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/lttng.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_list_traces(void);
  46 static int process_opt_create_session(void);
  47 static void sighandler(int sig);
  48 static int set_signal_handler(void);
  49 static int validate_options(void);
  50 static char *get_cmdline_by_pid(pid_t pid);
  51
  52 /*
  53  *  start_client
  54  *
  55  *  Process client request from the command line
  56  *  options. Every tracing action is done by the
  57  *  liblttngctl API.
  58  */
  59 static int process_client_opt(void)
  60 {
  61         int ret;
  62         uuid_t uuid;
  63
  64         /* Connect to the session daemon */
  65         ret = lttng_connect_sessiond();
  66         if (ret < 0) {
  67                 goto end;
  68         }
  69
  70         if (opt_list_apps) {
  71                 ret = process_opt_list_apps();
  72                 if (ret < 0) {
  73                         goto end;
  74                 }
  75         }
  76
  77         if (opt_list_session) {
  78                 ret = process_opt_list_sessions();
  79                 if (ret < 0) {
  80                         goto end;
  81                 }
  82         }
  83
  84         if (opt_list_traces) {
  85                 ret = process_opt_list_traces();
  86                 if (ret < 0) {
  87                         goto end;
  88                 }
  89         }
  90
  91         if (opt_create_session != NULL) {
  92                 ret = process_opt_create_session();
  93                 if (ret < 0) {
  94                         goto end;
  95                 }
  96         }
  97
  98         if (opt_destroy_session != NULL) {
  99                 uuid_parse(opt_destroy_session, uuid);
 100                 ret = lttng_destroy_session(&uuid);
 101                 if (ret < 0) {
 102                         goto end;
 103                 }
 104         }
 105
 106         if (opt_session_uuid != NULL) {
 107                 DBG("Set session uuid to %s", opt_session_uuid);
 108                 lttng_set_current_session_uuid(opt_session_uuid);
 109         }
 110
 111         if (opt_trace_kernel) {
 112                 ERR("Not implemented yet");
 113                 goto end;
 114         }
 115
 116         if (opt_trace_pid != 0) {
 117                 if (opt_create_trace) {
 118                         DBG("Create a userspace trace for pid %d", opt_trace_pid);
 119                         ret = lttng_ust_create_trace(opt_trace_pid);
 120                         if (ret < 0) {
 121                                 goto end;
 122                         }
 123                         MSG("Trace created successfully!\nUse --start to start tracing.");
 124                 }
 125
 126                 if (opt_start_trace) {
 127                         DBG("Start trace for pid %d", opt_trace_pid);
 128                         ret = lttng_ust_start_trace(opt_trace_pid);
 129                         if (ret < 0) {
 130                                 goto end;
 131                         }
 132                         MSG("Trace started successfully!");
 133                 } else if (opt_stop_trace) {
 134                         DBG("Stop trace for pid %d", opt_trace_pid);
 135                         ret = lttng_ust_stop_trace(opt_trace_pid);
 136                         if (ret < 0) {
 137                                 goto end;
 138                         }
 139                         MSG("Trace stopped successfully!");
 140                 }
 141
 142         }
 143
 144         return 0;
 145
 146 end:
 147         ERR("%s", lttng_get_readable_code(ret));
 148         return ret;
 149 }
 150
 151 /*
 152  *  process_opt_list_traces
 153  *
 154  *  Get list of all traces for a specific session uuid.
 155  */
 156 static int process_opt_list_traces(void)
 157 {
 158         int ret, i;
 159         uuid_t uuid;
 160         struct lttng_trace *traces;
 161
 162         uuid_parse(opt_session_uuid, uuid);
 163         ret = lttng_list_traces(&uuid, &traces);
 164         if (ret < 0) {
 165                 goto error;
 166         }
 167
 168         MSG("Userspace traces:");
 169         for (i = 0; i < ret; i++) {
 170                 if (traces[i].type == USERSPACE) {
 171                         MSG("\t%d) %s (pid: %d): %s",
 172                                         i, traces[i].name, traces[i].pid,
 173                                         get_cmdline_by_pid(traces[i].pid));
 174                 } else {
 175                         break;
 176                 }
 177         }
 178
 179         MSG("Kernel traces:");
 180         for (;i < ret; i++) {
 181                 if (traces[i].type == KERNEL) {
 182                         MSG("\t%d) %s", i, traces[i].name);
 183                 }
 184         }
 185
 186         free(traces);
 187
 188 error:
 189         return ret;
 190 }
 191
 192 /*
 193  *  process_opt_create_session
 194  *
 195  *  Create a new session using the name pass
 196  *  to the command line.
 197  */
 198 static int process_opt_create_session(void)
 199 {
 200         int ret;
 201         uuid_t session_id;
 202         char str_uuid[37];
 203
 204         ret = lttng_create_session(opt_create_session, &session_id);
 205         if (ret < 0) {
 206                 goto error;
 207         }
 208
 209         uuid_unparse(session_id, str_uuid);
 210
 211         MSG("Session created:");
 212         MSG("    %s (%s)", opt_create_session, str_uuid);
 213
 214 error:
 215         return ret;
 216 }
 217
 218 /*
 219  *  process_opt_list_sessions
 220  *
 221  *  Get the list of available sessions from
 222  *  the session daemon and print it to user.
 223  */
 224 static int process_opt_list_sessions(void)
 225 {
 226         int ret, count, i;
 227         struct lttng_session *sess;
 228
 229         count = lttng_list_sessions(&sess);
 230         if (count < 0) {
 231                 ret = count;
 232                 goto error;
 233         }
 234
 235         MSG("Available sessions [Name (uuid)]:");
 236         for (i = 0; i < count; i++) {
 237                 MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
 238         }
 239
 240         free(sess);
 241         MSG("\nTo select a session, use --session UUID.");
 242
 243         return 0;
 244
 245 error:
 246         return ret;
 247 }
 248
 249 /*
 250  *  process_opt_list_apps
 251  *
 252  *  Get the UST traceable pid list and print
 253  *  them to the user.
 254  */
 255 static int process_opt_list_apps(void)
 256 {
 257         int i, ret, count;
 258         pid_t *pids;
 259         char *cmdline;
 260
 261         count = lttng_ust_list_apps(&pids);
 262         if (count < 0) {
 263                 ret = count;
 264                 goto error;
 265         }
 266
 267         MSG("LTTng UST traceable application [name (pid)]:");
 268         for (i=0; i < count; i++) {
 269                 cmdline = get_cmdline_by_pid(pids[i]);
 270                 if (cmdline == NULL) {
 271                         MSG("\t(not running) (%d)", pids[i]);
 272                         continue;
 273                 }
 274                 MSG("\t%s (%d)", cmdline, pids[i]);
 275                 free(cmdline);
 276         }
 277
 278         /* Allocated by lttng_ust_list_apps() */
 279         free(pids);
 280
 281         return 0;
 282
 283 error:
 284         return ret;
 285 }
 286
 287 /*
 288  *  get_cmdline_by_pid
 289  *
 290  *  Get command line from /proc for a specific pid.
 291  *
 292  *  On success, return an allocated string pointer pointing to
 293  *  the proc cmdline.
 294  *  On error, return NULL.
 295  */
 296 static char *get_cmdline_by_pid(pid_t pid)
 297 {
 298         int ret;
 299         FILE *fp;
 300         char *cmdline = NULL;
 301         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 302
 303         snprintf(path, sizeof(path), "/proc/%d/cmdline", pid);
 304         fp = fopen(path, "r");
 305         if (fp == NULL) {
 306                 goto end;
 307         }
 308
 309         /* Caller must free() *cmdline */
 310         cmdline = malloc(PATH_MAX);
 311         ret = fread(cmdline, 1, PATH_MAX, fp);
 312         fclose(fp);
 313
 314 end:
 315         return cmdline;
 316 }
 317
 318 /*
 319  *  validate_options
 320  *
 321  *  Make sure that all options passed to the command line
 322  *  are compatible with each others.
 323  *
 324  *  On error, return -1
 325  *  On success, return 0
 326  */
 327 static int validate_options(void)
 328 {
 329         /* Conflicting command */
 330         if (opt_start_trace && opt_stop_trace) {
 331                 ERR("Can't use --start and --stop together.");
 332                 goto error;
 333         /* Must have a session UUID for trace action. */
 334         } else if ((opt_session_uuid == NULL) &&
 335                         (opt_create_trace || opt_start_trace || opt_stop_trace || opt_list_traces)) {
 336                 ERR("You need to specify a session UUID.\nPlease use --session UUID to do so.");
 337                 goto error;
 338         /* If no PID specified and trace_kernel is off */
 339         } else if ((opt_trace_pid == 0 && opt_trace_kernel == 0) &&
 340                         (opt_create_trace || opt_start_trace || opt_stop_trace)) {
 341                 ERR("Please specify a PID using -p, --pid PID.");
 342                 goto error;
 343         }
 344
 345         return 0;
 346
 347 error:
 348         return -1;
 349 }
 350
 351 /*
 352  *  spawn_sessiond
 353  *
 354  *  Spawn a session daemon by forking and execv.
 355  */
 356 static int spawn_sessiond(char *pathname)
 357 {
 358         int ret = 0;
 359         pid_t pid;
 360
 361         MSG("Spawning session daemon");
 362         pid = fork();
 363         if (pid == 0) {
 364                 /* Spawn session daemon and tell
 365                  * it to signal us when ready.
 366                  */
 367                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 368                 if (ret < 0) {
 369                         if (errno == ENOENT) {
 370                                 ERR("No session daemon found. Use --sessiond-path.");
 371                         } else {
 372                                 perror("execlp");
 373                         }
 374                         kill(getppid(), SIGTERM);
 375                         exit(EXIT_FAILURE);
 376                 }
 377                 exit(EXIT_SUCCESS);
 378         } else if (pid > 0) {
 379                 /* Wait for ltt-sessiond to start */
 380                 pause();
 381                 goto end;
 382         } else {
 383                 perror("fork");
 384                 ret = -1;
 385                 goto end;
 386         }
 387
 388 end:
 389         return ret;
 390 }
 391
 392 /*
 393  *  check_ltt_sessiond
 394  *
 395  *  Check if the session daemon is available using
 396  *  the liblttngctl API for the check. If not, try to
 397  *  spawn a daemon.
 398  */
 399 static int check_ltt_sessiond(void)
 400 {
 401         int ret;
 402         char *pathname = NULL;
 403
 404         ret = lttng_check_session_daemon();
 405         if (ret < 0) {
 406                 /* Try command line option path */
 407                 if (opt_sessiond_path != NULL) {
 408                         ret = access(opt_sessiond_path, F_OK | X_OK);
 409                         if (ret < 0) {
 410                                 ERR("No such file: %s", opt_sessiond_path);
 411                                 goto end;
 412                         }
 413                         pathname = opt_sessiond_path;
 414                 } else {
 415                         /* Try LTTNG_SESSIOND_PATH env variable */
 416                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 417                         if (pathname != NULL) {
 418                                 /* strdup here in order to make the free()
 419                                  * not fail later on.
 420                                  */
 421                                 pathname = strdup(pathname);
 422                         }
 423                 }
 424
 425                 /* Let's rock and roll */
 426                 if (pathname == NULL) {
 427                         ret = asprintf(&pathname, "ltt-sessiond");
 428                         if (ret < 0) {
 429                                 goto end;
 430                         }
 431                 }
 432
 433                 ret = spawn_sessiond(pathname);
 434                 free(pathname);
 435                 if (ret < 0) {
 436                         ERR("Problem occurs when starting %s", pathname);
 437                         goto end;
 438                 }
 439         }
 440
 441 end:
 442         return ret;
 443 }
 444
 445 /*
 446  *  set_signal_handler
 447  *
 448  *  Setup signal handler for SIGCHLD and SIGTERM.
 449  */
 450 static int set_signal_handler(void)
 451 {
 452         int ret = 0;
 453         struct sigaction sa;
 454         sigset_t sigset;
 455
 456         if ((ret = sigemptyset(&sigset)) < 0) {
 457                 perror("sigemptyset");
 458                 goto end;
 459         }
 460
 461         sa.sa_handler = sighandler;
 462         sa.sa_mask = sigset;
 463         sa.sa_flags = 0;
 464         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 465                 perror("sigaction");
 466                 goto end;
 467         }
 468
 469         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 470                 perror("sigaction");
 471                 goto end;
 472         }
 473
 474 end:
 475         return ret;
 476 }
 477
 478 /*
 479  *  sighandler
 480  *
 481  *  Signal handler for the daemon
 482  */
 483 static void sighandler(int sig)
 484 {
 485         switch (sig) {
 486                 case SIGTERM:
 487                         DBG("SIGTERM catched");
 488                         clean_exit(EXIT_FAILURE);
 489                         break;
 490                 case SIGCHLD:
 491                         /* Notify is done */
 492                         DBG("SIGCHLD catched");
 493                         break;
 494                 default:
 495                         DBG("Unknown signal %d catched", sig);
 496                         break;
 497         }
 498
 499         return;
 500 }
 501 /*
 502  * clean_exit
 503  */
 504 void clean_exit(int code)
 505 {
 506         DBG("Clean exit");
 507         if (lttng_disconnect_sessiond() < 0) {
 508                 ERR("Session daemon disconnect failed.");
 509         }
 510         exit(code);
 511 }
 512
 513 /*
 514  *  main
 515  */
 516 int main(int argc, char *argv[])
 517 {
 518         int ret;
 519
 520         progname = argv[0] ? argv[0] : "lttng";
 521
 522         /* For Mathieu Desnoyers aka Dr Tracing */
 523         if (strncmp(progname, "drtrace", 7) == 0) {
 524                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 525         }
 526
 527         ret = parse_args(argc, (const char **) argv);
 528         if (ret < 0) {
 529                 clean_exit(EXIT_FAILURE);
 530         }
 531
 532         ret = validate_options();
 533         if (ret < 0) {
 534                 return EXIT_FAILURE;
 535         }
 536
 537         ret = set_signal_handler();
 538         if (ret < 0) {
 539                 clean_exit(ret);
 540         }
 541
 542         if (opt_tracing_group != NULL) {
 543                 DBG("Set tracing group to '%s'", opt_tracing_group);
 544                 lttng_set_tracing_group(opt_tracing_group);
 545         }
 546
 547         /* If ask for kernel tracing, need root perms */
 548         if (opt_trace_kernel) {
 549                 DBG("Kernel tracing activated");
 550                 if (getuid() != 0) {
 551                         ERR("%s must be setuid root", progname);
 552                         clean_exit(-EPERM);
 553                 }
 554         }
 555
 556         /* Check if the lttng session daemon is running.
 557          * If no, a daemon will be spawned.
 558          */
 559         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 560                 clean_exit(EXIT_FAILURE);
 561         }
 562
 563         ret = process_client_opt();
 564         if (ret < 0) {
 565                 clean_exit(ret);
 566         }
 567
 568         clean_exit(0);
 569
 570         return 0;
 571 }