liblttngctl/liblttngctl.c

   1 /*
   2  * liblttngctl.c
   3  *
   4  * Linux Trace Toolkit Control Library
   5  *
   6  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #define _GNU_SOURCE
  24 #include <errno.h>
  25 #include <grp.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <lttng/lttng.h>
  32
  33 #include "liblttsessiondcomm.h"
  34 #include "lttngerr.h"
  35 #include "lttng-share.h"
  36
  37 /* Socket to session daemon for communication */
  38 static int sessiond_socket;
  39 static char sessiond_sock_path[PATH_MAX];
  40
  41 /* Communication structure to ltt-sessiond */
  42 static struct lttcomm_session_msg lsm;
  43 static struct lttcomm_lttng_msg llm;
  44
  45 /* Variables */
  46 static char *tracing_group;
  47 static int connected;
  48
  49 /*
  50  *  send_data_sessiond
  51  *
  52  *  Send lttcomm_session_msg to the session daemon.
  53  *
  54  *  On success, return 0
  55  *  On error, return error code
  56  */
  57 static int send_data_sessiond(void)
  58 {
  59         int ret;
  60
  61         if (!connected) {
  62                 ret = -ENOTCONN;
  63                 goto end;
  64         }
  65
  66         ret = lttcomm_send_unix_sock(sessiond_socket, &lsm, sizeof(lsm));
  67
  68 end:
  69         return ret;
  70 }
  71
  72 /*
  73  *  recv_data_sessiond
  74  *
  75  *  Receive data from the sessiond socket.
  76  *
  77  *  On success, return 0
  78  *  On error, return recv() error code
  79  */
  80 static int recv_data_sessiond(void *buf, size_t len)
  81 {
  82         int ret;
  83
  84         if (!connected) {
  85                 ret = -ENOTCONN;
  86                 goto end;
  87         }
  88
  89         ret = lttcomm_recv_unix_sock(sessiond_socket, buf, len);
  90
  91 end:
  92         return ret;
  93 }
  94
  95 /*
  96  *  Check if the specified group name exist.
  97  *
  98  *  If yes return 0, else return -1.
  99  */
 100 static int check_tracing_group(const char *grp_name)
 101 {
 102         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 103         gid_t *grp_list;
 104         int grp_list_size, grp_id, i;
 105         int ret = -1;
 106
 107         /* Get GID of group 'tracing' */
 108         grp_tracing = getgrnam(grp_name);
 109         if (grp_tracing == NULL) {
 110                 /* NULL means not found also. getgrnam(3) */
 111                 if (errno != 0) {
 112                         perror("getgrnam");
 113                 }
 114                 goto end;
 115         }
 116
 117         /* Get number of supplementary group IDs */
 118         grp_list_size = getgroups(0, NULL);
 119         if (grp_list_size < 0) {
 120                 perror("getgroups");
 121                 goto end;
 122         }
 123
 124         /* Alloc group list of the right size */
 125         grp_list = malloc(grp_list_size * sizeof(gid_t));
 126         grp_id = getgroups(grp_list_size, grp_list);
 127         if (grp_id < -1) {
 128                 perror("getgroups");
 129                 goto free_list;
 130         }
 131
 132         for (i = 0; i < grp_list_size; i++) {
 133                 if (grp_list[i] == grp_tracing->gr_gid) {
 134                         ret = 0;
 135                         break;
 136                 }
 137         }
 138
 139 free_list:
 140         free(grp_list);
 141
 142 end:
 143         return ret;
 144 }
 145
 146 /*
 147  *  Set sessiond socket path by putting it in the global sessiond_sock_path
 148  *  variable.
 149  */
 150 static int set_session_daemon_path(void)
 151 {
 152         int ret;
 153
 154         /* Are we in the tracing group ? */
 155         ret = check_tracing_group(tracing_group);
 156         if (ret < 0 && getuid() != 0) {
 157                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 158                                         getenv("HOME")) < 0) {
 159                         return -ENOMEM;
 160                 }
 161         } else {
 162                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 163                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 164         }
 165
 166         return 0;
 167 }
 168
 169 /*
 170  *  Connect to the LTTng session daemon.
 171  *
 172  *  On success, return 0. On error, return -1.
 173  */
 174 static int connect_sessiond(void)
 175 {
 176         int ret;
 177
 178         ret = set_session_daemon_path();
 179         if (ret < 0) {
 180                 return ret;
 181         }
 182
 183         /* Connect to the sesssion daemon */
 184         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 185         if (ret < 0) {
 186                 return ret;
 187         }
 188
 189         sessiond_socket = ret;
 190         connected = 1;
 191
 192         return 0;
 193 }
 194
 195 /*
 196  *  Clean disconnect the session daemon.
 197  */
 198 static int disconnect_sessiond(void)
 199 {
 200         int ret = 0;
 201
 202         if (connected) {
 203                 ret = lttcomm_close_unix_sock(sessiond_socket);
 204                 sessiond_socket = 0;
 205                 connected = 0;
 206         }
 207
 208         return ret;
 209 }
 210
 211 /*
 212  *  ask_sessiond
 213  *
 214  *  Ask the session daemon a specific command and put the data into buf.
 215  *
 216  *  Return size of data (only payload, not header).
 217  */
 218 static int ask_sessiond(enum lttcomm_sessiond_command lct, void **buf)
 219 {
 220         int ret;
 221         size_t size;
 222         void *data = NULL;
 223
 224         ret = connect_sessiond();
 225         if (ret < 0) {
 226                 goto end;
 227         }
 228
 229         lsm.cmd_type = lct;
 230
 231         /* Send command to session daemon */
 232         ret = send_data_sessiond();
 233         if (ret < 0) {
 234                 goto end;
 235         }
 236
 237         /* Get header from data transmission */
 238         ret = recv_data_sessiond(&llm, sizeof(llm));
 239         if (ret < 0) {
 240                 goto end;
 241         }
 242
 243         /* Check error code if OK */
 244         if (llm.ret_code != LTTCOMM_OK) {
 245                 ret = -llm.ret_code;
 246                 goto end;
 247         }
 248
 249         size = llm.data_size;
 250         if (size == 0) {
 251                 ret = 0;
 252                 goto end;
 253         }
 254
 255         data = (void*) malloc(size);
 256
 257         /* Get payload data */
 258         ret = recv_data_sessiond(data, size);
 259         if (ret < 0) {
 260                 free(data);
 261                 goto end;
 262         }
 263
 264         *buf = data;
 265         ret = size;
 266
 267 end:
 268         disconnect_sessiond();
 269         return ret;
 270 }
 271
 272 /*
 273  *  Start tracing for all trace of the session.
 274  */
 275 int lttng_start_tracing(const char *session_name)
 276 {
 277         strncpy(lsm.session_name, session_name, NAME_MAX);
 278         return ask_sessiond(LTTNG_START_TRACE, NULL);
 279 }
 280
 281 /*
 282  *  Stop tracing for all trace of the session.
 283  */
 284 int lttng_stop_tracing(const char *session_name)
 285 {
 286         strncpy(lsm.session_name, session_name, NAME_MAX);
 287         return ask_sessiond(LTTNG_STOP_TRACE, NULL);
 288 }
 289
 290 /*
 291  *  lttng_add_context
 292  */
 293 int lttng_add_context(struct lttng_domain *domain,
 294                 struct lttng_event_context *ctx, const char *event_name,
 295                 const char *channel_name)
 296 {
 297         int ret;
 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_event_context));
 308
 309         switch (domain->type) {
 310         case LTTNG_DOMAIN_KERNEL:
 311                 ret = ask_sessiond(LTTNG_KERNEL_ADD_CONTEXT, NULL);
 312                 break;
 313         case LTTNG_DOMAIN_UST:
 314                 ret = LTTCOMM_NOT_IMPLEMENTED;
 315                 break;
 316         default:
 317                 ret = LTTCOMM_UNKNOWN_DOMAIN;
 318                 break;
 319         };
 320
 321         return ret;
 322 }
 323
 324 /*
 325  *  lttng_enable_event
 326  */
 327 int lttng_enable_event(struct lttng_domain *domain,
 328                 struct lttng_event *ev, const char *channel_name)
 329 {
 330         int ret;
 331
 332         if (channel_name == NULL) {
 333                 strncpy(lsm.u.enable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 334         } else {
 335                 strncpy(lsm.u.enable.channel_name, channel_name, NAME_MAX);
 336         }
 337
 338         switch (domain->type) {
 339                 case LTTNG_DOMAIN_KERNEL:
 340                         if (ev == NULL) {
 341                                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_ALL_EVENT, NULL);
 342                         } else {
 343                                 memcpy(&lsm.u.enable.event, ev, sizeof(struct lttng_event));
 344                                 ret = ask_sessiond(LTTNG_KERNEL_ENABLE_EVENT, NULL);
 345                         }
 346                         break;
 347                 case LTTNG_DOMAIN_UST:
 348                         ret = LTTCOMM_NOT_IMPLEMENTED;
 349                         break;
 350                 default:
 351                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 352                         break;
 353         };
 354
 355         return ret;
 356 }
 357
 358 /*
 359  * Disable an event in the kernel tracer.
 360  */
 361 int lttng_disable_event(struct lttng_domain *domain, const char *name,
 362                 const char *channel_name)
 363 {
 364         int ret;
 365
 366         if (channel_name == NULL) {
 367                 strncpy(lsm.u.disable.channel_name, DEFAULT_CHANNEL_NAME, NAME_MAX);
 368         } else {
 369                 strncpy(lsm.u.disable.channel_name, channel_name, NAME_MAX);
 370         }
 371
 372         switch (domain->type) {
 373                 case LTTNG_DOMAIN_KERNEL:
 374                         if (name == NULL) {
 375                                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_ALL_EVENT, NULL);
 376                         } else {
 377                                 strncpy(lsm.u.disable.name, name, NAME_MAX);
 378                                 ret = ask_sessiond(LTTNG_KERNEL_DISABLE_EVENT, NULL);
 379                         }
 380                         break;
 381                 case LTTNG_DOMAIN_UST:
 382                         ret = LTTCOMM_NOT_IMPLEMENTED;
 383                         break;
 384                 default:
 385                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 386                         break;
 387         };
 388
 389         return ret;
 390 }
 391
 392 /*
 393  * Enable recording for a channel for the kernel tracer.
 394  */
 395 int lttng_enable_channel(struct lttng_domain *domain,
 396                 struct lttng_channel *chan)
 397 {
 398         int ret;
 399
 400         memcpy(&lsm.u.channel.chan, chan, sizeof(struct lttng_channel));
 401
 402         switch (domain->type) {
 403                 case LTTNG_DOMAIN_KERNEL:
 404                         ret = ask_sessiond(LTTNG_KERNEL_ENABLE_CHANNEL, NULL);
 405                         break;
 406                 case LTTNG_DOMAIN_UST:
 407                         ret = LTTCOMM_NOT_IMPLEMENTED;
 408                         break;
 409                 default:
 410                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 411                         break;
 412         };
 413
 414         return ret;
 415 }
 416
 417 /*
 418  * Disable recording for the channel for the kernel tracer.
 419  */
 420 int lttng_disable_channel(struct lttng_domain *domain, const char *name)
 421 {
 422         int ret;
 423
 424         strncpy(lsm.u.disable.channel_name, name, NAME_MAX);
 425
 426         switch (domain->type) {
 427                 case LTTNG_DOMAIN_KERNEL:
 428                         ret = ask_sessiond(LTTNG_KERNEL_DISABLE_CHANNEL, NULL);
 429                         break;
 430                 case LTTNG_DOMAIN_UST:
 431                         ret = LTTCOMM_NOT_IMPLEMENTED;
 432                         break;
 433                 default:
 434                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 435                         break;
 436         };
 437
 438         return ret;
 439 }
 440
 441 /*
 442  * List all available events in the kernel.
 443  *
 444  * Return the size (bytes) of the list and set the event_list array.
 445  * On error, return negative value.
 446  */
 447 int lttng_list_events(struct lttng_domain *domain, char **event_list)
 448 {
 449         int ret;
 450
 451         switch (domain->type) {
 452                 case LTTNG_DOMAIN_KERNEL:
 453                         ret = ask_sessiond(LTTNG_KERNEL_LIST_EVENTS, (void **) event_list);
 454                         break;
 455                 case LTTNG_DOMAIN_UST:
 456                         ret = LTTCOMM_NOT_IMPLEMENTED;
 457                         break;
 458                 default:
 459                         ret = LTTCOMM_UNKNOWN_DOMAIN;
 460                         break;
 461         };
 462
 463         return ret;
 464 }
 465
 466 /*
 467  *  Return a human readable string of code
 468  */
 469 const char *lttng_get_readable_code(int code)
 470 {
 471         if (code > -LTTCOMM_OK) {
 472                 return "Ended with errors";
 473         }
 474
 475         return lttcomm_get_readable_code(code);
 476 }
 477
 478 /*
 479  *  Create a brand new session using name.
 480  */
 481 int lttng_create_session(const char *name, const char *path)
 482 {
 483         strncpy(lsm.session_name, name, NAME_MAX);
 484         strncpy(lsm.path, path, PATH_MAX);
 485         return ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 486 }
 487
 488 /*
 489  *  Destroy session using name.
 490  */
 491 int lttng_destroy_session(const char *name)
 492 {
 493         strncpy(lsm.session_name, name, NAME_MAX);
 494         return ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 495 }
 496
 497 /*
 498  *  Ask the session daemon for all available sessions.
 499  *
 500  *  Return number of session.
 501  *  On error, return negative value.
 502  */
 503 int lttng_list_sessions(struct lttng_session **sessions)
 504 {
 505         int ret;
 506
 507         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 508         if (ret < 0) {
 509                 return ret;
 510         }
 511
 512         return ret / sizeof(struct lttng_session);
 513 }
 514
 515 /*
 516  * Set session name for the current lsm.
 517  */
 518 void lttng_set_session_name(const 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 }