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
  32 /* Socket to session daemon for communication */
  33 static int sessiond_socket;
  34 static char sessiond_sock_path[PATH_MAX];
  35
  36 /* Communication structure to ltt-sessiond */
  37 static struct lttcomm_session_msg lsm;
  38 static struct lttcomm_lttng_msg llm;
  39
  40 /* Prototypes */
  41 static int check_tracing_group(const char *grp_name);
  42 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf);
  43 static int recv_data_sessiond(void *buf, size_t len);
  44 static int send_data_sessiond(void);
  45 static int set_session_daemon_path(void);
  46
  47 /* Variables */
  48 static char *tracing_group;
  49 static int connected;
  50
  51 /*
  52  *  send_data_sessiond
  53  *
  54  *  Send lttcomm_session_msg to the session daemon.
  55  *
  56  *  On success, return 0
  57  *  On error, return error code
  58  */
  59 static int send_data_sessiond(void)
  60 {
  61         int ret;
  62
  63         if (!connected) {
  64                 ret = -ENOTCONN;
  65                 goto end;
  66         }
  67
  68         ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
  69
  70 end:
  71         return ret;
  72 }
  73
  74 /*
  75  *  recv_data_sessiond
  76  *
  77  *  Receive data from the sessiond socket.
  78  *
  79  *  On success, return 0
  80  *  On error, return recv() error code
  81  */
  82 static int recv_data_sessiond(void *buf, size_t len)
  83 {
  84         int ret;
  85
  86         if (!connected) {
  87                 ret = -ENOTCONN;
  88                 goto end;
  89         }
  90
  91         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
  92         if (ret < 0) {
  93                 goto end;
  94         }
  95
  96 end:
  97         return ret;
  98 }
  99
 100 /*
 101  *  ask_sessiond
 102  *
 103  *  Ask the session daemon a specific command
 104  *  and put the data into buf.
 105  *
 106  *  Return size of data (only payload, not header).
 107  */
 108 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf)
 109 {
 110         int ret;
 111         size_t size;
 112         void *data = NULL;
 113
 114         ret = lttng_connect_sessiond();
 115         if (ret < 0) {
 116                 goto end;
 117         }
 118
 119         lsm.cmd_type = lct;
 120
 121         /* Send command to session daemon */
 122         ret = send_data_sessiond();
 123         if (ret < 0) {
 124                 goto end;
 125         }
 126
 127         /* Get header from data transmission */
 128         ret = recv_data_sessiond(&llm, sizeof(llm));
 129         if (ret < 0) {
 130                 goto end;
 131         }
 132
 133         /* Check error code if OK */
 134         if (llm.ret_code != LTTCOMM_OK) {
 135                 ret = -llm.ret_code;
 136                 goto end;
 137         }
 138
 139         size = llm.trace_name_offset + llm.data_size;
 140         if (size == 0) {
 141                 goto end;
 142         }
 143
 144         data = (void*) malloc(size);
 145
 146         /* Get payload data */
 147         ret = recv_data_sessiond(data, size);
 148         if (ret < 0) {
 149                 goto end;
 150         }
 151
 152         *buf = data;
 153         ret = size;
 154
 155 end:
 156         lttng_disconnect_sessiond();
 157         return ret;
 158 }
 159
 160 /*
 161  * BEGIN KERNEL CONTROL
 162  */
 163
 164 /*
 165  *  lttng_kernel_enable_event
 166  *
 167  *  Enable an event in the kernel tracer.
 168  */
 169 int lttng_kernel_enable_event(char *event_name)
 170 {
 171         strncpy(lsm.u.event.event_name, event_name, NAME_MAX);
 172         return ask_sessiond(KERNEL_ENABLE_EVENT, NULL);
 173 }
 174
 175 /*
 176  *  lttng_kernel_disable_event
 177  *
 178  *  Disable an event in the kernel tracer.
 179  */
 180 int lttng_kernel_disable_event(char *event_name)
 181 {
 182         strncpy(lsm.u.event.event_name, event_name, NAME_MAX);
 183         return ask_sessiond(KERNEL_DISABLE_EVENT, NULL);
 184 }
 185
 186 /*
 187  *  lttng_kernel_create_session
 188  *
 189  *  Create a session in the kernel tracer.
 190  */
 191 int lttng_kernel_create_session(void)
 192 {
 193         return ask_sessiond(KERNEL_CREATE_SESSION, NULL);
 194 }
 195
 196 /*
 197  *  lttng_kernel_create_channel
 198  *
 199  *  Create a channel in the kernel tracer.
 200  */
 201 int lttng_kernel_create_channel(void)
 202 {
 203         return ask_sessiond(KERNEL_CREATE_CHANNEL, NULL);
 204 }
 205
 206 /*
 207  *  lttng_kernel_open_metadata
 208  *
 209  *  Open metadata in the kernel tracer.
 210  */
 211 int lttng_kernel_open_metadata(void)
 212 {
 213         return ask_sessiond(KERNEL_OPEN_METADATA, NULL);
 214 }
 215
 216 /*
 217  *  lttng_kernel_create_stream
 218  *
 219  *  Create stream in the kernel tracer.
 220  */
 221 int lttng_kernel_create_stream(void)
 222 {
 223         return ask_sessiond(KERNEL_CREATE_STREAM, NULL);
 224 }
 225
 226 /*
 227  *  lttng_kernel_start_tracing
 228  *
 229  *  Start kernel tracing.
 230  */
 231 int lttng_kernel_start_tracing(void)
 232 {
 233         return ask_sessiond(KERNEL_START_TRACE, NULL);
 234 }
 235
 236 /*
 237  *  lttng_kernel_stop_tracing
 238  *
 239  *  Stop kernel tracing.
 240  */
 241 int lttng_kernel_stop_tracing(void)
 242 {
 243         return ask_sessiond(KERNEL_STOP_TRACE, NULL);
 244 }
 245
 246 /*
 247  * END KERNEL CONTROL
 248  */
 249
 250 /*
 251  *  lttng_get_readable_code
 252  *
 253  *  Return a human readable string of code
 254  */
 255 const char *lttng_get_readable_code(int code)
 256 {
 257         if (code > -LTTCOMM_OK) {
 258                 return "Ended with errors";
 259         }
 260
 261         return lttcomm_get_readable_code(code);
 262 }
 263
 264 /*
 265  *  lttng_ust_start_trace
 266  *
 267  *  Request a trace start for pid.
 268  */
 269 int lttng_ust_start_trace(pid_t pid)
 270 {
 271         int ret;
 272
 273         lsm.pid = pid;
 274         ret = ask_sessiond(UST_START_TRACE, NULL);
 275
 276         return ret;
 277 }
 278
 279 /*
 280  *  lttng_ust_stop_trace
 281  *
 282  *  Request a trace stop for pid.
 283  */
 284 int lttng_ust_stop_trace(pid_t pid)
 285 {
 286         int ret;
 287
 288         lsm.pid = pid;
 289         ret = ask_sessiond(UST_STOP_TRACE, NULL);
 290
 291         return ret;
 292 }
 293
 294 /*
 295  *  lttng_ust_create_trace
 296  *
 297  *  Request a trace creation for pid.
 298  */
 299 int lttng_ust_create_trace(pid_t pid)
 300 {
 301         int ret;
 302
 303         lsm.pid = pid;
 304         ret = ask_sessiond(UST_CREATE_TRACE, NULL);
 305
 306         return ret;
 307 }
 308
 309 /*
 310  *  lttng_ust_list_apps
 311  *
 312  *  Ask the session daemon for all UST traceable
 313  *  applications.
 314  *
 315  *  Return the number of pids.
 316  *  On error, return negative value.
 317  */
 318 int lttng_ust_list_apps(pid_t **pids)
 319 {
 320         int ret;
 321
 322         ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
 323         if (ret < 0) {
 324                 return ret;
 325         }
 326
 327         return ret / sizeof(pid_t);
 328 }
 329
 330 /*
 331  *  lttng_list_traces
 332  *
 333  *  Ask the session daemon for all traces (kernel and ust)
 334  *  for the session identified by uuid.
 335  *
 336  *  Return the number of traces.
 337  */
 338 int lttng_list_traces(uuid_t *uuid, struct lttng_trace **traces)
 339 {
 340         int ret;
 341
 342         uuid_copy(lsm.session_uuid, *uuid);
 343
 344         ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
 345         if (ret < 0) {
 346                 return ret;
 347         }
 348
 349         return ret / sizeof(struct lttng_trace);
 350 }
 351
 352 /*
 353  *  lttng_create_session
 354  *
 355  *  Create a brand new session using name.
 356  */
 357 int lttng_create_session(char *name)
 358 {
 359         int ret;
 360
 361         strncpy(lsm.session_name, name, sizeof(lsm.session_name));
 362         lsm.session_name[sizeof(lsm.session_name) - 1] = '\0';
 363
 364         ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 365         if (ret < 0) {
 366                 goto end;
 367         }
 368
 369 end:
 370         return ret;
 371 }
 372
 373 /*
 374  *  lttng_destroy_session
 375  *
 376  *  Destroy session using name.
 377  */
 378 int lttng_destroy_session(uuid_t *uuid)
 379 {
 380         int ret;
 381
 382         uuid_copy(lsm.session_uuid, *uuid);
 383
 384         ret = ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 385         if (ret < 0) {
 386                 goto end;
 387         }
 388
 389 end:
 390         return ret;
 391 }
 392
 393 /*
 394  *  lttng_list_sessions
 395  *
 396  *  Ask the session daemon for all available sessions.
 397  *
 398  *  Return number of session.
 399  *  On error, return negative value.
 400  */
 401 int lttng_list_sessions(struct lttng_session **sessions)
 402 {
 403         int ret;
 404
 405         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 406         if (ret < 0) {
 407                 return ret;
 408         }
 409
 410         return ret / sizeof(struct lttng_session);
 411 }
 412
 413 /*
 414  *  lttng_connect_sessiond
 415  *
 416  *  Connect to the LTTng session daemon.
 417  *  On success, return 0
 418  *  On error, return a negative value
 419  */
 420 int lttng_connect_sessiond(void)
 421 {
 422         int ret;
 423
 424         ret = set_session_daemon_path();
 425         if (ret < 0) {
 426                 return ret;
 427         }
 428
 429         /* Connect to the sesssion daemon */
 430         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 431         if (ret < 0) {
 432                 return ret;
 433         }
 434
 435         sessiond_socket = ret;
 436         connected = 1;
 437
 438         return 0;
 439 }
 440
 441 /*
 442  *  lttng_disconnect_sessiond
 443  *
 444  *  Clean disconnect the session daemon.
 445  */
 446 int lttng_disconnect_sessiond(void)
 447 {
 448         int ret = 0;
 449
 450         if (connected) {
 451                 ret = lttcomm_close_unix_sock(sessiond_socket);
 452                 sessiond_socket = 0;
 453                 connected = 0;
 454         }
 455
 456         return ret;
 457 }
 458
 459 /*
 460  *  lttng_set_current_session_uuid
 461  *
 462  *  Set the session uuid for current lsm.
 463  */
 464 void lttng_set_current_session_uuid(uuid_t *uuid)
 465 {
 466         uuid_copy(lsm.session_uuid, *uuid);
 467 }
 468
 469 /*
 470  *  lttng_set_tracing_group
 471  *
 472  *  Set tracing group variable with name. This function
 473  *  allocate memory pointed by tracing_group.
 474  */
 475 int lttng_set_tracing_group(const char *name)
 476 {
 477         if (asprintf(&tracing_group, "%s", name) < 0) {
 478                 return -ENOMEM;
 479         }
 480
 481         return 0;
 482 }
 483
 484 /*
 485  *  lttng_check_session_daemon
 486  *
 487  *  Return 0 if a sesssion daemon is available
 488  *  else return -1
 489  */
 490 int lttng_check_session_daemon(void)
 491 {
 492         int ret;
 493
 494         ret = set_session_daemon_path();
 495         if (ret < 0) {
 496                 return ret;
 497         }
 498
 499         /* If socket exist, we consider the daemon started */
 500         ret = access(sessiond_sock_path, F_OK);
 501         if (ret < 0) {
 502                 return ret;
 503         }
 504
 505         return 0;
 506 }
 507
 508 /*
 509  *  set_session_daemon_path
 510  *
 511  *  Set sessiond socket path by putting it in
 512  *  the global sessiond_sock_path variable.
 513  */
 514 static int set_session_daemon_path(void)
 515 {
 516         int ret;
 517
 518         /* Are we in the tracing group ? */
 519         ret = check_tracing_group(tracing_group);
 520         if (ret < 0 && getuid() != 0) {
 521                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 522                                         getenv("HOME")) < 0) {
 523                         return -ENOMEM;
 524                 }
 525         } else {
 526                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 527                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 528         }
 529
 530         return 0;
 531 }
 532
 533 /*
 534  *  check_tracing_group
 535  *
 536  *  Check if the specified group name exist.
 537  *  If yes, 0, else -1
 538  */
 539 static int check_tracing_group(const char *grp_name)
 540 {
 541         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 542         gid_t *grp_list;
 543         int grp_list_size, grp_id, i;
 544         int ret = -1;
 545
 546         /* Get GID of group 'tracing' */
 547         grp_tracing = getgrnam(grp_name);
 548         if (grp_tracing == NULL) {
 549                 /* NULL means not found also. getgrnam(3) */
 550                 if (errno != 0) {
 551                         perror("getgrnam");
 552                 }
 553                 goto end;
 554         }
 555
 556         /* Get number of supplementary group IDs */
 557         grp_list_size = getgroups(0, NULL);
 558         if (grp_list_size < 0) {
 559                 perror("getgroups");
 560                 goto end;
 561         }
 562
 563         /* Alloc group list of the right size */
 564         grp_list = malloc(grp_list_size * sizeof(gid_t));
 565         grp_id = getgroups(grp_list_size, grp_list);
 566         if (grp_id < -1) {
 567                 perror("getgroups");
 568                 goto free_list;
 569         }
 570
 571         for (i = 0; i < grp_list_size; i++) {
 572                 if (grp_list[i] == grp_tracing->gr_gid) {
 573                         ret = 0;
 574                         break;
 575                 }
 576         }
 577
 578 free_list:
 579         free(grp_list);
 580
 581 end:
 582         return ret;
 583 }
 584
 585 /*
 586  * lib constructor
 587  */
 588 static void __attribute__((constructor)) init()
 589 {
 590         /* Set default session group */
 591         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 592 }