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