Return void* and drop nul internal nul termination

Author: KonradBreitsprecherBkd

SilKit/IntegrationTests/Hourglass/MockCapi.cpp

@@ -769,7 +769,7 @@ extern "C"
         return globalCapi->SilKit_Participant_GetLogger(outLogger, participant);
     }
 
-    SilKit_ReturnCode SilKitCALL SilKit_Participant_GetParameter(char* outParameterValue,
+    SilKit_ReturnCode SilKitCALL SilKit_Participant_GetParameter(void* outParameterValue,
                                                                  size_t* inOutParameterValueSize,
                                                                  SilKit_Parameter parameter,
                                                                  SilKit_Participant* participant)

SilKit/IntegrationTests/Hourglass/MockCapi.hpp

@@ -408,7 +408,7 @@ class MockCapi
                 (SilKit_Logger * *outLogger, SilKit_Participant* participant));
 
     MOCK_METHOD(SilKit_ReturnCode, SilKit_Participant_GetParameter,
-                (char* outParameterValue, size_t* outParameterValueSize, SilKit_Parameter parameter,
+                (void* outParameterValue, size_t* outParameterValueSize, SilKit_Parameter parameter,
                  SilKit_Participant* participant));
 
     // ParticipantConfiguration

SilKit/include/silkit/capi/Participant.h

@@ -76,12 +76,12 @@ typedef SilKit_ReturnCode(SilKitFPTR* SilKit_Participant_GetLogger_t)(SilKit_Log
  * Returns the current value of the given parameter. 
  * Useful for parameters that are passed to the participant via the API and the participant configuration.
  */
-SilKitAPI SilKit_ReturnCode SilKitCALL SilKit_Participant_GetParameter(char* outParameterValue,
+SilKitAPI SilKit_ReturnCode SilKitCALL SilKit_Participant_GetParameter(void* outParameterValue,
                                                                        size_t* inOutParameterValueSize,
                                                                        SilKit_Parameter parameter,
                                                                        SilKit_Participant* participant);
 
-typedef SilKit_ReturnCode(SilKitFPTR* SilKit_Participant_GetParameter_t)(char* outParameterValue,
+typedef SilKit_ReturnCode(SilKitFPTR* SilKit_Participant_GetParameter_t)(void* outParameterValue,
                                                                          size_t* inOutParameterValueSize,
                                                                          SilKit_Parameter parameter,
                                                                          SilKit_Participant* participant);

SilKit/include/silkit/detail/impl/participant/ParameterProvider.hpp

@@ -46,17 +46,23 @@ auto ParameterProvider::GetParameter(SilKit_Participant* participant, Parameter
     std::vector<char> buffer;
     size_t size = 0;
     SilKit_Parameter cParameter = static_cast<SilKit_Parameter>(parameter);
+
+    // Query the size by passing nullptr for the outParameterValue
     {
         const auto returnCode = SilKit_Participant_GetParameter(nullptr, &size, cParameter, participant);
         ThrowOnError(returnCode);
     }
+
+    // Loop as the size might changed intermediately
     while (size > buffer.size())
     {
         buffer.resize(size);
         const auto returnCode = SilKit_Participant_GetParameter(buffer.data(), &size, cParameter, participant);
         ThrowOnError(returnCode);
     }
-    buffer.resize(size);
+
+    // Value-initialized to nul
+    buffer.resize(size + 1); 
 
     return std::string{buffer.data()};
 }

SilKit/source/capi/CapiParticipant.cpp

@@ -86,7 +86,7 @@ try
 }
 CAPI_CATCH_EXCEPTIONS
 
-SilKit_ReturnCode SilKitCALL SilKit_Participant_GetParameter(char* outParameterValue, size_t* inOutParameterValueSize,
+SilKit_ReturnCode SilKitCALL SilKit_Participant_GetParameter(void* outParameterValue, size_t* inOutParameterValueSize,
                                                              SilKit_Parameter parameter,
                                                              SilKit_Participant* participant)
 try
@@ -102,20 +102,19 @@ try
     if (outParameterValue != nullptr)
     {
         size_t sizeToCopy;
-        if (*inOutParameterValueSize >= parameterValue.size() + 1)
+        if (*inOutParameterValueSize > parameterValue.size())
         {
             // Don't copy more than we actually have
             sizeToCopy = parameterValue.size();
         }
         else
         {
             // Don't copy more than the given size
-            sizeToCopy = *inOutParameterValueSize - 1;
+            sizeToCopy = *inOutParameterValueSize;
         }
-        parameterValue.copy(outParameterValue, sizeToCopy);
-        outParameterValue[sizeToCopy] = '\0';
+        parameterValue.copy(static_cast<char*>(outParameterValue), sizeToCopy);
     }
-    *inOutParameterValueSize = parameterValue.size() + 1;
+    *inOutParameterValueSize = parameterValue.size();
     return SilKit_ReturnCode_SUCCESS;
 }
 CAPI_CATCH_EXCEPTIONS

SilKit/source/capi/Test_CapiGetParameter.cpp

@@ -1,6 +1,7 @@
 // SPDX-FileCopyrightText: 2024 Vector Informatik GmbH
 //
 // SPDX-License-Identifier: MIT
+
 #include "gtest/gtest.h"
 #include "gmock/gmock.h"
 #include "silkit/capi/SilKit.h"
@@ -31,8 +32,10 @@ TEST_F(Test_CapiGetParameter, getparameter_bad_params)
     char* parameterValue{nullptr};
     size_t parameterSize;
 
-    returnCode =
-        SilKit_Participant_GetParameter(nullptr, &parameterSize, SilKit_Parameter_ParticipantName, cMockParticipant);
+    EXPECT_CALL(mockParticipant, GetParameter(SilKit::Parameter::ParticipantName)).Times(testing::Exactly(1));
+
+    returnCode = SilKit_Participant_GetParameter(nullptr, &parameterSize, SilKit_Parameter_ParticipantName,
+                                                    cMockParticipant);
     EXPECT_EQ(returnCode, SilKit_ReturnCode_SUCCESS);
 
     returnCode =