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         memset(&lsm, 0, sizeof(lsm));
 158         return ret;
 159 }
 160
 161 /*
 162  * BEGIN KERNEL CONTROL
 163  */
 164
 165 /*
 166  *  lttng_kernel_enable_event
 167  *
 168  *  Enable an event in the kernel tracer.
 169  */
 170 int lttng_kernel_enable_event(char *event_name)
 171 {
 172         strncpy(lsm.u.event.event_name, event_name, NAME_MAX);
 173         return ask_sessiond(KERNEL_ENABLE_EVENT, NULL);
 174 }
 175
 176 /*
 177  *  lttng_kernel_disable_event
 178  *
 179  *  Disable an event in the kernel tracer.
 180  */
 181 int lttng_kernel_disable_event(char *event_name)
 182 {
 183         strncpy(lsm.u.event.event_name, event_name, NAME_MAX);
 184         return ask_sessiond(KERNEL_DISABLE_EVENT, NULL);
 185 }
 186
 187 /*
 188  *  lttng_kernel_create_session
 189  *
 190  *  Create a session in the kernel tracer.
 191  */
 192 int lttng_kernel_create_session(void)
 193 {
 194         return ask_sessiond(KERNEL_CREATE_SESSION, NULL);
 195 }
 196
 197 /*
 198  *  lttng_kernel_create_channel
 199  *
 200  *  Create a channel in the kernel tracer.
 201  */
 202 int lttng_kernel_create_channel(int overwrite,
 203                 u64 subbuf_size, u64 num_subbuf,
 204                 unsigned int switch_timer_interval,
 205                 unsigned int read_timer_interval)
 206 {
 207         /* Write setting to the session message */
 208         lsm.u.create_channel.overwrite = overwrite;
 209         lsm.u.create_channel.subbuf_size = subbuf_size;
 210         lsm.u.create_channel.num_subbuf = num_subbuf;
 211         lsm.u.create_channel.switch_timer_interval = switch_timer_interval;
 212         lsm.u.create_channel.read_timer_interval = read_timer_interval;
 213
 214         return ask_sessiond(KERNEL_CREATE_CHANNEL, NULL);
 215 }
 216
 217 /*
 218  *  lttng_kernel_start_tracing
 219  *
 220  *  Start kernel tracing.
 221  */
 222 int lttng_kernel_start_tracing(void)
 223 {
 224         return ask_sessiond(KERNEL_START_TRACE, NULL);
 225 }
 226
 227 /*
 228  *  lttng_kernel_stop_tracing
 229  *
 230  *  Stop kernel tracing.
 231  */
 232 int lttng_kernel_stop_tracing(void)
 233 {
 234         return ask_sessiond(KERNEL_STOP_TRACE, NULL);
 235 }
 236
 237 /*
 238  * END KERNEL CONTROL
 239  */
 240
 241 /*
 242  *  lttng_get_readable_code
 243  *
 244  *  Return a human readable string of code
 245  */
 246 const char *lttng_get_readable_code(int code)
 247 {
 248         if (code > -LTTCOMM_OK) {
 249                 return "Ended with errors";
 250         }
 251
 252         return lttcomm_get_readable_code(code);
 253 }
 254
 255 /*
 256  *  lttng_ust_start_trace
 257  *
 258  *  Request a trace start for pid.
 259  */
 260 int lttng_ust_start_trace(pid_t pid)
 261 {
 262         int ret;
 263
 264         lsm.pid = pid;
 265         ret = ask_sessiond(UST_START_TRACE, NULL);
 266
 267         return ret;
 268 }
 269
 270 /*
 271  *  lttng_ust_stop_trace
 272  *
 273  *  Request a trace stop for pid.
 274  */
 275 int lttng_ust_stop_trace(pid_t pid)
 276 {
 277         int ret;
 278
 279         lsm.pid = pid;
 280         ret = ask_sessiond(UST_STOP_TRACE, NULL);
 281
 282         return ret;
 283 }
 284
 285 /*
 286  *  lttng_ust_create_trace
 287  *
 288  *  Request a trace creation for pid.
 289  */
 290 int lttng_ust_create_trace(pid_t pid)
 291 {
 292         int ret;
 293
 294         lsm.pid = pid;
 295         ret = ask_sessiond(UST_CREATE_TRACE, NULL);
 296
 297         return ret;
 298 }
 299
 300 /*
 301  *  lttng_ust_list_apps
 302  *
 303  *  Ask the session daemon for all UST traceable
 304  *  applications.
 305  *
 306  *  Return the number of pids.
 307  *  On error, return negative value.
 308  */
 309 int lttng_ust_list_apps(pid_t **pids)
 310 {
 311         int ret;
 312
 313         ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
 314         if (ret < 0) {
 315                 return ret;
 316         }
 317
 318         return ret / sizeof(pid_t);
 319 }
 320
 321 /*
 322  *  lttng_list_traces
 323  *
 324  *  Ask the session daemon for all traces (kernel and ust)
 325  *  for the session identified by uuid.
 326  *
 327  *  Return the number of traces.
 328  */
 329 int lttng_list_traces(uuid_t *uuid, struct lttng_trace **traces)
 330 {
 331         int ret;
 332
 333         uuid_copy(lsm.session_uuid, *uuid);
 334
 335         ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
 336         if (ret < 0) {
 337                 return ret;
 338         }
 339
 340         return ret / sizeof(struct lttng_trace);
 341 }
 342
 343 /*
 344  *  lttng_create_session
 345  *
 346  *  Create a brand new session using name. Allocate
 347  *  the session_id param pointing to the UUID.
 348  */
 349 int lttng_create_session(char *name, uuid_t *session_id)
 350 {
 351         int ret;
 352
 353         strncpy(lsm.session_name, name, sizeof(lsm.session_name));
 354         lsm.session_name[sizeof(lsm.session_name) - 1] = '\0';
 355
 356         ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 357         if (ret < 0) {
 358                 goto end;
 359         }
 360
 361         uuid_copy(*session_id, llm.session_uuid);
 362
 363 end:
 364         return ret;
 365 }
 366
 367 /*
 368  *  lttng_destroy_session
 369  *
 370  *  Destroy session using name.
 371  */
 372 int lttng_destroy_session(uuid_t *uuid)
 373 {
 374         int ret;
 375
 376         uuid_copy(lsm.session_uuid, *uuid);
 377
 378         ret = ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 379         if (ret < 0) {
 380                 goto end;
 381         }
 382
 383 end:
 384         return ret;
 385 }
 386
 387 /*
 388  *  lttng_list_sessions
 389  *
 390  *  Ask the session daemon for all available sessions.
 391  *
 392  *  Return number of session.
 393  *  On error, return negative value.
 394  */
 395 int lttng_list_sessions(struct lttng_session **sessions)
 396 {
 397         int ret;
 398
 399         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 400         if (ret < 0) {
 401                 return ret;
 402         }
 403
 404         return ret / sizeof(struct lttng_session);
 405 }
 406
 407 /*
 408  *  lttng_connect_sessiond
 409  *
 410  *  Connect to the LTTng session daemon.
 411  *  On success, return 0
 412  *  On error, return a negative value
 413  */
 414 int lttng_connect_sessiond(void)
 415 {
 416         int ret;
 417
 418         ret = set_session_daemon_path();
 419         if (ret < 0) {
 420                 return ret;
 421         }
 422
 423         /* Connect to the sesssion daemon */
 424         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 425         if (ret < 0) {
 426                 return ret;
 427         }
 428
 429         sessiond_socket = ret;
 430         connected = 1;
 431
 432         return 0;
 433 }
 434
 435 /*
 436  *  lttng_disconnect_sessiond
 437  *
 438  *  Clean disconnect the session daemon.
 439  */
 440 int lttng_disconnect_sessiond(void)
 441 {
 442         int ret = 0;
 443
 444         if (connected) {
 445                 ret = lttcomm_close_unix_sock(sessiond_socket);
 446                 sessiond_socket = 0;
 447                 connected = 0;
 448         }
 449
 450         return ret;
 451 }
 452
 453 /*
 454  *  lttng_set_current_session_uuid
 455  *
 456  *  Set the session uuid for current lsm.
 457  */
 458 void lttng_set_current_session_uuid(uuid_t *uuid)
 459 {
 460         uuid_copy(lsm.session_uuid, *uuid);
 461 }
 462
 463 /*
 464  *  lttng_set_tracing_group
 465  *
 466  *  Set tracing group variable with name. This function
 467  *  allocate memory pointed by tracing_group.
 468  */
 469 int lttng_set_tracing_group(const char *name)
 470 {
 471         if (asprintf(&tracing_group, "%s", name) < 0) {
 472                 return -ENOMEM;
 473         }
 474
 475         return 0;
 476 }
 477
 478 /*
 479  *  lttng_check_session_daemon
 480  *
 481  *  Return 0 if a sesssion daemon is available
 482  *  else return -1
 483  */
 484 int lttng_check_session_daemon(void)
 485 {
 486         int ret;
 487
 488         ret = set_session_daemon_path();
 489         if (ret < 0) {
 490                 return ret;
 491         }
 492
 493         /* If socket exist, we consider the daemon started */
 494         ret = access(sessiond_sock_path, F_OK);
 495         if (ret < 0) {
 496                 return ret;
 497         }
 498
 499         return 0;
 500 }
 501
 502 /*
 503  *  set_session_daemon_path
 504  *
 505  *  Set sessiond socket path by putting it in
 506  *  the global sessiond_sock_path variable.
 507  */
 508 static int set_session_daemon_path(void)
 509 {
 510         int ret;
 511
 512         /* Are we in the tracing group ? */
 513         ret = check_tracing_group(tracing_group);
 514         if (ret < 0 && getuid() != 0) {
 515                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 516                                         getenv("HOME")) < 0) {
 517                         return -ENOMEM;
 518                 }
 519         } else {
 520                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 521                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 522         }
 523
 524         return 0;
 525 }
 526
 527 /*
 528  *  check_tracing_group
 529  *
 530  *  Check if the specified group name exist.
 531  *  If yes, 0, else -1
 532  */
 533 static int check_tracing_group(const char *grp_name)
 534 {
 535         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 536         gid_t *grp_list;
 537         int grp_list_size, grp_id, i;
 538         int ret = -1;
 539
 540         /* Get GID of group 'tracing' */
 541         grp_tracing = getgrnam(grp_name);
 542         if (grp_tracing == NULL) {
 543                 /* NULL means not found also. getgrnam(3) */
 544                 if (errno != 0) {
 545                         perror("getgrnam");
 546                 }
 547                 goto end;
 548         }
 549
 550         /* Get number of supplementary group IDs */
 551         grp_list_size = getgroups(0, NULL);
 552         if (grp_list_size < 0) {
 553                 perror("getgroups");
 554                 goto end;
 555         }
 556
 557         /* Alloc group list of the right size */
 558         grp_list = malloc(grp_list_size * sizeof(gid_t));
 559         grp_id = getgroups(grp_list_size, grp_list);
 560         if (grp_id < -1) {
 561                 perror("getgroups");
 562                 goto free_list;
 563         }
 564
 565         for (i = 0; i < grp_list_size; i++) {
 566                 if (grp_list[i] == grp_tracing->gr_gid) {
 567                         ret = 0;
 568                         break;
 569                 }
 570         }
 571
 572 free_list:
 573         free(grp_list);
 574
 575 end:
 576         return ret;
 577 }
 578
 579 /*
 580  * lib constructor
 581  */
 582 static void __attribute__((constructor)) init()
 583 {
 584         /* Set default session group */
 585         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 586 }