&sigset)) < 0) {
 385                 perror("sigemptyset");
 386                 goto end;
 387         }
 388
 389         sa.sa_handler = sighandler;
 390         sa.sa_mask = sigset;
 391         sa.sa_flags = 0;
 392         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 393                 perror("sigaction");
 394                 goto end;
 395         }
 396
 397         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 398                 perror("sigaction");
 399                 goto end;
 400         }
 401
 402 end:
 403         return ret;
 404 }
 405
 406 /*
 407  *  sighandler
 408  *
 409  *  Signal handler for the daemon
 410  */
 411 static void sighandler(int sig)
 412 {
 413         switch (sig) {
 414                 case SIGTERM:
 415                         DBG("SIGTERM catched");
 416                         clean_exit(EXIT_FAILURE);
 417                         break;
 418                 case SIGCHLD:
 419                         /* Notify is done */
 420                         DBG("SIGCHLD catched");
 421                         break;
 422                 default:
 423                         DBG("Unknown signal %d catched", sig);
 424                         break;
 425         }
 426
 427         return;
 428 }
 429 /*
 430  * clean_exit
 431  */
 432 void clean_exit(int code)
 433 {
 434         DBG("Clean exit");
 435         if (lttng_disconnect_sessiond() < 0) {
 436                 ERR("Session daemon disconnect failed.");
 437         }
 438         exit(code);
 439 }
 440
 441 /*
 442  *  main
 443  */
 444 int main(int argc, char *argv[])
 445 {
 446         int ret;
 447
 448         progname = argv[0] ? argv[0] : "lttng";
 449
 450         /* For Mathieu Desnoyers aka Dr Tracing */
 451         if (strncmp(progname, "drtrace", 7) == 0) {
 452                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 453         }
 454
 455         ret = parse_args(argc, (const char **) argv);
 456         if (ret < 0) {
 457                 clean_exit(EXIT_FAILURE);
 458         }
 459
 460         ret = validate_options();
 461         if (ret < 0) {
 462                 return EXIT_FAILURE;
 463         }
 464
 465         ret = set_signal_handler();
 466         if (ret < 0) {
 467                 clean_exit(ret);
 468         }
 469
 470         if (opt_tracing_group != NULL) {
 471                 DBG("Set tracing group to '%s'", opt_tracing_group);
 472                 lttng_set_tracing_group(opt_tracing_group);
 473         }
 474
 475         /* If ask for kernel tracing, need root perms */
 476         if (opt_trace_kernel) {
 477                 DBG("Kernel tracing activated");
 478                 if (getuid() != 0) {
 479                         ERR("%s must be setuid root", progname);
 480                         clean_exit(-EPERM);
 481                 }
 482         }
 483
 484         /* Check if the lttng session daemon is running.
 485          * If no, a daemon will be spawned.
 486          */
 487         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 488                 clean_exit(EXIT_FAILURE);
 489         }
 490
 491         ret = process_client_opt();
 492         if (ret < 0) {
 493                 clean_exit(ret);
 494         }
 495
 496         clean_exit(0);
 497
 498         return 0;
 499 }