Refactor ipmi::sensor::GetSensorResponse away from std::array

This change refactors GetSensorResponse from std::array to struct.
This change depends on change #23544.

GetSensorResponse is an internal, intermediate structure, an unpacked
form of a Get Sensor Reading response, providing direct access to its
fields. Its life time is:
GetReadingResponse -> GetSensorResponse -> ipmi::RspType.

It is written to in 5 functions in the ipmi::sensor::get namespace, by
four setter functions (setOffset, setReading, setAssertionBytes,
enableScanning).
It is currently read from by 1 function (ipmiSensorGetSensorReading)
for transforming to an ipmi::RspType.

Originally, the setter functions assumed bitwise equivalence between
GetSensorResponse and GetReadingResponse, and the setter functions
used reinterpret_cast to assign to a GetSensorResponse as if it were
a GetReadingResponse.

With this change, the reinterpret_cast's are removed, and the set
functions now accept GetSensorResponse instead of GetReadingResponse,
so the code gets a bit easier to read.

Tested: Tested using a server with a BMC; sensor readings obtained
through `ipmitool` appear to be correct (the reading might change
within a small range):
 # ipmitool raw 0x04 0x2d 0x16
   9B 40 00 00

Signed-off-by: Sui Chen <suichen@google.com>
Change-Id: I5d454d6249f5431fb98169e6ef7c585c34024004

1 files changed, 2 insertions, 4 deletions

diff --git a/sensordatahandler.cpp b/sensordatahandler.cpp
index 923b96a..0d1182d 100644
--- a/sensordatahandler.cpp
+++ b/sensordatahandler.cpp
@@ -132,7 +132,6 @@ GetSensorResponse mapDbusToAssertion(const Info& sensorInfo,
 {
     sdbusplus::bus::bus bus{ipmid_get_sd_bus_connection()};
     GetSensorResponse response{};
-    auto responseData = reinterpret_cast<GetReadingResponse*>(response.data());
 
     auto service = ipmi::getService(bus, interface, path);
 
@@ -149,7 +148,7 @@ GetSensorResponse mapDbusToAssertion(const Info& sensorInfo,
             {
                 if (propValue == value.second.assert)
                 {
-                    setOffset(value.first, responseData);
+                    setOffset(value.first, &response);
                     break;
                 }
             }
@@ -169,7 +168,6 @@ GetSensorResponse eventdata2(const Info& sensorInfo)
 {
     sdbusplus::bus::bus bus{ipmid_get_sd_bus_connection()};
     GetSensorResponse response{};
-    auto responseData = reinterpret_cast<GetReadingResponse*>(response.data());
 
     auto service = ipmi::getService(bus, sensorInfo.sensorInterface,
                                     sensorInfo.sensorPath);
@@ -188,7 +186,7 @@ GetSensorResponse eventdata2(const Info& sensorInfo)
             {
                 if (propValue == value.second.assert)
                 {
-                    setReading(value.first, responseData);
+                    setReading(value.first, &response);
                     break;
                 }
             }