Add listing session option

[lttng-tools.git] / lttng / lttng.c

diff --git a/lttng/lttng.c b/lttng/lttng.c
index 6cc540922a77b78ebd29c505255bfa54ad65996b..095ebe5e1c898343b86d177bfd39a926115b3090 100644 (file)
--- a/lttng/lttng.c
+++ b/lttng/lttng.c
@@ -41,6 +41,9 @@ static char *progname;
 /* Prototypes */
 static int process_client_opt(void);
 static int process_opt_list_apps(void);
+static int process_opt_list_sessions(void);
+static void sighandler(int sig);
+static int set_signal_handler(void);
 
 /*
  *  start_client
@@ -56,14 +59,19 @@ static int process_client_opt(void)
        /* Connect to the session daemon */
        ret = lttng_connect_sessiond();
        if (ret < 0) {
-               ERR("%s", lttng_get_readable_code(ret));
                goto end;
        }
 
        if (opt_list_apps) {
                ret = process_opt_list_apps();
                if (ret < 0) {
-                       ERR("%s", lttng_get_readable_code(ret));
+                       goto end;
+               }
+       }
+
+       if (opt_list_session) {
+               ret = process_opt_list_sessions();
+               if (ret < 0) {
                        goto end;
                }
        }
@@ -71,6 +79,38 @@ static int process_client_opt(void)
        return 0;
 
 end:
+       ERR("%s", lttng_get_readable_code(ret));
+       return ret;
+}
+
+/*
+ *  process_opt_list_sessions
+ *
+ *  Get the list of available sessions from
+ *  the session daemon and print it to user.
+ */
+static int process_opt_list_sessions(void)
+{
+       int ret, count, i;
+       struct lttng_session *sess;
+
+       count = lttng_list_sessions(&sess);
+       if (count < 0) {
+               ret = count;
+               goto error;
+       }
+
+       MSG("Available sessions [Name (uuid)]:");
+       for (i = 0; i < count; i++) {
+               MSG("\tName: %s (uuid: %s)", sess[i].name, sess[i].uuid);
+       }
+
+       free(sess);
+       MSG("\nTo select a session, use --session UUID.");
+
+       return 0;
+
+error:
        return ret;
 }
 
@@ -114,25 +154,148 @@ error:
        return ret;
 }
 
+/*
+ *  spawn_sessiond
+ *
+ *  Spawn a session daemon by forking and execv.
+ */
+static int spawn_sessiond(char *pathname)
+{
+       int ret = 0;
+       pid_t pid;
+
+       MSG("Spawning session daemon");
+       pid = fork();
+       if (pid == 0) {
+               /* Spawn session daemon and tell
+                * it to signal us when ready.
+                */
+               ret = execlp(pathname, "ltt-sessiond", "--sig-parent", NULL);
+               if (ret < 0) {
+                       if (errno == ENOENT) {
+                               ERR("No session daemon found. Use --sessiond-path.");
+                       } else {
+                               perror("execlp");
+                       }
+                       kill(getppid(), SIGTERM);
+                       exit(EXIT_FAILURE);
+               }
+               exit(EXIT_SUCCESS);
+       } else if (pid > 0) {
+               /* Wait for ltt-sessiond to start */
+               pause();
+               goto end;
+       } else {
+               perror("fork");
+               ret = -1;
+               goto end;
+       }
+
+end:
+       return ret;
+}
+
 /*
  *  check_ltt_sessiond
  *
  *  Check if the session daemon is available using
- *  the liblttngctl API for the check.
+ *  the liblttngctl API for the check. If not, try to
+ *  spawn a daemon.
  */
 static int check_ltt_sessiond(void)
 {
        int ret;
+       char *pathname = NULL;
 
        ret = lttng_check_session_daemon();
        if (ret < 0) {
-               ERR("No session daemon found. Aborting.");
+               /* Try command line option path */
+               if (opt_sessiond_path != NULL) {
+                       ret = access(opt_sessiond_path, F_OK | X_OK);
+                       if (ret < 0) {
+                               ERR("No such file: %s", opt_sessiond_path);
+                               goto end;
+                       }
+                       pathname = opt_sessiond_path;
+               } else {
+                       /* Try LTTNG_SESSIOND_PATH env variable */
+                       pathname = strdup(getenv(LTTNG_SESSIOND_PATH_ENV));
+               }
+
+               /* Let's rock and roll */
+               if (pathname == NULL) {
+                       ret = asprintf(&pathname, "ltt-sessiond");
+                       if (ret < 0) {
+                               goto end;
+                       }
+               }
+
+               ret = spawn_sessiond(pathname);
+               free(pathname);
+               if (ret < 0) {
+                       ERR("Problem occurs when starting %s", pathname);
+                       goto end;
+               }
+       }
+
+end:
+       return ret;
+}
+
+/*
+ *  set_signal_handler
+ *
+ *  Setup signal handler for SIGCHLD and SIGTERM.
+ */
+static int set_signal_handler(void)
+{
+       int ret = 0;
+       struct sigaction sa;
+       sigset_t sigset;
+
+       if ((ret = sigemptyset(&sigset)) < 0) {
+               perror("sigemptyset");
+               goto end;
        }
 
+       sa.sa_handler = sighandler;
+       sa.sa_mask = sigset;
+       sa.sa_flags = 0;
+       if ((ret = sigaction(SIGCHLD, &sa, NULL)) < 0) {
+               perror("sigaction");
+               goto end;
+       }
+
+       if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
+               perror("sigaction");
+               goto end;
+       }
+
+end:
        return ret;
 }
 
+/*
+ *  sighandler
+ *
+ *  Signal handler for the daemon
+ */
+static void sighandler(int sig)
+{
+       DBG("%d received", sig);
+       switch (sig) {
+               case SIGTERM:
+                       clean_exit(EXIT_FAILURE);
+                       break;
+               case SIGCHLD:
+                       /* Notify is done */
+                       break;
+               default:
+                       break;
+       }
 
+       return;
+}
 /*
  * clean_exit
  */
@@ -143,7 +306,7 @@ void clean_exit(int code)
 }
 
 /*
- * main
+ *  main
  */
 int main(int argc, char *argv[])
 {
@@ -161,6 +324,11 @@ int main(int argc, char *argv[])
                return EXIT_FAILURE;
        }
 
+       ret = set_signal_handler();
+       if (ret < 0) {
+               return ret;
+       }
+
        if (opt_tracing_group != NULL) {
                DBG("Set tracing group to '%s'", opt_tracing_group);
                lttng_set_tracing_group(opt_tracing_group);
@@ -178,7 +346,7 @@ int main(int argc, char *argv[])
        /* Check if the lttng session daemon is running.
         * If no, a daemon will be spawned.
         */
-       if (check_ltt_sessiond() < 0) {
+       if (opt_no_sessiond == 0 && (check_ltt_sessiond() < 0)) {
                return EXIT_FAILURE;
        }