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