Add API endpoint for accecssing the specified IDF path

src/EnergyPlus/api/datatransfer.cc

@@ -56,6 +56,7 @@
 #include <EnergyPlus/DataGlobalConstants.hh>
 #include <EnergyPlus/DataHVACGlobals.hh>
 #include <EnergyPlus/DataRuntimeLanguage.hh>
+#include <EnergyPlus/DataStringGlobals.hh>
 #include <EnergyPlus/HeatBalFiniteDiffManager.hh>
 #include <EnergyPlus/InputProcessing/InputProcessor.hh>
 #include <EnergyPlus/OutputProcessor.hh>
@@ -239,6 +240,14 @@ void resetErrorFlag(EnergyPlusState state)
     thisState->dataPluginManager->apiErrorFlag = false;
 }
 
+char *inputFilePath(EnergyPlusState state)
+{
+    const auto *thisState = static_cast<EnergyPlus::EnergyPlusData *>(state);
+    char *p = new char[std::strlen(thisState->dataStrGlobals->inputFilePath.c_str()) + 1];
+    std::strcpy(p, thisState->dataStrGlobals->inputFilePath.c_str());
+    return p;
+}
+
 char **getObjectNames(EnergyPlusState state, const char *objectType, unsigned int *resultingSize)
 {
     const auto *thisState = static_cast<EnergyPlus::EnergyPlusData *>(state);

src/EnergyPlus/api/datatransfer.h

@@ -121,6 +121,12 @@ ENERGYPLUSLIB_API int apiErrorFlag(EnergyPlusState state);
 ///          a calculation to continue, this function can reset the flag.
 /// \param[in] state An active EnergyPlusState instance created with `stateNew`.
 ENERGYPLUSLIB_API void resetErrorFlag(EnergyPlusState state);
+/// \brief Provides the input file path back to the user
+/// \details In most circumstances the client will know the path to the input file, but there are some cases where code
+///          is generalized in unexpected workflows.  Users have requested a way to get the input file path back from the running instance.
+/// \param[in] state An active EnergyPlusState instance created with `stateNew`.
+/// \return A char * of the input file path.  This allocates a new char *, and calling clients must free this when done with it!
+ENERGYPLUSLIB_API char *inputFilePath(EnergyPlusState state);
 
 // ----- DATA TRANSFER HELPER FUNCTIONS
 

src/EnergyPlus/api/datatransfer.py

@@ -139,6 +139,8 @@ def __init__(self, api: cdll, running_as_python_plugin: bool = False):
         self.api.apiErrorFlag.restype = c_int
         self.api.resetErrorFlag.argtypes = [c_void_p]
         self.api.resetErrorFlag.restype = c_void_p
+        self.api.inputFilePath.argtypes = [c_void_p]
+        self.api.inputFilePath.restype = c_char_p
         self.api.requestVariable.argtypes = [c_void_p, c_char_p, c_char_p]
         self.api.getNumNodesInCondFDSurfaceLayer.argtypes = [c_void_p, c_char_p, c_char_p]
         self.api.requestVariable.restype = c_void_p
@@ -359,6 +361,17 @@ def reset_api_error_flag(self, state: c_void_p) -> None:
         """
         self.api.resetErrorFlag(state)
 
+    def get_input_file_path(self, state: c_void_p) -> bytes:
+        """
+        Provides the input file path back to the client. In most circumstances the client will know the path to the
+        input file, but there are some cases where code is generalized in unexpected workflows.  Users have requested
+        a way to get the input file path back from the running instance.
+
+        :param state: An active EnergyPlus "state" that is returned from a call to `api.state_manager.new_state()`.
+        :return: Returns a raw bytes representation of the input file path
+        """
+        return self.api.inputFilePath(state)
+
     def get_object_names(self, state: c_void_p, object_type_name: Union[str, bytes]) -> List[str]:
         """
         Gets the instance names for a given object type in the current input file

tst/EnergyPlus/api/TestDataTransfer.c

@@ -95,7 +95,7 @@ void afterZoneTimeStepHandler(EnergyPlusState state)
         freeAPIData(data, arraySize);
         freeObjectNames(surfaceNames, arraySize);
 
-        printf("Got handles %d, %d, %d, %d, %d, %d",
+        printf("Got handles %d, %d, %d, %d, %d, %d\n",
                outdoorDewPointActuator,
                outdoorTempSensor,
                outdoorDewPointSensor,
@@ -106,6 +106,11 @@ void afterZoneTimeStepHandler(EnergyPlusState state)
             wallConstruction == -1 || floorConstruction == -1) {
             exit(1);
         }
+
+        char * filePath = inputFilePath(state);
+        printf("Input file path accessed via API: %s\n", filePath);
+        free(filePath);
+
         handlesRetrieved = 1;
     }
     setActuatorValue(state, outdoorDewPointActuator, -25.0);