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Raise BadPythonDllException instead of confusing TypeLoadException when PythonDLL was not configured properly #1577

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Merged
merged 1 commit into from
Sep 29, 2021
Merged

Raise BadPythonDllException instead of confusing TypeLoadException when PythonDLL was not configured properly #1577

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9 changes: 5 additions & 4 deletions README.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -45,10 +45,11 @@ module:
Embedding Python in .NET
------------------------

- You must set `Runtime.PythonDLL` property or `PYTHONNET_PYDLL` environment variable
starting with version 3.0, otherwise you will receive `TypeInitializationException`.
Typical values are `python38.dll` (Windows), `libpython3.8.dylib` (Mac),
`libpython3.8.so` (most other *nix).
- You must set ``Runtime.PythonDLL`` property or ``PYTHONNET_PYDLL`` environment variable
starting with version 3.0, otherwise you will receive ``BadPythonDllException``
(internal, derived from ``MissingMethodException``) upon calling ``Initialize``.
Typical values are ``python38.dll`` (Windows), ``libpython3.8.dylib`` (Mac),
``libpython3.8.so`` (most other *nix).
- All calls to python should be inside a
``using (Py.GIL()) {/* Your code here */}`` block.
- Import python modules using ``dynamic mod = Py.Import("mod")``, then
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2 changes: 1 addition & 1 deletion src/embed_tests/TestPythonEngineProperties.cs
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Expand Up @@ -81,7 +81,7 @@ public static void GetPythonPathDefault()
public static void GetProgramNameDefault()
{
PythonEngine.Initialize();
string s = PythonEngine.PythonHome;
string s = PythonEngine.ProgramName;

Assert.NotNull(s);
PythonEngine.Shutdown();
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4 changes: 2 additions & 2 deletions src/runtime/platform/LibraryLoader.cs
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Expand Up @@ -111,7 +111,7 @@ public IntPtr Load(string dllToLoad)
{
var res = WindowsLoader.LoadLibrary(dllToLoad);
if (res == IntPtr.Zero)
throw new DllNotFoundException($"Could not load {dllToLoad}", new Win32Exception());
throw new DllNotFoundException($"Could not load {dllToLoad}.", new Win32Exception());
return res;
}

Expand All @@ -128,7 +128,7 @@ public IntPtr GetFunction(IntPtr hModule, string procedureName)

var res = WindowsLoader.GetProcAddress(hModule, procedureName);
if (res == IntPtr.Zero)
throw new MissingMethodException($"Failed to load symbol {procedureName}", new Win32Exception());
throw new MissingMethodException($"Failed to load symbol {procedureName}.", new Win32Exception());
return res;
}

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18 changes: 12 additions & 6 deletions src/runtime/pythonengine.cs
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Expand Up @@ -86,13 +86,15 @@ public static string ProgramName
{
get
{
IntPtr p = Runtime.Py_GetProgramName();
IntPtr p = Runtime.TryUsingDll(() => Runtime.Py_GetProgramName());
return UcsMarshaler.PtrToPy3UnicodePy2String(p) ?? "";
}
set
{
Marshal.FreeHGlobal(_programName);
_programName = UcsMarshaler.Py3UnicodePy2StringtoPtr(value);
_programName = Runtime.TryUsingDll(
() => UcsMarshaler.Py3UnicodePy2StringtoPtr(value)
);
Runtime.Py_SetProgramName(_programName);
}
}
Expand All @@ -101,14 +103,16 @@ public static string PythonHome
{
get
{
IntPtr p = Runtime.Py_GetPythonHome();
IntPtr p = Runtime.TryUsingDll(() => Runtime.Py_GetPythonHome());
return UcsMarshaler.PtrToPy3UnicodePy2String(p) ?? "";
}
set
{
// this value is null in the beginning
Marshal.FreeHGlobal(_pythonHome);
_pythonHome = UcsMarshaler.Py3UnicodePy2StringtoPtr(value);
_pythonHome = Runtime.TryUsingDll(
() => UcsMarshaler.Py3UnicodePy2StringtoPtr(value)
);
Runtime.Py_SetPythonHome(_pythonHome);
}
}
Expand All @@ -117,13 +121,15 @@ public static string PythonPath
{
get
{
IntPtr p = Runtime.Py_GetPath();
IntPtr p = Runtime.TryUsingDll(() => Runtime.Py_GetPath());
return UcsMarshaler.PtrToPy3UnicodePy2String(p) ?? "";
}
set
{
Marshal.FreeHGlobal(_pythonPath);
_pythonPath = UcsMarshaler.Py3UnicodePy2StringtoPtr(value);
_pythonPath = Runtime.TryUsingDll(
() => UcsMarshaler.Py3UnicodePy2StringtoPtr(value)
);
Runtime.Py_SetPath(_pythonPath);
}
}
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48 changes: 40 additions & 8 deletions src/runtime/runtime.cs
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Expand Up @@ -93,7 +93,6 @@ internal static Version PyVersion
}
}


/// <summary>
/// Initialize the runtime...
/// </summary>
Expand All @@ -113,7 +112,10 @@ internal static void Initialize(bool initSigs = false, ShutdownMode mode = Shutd
}
ShutdownMode = mode;

if (Py_IsInitialized() == 0)
bool interpreterAlreadyInitialized = TryUsingDll(
() => Py_IsInitialized() != 0
);
if (!interpreterAlreadyInitialized)
{
Py_InitializeEx(initSigs ? 1 : 0);
if (PyEval_ThreadsInitialized() == 0)
Expand Down Expand Up @@ -787,6 +789,34 @@ internal static unsafe long Refcount(IntPtr op)
return *p;
}

/// <summary>
/// Call specified function, and handle PythonDLL-related failures.
/// </summary>
internal static T TryUsingDll<T>(Func<T> op)
{
try
{
return op();
}
catch (TypeInitializationException loadFailure)
{
var delegatesLoadFailure = loadFailure;
// failure to load Delegates type might have been the cause
// of failure to load some higher-level type
while (delegatesLoadFailure.InnerException is TypeInitializationException nested)
{
delegatesLoadFailure = nested;
}

if (delegatesLoadFailure.InnerException is BadPythonDllException badDll)
{
throw badDll;
}

throw;
}
}

/// <summary>
/// Export of Macro Py_XIncRef. Use XIncref instead.
/// Limit this function usage for Testing and Py_Debug builds
Expand Down Expand Up @@ -2270,10 +2300,6 @@ internal static void SetNoSiteFlag()
if (_PythonDll != "__Internal")
{
dllLocal = loader.Load(_PythonDll);
if (dllLocal == IntPtr.Zero)
{
throw new Exception($"Cannot load {_PythonDll}");
}
}
try
{
Expand Down Expand Up @@ -2617,8 +2643,8 @@ static Delegates()
}
catch (MissingMethodException e) when (libraryHandle == IntPtr.Zero)
{
throw new MissingMethodException(
"Did you forget to set Runtime.PythonDLL?" +
throw new BadPythonDllException(
"Runtime.PythonDLL was not set or does not point to a supported Python runtime DLL." +
" See https://github.com/pythonnet/pythonnet#embedding-python-in-net",
e);
}
Expand Down Expand Up @@ -2889,6 +2915,12 @@ static Delegates()
}
}

internal class BadPythonDllException : MissingMethodException
{
public BadPythonDllException(string message, Exception innerException)
: base(message, innerException) { }
}


public enum ShutdownMode
{
Expand Down