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/liblttngctl.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         lsm.cmd_type = lct;
 115
 116         /* Send command to session daemon */
 117         ret = send_data_sessiond();
 118         if (ret < 0) {
 119                 goto end;
 120         }
 121
 122         /* Get header from data transmission */
 123         ret = recv_data_sessiond(&llm, sizeof(llm));
 124         if (ret < 0) {
 125                 goto end;
 126         }
 127
 128         /* Check error code if OK */
 129         if (llm.ret_code != LTTCOMM_OK) {
 130                 ret = -llm.ret_code;
 131                 goto end;
 132         }
 133
 134         size = llm.size_payload;
 135         if (size == 0) {
 136                 goto end;
 137         }
 138
 139         data = (void*) malloc(size);
 140
 141         /* Get payload data */
 142         ret = recv_data_sessiond(data, size);
 143         if (ret < 0) {
 144                 goto end;
 145         }
 146
 147         *buf = data;
 148         ret = size;
 149
 150 end:
 151         /* Reset lsm data struct */
 152         memset(&lsm, 0, sizeof(lsm));
 153         return ret;
 154 }
 155
 156 /*
 157  *  lttng_get_readable_code
 158  *
 159  *  Return a human readable string of code
 160  */
 161 const char *lttng_get_readable_code(int code)
 162 {
 163         if (code > -LTTCOMM_OK) {
 164                 return "Ended with errors";
 165         }
 166
 167         return lttcomm_get_readable_code(code);
 168 }
 169
 170 /*
 171  *  lttng_ust_start_trace
 172  *
 173  *  Request a trace start for pid.
 174  */
 175 int lttng_ust_start_trace(pid_t pid)
 176 {
 177         int ret;
 178
 179         lsm.pid = pid;
 180         ret = ask_sessiond(UST_START_TRACE, NULL);
 181
 182         return ret;
 183 }
 184
 185 /*
 186  *  lttng_ust_stop_trace
 187  *
 188  *  Request a trace stop for pid.
 189  */
 190 int lttng_ust_stop_trace(pid_t pid)
 191 {
 192         int ret;
 193
 194         lsm.pid = pid;
 195         ret = ask_sessiond(UST_STOP_TRACE, NULL);
 196
 197         return ret;
 198 }
 199
 200 /*
 201  *  lttng_ust_create_trace
 202  *
 203  *  Request a trace creation for pid.
 204  */
 205 int lttng_ust_create_trace(pid_t pid)
 206 {
 207         int ret;
 208
 209         lsm.pid = pid;
 210         ret = ask_sessiond(UST_CREATE_TRACE, NULL);
 211
 212         return ret;
 213 }
 214
 215 /*
 216  *  lttng_ust_list_apps
 217  *
 218  *  Ask the session daemon for all UST traceable
 219  *  applications.
 220  *
 221  *  Return the number of pids.
 222  *  On error, return negative value.
 223  */
 224 int lttng_ust_list_apps(pid_t **pids)
 225 {
 226         int ret;
 227
 228         ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
 229         if (ret < 0) {
 230                 return ret;
 231         }
 232
 233         return ret / sizeof(pid_t);
 234 }
 235
 236 /*
 237  *  lttng_list_traces
 238  *
 239  *  Ask the session daemon for all traces (kernel and ust)
 240  *  for the session identified by uuid.
 241  *
 242  *  Return the number of traces.
 243  */
 244 int lttng_list_traces(uuid_t *uuid, struct lttng_trace **traces)
 245 {
 246         int ret;
 247
 248         uuid_copy(lsm.session_id, *uuid);
 249
 250         ret = ask_sessiond(LTTNG_LIST_TRACES, (void **) traces);
 251         if (ret < 0) {
 252                 return ret;
 253         }
 254
 255         return ret / sizeof(struct lttng_trace);
 256 }
 257
 258 /*
 259  *  lttng_create_session
 260  *
 261  *  Create a brand new session using name. Allocate
 262  *  the session_id param pointing to the UUID.
 263  */
 264 int lttng_create_session(char *name, uuid_t *session_id)
 265 {
 266         int ret;
 267
 268         strncpy(lsm.session_name, name, sizeof(lsm.session_name));
 269         lsm.session_name[sizeof(lsm.session_name) - 1] = '\0';
 270
 271         ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 272         if (ret < 0) {
 273                 goto end;
 274         }
 275
 276         uuid_copy(*session_id, llm.session_id);
 277
 278 end:
 279         return ret;
 280 }
 281
 282 /*
 283  *  lttng_destroy_session
 284  *
 285  *  Destroy session using name.
 286  */
 287 int lttng_destroy_session(uuid_t *uuid)
 288 {
 289         int ret;
 290
 291         uuid_copy(lsm.session_id, *uuid);
 292
 293         ret = ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 294         if (ret < 0) {
 295                 goto end;
 296         }
 297
 298 end:
 299         return ret;
 300 }
 301
 302 /*
 303  *  lttng_list_sessions
 304  *
 305  *  Ask the session daemon for all available sessions.
 306  *
 307  *  Return number of session.
 308  *  On error, return negative value.
 309  */
 310 int lttng_list_sessions(struct lttng_session **sessions)
 311 {
 312         int ret;
 313
 314         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 315         if (ret < 0) {
 316                 return ret;
 317         }
 318
 319         return ret / sizeof(struct lttng_session);
 320 }
 321
 322 /*
 323  *  lttng_connect_sessiond
 324  *
 325  *  Connect to the LTTng session daemon.
 326  *  On success, return 0
 327  *  On error, return a negative value
 328  */
 329 int lttng_connect_sessiond(void)
 330 {
 331         int ret;
 332
 333         ret = set_session_daemon_path();
 334         if (ret < 0) {
 335                 return ret;
 336         }
 337
 338         /* Connect to the sesssion daemon */
 339         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 340         if (ret < 0) {
 341                 return ret;
 342         }
 343
 344         sessiond_socket = ret;
 345         connected = 1;
 346
 347         return 0;
 348 }
 349
 350 /*
 351  *  lttng_disconnect_sessiond
 352  *
 353  *  Clean disconnect the session daemon.
 354  */
 355 int lttng_disconnect_sessiond(void)
 356 {
 357         int ret = 0;
 358
 359         if (connected) {
 360                 ret = lttcomm_close_unix_sock(sessiond_socket);
 361                 sessiond_socket = 0;
 362                 connected = 0;
 363         }
 364
 365         return ret;
 366 }
 367
 368 /*
 369  *  lttng_set_current_session_uuid
 370  *
 371  *  Set the session uuid for current lsm.
 372  */
 373 void lttng_set_current_session_uuid(char *uuid)
 374 {
 375         uuid_parse(uuid, lsm.session_id);
 376 }
 377
 378 /*
 379  *  lttng_set_tracing_group
 380  *
 381  *  Set tracing group variable with name. This function
 382  *  allocate memory pointed by tracing_group.
 383  */
 384 int lttng_set_tracing_group(const char *name)
 385 {
 386         if (asprintf(&tracing_group, "%s", name) < 0) {
 387                 return -ENOMEM;
 388         }
 389
 390         return 0;
 391 }
 392
 393 /*
 394  *  lttng_check_session_daemon
 395  *
 396  *  Return 0 if a sesssion daemon is available
 397  *  else return -1
 398  */
 399 int lttng_check_session_daemon(void)
 400 {
 401         int ret;
 402
 403         ret = set_session_daemon_path();
 404         if (ret < 0) {
 405                 return ret;
 406         }
 407
 408         /* If socket exist, we consider the daemon started */
 409         ret = access(sessiond_sock_path, F_OK);
 410         if (ret < 0) {
 411                 return ret;
 412         }
 413
 414         return 0;
 415 }
 416
 417 /*
 418  *  set_session_daemon_path
 419  *
 420  *  Set sessiond socket path by putting it in
 421  *  the global sessiond_sock_path variable.
 422  */
 423 static int set_session_daemon_path(void)
 424 {
 425         int ret;
 426
 427         /* Are we in the tracing group ? */
 428         ret = check_tracing_group(tracing_group);
 429         if (ret < 0) {
 430                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 431                                         getenv("HOME")) < 0) {
 432                         return -ENOMEM;
 433                 }
 434         } else {
 435                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 436                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 437         }
 438
 439         return 0;
 440 }
 441
 442 /*
 443  *  check_tracing_group
 444  *
 445  *  Check if the specified group name exist.
 446  *  If yes, 0, else -1
 447  */
 448 static int check_tracing_group(const char *grp_name)
 449 {
 450         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 451         gid_t *grp_list;
 452         int grp_list_size, grp_id, i;
 453         int ret = -1;
 454
 455         /* Get GID of group 'tracing' */
 456         grp_tracing = getgrnam(grp_name);
 457         if (grp_tracing == NULL) {
 458                 /* NULL means not found also. getgrnam(3) */
 459                 if (errno != 0) {
 460                         perror("getgrnam");
 461                 }
 462                 goto end;
 463         }
 464
 465         /* Get number of supplementary group IDs */
 466         grp_list_size = getgroups(0, NULL);
 467         if (grp_list_size < 0) {
 468                 perror("getgroups");
 469                 goto end;
 470         }
 471
 472         /* Alloc group list of the right size */
 473         grp_list = malloc(grp_list_size * sizeof(gid_t));
 474         grp_id = getgroups(grp_list_size, grp_list);
 475         if (grp_id < -1) {
 476                 perror("getgroups");
 477                 goto free_list;
 478         }
 479
 480         for (i = 0; i < grp_list_size; i++) {
 481                 if (grp_list[i] == grp_tracing->gr_gid) {
 482                         ret = 0;
 483                         break;
 484                 }
 485         }
 486
 487 free_list:
 488         free(grp_list);
 489
 490 end:
 491         return ret;
 492 }
 493
 494 /*
 495  * lib constructor
 496  */
 497 static void __attribute__((constructor)) init()
 498 {
 499         /* Set default session group */
 500         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 501 }