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