Fix: report to client when snapshot will be empty

[lttng-tools.git] / src / bin / lttng-sessiond / ust-app.c

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 315e503edec59673217e97cbf2ef911797f5dcaa..1451963ad41f14cb1809e37594a3960238112819 100644 (file)
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -4992,6 +4992,7 @@ int ust_app_snapshot_record(struct ltt_ust_session *usess,
                struct snapshot_output *output, int wait, unsigned int nb_streams)
 {
        int ret = 0;
+       unsigned int snapshot_done = 0;
        struct lttng_ht_iter iter;
        struct ust_app *app;
        char pathname[PATH_MAX];
@@ -5066,6 +5067,7 @@ int ust_app_snapshot_record(struct ltt_ust_session *usess,
                        if (ret < 0) {
                                goto error;
                        }
+                       snapshot_done = 1;
                }
                break;
        }
@@ -5133,6 +5135,7 @@ int ust_app_snapshot_record(struct ltt_ust_session *usess,
                        if (ret < 0) {
                                goto error;
                        }
+                       snapshot_done = 1;
                }
                break;
        }
@@ -5141,6 +5144,15 @@ int ust_app_snapshot_record(struct ltt_ust_session *usess,
                break;
        }
 
+       if (!snapshot_done) {
+               /*
+                * If no snapshot was made and we are not in the error path, this means
+                * that there are no buffers thus no (prior) application to snapshot
+                * data from so we have simply NO data.
+                */
+               ret = -ENODATA;
+       }
+
 error:
        rcu_read_unlock();
        return ret;