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, count;
 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         count = lttng_ust_list_apps(&pids);
 132         if (count < 0) {
 133                 ret = count;
 134                 goto error;
 135         }
 136
 137         MSG("LTTng UST traceable application [name (pid)]:");
 138         for (i=0; i < count; i++) {
 139                 snprintf(path, sizeof(path), "/proc/%d/cmdline", pids[i]);
 140                 fp = fopen(path, "r");
 141                 if (fp == NULL) {
 142                         MSG("\t(not running) (%d)", pids[i]);
 143                         continue;
 144                 }
 145                 ret = fread(cmdline, 1, sizeof(cmdline), fp);
 146                 MSG("\t%s (%d)", cmdline, pids[i]);
 147                 fclose(fp);
 148         }
 149
 150         /* Allocated by lttng_ust_list_apps() */
 151         free(pids);
 152
 153         return 0;
 154
 155 error:
 156         return ret;
 157 }
 158
 159 /*
 160  *  spawn_sessiond
 161  *
 162  *  Spawn a session daemon by forking and execv.
 163  */
 164 static int spawn_sessiond(char *pathname)
 165 {
 166         int ret = 0;
 167         pid_t pid;
 168
 169         MSG("Spawning session daemon");
 170         pid = fork();
 171         if (pid == 0) {
 172                 /* Spawn session daemon and tell
 173                  * it to signal us when ready.
 174                  */
 175                 ret = execlp(pathname, "ltt-sessiond", "--sig-parent", "--quiet", NULL);
 176                 if (ret < 0) {
 177                         if (errno == ENOENT) {
 178                                 ERR("No session daemon found. Use --sessiond-path.");
 179                         } else {
 180                                 perror("execlp");
 181                         }
 182                         kill(getppid(), SIGTERM);
 183                         exit(EXIT_FAILURE);
 184                 }
 185                 exit(EXIT_SUCCESS);
 186         } else if (pid > 0) {
 187                 /* Wait for ltt-sessiond to start */
 188                 pause();
 189                 goto end;
 190         } else {
 191                 perror("fork");
 192                 ret = -1;
 193                 goto end;
 194         }
 195
 196 end:
 197         return ret;
 198 }
 199
 200 /*
 201  *  check_ltt_sessiond
 202  *
 203  *  Check if the session daemon is available using
 204  *  the liblttngctl API for the check. If not, try to
 205  *  spawn a daemon.
 206  */
 207 static int check_ltt_sessiond(void)
 208 {
 209         int ret;
 210         char *pathname = NULL;
 211
 212         ret = lttng_check_session_daemon();
 213         if (ret < 0) {
 214                 /* Try command line option path */
 215                 if (opt_sessiond_path != NULL) {
 216                         ret = access(opt_sessiond_path, F_OK | X_OK);
 217                         if (ret < 0) {
 218                                 ERR("No such file: %s", opt_sessiond_path);
 219                                 goto end;
 220                         }
 221                         pathname = opt_sessiond_path;
 222                 } else {
 223                         /* Try LTTNG_SESSIOND_PATH env variable */
 224                         pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
 225                         if (pathname != NULL) {
 226                                 /* strdup here in order to make the free()
 227                                  * not fail later on.
 228                                  */
 229                                 pathname = strdup(pathname);
 230                         }
 231                 }
 232
 233                 /* Let's rock and roll */
 234                 if (pathname == NULL) {
 235                         ret = asprintf(&pathname, "ltt-sessiond");
 236                         if (ret < 0) {
 237                                 goto end;
 238                         }
 239                 }
 240
 241                 ret = spawn_sessiond(pathname);
 242                 free(pathname);
 243                 if (ret < 0) {
 244                         ERR("Problem occurs when starting %s", pathname);
 245                         goto end;
 246                 }
 247         }
 248
 249 end:
 250         return ret;
 251 }
 252
 253 /*
 254  *  set_signal_handler
 255  *
 256  *  Setup signal handler for SIGCHLD and SIGTERM.
 257  */
 258 static int set_signal_handler(void)
 259 {
 260         int ret = 0;
 261         struct sigaction sa;
 262         sigset_t sigset;
 263
 264         if ((ret = sigemptyset(&sigset)) < 0) {
 265                 perror("sigemptyset");
 266                 goto end;
 267         }
 268
 269         sa.sa_handler = sighandler;
 270         sa.sa_mask = sigset;
 271         sa.sa_flags = 0;
 272         if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
 273                 perror("sigaction");
 274                 goto end;
 275         }
 276
 277         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
 278                 perror("sigaction");
 279                 goto end;
 280         }
 281
 282 end:
 283         return ret;
 284 }
 285
 286 /*
 287  *  sighandler
 288  *
 289  *  Signal handler for the daemon
 290  */
 291 static void sighandler(int sig)
 292 {
 293         DBG("%d received", sig);
 294         switch (sig) {
 295                 case SIGTERM:
 296                         clean_exit(EXIT_FAILURE);
 297                         break;
 298                 case SIGCHLD:
 299                         /* Notify is done */
 300                         break;
 301                 default:
 302                         break;
 303         }
 304
 305         return;
 306 }
 307 /*
 308  * clean_exit
 309  */
 310 void clean_exit(int code)
 311 {
 312         DBG("Clean exit");
 313         exit(code);
 314 }
 315
 316 /*
 317  *  main
 318  */
 319 int main(int argc, char *argv[])
 320 {
 321         int ret;
 322
 323         progname = argv[0] ? argv[0] : "lttng";
 324
 325         /* For Mathieu Desnoyers aka Dr Tracing */
 326         if (strncmp(progname, "drtrace", 7) == 0) {
 327                 MSG("%c[%d;%dmWelcome back Dr Tracing!%c[%dm\n\n", 27,1,33,27,0);
 328         }
 329
 330         ret = parse_args(argc, (const char **) argv);
 331         if (ret < 0) {
 332                 return EXIT_FAILURE;
 333         }
 334
 335         ret = set_signal_handler();
 336         if (ret < 0) {
 337                 return ret;
 338         }
 339
 340         if (opt_tracing_group != NULL) {
 341                 DBG("Set tracing group to '%s'", opt_tracing_group);
 342                 lttng_set_tracing_group(opt_tracing_group);
 343         }
 344
 345         /* If ask for kernel tracing, need root perms */
 346         if (opt_trace_kernel) {
 347                 DBG("Kernel tracing activated");
 348                 if (getuid() != 0) {
 349                         ERR("%s must be setuid root", progname);
 350                         return -EPERM;
 351                 }
 352         }
 353
 354         /* Check if the lttng session daemon is running.
 355          * If no, a daemon will be spawned.
 356          */
 357         if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
 358                 return EXIT_FAILURE;
 359         }
 360
 361         ret = process_client_opt();
 362         if (ret < 0) {
 363                 return ret;
 364         }
 365
 366         return 0;
 367 }