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, char **session_id)
 198 {
 199         int ret;
 200         char *uuid;
 201
 202         strncpy(lsm.session_name, name, sizeof(lsm.session_name));
 203
 204         ret = ask_sessiond(LTTNG_CREATE_SESSION, NULL);
 205         if (ret < 0) {
 206                 goto end;
 207         }
 208
 209         /* Allocate UUID string length */
 210         uuid = malloc(UUID_STR_LEN);
 211
 212         strncpy(uuid, llm.session_id, UUID_STR_LEN);
 213         *session_id = uuid;
 214
 215 end:
 216         return ret;
 217 }
 218
 219 /*
 220  *  lttng_list_sessions
 221  *
 222  *  Ask the session daemon for all available sessions.
 223  *
 224  *  Return number of session.
 225  *  On error, return negative value.
 226  */
 227 int lttng_list_sessions(struct lttng_session **sessions)
 228 {
 229         int ret;
 230
 231         ret = ask_sessiond(LTTNG_LIST_SESSIONS, (void**) sessions);
 232         if (ret < 0) {
 233                 return ret;
 234         }
 235
 236         return ret / sizeof(struct lttng_session);
 237 }
 238
 239 /*
 240  *  lttng_connect_sessiond
 241  *
 242  *  Connect to the LTTng session daemon.
 243  *  On success, return 0
 244  *  On error, return a negative value
 245  */
 246 int lttng_connect_sessiond(void)
 247 {
 248         int ret;
 249
 250         ret = set_session_daemon_path();
 251         if (ret < 0) {
 252                 return ret;
 253         }
 254
 255         /* Connect to the sesssion daemon */
 256         ret = lttcomm_connect_unix_sock(sessiond_sock_path);
 257         if (ret < 0) {
 258                 return ret;
 259         }
 260
 261         sessiond_socket = ret;
 262         connected = 1;
 263
 264         return 0;
 265 }
 266
 267 /*
 268  *  lttng_set_tracing_group
 269  *
 270  *  Set tracing group variable with name. This function
 271  *  allocate memory pointed by tracing_group.
 272  */
 273 int lttng_set_tracing_group(const char *name)
 274 {
 275         if (asprintf(&tracing_group, "%s", name) < 0) {
 276                 return -ENOMEM;
 277         }
 278
 279         return 0;
 280 }
 281
 282 /*
 283  *  lttng_check_session_daemon
 284  *
 285  *  Return 0 if a sesssion daemon is available
 286  *  else return -1
 287  */
 288 int lttng_check_session_daemon(void)
 289 {
 290         int ret;
 291
 292         ret = set_session_daemon_path();
 293         if (ret < 0) {
 294                 return ret;
 295         }
 296
 297         /* If socket exist, we consider the daemon started */
 298         ret = access(sessiond_sock_path, F_OK);
 299         if (ret < 0) {
 300                 return ret;
 301         }
 302
 303         return 0;
 304 }
 305
 306 /*
 307  *  set_session_daemon_path
 308  *
 309  *  Set sessiond socket path by putting it in
 310  *  the global sessiond_sock_path variable.
 311  */
 312 static int set_session_daemon_path(void)
 313 {
 314         int ret;
 315
 316         /* Are we in the tracing group ? */
 317         ret = check_tracing_group(tracing_group);
 318         if (ret < 0) {
 319                 if (sprintf(sessiond_sock_path, DEFAULT_HOME_CLIENT_UNIX_SOCK,
 320                                         getenv("HOME")) < 0) {
 321                         return -ENOMEM;
 322                 }
 323         } else {
 324                 strncpy(sessiond_sock_path, DEFAULT_GLOBAL_CLIENT_UNIX_SOCK,
 325                                 sizeof(DEFAULT_GLOBAL_CLIENT_UNIX_SOCK));
 326         }
 327
 328         return 0;
 329 }
 330
 331 /*
 332  *  check_tracing_group
 333  *
 334  *  Check if the specified group name exist.
 335  *  If yes, 0, else -1
 336  */
 337 static int check_tracing_group(const char *grp_name)
 338 {
 339         struct group *grp_tracing;      /* no free(). See getgrnam(3) */
 340         gid_t *grp_list;
 341         int grp_list_size, grp_id, i;
 342         int ret = -1;
 343
 344         /* Get GID of group 'tracing' */
 345         grp_tracing = getgrnam(grp_name);
 346         if (grp_tracing == NULL) {
 347                 /* NULL means not found also. getgrnam(3) */
 348                 if (errno != 0) {
 349                         perror("getgrnam");
 350                 }
 351                 goto end;
 352         }
 353
 354         /* Get number of supplementary group IDs */
 355         grp_list_size = getgroups(0, NULL);
 356         if (grp_list_size < 0) {
 357                 perror("getgroups");
 358                 goto end;
 359         }
 360
 361         /* Alloc group list of the right size */
 362         grp_list = malloc(grp_list_size * sizeof(gid_t));
 363         grp_id = getgroups(grp_list_size, grp_list);
 364         if (grp_id < -1) {
 365                 perror("getgroups");
 366                 goto free_list;
 367         }
 368
 369         for (i = 0; i < grp_list_size; i++) {
 370                 if (grp_list[i] == grp_tracing->gr_gid) {
 371                         ret = 0;
 372                         break;
 373                 }
 374         }
 375
 376 free_list:
 377         free(grp_list);
 378
 379 end:
 380         return ret;
 381 }
 382
 383 /*
 384  * lib constructor
 385  */
 386 static void __attribute__((constructor)) init()
 387 {
 388         /* Set default session group */
 389         lttng_set_tracing_group(DEFAULT_TRACING_GROUP);
 390 }