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 send_reply(int sock, struct lttcomm_ust_reply *lur)
  99 {
 100         ssize_t len;
 101
 102         len = lttcomm_send_unix_sock(sock, &lur, sizeof(lur));
 103         switch (len) {
 104         case sizeof(lur):
 105                 DBG("message successfully sent");
 106                 return 0;
 107         case -1:
 108                 if (errno == ECONNRESET) {
 109                         printf("remote end closed connection\n");
 110                         return 0;
 111                 }
 112                 return -1;
 113         default:
 114                 printf("incorrect message size: %zd\n", len);
 115                 return -1;
 116         }
 117 }
 118
 119 static
 120 int handle_message(int sock, struct lttcomm_ust_msg *lum)
 121 {
 122         int ret = 0;
 123
 124         pthread_mutex_lock(&lttng_ust_comm_mutex);
 125
 126         if (lttng_ust_comm_should_quit) {
 127                 ret = 0;
 128                 goto end;
 129         }
 130
 131         switch (lum->cmd_type) {
 132         case UST_CREATE_SESSION:
 133         {
 134                 struct lttcomm_ust_reply lur;
 135
 136                 DBG("Handling create session message");
 137                 memset(&lur, 0, sizeof(lur));
 138                 lur.cmd_type = UST_CREATE_SESSION;
 139                 ret = lttng_abi_create_session();
 140                 if (ret >= 0) {
 141                         lur.ret_val = ret;
 142                         lur.ret_code = LTTCOMM_OK;
 143                 } else {
 144                         lur.ret_code = LTTCOMM_SESSION_FAIL;
 145                 }
 146                 ret = send_reply(sock, &lur);
 147                 break;
 148         }
 149         case UST_RELEASE:
 150         {
 151                 struct lttcomm_ust_reply lur;
 152
 153                 DBG("Handling release message, handle: %d",
 154                         lum->handle);
 155                 memset(&lur, 0, sizeof(lur));
 156                 lur.cmd_type = UST_RELEASE;
 157                 ret = objd_unref(lum->handle);
 158                 if (!ret) {
 159                         lur.ret_code = LTTCOMM_OK;
 160                 } else {
 161                         lur.ret_code = LTTCOMM_ERR;
 162                 }
 163                 ret = send_reply(sock, &lur);
 164                 break;
 165         }
 166         default:
 167                 ERR("Unimplemented command %d", (int) lum->cmd_type);
 168                 ret = -1;
 169                 goto end;
 170         }
 171 end:
 172         pthread_mutex_unlock(&lttng_ust_comm_mutex);
 173         return ret;
 174 }
 175
 176 /*
 177  * This thread does not allocate any resource, except within
 178  * handle_message, within mutex protection. This mutex protects against
 179  * fork and exit.
 180  * The other moment it allocates resources is at socket connexion, which
 181  * is also protected by the mutex.
 182  */
 183 static
 184 void *ust_listener_thread(void *arg)
 185 {
 186         struct sock_info *sock_info = arg;
 187         int sock, ret;
 188
 189         /* Restart trying to connect to the session daemon */
 190 restart:
 191         pthread_mutex_lock(&lttng_ust_comm_mutex);
 192
 193         if (lttng_ust_comm_should_quit) {
 194                 pthread_mutex_unlock(&lttng_ust_comm_mutex);
 195                 goto quit;
 196         }
 197
 198         if (sock_info->socket != -1) {
 199                 ret = close(sock_info->socket);
 200                 if (ret) {
 201                         ERR("Error closing local apps socket");
 202                 }
 203                 sock_info->socket = -1;
 204         }
 205         /* Check for sessiond availability with pipe TODO */
 206
 207         /* Register */
 208         ret = lttcomm_connect_unix_sock(sock_info->sock_path);
 209         if (ret < 0) {
 210                 ERR("Error connecting to global apps socket");
 211                 pthread_mutex_unlock(&lttng_ust_comm_mutex);
 212                 goto restart;
 213         } else {
 214                 sock_info->socket = sock = ret;
 215                 pthread_mutex_unlock(&lttng_ust_comm_mutex);
 216         }
 217
 218         ret = register_app_to_sessiond(sock);
 219         if (ret < 0) {
 220                 ERR("Error registering app to local apps socket");
 221                 sleep(5);
 222                 goto restart;
 223         }
 224         for (;;) {
 225                 ssize_t len;
 226                 struct lttcomm_ust_msg lum;
 227
 228                 /* Receive session handle */
 229                 len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
 230                 switch (len) {
 231                 case 0: /* orderly shutdown */
 232                         DBG("ltt-sessiond has performed an orderly shutdown\n");
 233                         goto end;
 234                 case sizeof(lum):
 235                         DBG("message received\n");
 236                         ret = handle_message(sock, &lum);
 237                         if (ret < 0) {
 238                                 ERR("Error handling message\n");
 239                         }
 240                         continue;
 241                 case -1:
 242                         if (errno == ECONNRESET) {
 243                                 ERR("remote end closed connection\n");
 244                                 goto end;
 245                         }
 246                         goto end;
 247                 default:
 248                         ERR("incorrect message size: %zd\n", len);
 249                         continue;
 250                 }
 251
 252         }
 253 end:
 254         goto restart;   /* try to reconnect */
 255 quit:
 256         return NULL;
 257 }
 258
 259
 260 /*
 261  * sessiond monitoring thread: monitor presence of global and per-user
 262  * sessiond by polling the application common named pipe.
 263  */
 264 /* TODO */
 265
 266 void __attribute__((constructor)) lttng_ust_comm_init(void)
 267 {
 268         int ret;
 269
 270         init_usterr();
 271
 272         ret = setup_local_apps_socket();
 273         if (ret) {
 274                 ERR("Error setting up to local apps socket");
 275         }
 276 #if 0
 277         ret = pthread_create(&global_apps.ust_listener, NULL,
 278                         ust_listener_thread, &global_apps);
 279 #endif //0
 280         ret = pthread_create(&local_apps.ust_listener, NULL,
 281                         ust_listener_thread, &local_apps);
 282 }
 283
 284 void __attribute__((destructor)) lttng_ust_comm_exit(void)
 285 {
 286         int ret;
 287
 288         /*
 289          * Using pthread_cancel here because:
 290          * A) we don't want to hang application teardown.
 291          * B) the thread is not allocating any resource.
 292          */
 293
 294         /*
 295          * Require the communication thread to quit. Synchronize with
 296          * mutexes to ensure it is not in a mutex critical section when
 297          * pthread_cancel is later called.
 298          */
 299         pthread_mutex_lock(&lttng_ust_comm_mutex);
 300         lttng_ust_comm_should_quit = 1;
 301         pthread_mutex_unlock(&lttng_ust_comm_mutex);
 302
 303 #if 0
 304         ret = pthread_cancel(global_apps.ust_listener);
 305         if (ret) {
 306                 ERR("Error cancelling global ust listener thread");
 307         }
 308 #endif //0
 309         if (global_apps.socket != -1) {
 310                 ret = close(global_apps.socket);
 311                 assert(!ret);
 312         }
 313
 314         ret = pthread_cancel(local_apps.ust_listener);
 315         if (ret) {
 316                 ERR("Error cancelling local ust listener thread");
 317         }
 318
 319         if (local_apps.socket != -1) {
 320                 ret = close(local_apps.socket);
 321                 assert(!ret);
 322         }
 323
 324         lttng_ust_abi_exit();
 325         ltt_events_exit();
 326 }