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_list_apps
 172  *
 173  *  Ask the session daemon for all UST traceable
 174  *  applications.
 175  *
 176  *  Return the number of pids.
 177  *  On error, return negative value.
 178  */
 179 int lttng_ust_list_apps(pid_t **pids)
 180 {
 181         int ret;
 182
 183         ret = ask_sessiond(UST_LIST_APPS, (void**) pids);
 184         if (ret < 0) {
 185                 return ret;
 186         }
 187
 188         return ret / sizeof(pid_t);
 189 }
 190
 191 /*
 192  *  lttng_create_session
 193  *
 194  *  Create a brand new session using name. Allocate
 195  *  the session_id param pointing to the UUID.
 196  */
 197 int lttng_create_session(char *name, uuid_t *session_id)
 198 {
 199         int ret;
 200
 201         strncpy(lsm.session_name, name, sizeof(lsm.session_name));
 202         lsm.session_name[sizeof(lsm.session_name) - 1] = '\0';
 203
 204         ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 205         if (ret < 0) {
 206                 goto end;
 207         }
 208
 209         uuid_copy(*session_id, llm.session_id);
 210
 211 end:
 212         return ret;
 213 }
 214
 215 /*
 216  *  lttng_destroy_session
 217  *
 218  *  Destroy session using name.
 219  */
 220 int lttng_destroy_session(uuid_t *uuid)
 221 {
 222         int ret;
 223
 224         uuid_copy(lsm.session_id, *uuid);
 225
 226         ret = ask_sessiond(LTTNG_DESTROY_SESSION, NULL);
 227         if (ret < 0) {
 228                 goto end;
 229         }
 230
 231 end:
 232         return ret;
 233 }
 234
 235 /*
 236  *  lttng_list_sessions
 237  *
 238  *  Ask the session daemon for all available sessions.
 239  *
 240  *  Return number of session.
 241  *  On error, return negative value.
 242  */
 243 int lttng_list_sessions(struct lttng_session **sessions)
 244 {
 245         int ret;
 246
 247         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 248         if (ret < 0) {
 249                 return ret;
 250         }
 251
 252         return ret / sizeof(struct lttng_session);
 253 }
 254
 255 /*
 256  *  lttng_connect_sessiond
 257  *
 258  *  Connect to the LTTng session daemon.
 259  *  On success, return 0
 260  *  On error, return a negative value
 261  */
 262 int lttng_connect_sessiond(void)
 263 {
 264         int ret;
 265
 266         ret = set_session_daemon_path();
 267         if (ret < 0) {
 268                 return ret;
 269         }
 270
 271         /* Connect to the sesssion daemon */
 272         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 273         if (ret < 0) {
 274                 return ret;
 275         }
 276
 277         sessiond_socket = ret;
 278         connected = 1;
 279
 280         return 0;
 281 }
 282
 283 /*
 284  *  lttng_disconnect_sessiond
 285  *
 286  *  Clean disconnect the session daemon.
 287  */
 288 int lttng_disconnect_sessiond(void)
 289 {
 290         int ret = 0;
 291
 292         if (connected) {
 293                 ret = lttcomm_close_unix_sock(sessiond_socket);
 294                 sessiond_socket = 0;
 295                 connected = 0;
 296         }
 297
 298         return ret;
 299 }
 300
 301 /*
 302  *  lttng_set_current_session_uuid
 303  *
 304  *  Set the session uuid for current lsm.
 305  */
 306 void lttng_set_current_session_uuid(char *uuid)
 307 {
 308         uuid_parse(uuid, lsm.session_id);
 309 }
 310
 311 /*
 312  *  lttng_set_tracing_group
 313  *
 314  *  Set tracing group variable with name. This function
 315  *  allocate memory pointed by tracing_group.
 316  */
 317 int lttng_set_tracing_group(const char *name)
 318 {
 319         if (asprintf(&tracing_group, "%s", name) < 0) {
 320                 return -ENOMEM;
 321         }
 322
 323         return 0;
 324 }
 325
 326 /*
 327  *  lttng_check_session_daemon
 328  *
 329  *  Return 0 if a sesssion daemon is available
 330  *  else return -1
 331  */
 332 int lttng_check_session_daemon(void)
 333 {
 334         int ret;
 335
 336         ret = set_session_daemon_path();
 337         if (ret < 0) {
 338                 return ret;
 339         }
 340
 341         /* If socket exist, we consider the daemon started */
 342         ret = access(sessiond_sock_path, F_OK);
 343         if (ret < 0) {
 344                 return ret;
 345         }
 346
 347         return 0;
 348 }
 349
 350 /*
 351  *  set_session_daemon_path
 352  *
 353  *  Set sessiond socket path by putting it in
 354  *  the global sessiond_sock_path variable.
 355  */
 356 static int set_session_daemon_path(void)
 357 {
 358         int ret;
 359
 360         /* Are we in the tracing group ? */
 361         ret = check_tracing_group(tracing_group);
 362         if (ret < 0) {
 363                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 364                                         getenv("HOME")) < 0) {
 365                         return -ENOMEM;
 366                 }
 367         } else {
 368                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 369                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 370         }
 371
 372         return 0;
 373 }
 374
 375 /*
 376  *  check_tracing_group
 377  *
 378  *  Check if the specified group name exist.
 379  *  If yes, 0, else -1
 380  */
 381 static int check_tracing_group(const char *grp_name)
 382 {
 383         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 384         gid_t *grp_list;
 385         int grp_list_size, grp_id, i;
 386         int ret = -1;
 387
 388         /* Get GID of group 'tracing' */
 389         grp_tracing = getgrnam(grp_name);
 390         if (grp_tracing == NULL) {
 391                 /* NULL means not found also. getgrnam(3) */
 392                 if (errno != 0) {
 393                         perror("getgrnam");
 394                 }
 395                 goto end;
 396         }
 397
 398         /* Get number of supplementary group IDs */
 399         grp_list_size = getgroups(0, NULL);
 400         if (grp_list_size < 0) {
 401                 perror("getgroups");
 402                 goto end;
 403         }
 404
 405         /* Alloc group list of the right size */
 406         grp_list = malloc(grp_list_size * sizeof(gid_t));
 407         grp_id = getgroups(grp_list_size, grp_list);
 408         if (grp_id < -1) {
 409                 perror("getgroups");
 410                 goto free_list;
 411         }
 412
 413         for (i = 0; i < grp_list_size; i++) {
 414                 if (grp_list[i] == grp_tracing->gr_gid) {
 415                         ret = 0;
 416                         break;
 417                 }
 418         }
 419
 420 free_list:
 421         free(grp_list);
 422
 423 end:
 424         return ret;
 425 }
 426
 427 /*
 428  * lib constructor
 429  */
 430 static void __attribute__((constructor)) init()
 431 {
 432         /* Set default session group */
 433         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 434 }