illumos gate

Libtopo implements an interface, topo_sensor_state_name(), which takes a sensor state value and returns a string containing a descriptive representation of the sensor state.

The primary consumers of this interface are fmtopo and hwgrok, both of which use it to provide a more human-readable representation of the sensor state.

There are two issues with how it's currently implemented:

1) It makes the assumption that only one discrete state will be asserted at any time. This is true for some sensors, but not all sensors.

2) Because it's working with a raw state value from IPMI, where certain reserved bits haven't been masked off, there no way for it to return a string to indicate the situation where no state are asserted (which is the normal state for many sensors). The facility/state property method should be masking off reserved bits - such that when no states are asserted, the state value is 0.