libust/lttng-ust-comm.c

   1 /*
   2  * lttng-ust-comm.c
   3  *
   4  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   5  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; only
  10  * version 2.1 of the License.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include <sys/types.h>
  23 #include <sys/socket.h>
  24 #include <unistd.h>
  25 #include <errno.h>
  26 #include <ust/lttng-ust-abi.h>
  27 #include <lttng-ust-comm.h>
  28 #include <ust/usterr-signal-safe.h>
  29 #include <pthread.h>
  30 #include <assert.h>
  31
  32 /*
  33  * communication thread mutex. Held when handling a command, also held
  34  * by fork() to deal with removal of threads, and by exit path.
  35  */
  36 static pthread_mutex_t lttng_ust_comm_mutex = PTHREAD_MUTEX_INITIALIZER;
  37
  38 /* Should the ust comm thread quit ? */
  39 static int lttng_ust_comm_should_quit;
  40
  41 /*
  42  * Info about socket and associated listener thread.
  43  */
  44 struct sock_info {
  45         char sock_path[PATH_MAX];
  46         int socket;
  47         pthread_t ust_listener; /* listener thread */
  48 };
  49
  50 /* Socket from app (connect) to session daemon (listen) for communication */
  51 struct sock_info global_apps = {
  52         .sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK,
  53         .socket = -1,
  54 };
  55
  56 /* TODO: allow global_apps_sock_path override */
  57
  58 struct sock_info local_apps = {
  59         .socket = -1,
  60 };
  61
  62 static
  63 int setup_local_apps_socket(void)
  64 {
  65         const char *home_dir;
  66
  67         home_dir = (const char *) getenv("HOME");
  68         if (!home_dir)
  69                 return -ENOENT;
  70         snprintf(local_apps.sock_path, PATH_MAX,
  71                  DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
  72         return 0;
  73 }
  74
  75 static
  76 int register_app_to_sessiond(int socket)
  77 {
  78         ssize_t ret;
  79         struct {
  80                 uint32_t major;
  81                 uint32_t minor;
  82                 pid_t pid;
  83                 uid_t uid;
  84         } reg_msg;
  85
  86         reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR;
  87         reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR;
  88         reg_msg.pid = getpid();
  89         reg_msg.uid = getuid();
  90
  91         ret = lttcomm_send_unix_sock(socket, &reg_msg, sizeof(reg_msg));
  92         if (ret >= 0 && ret != sizeof(reg_msg))
  93                 return -EIO;
  94         return ret;
  95 }
  96
  97 static
  98 int handle_message(int sock, struct lttcomm_ust_msg *lum)
  99 {
 100         ssize_t len;
 101         int ret = 0;
 102
 103         pthread_mutex_lock(&lttng_ust_comm_mutex);
 104
 105         if (lttng_ust_comm_should_quit) {
 106                 ret = 0;
 107                 goto end;
 108         }
 109
 110         switch (lum->cmd_type) {
 111         case UST_CREATE_SESSION:
 112         {
 113                 struct lttcomm_ust_reply lur;
 114
 115                 DBG("Handling create session message");
 116                 memset(&lur, 0, sizeof(lur));
 117                 lur.cmd_type = UST_CREATE_SESSION;
 118
 119                 ret = lttng_abi_create_session();
 120                 if (ret >= 0) {
 121                         lur.ret_val = ret;
 122                         lur.ret_code = LTTCOMM_OK;
 123                 } else {
 124                         lur.ret_code = LTTCOMM_SESSION_FAIL;
 125                 }
 126                 len = lttcomm_send_unix_sock(sock, &lur, sizeof(lur));
 127                 switch (len) {
 128                 case sizeof(lur):
 129                         DBG("message successfully sent");
 130                         break;
 131                 case -1:
 132                         if (errno == ECONNRESET) {
 133                                 printf("remote end closed connection\n");
 134                                 ret = 0;
 135                                 goto end;
 136                         }
 137                         ret = -1;
 138                         goto end;
 139                 default:
 140                         printf("incorrect message size: %zd\n", len);
 141                         ret = -1;
 142                         goto end;
 143                 }
 144                 break;
 145         }
 146         case UST_RELEASE:
 147         {
 148                 struct lttcomm_ust_reply lur;
 149
 150                 DBG("Handling release message, handle: %d",
 151                         lum->handle);
 152                 memset(&lur, 0, sizeof(lur));
 153                 lur.cmd_type = UST_RELEASE;
 154
 155                 ret = objd_unref(lum->handle);
 156                 if (!ret) {
 157                         lur.ret_code = LTTCOMM_OK;
 158                 } else {
 159                         lur.ret_code = LTTCOMM_ERR;
 160                 }
 161                 len = lttcomm_send_unix_sock(sock, &lur, sizeof(lur));
 162                 switch (len) {
 163                 case sizeof(lur):
 164                         DBG("message successfully sent\n");
 165                         break;
 166                 case -1:
 167                         if (errno == ECONNRESET) {
 168                                 printf("remote end closed connection\n");
 169                                 ret = 0;
 170                                 goto end;
 171                         }
 172                         ret = -1;
 173                         goto end;
 174                 default:
 175                         printf("incorrect message size: %zd\n", len);
 176                         ret = -1;
 177                         goto end;
 178                 }
 179                 break;
 180         }
 181         default:
 182                 ERR("Unimplemented command %d", (int) lum->cmd_type);
 183                 ret = -1;
 184                 goto end;
 185         }
 186 end:
 187         pthread_mutex_unlock(&lttng_ust_comm_mutex);
 188         return ret;
 189 }
 190
 191 /*
 192  * This thread does not allocate any resource, except within
 193  * handle_message, within mutex protection. This mutex protects against
 194  * fork and exit.
 195  * The other moment it allocates resources is at socket connexion, which
 196  * is also protected by the mutex.
 197  */
 198 static
 199 void *ust_listener_thread(void *arg)
 200 {
 201         struct sock_info *sock_info = arg;
 202         int sock, ret;
 203
 204         /* Restart trying to connect to the session daemon */
 205 restart:
 206         pthread_mutex_lock(&lttng_ust_comm_mutex);
 207
 208         if (lttng_ust_comm_should_quit) {
 209                 pthread_mutex_unlock(&lttng_ust_comm_mutex);
 210                 goto quit;
 211         }
 212
 213         if (sock_info->socket != -1) {
 214                 ret = close(sock_info->socket);
 215                 if (ret) {
 216                         ERR("Error closing local apps socket");
 217                 }
 218                 sock_info->socket = -1;
 219         }
 220         /* Check for sessiond availability with pipe TODO */
 221
 222         /* Register */
 223         ret = lttcomm_connect_unix_sock(sock_info->sock_path);
 224         if (ret < 0) {
 225                 ERR("Error connecting to global apps socket");
 226                 pthread_mutex_unlock(&lttng_ust_comm_mutex);
 227                 goto restart;
 228         } else {
 229                 sock_info->socket = sock = ret;
 230                 pthread_mutex_unlock(&lttng_ust_comm_mutex);
 231         }
 232
 233         ret = register_app_to_sessiond(sock);
 234         if (ret < 0) {
 235                 ERR("Error registering app to local apps socket");
 236                 sleep(5);
 237                 goto restart;
 238         }
 239         for (;;) {
 240                 ssize_t len;
 241                 struct lttcomm_ust_msg lum;
 242
 243                 /* Receive session handle */
 244                 len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
 245                 switch (len) {
 246                 case 0: /* orderly shutdown */
 247                         DBG("ltt-sessiond has performed an orderly shutdown\n");
 248                         goto end;
 249                 case sizeof(lum):
 250                         DBG("message received\n");
 251                         ret = handle_message(sock, &lum);
 252                         if (ret < 0) {
 253                                 ERR("Error handling message\n");
 254                         }
 255                         continue;
 256                 case -1:
 257                         if (errno == ECONNRESET) {
 258                                 ERR("remote end closed connection\n");
 259                                 goto end;
 260                         }
 261                         goto end;
 262                 default:
 263                         ERR("incorrect message size: %zd\n", len);
 264                         continue;
 265                 }
 266
 267         }
 268 end:
 269         goto restart;   /* try to reconnect */
 270 quit:
 271         return NULL;
 272 }
 273
 274
 275 /*
 276  * sessiond monitoring thread: monitor presence of global and per-user
 277  * sessiond by polling the application common named pipe.
 278  */
 279 /* TODO */
 280
 281 void __attribute__((constructor)) lttng_ust_comm_init(void)
 282 {
 283         int ret;
 284
 285         init_usterr();
 286
 287         ret = setup_local_apps_socket();
 288         if (ret) {
 289                 ERR("Error setting up to local apps socket");
 290         }
 291 #if 0
 292         ret = pthread_create(&global_apps.ust_listener, NULL,
 293                         ust_listener_thread, &global_apps);
 294 #endif //0
 295         ret = pthread_create(&local_apps.ust_listener, NULL,
 296                         ust_listener_thread, &local_apps);
 297 }
 298
 299 void __attribute__((destructor)) lttng_ust_comm_exit(void)
 300 {
 301         int ret;
 302
 303         /*
 304          * Using pthread_cancel here because:
 305          * A) we don't want to hang application teardown.
 306          * B) the thread is not allocating any resource.
 307          */
 308
 309         /*
 310          * Require the communication thread to quit. Synchronize with
 311          * mutexes to ensure it is not in a mutex critical section when
 312          * pthread_cancel is later called.
 313          */
 314         pthread_mutex_lock(&lttng_ust_comm_mutex);
 315         lttng_ust_comm_should_quit = 1;
 316         pthread_mutex_unlock(&lttng_ust_comm_mutex);
 317
 318 #if 0
 319         ret = pthread_cancel(global_apps.ust_listener);
 320         if (ret) {
 321                 ERR("Error cancelling global ust listener thread");
 322         }
 323 #endif //0
 324         if (global_apps.socket != -1) {
 325                 ret = close(global_apps.socket);
 326                 assert(!ret);
 327         }
 328
 329         ret = pthread_cancel(local_apps.ust_listener);
 330         if (ret) {
 331                 ERR("Error cancelling local ust listener thread");
 332         }
 333
 334         if (local_apps.socket != -1) {
 335                 ret = close(local_apps.socket);
 336                 assert(!ret);
 337         }
 338
 339         lttng_ust_abi_exit();
 340         ltt_events_exit();
 341 }