Add ust start trace feature

[lttng-tools.git] / ltt-sessiond / main.c

diff --git a/ltt-sessiond/main.c b/ltt-sessiond/main.c
index 56266db3ce429bb6074bf34af85391ce6e7b865e..720d23439c99b855546617f503ad2fc609373b46 100644 (file)
--- a/ltt-sessiond/main.c
+++ b/ltt-sessiond/main.c
@@ -322,6 +322,42 @@ error:
        return ret;
 }
 
+/*
+ *  ust_start_trace
+ *
+ *  Start a trace. This trace, identified by the pid, must be
+ *  in the current session ust_traces list.
+ */
+static int ust_start_trace(pid_t pid)
+{
+       int sock, ret;
+       struct ltt_ust_trace *trace;
+
+       DBG("Starting trace for pid %d", pid);
+
+       trace = find_session_ust_trace_by_pid(current_session, pid);
+       if (trace == NULL) {
+               ret = LTTCOMM_NO_TRACE;
+               goto error;
+       }
+
+       /* Connect to app using ustctl API */
+       sock = connect_app(pid);
+       if (sock < 0) {
+               ret = LTTCOMM_NO_TRACEABLE;
+               goto error;
+       }
+
+       ret = ustctl_start_trace(sock, "auto");
+       if (ret < 0) {
+               ret = LTTCOMM_START_FAIL;
+               goto error;
+       }
+
+error:
+       return ret;
+}
+
 /*
  *  copy_common_data
  *
@@ -453,7 +489,10 @@ static int process_client_msg(int sock, struct lttcomm_session_msg *lsm)
                {
                        ret = ust_create_trace(lsm->pid);
                        if (ret < 0) {
-                               ret = LTTCOMM_CREATE_FAIL;
+                               /* If -1 is returned from ust_create_trace, malloc
+                                * failed so it's pretty much a fatal error.
+                                */
+                               ret = LTTCOMM_FATAL;
                                goto end;
                        }
 
@@ -481,6 +520,13 @@ static int process_client_msg(int sock, struct lttcomm_session_msg *lsm)
 
                        break;
                }
+               case UST_START_TRACE:
+               {
+                       ret = ust_start_trace(lsm->pid);
+
+                       /* No auxiliary data so only send the llm struct. */
+                       goto end;
+               }
                case LTTNG_LIST_SESSIONS:
                {
                        unsigned int session_count = get_session_count();