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 void sighandler(int sig);
  46 static int set_signal_handler(void);
  47
  48 /*
  49  *  start_client
  50  *
  51  *  Process client request from the command line
  52  *  options. Every tracing action is done by the
  53  *  liblttngctl API.
  54  */
  55 static int process_client_opt(void)
  56 {
  57         int ret;
  58
  59         /* Connect to the session daemon */
  60         ret = lttng_connect_sessiond();
  61         if (ret < 0) {
  62                 goto end;
  63         }
  64
  65         if (opt_list_apps) {
  66                 ret = process_opt_list_apps();
  67                 if (ret < 0) {
  68                         goto end;
  69                 }
  70         }
  71
  72         if (opt_list_session) {
  73                 ret = process_opt_list_sessions();
  74                 if (ret < 0) {
  75                         goto end;
  76                 }
  77         }
  78
  79         return 0;
  80
  81 end:
  82         ERR("%s", lttng_get_readable_code(ret));
  83         return ret;
  84 }
  85
  86 /*
  87  *  process_opt_list_sessions
  88  *
  89  *  Get the list of available sessions from
  90  *  the session daemon and print it to user.
  91  */
  92 static int process_opt_list_sessions(void)
  93 {
  94         int ret, count, i;
  95         struct lttng_session *sess;
  96
  97         count = lttng_list_sessions(&sess);
  98         if (count < 0) {
  99                 ret = count;
 100                 goto error;
 101         }
 102
 103         MSG("Available sessions [Name (uuid)]:");
 104         for (i = 0; i < count; i++) {
 105                 MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
 106         }
 107
 108         free(sess);
 109         MSG("\nTo select a session, use --session UUID.");
 110
 111         return 0;
 112
 113 error:
 114         return ret;
 115 }
 116
 117 /*
 118  *  process_opt_list_apps
 119  *
 120  *  Get the UST traceable pid list and print
 121  *  them to the user.
 122  */
 123 static int process_opt_list_apps(void)
 124 {
 125         int i, ret;
 126         pid_t *pids;
 127         FILE *fp;
 128         char path[24];  /* Can't go bigger than /proc/65535/cmdline */
 129         char cmdline[PATH_MAX];
 130
 131         ret = lttng_ust_list_apps(&pids);
 132         if (ret < 0) {
 133                 goto error;
 134         }
 135
 136         MSG("LTTng UST traceable application [name (pid)]:");
 137         for (i=0; i < ret; i++) {
 138                 snprintf(path, sizeof(path), "/proc/%d/cmdline", pids[i]);
 139                 fp = fopen(path, "r");
 140                 if (fp == NULL) {
 141                         continue;
 142                 }
 143                 ret = fread(cmdline, 1, sizeof(cmdline), fp);
 144                 MSG("\t%s (%d)", cmdline, pids[i]);
 145                 fclose(fp);
 146         }
 147
 148         /* Allocated by lttng_ust_list_apps() */
 149         free(pids);
 150
 151         return 0;
 152
 153 error:
 154         return ret;
 155 }
 156
 157 /*
 158  *  spawn_sessiond
 159  *
 160  *  Spawn a session daemon by forking and execv.
 161  */
 162 static int spawn_sessiond(char *pathname)
 163 {
 164         int ret = 0;
 165         pid_t pid;
 166
 167         MSG("Spawning session daemon");
 168         pid = fork();
 169         if (pid == 0) {
 170                 /* Spawn session daemon and tell
 171                  * it to signal us when ready.
 172                  */
 173                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 174                 if (ret < 0) {
 175                         if (errno == ENOENT) {
 176                                 ERR("No session daemon found. Use --sessiond-path.");
 177                         } else {
 178                                 perror("execlp");
 179                         }
 180                         kill(getppid(), SIGTERM);
 181                         exit(EXIT_FAILURE);
 182                 }
 183                 exit(EXIT_SUCCESS);
 184         } else if (pid > 0) {
 185                 /* Wait for ltt-sessiond to start */
 186                 pause();
 187                 goto end;
 188         } else {
 189                 perror("fork");
 190                 ret = -1;
 191                 goto end;
 192         }
 193
 194 end:
 195         return ret;
 196 }
 197
 198 /*
 199  *  check_ltt_sessiond
 200  *
 201  *  Check if the session daemon is available using
 202  *  the liblttngctl API for the check. If not, try to
 203  *  spawn a daemon.
 204  */
 205 static int check_ltt_sessiond(void)
 206 {
 207         int ret;
 208         char *pathname = NULL;
 209
 210         ret = lttng_check_session_daemon();
 211         if (ret < 0) {
 212                 /* Try command line option path */
 213                 if (opt_sessiond_path != NULL) {
 214                         ret = access(opt_sessiond_path, F_OK | X_OK);
 215                         if (ret < 0) {
 216                                 ERR("No such file: %s", opt_sessiond_path);
 217                                 goto end;
 218                         }
 219                         pathname = opt_sessiond_path;
 220                 } else {
 221                         /* Try LTTNG_SESSIOND_PATH env variable */
 222                         pathname = strdup(getenv(LTTNG_SESSIOND_PATH_ENV));
 223                 }
 224
 225                 /* Let's rock and roll */
 226                 if (pathname == NULL) {
 227                         ret = asprintf(&pathname, "ltt-sessiond");
 228                         if (ret < 0) {
 229                                 goto end;
 230                         }
 231                 }
 232
 233                 ret = spawn_sessiond(pathname);
 234                 free(pathname);
 235                 if (ret < 0) {
 236                         ERR("Problem occurs when starting %s", pathname);
 237                         goto end;
 238                 }
 239         }
 240
 241 end:
 242         return ret;
 243 }
 244
 245 /*
 246  *  set_signal_handler
 247  *
 248  *  Setup signal handler for SIGCHLD and SIGTERM.
 249  */
 250 static int set_signal_handler(void)
 251 {
 252         int ret = 0;
 253         struct sigaction sa;
 254         sigset_t sigset;
 255
 256         if ((ret = sigemptyset(&sigset)) < 0) {
 257                 perror("sigemptyset");
 258                 goto end;
 259         }
 260
 261         sa.sa_handler = sighandler;
 262         sa.sa_mask = sigset;
 263         sa.sa_flags = 0;
 264         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 265                 perror("sigaction");
 266                 goto end;
 267         }
 268
 269         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 270                 perror("sigaction");
 271                 goto end;
 272         }
 273
 274 end:
 275         return ret;
 276 }
 277
 278 /*
 279  *  sighandler
 280  *
 281  *  Signal handler for the daemon
 282  */
 283 static void sighandler(int sig)
 284 {
 285         DBG("%d received", sig);
 286         switch (sig) {
 287                 case SIGTERM:
 288                         clean_exit(EXIT_FAILURE);
 289                         break;
 290                 case SIGCHLD:
 291                         /* Notify is done */
 292                         break;
 293                 default:
 294                         break;
 295         }
 296
 297         return;
 298 }
 299 /*
 300  * clean_exit
 301  */
 302 void clean_exit(int code)
 303 {
 304         DBG("Clean exit");
 305         exit(code);
 306 }
 307
 308 /*
 309  *  main
 310  */
 311 int main(int argc, char *argv[])
 312 {
 313         int ret;
 314
 315         progname = argv[0] ? argv[0] : "lttng";
 316
 317         /* For Mathieu Desnoyers aka Dr Tracing */
 318         if (strncmp(progname, "drtrace", 7) == 0) {
 319                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 320         }
 321
 322         ret = parse_args(argc, (const char **) argv);
 323         if (ret < 0) {
 324                 return EXIT_FAILURE;
 325         }
 326
 327         ret = set_signal_handler();
 328         if (ret < 0) {
 329                 return ret;
 330         }
 331
 332         if (opt_tracing_group != NULL) {
 333                 DBG("Set tracing group to '%s'", opt_tracing_group);
 334                 lttng_set_tracing_group(opt_tracing_group);
 335         }
 336
 337         /* If ask for kernel tracing, need root perms */
 338         if (opt_trace_kernel) {
 339                 DBG("Kernel tracing activated");
 340                 if (getuid() != 0) {
 341                         ERR("%s must be setuid root", progname);
 342                         return -EPERM;
 343                 }
 344         }
 345
 346         /* Check if the lttng session daemon is running.
 347          * If no, a daemon will be spawned.
 348          */
 349         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 350                 return EXIT_FAILURE;
 351         }
 352
 353         ret = process_client_opt();
 354         if (ret < 0) {
 355                 return ret;
 356         }
 357
 358         return 0;
 359 }