Don't start session with 0-channel devices.

Drivers aren't really able to deal with that in some cases, and it
denotes a frontend bug.

diff --git a/src/session.c b/src/session.c
index b84a41a5c2cf73f79a191c99ac613ef02ebe51cb..dc8fd4fbeaffc2ce3c78cdeabcd5156f30c44363 100644 (file)
--- a/src/session.c
+++ b/src/session.c
@@ -434,8 +434,9 @@ static int verify_trigger(struct sr_trigger *trigger)
 SR_API int sr_session_start(struct sr_session *session)
 {
        struct sr_dev_inst *sdi;
-       GSList *l;
-       int ret;
+       struct sr_channel *ch;
+       GSList *l, *c;
+       int enabled_channels, ret;
 
        if (!session) {
                sr_err("%s: session was NULL", __func__);
@@ -456,6 +457,21 @@ SR_API int sr_session_start(struct sr_session *session)
        ret = SR_OK;
        for (l = session->devs; l; l = l->next) {
                sdi = l->data;
+               enabled_channels = 0;
+               for (c = sdi->channels; c; c = c->next) {
+                       ch = c->data;
+                       if (ch->enabled) {
+                               enabled_channels++;
+                               break;
+                       }
+               }
+               if (enabled_channels == 0) {
+                       ret = SR_ERR;
+                       sr_err("%s instance %d has no enabled channels!",
+                                       sdi->driver->name, sdi->index);
+                       break;
+               }
+
                if ((ret = sr_config_commit(sdi)) != SR_OK) {
                        sr_err("Failed to commit device settings before "
                               "starting acquisition (%s)", sr_strerror(ret));