Skip updating value for faulted sensors

When a sensor is marked as faulted, the input value is skipped from
being read and updated in the sensor's dbus object during the monitoring
loop. This keeps the sensor's value set to its previously known state.

The hwmon documentation states that when a sensor input channel presents
an associated fault file, the measurement value provided for that
channel should not be trusted when the fault boolean has a value of
1. Not updating the sensor value follows this specification.

Tested:
    A non-functional sensor's input value is not read
    A non-functional sensor's value state in dbus object is not updated
    Any functional sensor's input value is read during monitoring
    Any functional sensor's value state is updated during monitoring
    All sensors without a fault sysfs file are read/updated normally

Change-Id: Iccf3e4e44125d6e481ce91c8f63e8f0e4ee3df4b
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>

1 files changed, 14 insertions, 3 deletions

diff --git a/mainloop.cpp b/mainloop.cpp
index ad73df7..9944e09 100644
--- a/mainloop.cpp
+++ b/mainloop.cpp
@@ -526,6 +526,20 @@ void MainLoop::read()
 
             try
             {
+                auto& objInfo = std::get<ObjectInfo>(i.second);
+                auto& obj = std::get<Object>(objInfo);
+
+                auto it = obj.find(InterfaceType::STATUS);
+                if (it != obj.end())
+                {
+                    auto statusIface = std::experimental::any_cast<
+                            std::shared_ptr<StatusObject>>(it->second);
+                    if (!statusIface->functional())
+                    {
+                        continue;
+                    }
+                }
+
                 // Retry for up to a second if device is busy
                 // or has a transient error.
 
@@ -539,9 +553,6 @@ void MainLoop::read()
 
                 value = adjustValue(i.first, value);
 
-                auto& objInfo = std::get<ObjectInfo>(i.second);
-                auto& obj = std::get<Object>(objInfo);
-
                 for (auto& iface : obj)
                 {
                     auto valueIface = std::shared_ptr<ValueObject>();