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  *  Check if the specified group name exist.
  93  *
  94  *  If yes return 0, else return -1.
  95  */
  96 static int check_tracing_group(const char *grp_name)
  97 {
  98         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
  99         gid_t *grp_list;
 100         int grp_list_size, grp_id, i;
 101         int ret = -1;
 102
 103         /* Get GID of group 'tracing' */
 104         grp_tracing = getgrnam(grp_name);
 105         if (grp_tracing == NULL) {
 106                 /* NULL means not found also. getgrnam(3) */
 107                 if (errno != 0) {
 108                         perror("getgrnam");
 109                 }
 110                 goto end;
 111         }
 112
 113         /* Get number of supplementary group IDs */
 114         grp_list_size = getgroups(0, NULL);
 115         if (grp_list_size < 0) {
 116                 perror("getgroups");
 117                 goto end;
 118         }
 119
 120         /* Alloc group list of the right size */
 121         grp_list = malloc(grp_list_size * sizeof(gid_t));
 122         grp_id = getgroups(grp_list_size, grp_list);
 123         if (grp_id < -1) {
 124                 perror("getgroups");
 125                 goto free_list;
 126         }
 127
 128         for (i = 0; i < grp_list_size; i++) {
 129                 if (grp_list[i] == grp_tracing->gr_gid) {
 130                         ret = 0;
 131                         break;
 132                 }
 133         }
 134
 135 free_list:
 136         free(grp_list);
 137
 138 end:
 139         return ret;
 140 }
 141
 142 /*
 143  *  Set sessiond socket path by putting it in the global sessiond_sock_path
 144  *  variable.
 145  */
 146 static int set_session_daemon_path(void)
 147 {
 148         int ret;
 149
 150         /* Are we in the tracing group ? */
 151         ret = check_tracing_group(tracing_group);
 152         if (ret < 0 && getuid() != 0) {
 153                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 154                                         getenv("HOME")) < 0) {
 155                         return -ENOMEM;
 156                 }
 157         } else {
 158                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 159                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 160         }
 161
 162         return 0;
 163 }
 164
 165 /*
 166  *  Connect to the LTTng session daemon.
 167  *
 168  *  On success, return 0. On error, return -1.
 169  */
 170 static int connect_sessiond(void)
 171 {
 172         int ret;
 173
 174         ret = set_session_daemon_path();
 175         if (ret < 0) {
 176                 return ret;
 177         }
 178
 179         /* Connect to the sesssion daemon */
 180         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 181         if (ret < 0) {
 182                 return ret;
 183         }
 184
 185         sessiond_socket = ret;
 186         connected = 1;
 187
 188         return 0;
 189 }
 190
 191 /*
 192  *  Clean disconnect the session daemon.
 193  */
 194 static int disconnect_sessiond(void)
 195 {
 196         int ret = 0;
 197
 198         if (connected) {
 199                 ret = lttcomm_close_unix_sock(sessiond_socket);
 200                 sessiond_socket = 0;
 201                 connected = 0;
 202         }
 203
 204         return ret;
 205 }
 206
 207 /*
 208  *  ask_sessiond
 209  *
 210  *  Ask the session daemon a specific command and put the data into buf.
 211  *
 212  *  Return size of data (only payload, not header).
 213  */
 214 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf)
 215 {
 216         int ret;
 217         size_t size;
 218         void *data = NULL;
 219
 220         ret = connect_sessiond();
 221         if (ret < 0) {
 222                 goto end;
 223         }
 224
 225         lsm.cmd_type = lct;
 226
 227         /* Send command to session daemon */
 228         ret = send_data_sessiond();
 229         if (ret < 0) {
 230                 goto end;
 231         }
 232
 233         /* Get header from data transmission */
 234         ret = recv_data_sessiond(&llm, sizeof(llm));
 235         if (ret < 0) {
 236                 goto end;
 237         }
 238
 239         /* Check error code if OK */
 240         if (llm.ret_code != LTTCOMM_OK) {
 241                 ret = -llm.ret_code;
 242                 goto end;
 243         }
 244
 245         size = llm.data_size;
 246         if (size == 0) {
 247                 goto end;
 248         }
 249
 250         data = (void*) malloc(size);
 251
 252         /* Get payload data */
 253         ret = recv_data_sessiond(data, size);
 254         if (ret < 0) {
 255                 free(data);
 256                 goto end;
 257         }
 258
 259         *buf = data;
 260         ret = size;
 261
 262 end:
 263         disconnect_sessiond();
 264         return ret;
 265 }
 266
 267 /*
 268  *  lttng_start_tracing
 269  *
 270  *  Start tracing for all trace of the session.
 271  */
 272 int lttng_start_tracing(char *session_name)
 273 {
 274         strncpy(lsm.session_name, session_name, NAME_MAX);
 275         return ask_sessiond(LTTNG_START_TRACE, NULL);
 276 }
 277
 278 /*
 279  *  lttng_stop_tracing
 280  *
 281  *  Stop tracing for all trace of the session.
 282  */
 283 int lttng_stop_tracing(char *session_name)
 284 {
 285         strncpy(lsm.session_name, session_name, NAME_MAX);
 286         return ask_sessiond(LTTNG_STOP_TRACE, NULL);
 287 }
 288
 289 /*
 290  * BEGIN Kernel control API
 291  */
 292
 293 /*
 294  *  lttng_kernel_add_context
 295  */
 296 int lttng_kernel_add_context(struct lttng_kernel_context *ctx,
 297                 char *event_name, char *channel_name)
 298 {
 299         if (channel_name != NULL) {
 300                 strncpy(lsm.u.context.channel_name, channel_name, NAME_MAX);
 301         }
 302
 303         if (event_name != NULL) {
 304                 strncpy(lsm.u.context.event_name, event_name, NAME_MAX);
 305         }
 306
 307         memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_kernel_context));
 308         return ask_sessiond(LTTNG_KERNEL_ADD_CONTEXT, NULL);
 309 }
 310
 311 /*
 312  *  lttng_kernel_enable_event
 313  */
 314 int lttng_kernel_enable_event(struct lttng_event *ev, char *channel_name)
 315 {
 316         int ret;
 317
 318         if (channel_name == NULL) {
 319                 strncpy(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 320         } else {
 321                 strncpy(lsm.u.enable.channel_name, channel_name, NAME_MAX);
 322         }
 323
 324         if (ev == NULL) {
 325                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_ALL_EVENT, NULL);
 326         } else {
 327                 memcpy(&lsm.u.enable.event, ev, sizeof(struct lttng_event));
 328                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_EVENT, NULL);
 329         }
 330
 331         return ret;
 332 }
 333
 334 /*
 335  *  lttng_kernel_disable_event
 336  *
 337  *  Disable an event in the kernel tracer.
 338  */
 339 int lttng_kernel_disable_event(char *name, char *channel_name)
 340 {
 341         int ret;
 342
 343         if (channel_name == NULL) {
 344                 strncpy(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 345         } else {
 346                 strncpy(lsm.u.disable.channel_name, channel_name, NAME_MAX);
 347         }
 348
 349         if (name == NULL) {
 350                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_ALL_EVENT, NULL);
 351         } else {
 352                 strncpy(lsm.u.disable.name, name, NAME_MAX);
 353                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_EVENT, NULL);
 354         }
 355
 356         return ret;
 357 }
 358
 359 /*
 360  *  lttng_kernel_enable_channel
 361  *
 362  *  Enable recording for a channel for the kernel tracer.
 363  */
 364 int lttng_kernel_enable_channel(char *name)
 365 {
 366         strncpy(lsm.u.enable.channel_name, name, NAME_MAX);
 367         return ask_sessiond(LTTNG_KERNEL_ENABLE_CHANNEL, NULL);
 368 }
 369
 370 /*
 371  *  lttng_kernel_disable_channel
 372  *
 373  *  Disable recording for the channel for the kernel tracer.
 374  */
 375 int lttng_kernel_disable_channel(char *name)
 376 {
 377         strncpy(lsm.u.disable.channel_name, name, NAME_MAX);
 378         return ask_sessiond(LTTNG_KERNEL_DISABLE_CHANNEL, NULL);
 379 }
 380
 381 /*
 382  *  lttng_kernel_create_channel
 383  *
 384  *  Create a channel in the kernel tracer.
 385  */
 386 int lttng_kernel_create_channel(struct lttng_channel *chan)
 387 {
 388         memcpy(&lsm.u.channel.chan, chan, sizeof(struct lttng_channel));
 389         return ask_sessiond(LTTNG_KERNEL_CREATE_CHANNEL, NULL);
 390 }
 391
 392 /*
 393  *  lttng_list_events
 394  *
 395  *  List all available events in the kernel.
 396  *
 397  *  Return the size (bytes) of the list and set the event_list array.
 398  *  On error, return negative value.
 399  */
 400 int lttng_kernel_list_events(char **event_list)
 401 {
 402         return ask_sessiond(LTTNG_KERNEL_LIST_EVENTS, (void **) event_list);
 403 }
 404
 405 /*
 406  * END Kernel control API
 407  */
 408
 409 /*
 410  *  lttng_get_readable_code
 411  *
 412  *  Return a human readable string of code
 413  */
 414 const char *lttng_get_readable_code(int code)
 415 {
 416         if (code > -LTTCOMM_OK) {
 417                 return "Ended with errors";
 418         }
 419
 420         return lttcomm_get_readable_code(code);
 421 }
 422
 423 /*
 424  *  lttng_ust_list_apps
 425  *
 426  *  Ask the session daemon for all UST traceable applications.
 427  *
 428  *  Return the number of pids.
 429  *  On error, return negative value.
 430  */
 431 int lttng_ust_list_traceable_apps(pid_t **pids)
 432 {
 433         int ret;
 434
 435         ret = ask_sessiond(LTTNG_LIST_TRACEABLE_APPS, (void**) pids);
 436         if (ret < 0) {
 437                 return ret;
 438         }
 439
 440         return ret / sizeof(pid_t);
 441 }
 442
 443 /*
 444  *  lttng_list_traces
 445  *
 446  *  Ask the session daemon for all traces (kernel and ust) for the session
 447  *  identified by name.
 448  *
 449  *  Return the number of traces.
 450  *  On error, return negative value.
 451  */
 452 /*
 453 int lttng_list_traces(char *session_name, struct lttng_trace **traces)
 454 {
 455         int ret;
 456
 457         strncpy(lsm.session_name, session_name, NAME_MAX);
 458
 459         ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
 460         if (ret < 0) {
 461                 return ret;
 462         }
 463
 464         return ret / sizeof(struct lttng_trace);
 465 }
 466 */
 467
 468 /*
 469  *  lttng_create_session
 470  *
 471  *  Create a brand new session using name.
 472  */
 473 int lttng_create_session(char *name, char *path)
 474 {
 475         strncpy(lsm.session_name, name, NAME_MAX);
 476         strncpy(lsm.path, path, PATH_MAX);
 477         return ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 478 }
 479
 480 /*
 481  *  lttng_destroy_session
 482  *
 483  *  Destroy session using name.
 484  */
 485 int lttng_destroy_session(char *name)
 486 {
 487         strncpy(lsm.session_name, name, NAME_MAX);
 488         return ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 489 }
 490
 491 /*
 492  *  lttng_list_sessions
 493  *
 494  *  Ask the session daemon for all available sessions.
 495  *
 496  *  Return number of session.
 497  *  On error, return negative value.
 498  */
 499 int lttng_list_sessions(struct lttng_session **sessions)
 500 {
 501         int ret;
 502
 503         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 504         if (ret < 0) {
 505                 return ret;
 506         }
 507
 508         return ret / sizeof(struct lttng_session);
 509 }
 510
 511 void lttng_set_session_name(char *name)
 512 {
 513         strncpy(lsm.session_name, name, NAME_MAX);
 514 }
 515
 516 /*
 517  *  lttng_set_tracing_group
 518  *
 519  *  Set tracing group variable with name. This function
 520  *  allocate memory pointed by tracing_group.
 521  */
 522 int lttng_set_tracing_group(const char *name)
 523 {
 524         if (asprintf(&tracing_group, "%s", name) < 0) {
 525                 return -ENOMEM;
 526         }
 527
 528         return 0;
 529 }
 530
 531 /*
 532  *  lttng_check_session_daemon
 533  *
 534  *  Yes, return 1
 535  *  No, return 0
 536  *  Error, return negative value
 537  */
 538 int lttng_session_daemon_alive(void)
 539 {
 540         int ret;
 541
 542         ret = set_session_daemon_path();
 543         if (ret < 0) {
 544                 /* Error */
 545                 return ret;
 546         }
 547
 548         /* If socket exist, we consider the daemon started */
 549         ret = access(sessiond_sock_path, F_OK);
 550         if (ret < 0) {
 551                 /* Not alive */
 552                 return 0;
 553         }
 554
 555         /* Is alive */
 556         return 1;
 557 }
 558
 559 /*
 560  * lib constructor
 561  */
 562 static void __attribute__((constructor)) init()
 563 {
 564         /* Set default session group */
 565         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 566 }