tinymix: Say if we can't open the mixer

Otherwise we just list a device with zero controls which isn't the most
obvious failure mode.

1 files changed, 4 insertions, 0 deletions

diff --git a/tinymix.c b/tinymix.c
index 7f593b3..3fc2e41 100644
--- a/tinymix.c
+++ b/tinymix.c
@@ -41,6 +41,10 @@ int main(int argc, char **argv)
     struct mixer *mixer;
 
     mixer = mixer_open(0);
+    if (!mixer) {
+        fprintf(stderr, "Failed to open mixer\n");
+        return EXIT_FAILURE;
+    }
 
     if (argc == 1)
         tinymix_list_controls(mixer);