Don't enable the device if the reachable count is zero.

A logic bug was introduced in bd451cfe1512fa69eac35a60dbe6df17bfc39154
in which running graph() several times with zero reachable nodes had
the effect of calling device_enable() (instead of keeping the device
disabled).

This results in weird behavior when DeviceStandby is enabled, especially
on Windows where calling device_enable() several times in a row corrupts
I/O structures for the device, rendering it unusable.

diff --git a/src/graph.c b/src/graph.c
index 8f601c2..690f4bd 100644 (file)
--- a/src/graph.c
+++ b/src/graph.c
@@ -292,7 +292,7 @@ static void check_reachability(void) {
        if (device_standby) {
                if (reachable_count == 0 && became_unreachable_count > 0)
                        device_disable();
-               else if (reachable_count == became_reachable_count)
+               else if (reachable_count > 0 && reachable_count == became_reachable_count)
                        device_enable();
        }
 }