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