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