alsamixer: fix division by zero

The attempt to divide by max-min fails if a control has only one valid
value.  In this case, adjust the maximum so that the computation can
succeed; the control will look like 0%.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/alsamixer/mixer_display.c b/alsamixer/mixer_display.c
index 9eadcc9..260c9b0 100644
--- a/alsamixer/mixer_display.c
+++ b/alsamixer/mixer_display.c
@@ -462,6 +462,8 @@ static void display_control(unsigned int control_index)
 			err = snd_mixer_selem_get_capture_volume_range(control->elem, &min, &max);
 		if (err < 0)
 			return;
+		if (min == max)
+			max = min + 1;
 
 		if (control->flags & IS_ACTIVE)
 			wattrset(mixer_widget.window, 0);