[Lldb-commits] [lldb] 15bbdd1 - [lldb][windows] print an error if python.dll is not in the DLL search path (#164893)
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lldb-commits at lists.llvm.org
Mon Nov 3 12:00:20 PST 2025
Author: Charles Zablit
Date: 2025-11-03T20:00:16Z
New Revision: 15bbdd143cb196be8d60ea4dc813bf7bc5e4650c
URL: https://github.com/llvm/llvm-project/commit/15bbdd143cb196be8d60ea4dc813bf7bc5e4650c
DIFF: https://github.com/llvm/llvm-project/commit/15bbdd143cb196be8d60ea4dc813bf7bc5e4650c.diff
LOG: [lldb][windows] print an error if python.dll is not in the DLL search path (#164893)
This is a follow up to https://github.com/llvm/llvm-project/pull/162509.
Using the `SearchPathW` API, we can ensure that the correct version of
Python is installed before `liblldb` is loaded (and `python.dll`
subsequently). If it's not, we try to add it to the search path with the
methods introduced in https://github.com/llvm/llvm-project/pull/162509.
If that fails or if that method is `#ifdef`'d out, we print an error
which will appear before lldb crashes due to the missing dll.
Before https://github.com/llvm/llvm-project/pull/162509, when invoked
from Powershell, lldb would silently crash (no error message/crash
report). After https://github.com/llvm/llvm-project/pull/162509, it
crashes without any indications that the root cause is the missing
python.dll. With this patch, we print the error before crashing.
Added:
Modified:
lldb/CMakeLists.txt
lldb/tools/driver/CMakeLists.txt
lldb/tools/driver/Driver.cpp
Removed:
################################################################################
diff --git a/lldb/CMakeLists.txt b/lldb/CMakeLists.txt
index e3b72e94d4beb..01b5546fee00d 100644
--- a/lldb/CMakeLists.txt
+++ b/lldb/CMakeLists.txt
@@ -87,6 +87,12 @@ if (LLDB_ENABLE_PYTHON)
set(LLDB_PYTHON_EXT_SUFFIX "_d${LLDB_PYTHON_EXT_SUFFIX}")
endif()
endif()
+ if(TARGET Python3::Python)
+ get_target_property(_Python3_LIB_PATH Python3::Python IMPORTED_LIBRARY_LOCATION)
+ if(_Python3_LIB_PATH)
+ get_filename_component(LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME "${_Python3_LIB_PATH}" NAME)
+ endif()
+ endif()
endif ()
if (LLDB_ENABLE_LUA)
diff --git a/lldb/tools/driver/CMakeLists.txt b/lldb/tools/driver/CMakeLists.txt
index 67956af7fe3fb..efe51506f3545 100644
--- a/lldb/tools/driver/CMakeLists.txt
+++ b/lldb/tools/driver/CMakeLists.txt
@@ -37,6 +37,9 @@ add_dependencies(lldb
if(DEFINED LLDB_PYTHON_DLL_RELATIVE_PATH)
target_compile_definitions(lldb PRIVATE LLDB_PYTHON_DLL_RELATIVE_PATH="${LLDB_PYTHON_DLL_RELATIVE_PATH}")
endif()
+if(DEFINED LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME)
+ target_compile_definitions(lldb PRIVATE LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME="${LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME}")
+endif()
if(LLDB_BUILD_FRAMEWORK)
# In the build-tree, we know the exact path to the framework directory.
diff --git a/lldb/tools/driver/Driver.cpp b/lldb/tools/driver/Driver.cpp
index 733331f4ddac0..bebf1a70d50e9 100644
--- a/lldb/tools/driver/Driver.cpp
+++ b/lldb/tools/driver/Driver.cpp
@@ -433,7 +433,8 @@ SBError Driver::ProcessArgs(const opt::InputArgList &args, bool &exiting) {
return error;
}
-#if defined(_WIN32) && defined(LLDB_PYTHON_DLL_RELATIVE_PATH)
+#ifdef _WIN32
+#ifdef LLDB_PYTHON_DLL_RELATIVE_PATH
/// Returns the full path to the lldb.exe executable.
inline std::wstring GetPathToExecutableW() {
// Iterate until we reach the Windows API maximum path length (32,767).
@@ -447,30 +448,73 @@ 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
+
+/// Try to setup the DLL search path for the Python Runtime Library
+/// (python3xx.dll).
+///
+/// If `LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME` is set, we first check if
+/// python3xx.dll is in the search path. If it's not, we try to add it and
+/// check for it a second time.
+/// If only `LLDB_PYTHON_DLL_RELATIVE_PATH` is set, we try to add python3xx.dll
+/// to the search path python.dll is already in the search path or not.
+void SetupPythonRuntimeLibrary() {
+#ifdef LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME
+ if (IsPythonDLLInPath())
+ return;
+#ifdef LLDB_PYTHON_DLL_RELATIVE_PATH
+ if (AddPythonDLLToSearchPath() && IsPythonDLLInPath())
+ 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
}
#endif
@@ -776,8 +820,8 @@ int main(int argc, char const *argv[]) {
"~/Library/Logs/DiagnosticReports/.\n");
#endif
-#if defined(_WIN32) && defined(LLDB_PYTHON_DLL_RELATIVE_PATH)
- AddPythonDLLToSearchPath();
+#ifdef _WIN32
+ SetupPythonRuntimeLibrary();
#endif
// Parse arguments.
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