Clearer error reporting when failing to launch session daemon

[lttng-tools.git] / src / bin / lttng / commands / create.c

diff --git a/src/bin/lttng/commands/create.c b/src/bin/lttng/commands/create.c
index 94c1c61836f5edd61dc5c4b8784d346875d0284b..19c560272bf3c35740adce8e05c5ddcf86c3a6f0 100644 (file)
--- a/src/bin/lttng/commands/create.c
+++ b/src/bin/lttng/commands/create.c
@@ -28,6 +28,7 @@
 #include <time.h>
 #include <unistd.h>
 #include <signal.h>
+#include <sys/wait.h>
 
 #include <common/mi-lttng.h>
 
@@ -562,14 +563,13 @@ static int spawn_sessiond(char *pathname)
        pid_t pid;
 
        MSG("Spawning a session daemon");
-       recv_child_signal = 0;
        pid = fork();
        if (pid == 0) {
                /*
-                * Spawn session daemon and tell
-                * it to signal us when ready.
+                * Spawn session daemon in daemon mode.
                 */
-               execlp(pathname, "lttng-sessiond", "--sig-parent", "--quiet", NULL);
+               execlp(pathname, "lttng-sessiond",
+                               "--daemonize", NULL);
                /* execlp only returns if error happened */
                if (errno == ENOENT) {
                        ERR("No session daemon found. Use --sessiond-path.");
@@ -579,25 +579,34 @@ static int spawn_sessiond(char *pathname)
                kill(getppid(), SIGTERM);       /* wake parent */
                exit(EXIT_FAILURE);
        } else if (pid > 0) {
-               sessiond_pid = pid;
-               /*
-                * Wait for lttng-sessiond to start. We need to use a flag to check if
-                * the signal has been sent to us, because the child can be scheduled
-                * before the parent, and thus send the signal before this check. In
-                * the signal handler, we set the recv_child_signal flag, so anytime we
-                * check it after the fork is fine. Note that sleep() is interrupted
-                * before the 1 second delay as soon as the signal is received, so it
-                * will not cause visible delay for the user.
-                */
-               while (!recv_child_signal) {
-                       sleep(1);
-               }
+               int status;
+
                /*
-                * The signal handler will nullify sessiond_pid on SIGCHLD
+                * In daemon mode (--daemonize), sessiond only exits when
+                * it's ready to accept commands.
                 */
-               if (!sessiond_pid) {
-                       exit(EXIT_FAILURE);
+               for (;;) {
+                       waitpid(pid, &status, 0);
+
+                       if (WIFSIGNALED(status)) {
+                               ERR("Session daemon was killed by signal %d",
+                                               WTERMSIG(status));
+                               ret = -1;
+                               goto end;
+                       } else if (WIFEXITED(status)) {
+                               DBG("Session daemon terminated normally (exit status: %d)",
+                                               WEXITSTATUS(status));
+
+                               if (WEXITSTATUS(status) != 0) {
+                                       ERR("Session daemon terminated with an error (exit status: %d)",
+                                                       WEXITSTATUS(status));
+                                       ret = -1;
+                                       goto end;
+                               }
+                               break;
+                       }
                }
+
                goto end;
        } else {
                PERROR("fork");
@@ -658,10 +667,11 @@ static int launch_sessiond(void)
        }
 
        ret = spawn_sessiond(pathname);
-       if (ret < 0) {
-               ERR("Problem occurred when starting %s", pathname);
-       }
 end:
+       if (ret) {
+               ERR("Problem occurred while launching session daemon (%s)",
+                               pathname);
+       }
        return ret;
 }