liblttngctl/liblttngctl.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
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (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
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20 #include <errno.h>
  21 #include <grp.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include <lttng/lttng.h>
  28
  29 #include "liblttsessiondcomm.h"
  30 #include "lttngerr.h"
  31 #include "lttng-share.h"
  32
  33 /* Socket to session daemon for communication */
  34 static int sessiond_socket;
  35 static char sessiond_sock_path[PATH_MAX];
  36
  37 /* Communication structure to ltt-sessiond */
  38 static struct lttcomm_session_msg lsm;
  39 static struct lttcomm_lttng_msg llm;
  40
  41 /* Variables */
  42 static char *tracing_group;
  43 static int connected;
  44
  45 /*
  46  *  send_data_sessiond
  47  *
  48  *  Send lttcomm_session_msg to the session daemon.
  49  *
  50  *  On success, return 0
  51  *  On error, return error code
  52  */
  53 static int send_data_sessiond(void)
  54 {
  55         int ret;
  56
  57         if (!connected) {
  58                 ret = -ENOTCONN;
  59                 goto end;
  60         }
  61
  62         ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
  63
  64 end:
  65         return ret;
  66 }
  67
  68 /*
  69  *  recv_data_sessiond
  70  *
  71  *  Receive data from the sessiond socket.
  72  *
  73  *  On success, return 0
  74  *  On error, return recv() error code
  75  */
  76 static int recv_data_sessiond(void *buf, size_t len)
  77 {
  78         int ret;
  79
  80         if (!connected) {
  81                 ret = -ENOTCONN;
  82                 goto end;
  83         }
  84
  85         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
  86
  87 end:
  88         return ret;
  89 }
  90
  91 /*
  92  *  ask_sessiond
  93  *
  94  *  Ask the session daemon a specific command and put the data into buf.
  95  *
  96  *  Return size of data (only payload, not header).
  97  */
  98 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf)
  99 {
 100         int ret;
 101         size_t size;
 102         void *data = NULL;
 103
 104         ret = lttng_connect_sessiond();
 105         if (ret < 0) {
 106                 goto end;
 107         }
 108
 109         lsm.cmd_type = lct;
 110
 111         /* Send command to session daemon */
 112         ret = send_data_sessiond();
 113         if (ret < 0) {
 114                 goto end;
 115         }
 116
 117         /* Get header from data transmission */
 118         ret = recv_data_sessiond(&llm, sizeof(llm));
 119         if (ret < 0) {
 120                 goto end;
 121         }
 122
 123         /* Check error code if OK */
 124         if (llm.ret_code != LTTCOMM_OK) {
 125                 ret = -llm.ret_code;
 126                 goto end;
 127         }
 128
 129         size = llm.data_size;
 130         if (size == 0) {
 131                 goto end;
 132         }
 133
 134         data = (void*) malloc(size);
 135
 136         /* Get payload data */
 137         ret = recv_data_sessiond(data, size);
 138         if (ret < 0) {
 139                 free(data);
 140                 goto end;
 141         }
 142
 143         *buf = data;
 144         ret = size;
 145
 146 end:
 147         lttng_disconnect_sessiond();
 148         return ret;
 149 }
 150
 151 /*
 152  *  check_tracing_group
 153  *
 154  *  Check if the specified group name exist.
 155  *  If yes, 0, else -1
 156  */
 157 static int check_tracing_group(const char *grp_name)
 158 {
 159         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 160         gid_t *grp_list;
 161         int grp_list_size, grp_id, i;
 162         int ret = -1;
 163
 164         /* Get GID of group 'tracing' */
 165         grp_tracing = getgrnam(grp_name);
 166         if (grp_tracing == NULL) {
 167                 /* NULL means not found also. getgrnam(3) */
 168                 if (errno != 0) {
 169                         perror("getgrnam");
 170                 }
 171                 goto end;
 172         }
 173
 174         /* Get number of supplementary group IDs */
 175         grp_list_size = getgroups(0, NULL);
 176         if (grp_list_size < 0) {
 177                 perror("getgroups");
 178                 goto end;
 179         }
 180
 181         /* Alloc group list of the right size */
 182         grp_list = malloc(grp_list_size * sizeof(gid_t));
 183         grp_id = getgroups(grp_list_size, grp_list);
 184         if (grp_id < -1) {
 185                 perror("getgroups");
 186                 goto free_list;
 187         }
 188
 189         for (i = 0; i < grp_list_size; i++) {
 190                 if (grp_list[i] == grp_tracing->gr_gid) {
 191                         ret = 0;
 192                         break;
 193                 }
 194         }
 195
 196 free_list:
 197         free(grp_list);
 198
 199 end:
 200         return ret;
 201 }
 202
 203 /*
 204  *  set_session_daemon_path
 205  *
 206  *  Set sessiond socket path by putting it in
 207  *  the global sessiond_sock_path variable.
 208  */
 209 static int set_session_daemon_path(void)
 210 {
 211         int ret;
 212
 213         /* Are we in the tracing group ? */
 214         ret = check_tracing_group(tracing_group);
 215         if (ret < 0 && getuid() != 0) {
 216                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 217                                         getenv("HOME")) < 0) {
 218                         return -ENOMEM;
 219                 }
 220         } else {
 221                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 222                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 223         }
 224
 225         return 0;
 226 }
 227
 228 /*
 229  *  lttng_start_tracing
 230  *
 231  *  Start tracing for all trace of the session.
 232  */
 233 int lttng_start_tracing(char *session_name)
 234 {
 235         strncpy(lsm.session_name, session_name, NAME_MAX);
 236         return ask_sessiond(LTTNG_START_TRACE, NULL);
 237 }
 238
 239 /*
 240  *  lttng_stop_tracing
 241  *
 242  *  Stop tracing for all trace of the session.
 243  */
 244 int lttng_stop_tracing(char *session_name)
 245 {
 246         strncpy(lsm.session_name, session_name, NAME_MAX);
 247         return ask_sessiond(LTTNG_STOP_TRACE, NULL);
 248 }
 249
 250 /*
 251  * BEGIN Kernel control API
 252  */
 253
 254 /*
 255  *  lttng_kernel_enable_event
 256  */
 257 int lttng_kernel_enable_event(struct lttng_event *ev, char *channel_name)
 258 {
 259         int ret;
 260
 261         if (strlen(channel_name) == 0) {
 262                 strncpy(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 263         } else {
 264                 strncpy(lsm.u.enable.channel_name, channel_name, NAME_MAX);
 265         }
 266
 267         if (ev == NULL) {
 268                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_ALL_EVENT, NULL);
 269         } else {
 270                 memcpy(&lsm.u.enable.event, ev, sizeof(struct lttng_event));
 271                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_EVENT, NULL);
 272         }
 273
 274         return ret;
 275 }
 276
 277 /*
 278  *  lttng_kernel_disable_event
 279  *
 280  *  Disable an event in the kernel tracer.
 281  */
 282 int lttng_kernel_disable_event(char *name, char *channel_name)
 283 {
 284         int ret;
 285
 286         if (strlen(channel_name) == 0) {
 287                 strncpy(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 288         } else {
 289                 strncpy(lsm.u.disable.channel_name, channel_name, NAME_MAX);
 290         }
 291
 292         if (name == NULL) {
 293                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_ALL_EVENT, NULL);
 294         } else {
 295                 strncpy(lsm.u.disable.name, name, NAME_MAX);
 296                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_EVENT, NULL);
 297         }
 298
 299         return ret;
 300 }
 301
 302 /*
 303  *  lttng_kernel_enable_channel
 304  *
 305  *  Enable recording for a channel for the kernel tracer.
 306  */
 307 int lttng_kernel_enable_channel(char *name)
 308 {
 309         return ask_sessiond(LTTNG_KERNEL_ENABLE_CHANNEL, NULL);
 310 }
 311
 312 /*
 313  *  lttng_kernel_disable_channel
 314  *
 315  *  Disable recording for the channel for the kernel tracer.
 316  */
 317 int lttng_kernel_disable_channel(char *name)
 318 {
 319         return ask_sessiond(LTTNG_KERNEL_DISABLE_CHANNEL, NULL);
 320 }
 321
 322 /*
 323  *  lttng_kernel_create_channel
 324  *
 325  *  Create a channel in the kernel tracer.
 326  */
 327 int lttng_kernel_create_channel(struct lttng_channel *chan)
 328 {
 329         memcpy(&lsm.u.channel.chan, chan, sizeof(struct lttng_channel));
 330         return ask_sessiond(LTTNG_KERNEL_CREATE_CHANNEL, NULL);
 331 }
 332
 333 /*
 334  *  lttng_list_events
 335  *
 336  *  List all available events in the kernel.
 337  *
 338  *  Return the size (bytes) of the list and set the event_list array.
 339  *  On error, return negative value.
 340  */
 341 int lttng_kernel_list_events(char **event_list)
 342 {
 343         return ask_sessiond(LTTNG_KERNEL_LIST_EVENTS, (void **) event_list);
 344 }
 345
 346 /*
 347  * END Kernel control API
 348  */
 349
 350 /*
 351  *  lttng_get_readable_code
 352  *
 353  *  Return a human readable string of code
 354  */
 355 const char *lttng_get_readable_code(int code)
 356 {
 357         if (code > -LTTCOMM_OK) {
 358                 return "Ended with errors";
 359         }
 360
 361         return lttcomm_get_readable_code(code);
 362 }
 363
 364 /*
 365  *  lttng_ust_list_apps
 366  *
 367  *  Ask the session daemon for all UST traceable applications.
 368  *
 369  *  Return the number of pids.
 370  *  On error, return negative value.
 371  */
 372 int lttng_ust_list_traceable_apps(pid_t **pids)
 373 {
 374         int ret;
 375
 376         ret = ask_sessiond(LTTNG_LIST_TRACEABLE_APPS, (void**) pids);
 377         if (ret < 0) {
 378                 return ret;
 379         }
 380
 381         return ret / sizeof(pid_t);
 382 }
 383
 384 /*
 385  *  lttng_list_traces
 386  *
 387  *  Ask the session daemon for all traces (kernel and ust) for the session
 388  *  identified by name.
 389  *
 390  *  Return the number of traces.
 391  *  On error, return negative value.
 392  */
 393 /*
 394 int lttng_list_traces(char *session_name, struct lttng_trace **traces)
 395 {
 396         int ret;
 397
 398         strncpy(lsm.session_name, session_name, NAME_MAX);
 399
 400         ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
 401         if (ret < 0) {
 402                 return ret;
 403         }
 404
 405         return ret / sizeof(struct lttng_trace);
 406 }
 407 */
 408
 409 /*
 410  *  lttng_create_session
 411  *
 412  *  Create a brand new session using name.
 413  */
 414 int lttng_create_session(char *name, char *path)
 415 {
 416         strncpy(lsm.session_name, name, NAME_MAX);
 417         strncpy(lsm.path, path, PATH_MAX);
 418         return ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 419 }
 420
 421 /*
 422  *  lttng_destroy_session
 423  *
 424  *  Destroy session using name.
 425  */
 426 int lttng_destroy_session(char *name)
 427 {
 428         strncpy(lsm.session_name, name, NAME_MAX);
 429         return ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 430 }
 431
 432 /*
 433  *  lttng_list_sessions
 434  *
 435  *  Ask the session daemon for all available sessions.
 436  *
 437  *  Return number of session.
 438  *  On error, return negative value.
 439  */
 440 int lttng_list_sessions(struct lttng_session **sessions)
 441 {
 442         int ret;
 443
 444         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 445         if (ret < 0) {
 446                 return ret;
 447         }
 448
 449         return ret / sizeof(struct lttng_session);
 450 }
 451
 452 /*
 453  *  lttng_connect_sessiond
 454  *
 455  *  Connect to the LTTng session daemon.
 456  *  On success, return 0
 457  *  On error, return a negative value
 458  */
 459 int lttng_connect_sessiond(void)
 460 {
 461         int ret;
 462
 463         ret = set_session_daemon_path();
 464         if (ret < 0) {
 465                 return ret;
 466         }
 467
 468         /* Connect to the sesssion daemon */
 469         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 470         if (ret < 0) {
 471                 return ret;
 472         }
 473
 474         sessiond_socket = ret;
 475         connected = 1;
 476
 477         return 0;
 478 }
 479
 480 /*
 481  *  lttng_disconnect_sessiond
 482  *
 483  *  Clean disconnect the session daemon.
 484  */
 485 int lttng_disconnect_sessiond(void)
 486 {
 487         int ret = 0;
 488
 489         if (connected) {
 490                 ret = lttcomm_close_unix_sock(sessiond_socket);
 491                 sessiond_socket = 0;
 492                 connected = 0;
 493         }
 494
 495         return ret;
 496 }
 497
 498 void lttng_set_session_name(char *name)
 499 {
 500         strncpy(lsm.session_name, name, NAME_MAX);
 501 }
 502
 503 /*
 504  *  lttng_set_tracing_group
 505  *
 506  *  Set tracing group variable with name. This function
 507  *  allocate memory pointed by tracing_group.
 508  */
 509 int lttng_set_tracing_group(const char *name)
 510 {
 511         if (asprintf(&tracing_group, "%s", name) < 0) {
 512                 return -ENOMEM;
 513         }
 514
 515         return 0;
 516 }
 517
 518 /*
 519  *  lttng_check_session_daemon
 520  *
 521  *  Yes, return 1
 522  *  No, return 0
 523  *  Error, return negative value
 524  */
 525 int lttng_session_daemon_alive(void)
 526 {
 527         int ret;
 528
 529         ret = set_session_daemon_path();
 530         if (ret < 0) {
 531                 /* Error */
 532                 return ret;
 533         }
 534
 535         /* If socket exist, we consider the daemon started */
 536         ret = access(sessiond_sock_path, F_OK);
 537         if (ret < 0) {
 538                 /* Not alive */
 539                 return 0;
 540         }
 541
 542         /* Is alive */
 543         return 1;
 544 }
 545
 546 /*
 547  * lib constructor
 548  */
 549 static void __attribute__((constructor)) init()
 550 {
 551         /* Set default session group */
 552         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 553 }