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