[Lldb-commits] [lldb] [lldb][windows] print an error if python.dll is not in the DLL search path (PR #164893)

[Charles Zablit via lldb-commits]

================
@@ -447,30 +448,65 @@ inline std::wstring GetPathToExecutableW() {
   return L"";
 }
 
-/// Resolve the full path of the directory defined by
+/// \brief Resolve the full path of the directory defined by
 /// LLDB_PYTHON_DLL_RELATIVE_PATH. If it exists, add it to the list of DLL
 /// search directories.
-void AddPythonDLLToSearchPath() {
+/// \return `true` if the library was added to the search path.
+/// `false` otherwise.
+bool AddPythonDLLToSearchPath() {
   std::wstring modulePath = GetPathToExecutableW();
-  if (modulePath.empty()) {
-    llvm::errs() << "error: unable to find python.dll." << '\n';
-    return;
-  }
+  if (modulePath.empty())
+    return false;
 
   SmallVector<char, MAX_PATH> utf8Path;
   if (sys::windows::UTF16ToUTF8(modulePath.c_str(), modulePath.length(),
                                 utf8Path))
-    return;
+    return false;
   sys::path::remove_filename(utf8Path);
   sys::path::append(utf8Path, LLDB_PYTHON_DLL_RELATIVE_PATH);
   sys::fs::make_absolute(utf8Path);
 
   SmallVector<wchar_t, 1> widePath;
   if (sys::windows::widenPath(utf8Path.data(), widePath))
-    return;
+    return false;
 
   if (sys::fs::exists(utf8Path))
-    SetDllDirectoryW(widePath.data());
+    return SetDllDirectoryW(widePath.data());
+  return false;
+}
+#endif
+
+#ifdef LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME
+/// Returns whether `python3x.dll` is in the DLL search path.
+bool IsPythonDLLInPath() {
+#define WIDEN2(x) L##x
+#define WIDEN(x) WIDEN2(x)
+  WCHAR foundPath[MAX_PATH];
+  DWORD result =
+      SearchPathW(nullptr, WIDEN(LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME), nullptr,
+                  MAX_PATH, foundPath, nullptr);
+#undef WIDEN2
+#undef WIDEN
+
+  return result > 0;
+}
+#endif
+
+void SetupPythonRuntimeLibrary() {
+#ifdef LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME
+  if (IsPythonDLLInPath())
+    return;
+#ifdef LLDB_PYTHON_DLL_RELATIVE_PATH
+  if (AddPythonDLLToSearchPath())
+    return;
+#endif
+  llvm::errs() << "error: unable to find '"
+               << LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME << "'.\n";
+  return;
+#elif defined(LLDB_PYTHON_DLL_RELATIVE_PATH)
+  if (!AddPythonDLLToSearchPath())
+    llvm::errs() << "error: unable to find the Python runtime library.\n";
+#endif
----------------
charles-zablit wrote:

We want to be sure to check that `python.dll` is in the Path and/or try to add it to the Path whether `LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME` and `LLDB_PYTHON_DLL_RELATIVE_PATH` are both set or only one or the other.

If only `LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME` is set:

- Check if `python.dll` is in the Path
- Print a warning if it's not.

If only `LLDB_PYTHON_DLL_RELATIVE_PATH` is set:

- Try to add `python.dll` to the Path

If both are set:

- Check if `python.dll` is in the Path.
- If it's not try to add it.
- Check again if it's in the Path (not implemented yet).
- Print a warning if it's not.

https://github.com/llvm/llvm-project/pull/164893