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