Fix: set session in output mode if URL are set afterwards

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

diff --git a/src/bin/lttng-sessiond/cmd.c b/src/bin/lttng-sessiond/cmd.c
index 2a61eee064f5af2fa558e73db87f2057fd8eb120..c1f5a4e70b7ce83545ce0858db2f781b563fdc26 100644 (file)
--- a/src/bin/lttng-sessiond/cmd.c
+++ b/src/bin/lttng-sessiond/cmd.c
@@ -850,6 +850,16 @@ int cmd_enable_channel(struct ltt_session *session,
 
        rcu_read_lock();
 
+       /*
+        * The ringbuffer (both in user space and kernel) behave badly in overwrite
+        * mode and with less than 2 subbuf so block it right away and send back an
+        * invalid attribute error.
+        */
+       if (attr->attr.overwrite && attr->attr.num_subbuf < 2) {
+               ret = LTTNG_ERR_INVALID;
+               goto error;
+       }
+
        switch (domain->type) {
        case LTTNG_DOMAIN_KERNEL:
        {
@@ -1769,6 +1779,17 @@ int cmd_set_consumer_uri(int domain, struct ltt_session *session,
                }
        }
 
+       /*
+        * Make sure to set the session in output mode after we set URI since a
+        * session can be created without URL (thus flagged in no output mode).
+        */
+       session->output_traces = 1;
+       if (ksess) {
+               ksess->output_traces = 1;
+       } else if (usess) {
+               usess->output_traces = 1;
+       }
+
        /* All good! */
        ret = LTTNG_OK;
 
@@ -2301,6 +2322,21 @@ int cmd_data_pending(struct ltt_session *session)
        if (session->enabled) {
                ret = LTTNG_ERR_SESSION_STARTED;
                goto error;
+       } else {
+               /*
+                * If stopped, just make sure we've started before else the above call
+                * will always send that there is data pending.
+                *
+                * The consumer assumes that when the data pending command is received,
+                * the trace has been started before or else no output data is written
+                * by the streams which is a condition for data pending. So, this is
+                * *VERY* important that we don't ask the consumer before a start
+                * trace.
+                */
+               if (!session->started) {
+                       ret = 0;
+                       goto error;
+               }
        }
 
        if (ksess && ksess->consumer) {