unify string buffer handling

src/pycanape/__init__.py

@@ -25,6 +25,7 @@
     "CANapeDll",
     "CANapeVersion",
     "CurveCalibrationObject",
+    "DllVersion",
     "MapCalibrationObject",
     "ScalarCalibrationObject",
     "ValueBlockCalibrationObject",
@@ -69,7 +70,7 @@
     ScalarCalibrationObject,
     ValueBlockCalibrationObject,
 )
-from .canape import AppVersion, CANape
+from .canape import AppVersion, CANape, DllVersion
 from .cnp_api.cnp_constants import (
     Channels,
     DriverType,

src/pycanape/canape.py

@@ -177,14 +177,19 @@ def get_dll_version(self) -> DllVersion:
 
     def get_project_directory(self) -> str:
         """Get the current project Directory."""
-        c_buffer = ctypes.create_string_buffer(1024)
-        c_length = ctypes.c_ulong(1024)
+        length = ctypes.c_ulong()
         self._dll.Asap3GetProjectDirectory(
             self.asap3_handle,
-            ctypes.cast(c_buffer, ctypes.c_char_p),
-            ctypes.byref(c_length),
+            None,
+            ctypes.byref(length),
         )
-        return c_buffer.value.decode(RC["ENCODING"])
+        buffer = ctypes.create_string_buffer(length.value)
+        self._dll.Asap3GetProjectDirectory(
+            self.asap3_handle,
+            buffer,
+            ctypes.byref(length),
+        )
+        return buffer.value.decode(RC["ENCODING"])
 
     def create_module(
         self,
@@ -459,28 +464,18 @@ def get_cna_filename(self) -> str:
         :return:
             Path to .cna file
         """
-        # call function first time to determine max_size
-        size = ctypes.c_ulong(0)
-        try:
-            self._dll.Asap3GetCNAFilename(
-                self.asap3_handle,
-                None,
-                ctypes.byref(size),
-            )
-        except CANapeError:
-            if size.value > 0:
-                pass
-            else:
-                raise
-
-        # call function again to retrieve data
-        buffer = ctypes.create_string_buffer(size.value)
+        length = ctypes.c_ulong()
+        self._dll.Asap3GetCNAFilename(
+            self.asap3_handle,
+            None,
+            ctypes.byref(length),
+        )
+        buffer = ctypes.create_string_buffer(length.value)
         self._dll.Asap3GetCNAFilename(
             self.asap3_handle,
             buffer,
-            ctypes.byref(size),
+            ctypes.byref(length),
         )
-
         return buffer.value.decode(RC["ENCODING"])
 
     def load_cna_file(self, cna_file: Union[str, Path]) -> None:

src/pycanape/module.py

@@ -167,31 +167,25 @@ def get_database_objects(self) -> List[str]:
             List of object names
         """
         if self._objects_cache is None:
-            # call function first time to determine max_size
-            max_size = ctypes.c_ulong(0)
+            length = ctypes.c_ulong(0)
             self._dll.Asap3GetDatabaseObjects(
                 self.asap3_handle,
                 self.module_handle,
                 None,
-                ctypes.byref(max_size),
+                ctypes.byref(length),
                 TAsap3DBOType.DBTYPE_ALL,
             )
-
-            # call function again to retrieve data
-            buffer = ctypes.create_string_buffer(max_size.value)
+            buffer = ctypes.create_string_buffer(length.value)
             self._dll.Asap3GetDatabaseObjects(
                 self.asap3_handle,
                 self.module_handle,
                 buffer,
-                ctypes.byref(max_size),
+                ctypes.byref(length),
                 TAsap3DBOType.DBTYPE_ALL,
             )
             self._objects_cache = (
-                buffer.value.strip(b";")[: max_size.value]
-                .decode(RC["ENCODING"])
-                .split(";")
+                buffer.value.strip(b";").decode(RC["ENCODING"]).split(";")
             )
-
         return copy.copy(self._objects_cache)
 
     def get_ecu_tasks(self) -> Dict[str, EcuTask]:
@@ -225,15 +219,21 @@ def get_task_instance(task_info: TTaskInfo2) -> EcuTask:
 
     def get_network_name(self) -> str:
         """Receives the name of the used network."""
-        c_name = ctypes.create_string_buffer(256)
         size = ctypes.c_uint()
         self._dll.Asap3GetNetworkName(
             self.asap3_handle,
             self.module_handle,
-            ctypes.cast(ctypes.byref(c_name), ctypes.c_char_p),
+            None,
+            ctypes.byref(size),
+        )
+        buffer = ctypes.create_string_buffer(size.value)
+        self._dll.Asap3GetNetworkName(
+            self.asap3_handle,
+            self.module_handle,
+            buffer,
             ctypes.byref(size),
         )
-        return c_name.value[: size.value].decode(RC["ENCODING"])
+        return buffer.value.decode(RC["ENCODING"])
 
     def get_ecu_driver_type(self) -> DriverType:
         """Retrieves the drivertype of an ECU.

src/pycanape/recorder.py

@@ -35,15 +35,21 @@ def __init__(
 
     def get_name(self) -> str:
         """Get the name of the recorder."""
-        length = ctypes.c_long(256)
-        c_name = ctypes.create_string_buffer(length.value)
+        length = ctypes.c_long()
         self._dll.Asap3GetRecorderName(
             self._asap3_handle,
             self._recorder_id,
-            ctypes.cast(c_name, ctypes.c_char_p),
+            None,
             ctypes.byref(length),
         )
-        return c_name.value.decode(RC["ENCODING"])
+        buffer = ctypes.create_string_buffer(length.value)
+        self._dll.Asap3GetRecorderName(
+            self._asap3_handle,
+            self._recorder_id,
+            buffer,
+            ctypes.byref(length),
+        )
+        return buffer.value.decode(RC["ENCODING"])
 
     def get_state(self) -> cnp_constants.RecorderState:
         """Return the state of a Recorder"""
@@ -87,15 +93,21 @@ def disable(self) -> None:
 
     def get_mdf_filename(self) -> str:
         """Retrieve the MDF Filename of a Recorder."""
-        length = wintypes.DWORD(1024)
-        c_name = ctypes.create_string_buffer(length.value)
+        length = wintypes.DWORD()
+        self._dll.Asap3GetRecorderMdfFileName(
+            self._asap3_handle,
+            self._recorder_id,
+            None,
+            ctypes.byref(length),
+        )
+        buffer = ctypes.create_string_buffer(length.value)
         self._dll.Asap3GetRecorderMdfFileName(
             self._asap3_handle,
             self._recorder_id,
-            ctypes.cast(ctypes.byref(c_name), ctypes.c_char_p),
+            buffer,
             ctypes.byref(length),
         )
-        return c_name.value.decode(RC["ENCODING"])
+        return buffer.value.decode(RC["ENCODING"])
 
     def set_mdf_filename(self, filename: Union[str, Path]) -> None:
         """Set the MDF Filename for a Recorder.

src/pycanape/script.py

@@ -107,21 +107,18 @@ def get_script_result_string(self) -> str:
         :return:
             result string of the script
         """
-        # call function first time to determine max_size
-        max_size = ctypes.c_ulong(0)
+        length = ctypes.c_ulong()
         self._dll.Asap3GetScriptResultString(
             self.asap3_handle,
             self.script_handle,
             None,
-            ctypes.byref(max_size),
+            ctypes.byref(length),
         )
-
-        # call function again to retrieve data
-        c_buffer = ctypes.create_string_buffer(max_size.value)
+        buffer = ctypes.create_string_buffer(length.value)
         self._dll.Asap3GetScriptResultString(
             self.asap3_handle,
             self.script_handle,
-            c_buffer,
-            ctypes.byref(max_size),
+            buffer,
+            ctypes.byref(length),
         )
-        return c_buffer.value.decode(RC["ENCODING"])
+        return buffer.value.decode(RC["ENCODING"])