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 <lttng-sessiond-comm.h>
  27 #include <ust/usterr-signal-safe.h>
  28 #include <pthread.h>
  29
  30 /* Socket from app (connect) to session daemon (listen) for communication */
  31 static char global_apps_sock_path[PATH_MAX] = DEFAULT_GLOBAL_APPS_UNIX_SOCK;
  32 static pthread_t global_ust_listener;
  33
  34 /* TODO: allow global_apps_sock_path override */
  35
  36 static char local_apps_sock_path[PATH_MAX];
  37 static pthread_t local_ust_listener;
  38
  39 static
  40 int setup_local_apps_socket(void)
  41 {
  42         const char *home_dir;
  43
  44         home_dir = (const char *) getenv("HOME");
  45         if (!home_dir)
  46                 return -ENOENT;
  47         snprintf(local_apps_sock_path, PATH_MAX,
  48                  DEFAULT_HOME_APPS_UNIX_SOCK, home_dir);
  49         return 0;
  50 }
  51
  52 static
  53 int register_app_to_sessiond(int socket)
  54 {
  55         ssize_t ret;
  56         struct {
  57                 pid_t pid;
  58                 uid_t uid;
  59         } reg_msg;
  60
  61         reg_msg.pid = getpid();
  62         reg_msg.uid = getuid();
  63
  64         ret = lttcomm_send_unix_sock(socket, &reg_msg, sizeof(reg_msg));
  65         if (ret >= 0 && ret != sizeof(reg_msg))
  66                 return -EIO;
  67         return ret;
  68 }
  69
  70
  71 static
  72 int handle_message(int sock, struct lttcomm_ust_msg *lum)
  73 {
  74         ssize_t len;
  75         int ret;
  76
  77         switch (lum->cmd_type) {
  78         case LTTNG_CREATE_SESSION:
  79         {
  80                 struct lttcomm_ust_reply lur;
  81
  82                 DBG("Handling create session message");
  83                 memset(&lur, 0, sizeof(lur));
  84                 lur.cmd_type = LTTNG_CREATE_SESSION;
  85
  86                 /* ... */
  87                 ret = 0;
  88
  89                 if (!ret)
  90                         lur.ret_code = LTTCOMM_OK;
  91                 else
  92                         lur.ret_code = LTTCOMM_SESSION_FAIL;
  93                 lur.u.session.handle = 42;
  94                 len = lttcomm_send_unix_sock(sock, &lur, sizeof(lur));
  95                 switch (len) {
  96                 case sizeof(lur):
  97                         printf("message successfully sent\n");
  98                         break;
  99                 case -1:
 100                         if (errno == ECONNRESET) {
 101                                 printf("remote end closed connection\n");
 102                                 return 0;
 103                         }
 104                         return -1;
 105                 default:
 106                         printf("incorrect message size: %zd\n", len);
 107                         return -1;
 108                 }
 109                 break;
 110         }
 111         default:
 112                 ERR("Unimplemented command %d", (int) lum->cmd_type);
 113                 return -1;
 114         }
 115         return 0;
 116 }
 117
 118 static
 119 void *ust_listener_thread(void *arg)
 120 {
 121         const char *sock_path = (const char *) arg;
 122         int sock;
 123         int ret;
 124
 125         /* Restart trying to connect to the session daemon */
 126 restart:
 127
 128         /* Check for sessiond availability with pipe TODO */
 129
 130         /* Register */
 131         ret = lttcomm_connect_unix_sock(sock_path);
 132         if (ret < 0) {
 133                 ERR("Error connecting to global apps socket");
 134         }
 135         sock = ret;
 136         ret = register_app_to_sessiond(sock);
 137         if (ret < 0) {
 138                 ERR("Error registering app to local apps socket");
 139                 sleep(5);
 140                 goto restart;
 141         }
 142         for (;;) {
 143                 ssize_t len;
 144                 struct lttcomm_ust_msg lum;
 145
 146                 /* Receive session handle */
 147                 len = lttcomm_recv_unix_sock(sock, &lum, sizeof(lum));
 148                 switch (len) {
 149                 case 0: /* orderly shutdown */
 150                         DBG("ltt-sessiond has performed an orderly shutdown\n");
 151                         goto end;
 152                 case sizeof(lum):
 153                         DBG("message received\n");
 154                         ret = handle_message(sock, &lum);
 155                         if (ret) {
 156                                 ERR("Error handling message\n");
 157                         }
 158                         continue;
 159                 case -1:
 160                         if (errno == ECONNRESET) {
 161                                 ERR("remote end closed connection\n");
 162                                 goto end;
 163                         }
 164                         goto end;
 165                 default:
 166                         ERR("incorrect message size: %zd\n", len);
 167                         continue;
 168                 }
 169
 170         }
 171 end:
 172         ret = close(sock);
 173         if (ret) {
 174                 ERR("Error closing local apps socket");
 175         }
 176         goto restart;   /* try to reconnect */
 177         return NULL;
 178 }
 179
 180
 181 /*
 182  * sessiond monitoring thread: monitor presence of global and per-user
 183  * sessiond by polling the application common named pipe.
 184  */
 185 /* TODO */
 186
 187 void __attribute__((constructor)) lttng_ust_comm_init(void)
 188 {
 189         int ret;
 190
 191         init_usterr();
 192
 193         /* Connect to the per-user (local) sessiond apps socket */
 194         ret = setup_local_apps_socket();
 195         if (ret) {
 196                 ERR("Error setting up to local apps socket");
 197         }
 198 #if 0
 199         ret = pthread_create(&global_ust_listener, NULL,
 200                         ust_listener_thread, global_apps_sock_path);
 201 #endif //0
 202         ret = pthread_create(&local_ust_listener, NULL,
 203                         ust_listener_thread, local_apps_sock_path);
 204 }
 205
 206 void __attribute__((destructor)) lttng_ust_comm_exit(void)
 207 {
 208         int ret;
 209
 210         /*
 211          * Using pthread_cancel here because:
 212          * A) we don't want to hang application teardown.
 213          * B) the thread is not allocating any resource.
 214          */
 215         ret = pthread_cancel(global_ust_listener);
 216         if (ret) {
 217                 ERR("Error cancelling global ust listener thread");
 218         }
 219         ret = pthread_cancel(local_ust_listener);
 220         if (ret) {
 221                 ERR("Error cancelling local ust listener thread");
 222         }
 223 }