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_add_context
 256  */
 257 int lttng_kernel_add_context(struct lttng_kernel_context *ctx,
 258                 char *event_name, char *channel_name)
 259 {
 260         if (channel_name != NULL) {
 261                 strncpy(lsm.u.context.channel_name, channel_name, NAME_MAX);
 262         }
 263
 264         if (event_name != NULL) {
 265                 strncpy(lsm.u.context.event_name, event_name, NAME_MAX);
 266         }
 267
 268         memcpy(&lsm.u.context.ctx, ctx, sizeof(struct lttng_kernel_context));
 269         return ask_sessiond(LTTNG_KERNEL_ADD_CONTEXT, NULL);
 270 }
 271
 272 /*
 273  *  lttng_kernel_enable_event
 274  */
 275 int lttng_kernel_enable_event(struct lttng_event *ev, char *channel_name)
 276 {
 277         int ret;
 278
 279         if (channel_name == NULL) {
 280                 strncpy(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 281         } else {
 282                 strncpy(lsm.u.enable.channel_name, channel_name, NAME_MAX);
 283         }
 284
 285         if (ev == NULL) {
 286                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_ALL_EVENT, NULL);
 287         } else {
 288                 memcpy(&lsm.u.enable.event, ev, sizeof(struct lttng_event));
 289                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_EVENT, NULL);
 290         }
 291
 292         return ret;
 293 }
 294
 295 /*
 296  *  lttng_kernel_disable_event
 297  *
 298  *  Disable an event in the kernel tracer.
 299  */
 300 int lttng_kernel_disable_event(char *name, char *channel_name)
 301 {
 302         int ret;
 303
 304         if (channel_name == NULL) {
 305                 strncpy(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 306         } else {
 307                 strncpy(lsm.u.disable.channel_name, channel_name, NAME_MAX);
 308         }
 309
 310         if (name == NULL) {
 311                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_ALL_EVENT, NULL);
 312         } else {
 313                 strncpy(lsm.u.disable.name, name, NAME_MAX);
 314                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_EVENT, NULL);
 315         }
 316
 317         return ret;
 318 }
 319
 320 /*
 321  *  lttng_kernel_enable_channel
 322  *
 323  *  Enable recording for a channel for the kernel tracer.
 324  */
 325 int lttng_kernel_enable_channel(char *name)
 326 {
 327         strncpy(lsm.u.enable.channel_name, name, NAME_MAX);
 328         return ask_sessiond(LTTNG_KERNEL_ENABLE_CHANNEL, NULL);
 329 }
 330
 331 /*
 332  *  lttng_kernel_disable_channel
 333  *
 334  *  Disable recording for the channel for the kernel tracer.
 335  */
 336 int lttng_kernel_disable_channel(char *name)
 337 {
 338         strncpy(lsm.u.disable.channel_name, name, NAME_MAX);
 339         return ask_sessiond(LTTNG_KERNEL_DISABLE_CHANNEL, NULL);
 340 }
 341
 342 /*
 343  *  lttng_kernel_create_channel
 344  *
 345  *  Create a channel in the kernel tracer.
 346  */
 347 int lttng_kernel_create_channel(struct lttng_channel *chan)
 348 {
 349         memcpy(&lsm.u.channel.chan, chan, sizeof(struct lttng_channel));
 350         return ask_sessiond(LTTNG_KERNEL_CREATE_CHANNEL, NULL);
 351 }
 352
 353 /*
 354  *  lttng_list_events
 355  *
 356  *  List all available events in the kernel.
 357  *
 358  *  Return the size (bytes) of the list and set the event_list array.
 359  *  On error, return negative value.
 360  */
 361 int lttng_kernel_list_events(char **event_list)
 362 {
 363         return ask_sessiond(LTTNG_KERNEL_LIST_EVENTS, (void **) event_list);
 364 }
 365
 366 /*
 367  * END Kernel control API
 368  */
 369
 370 /*
 371  *  lttng_get_readable_code
 372  *
 373  *  Return a human readable string of code
 374  */
 375 const char *lttng_get_readable_code(int code)
 376 {
 377         if (code > -LTTCOMM_OK) {
 378                 return "Ended with errors";
 379         }
 380
 381         return lttcomm_get_readable_code(code);
 382 }
 383
 384 /*
 385  *  lttng_ust_list_apps
 386  *
 387  *  Ask the session daemon for all UST traceable applications.
 388  *
 389  *  Return the number of pids.
 390  *  On error, return negative value.
 391  */
 392 int lttng_ust_list_traceable_apps(pid_t **pids)
 393 {
 394         int ret;
 395
 396         ret = ask_sessiond(LTTNG_LIST_TRACEABLE_APPS, (void**) pids);
 397         if (ret < 0) {
 398                 return ret;
 399         }
 400
 401         return ret / sizeof(pid_t);
 402 }
 403
 404 /*
 405  *  lttng_list_traces
 406  *
 407  *  Ask the session daemon for all traces (kernel and ust) for the session
 408  *  identified by name.
 409  *
 410  *  Return the number of traces.
 411  *  On error, return negative value.
 412  */
 413 /*
 414 int lttng_list_traces(char *session_name, struct lttng_trace **traces)
 415 {
 416         int ret;
 417
 418         strncpy(lsm.session_name, session_name, NAME_MAX);
 419
 420         ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
 421         if (ret < 0) {
 422                 return ret;
 423         }
 424
 425         return ret / sizeof(struct lttng_trace);
 426 }
 427 */
 428
 429 /*
 430  *  lttng_create_session
 431  *
 432  *  Create a brand new session using name.
 433  */
 434 int lttng_create_session(char *name, char *path)
 435 {
 436         strncpy(lsm.session_name, name, NAME_MAX);
 437         strncpy(lsm.path, path, PATH_MAX);
 438         return ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 439 }
 440
 441 /*
 442  *  lttng_destroy_session
 443  *
 444  *  Destroy session using name.
 445  */
 446 int lttng_destroy_session(char *name)
 447 {
 448         strncpy(lsm.session_name, name, NAME_MAX);
 449         return ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 450 }
 451
 452 /*
 453  *  lttng_list_sessions
 454  *
 455  *  Ask the session daemon for all available sessions.
 456  *
 457  *  Return number of session.
 458  *  On error, return negative value.
 459  */
 460 int lttng_list_sessions(struct lttng_session **sessions)
 461 {
 462         int ret;
 463
 464         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 465         if (ret < 0) {
 466                 return ret;
 467         }
 468
 469         return ret / sizeof(struct lttng_session);
 470 }
 471
 472 /*
 473  *  lttng_connect_sessiond
 474  *
 475  *  Connect to the LTTng session daemon.
 476  *  On success, return 0
 477  *  On error, return a negative value
 478  */
 479 int lttng_connect_sessiond(void)
 480 {
 481         int ret;
 482
 483         ret = set_session_daemon_path();
 484         if (ret < 0) {
 485                 return ret;
 486         }
 487
 488         /* Connect to the sesssion daemon */
 489         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 490         if (ret < 0) {
 491                 return ret;
 492         }
 493
 494         sessiond_socket = ret;
 495         connected = 1;
 496
 497         return 0;
 498 }
 499
 500 /*
 501  *  lttng_disconnect_sessiond
 502  *
 503  *  Clean disconnect the session daemon.
 504  */
 505 int lttng_disconnect_sessiond(void)
 506 {
 507         int ret = 0;
 508
 509         if (connected) {
 510                 ret = lttcomm_close_unix_sock(sessiond_socket);
 511                 sessiond_socket = 0;
 512                 connected = 0;
 513         }
 514
 515         return ret;
 516 }
 517
 518 void lttng_set_session_name(char *name)
 519 {
 520         strncpy(lsm.session_name, name, NAME_MAX);
 521 }
 522
 523 /*
 524  *  lttng_set_tracing_group
 525  *
 526  *  Set tracing group variable with name. This function
 527  *  allocate memory pointed by tracing_group.
 528  */
 529 int lttng_set_tracing_group(const char *name)
 530 {
 531         if (asprintf(&tracing_group, "%s", name) < 0) {
 532                 return -ENOMEM;
 533         }
 534
 535         return 0;
 536 }
 537
 538 /*
 539  *  lttng_check_session_daemon
 540  *
 541  *  Yes, return 1
 542  *  No, return 0
 543  *  Error, return negative value
 544  */
 545 int lttng_session_daemon_alive(void)
 546 {
 547         int ret;
 548
 549         ret = set_session_daemon_path();
 550         if (ret < 0) {
 551                 /* Error */
 552                 return ret;
 553         }
 554
 555         /* If socket exist, we consider the daemon started */
 556         ret = access(sessiond_sock_path, F_OK);
 557         if (ret < 0) {
 558                 /* Not alive */
 559                 return 0;
 560         }
 561
 562         /* Is alive */
 563         return 1;
 564 }
 565
 566 /*
 567  * lib constructor
 568  */
 569 static void __attribute__((constructor)) init()
 570 {
 571         /* Set default session group */
 572         lttng_set_tracing_group(LTTNG_DEFAULT_TRACING_GROUP);
 573 }