🍒 [lldb-dap][vscode][windows] check if Python is installed properly before starting lldb-dap (llvm#181124)

lldb/include/lldb/Host/windows/PythonPathSetup/PythonPathSetup.h

@@ -42,7 +42,12 @@ bool AddPythonDLLToSearchPath();
 ///   can be loaded. If successful, returns immediately. Otherwise, attempts to
 ///   resolve the relative path and add it to the DLL search path, then checks
 ///   again if python3xx.dll can be loaded.
-llvm::Error SetupPythonRuntimeLibrary();
+///
+/// \return If LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME is defined, return the
+/// absolute path of the Python shared library which was resolved or an error if
+/// it could not be found. If LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME and
+/// LLDB_PYTHON_DLL_RELATIVE_PATH are not defined, return an empty string.
+llvm::Expected<std::string> SetupPythonRuntimeLibrary();
 
 // BEGIN SWIFT
 extern const std::string g_python_installation_note;

lldb/source/Host/windows/PythonPathSetup/PythonPathSetup.cpp

@@ -19,10 +19,11 @@
 
 using namespace llvm;
 
+#ifdef LLDB_PYTHON_DLL_RELATIVE_PATH
 static std::string GetModulePath(HMODULE module) {
   std::vector<WCHAR> buffer(MAX_PATH);
   while (buffer.size() <= PATHCCH_MAX_CCH) {
-    DWORD len = GetModuleFileNameW(NULL, buffer.data(), buffer.size());
+    DWORD len = GetModuleFileNameW(module, buffer.data(), buffer.size());
     if (len == 0)
       return "";
     if (len < buffer.size()) {
@@ -40,7 +41,6 @@ static std::string GetModulePath(HMODULE module) {
 /// Returns the full path to the lldb.exe executable.
 static std::string GetPathToExecutable() { return GetModulePath(NULL); }
 
-#ifdef LLDB_PYTHON_DLL_RELATIVE_PATH
 bool AddPythonDLLToSearchPath() {
   std::string path_str = GetPathToExecutable();
   if (path_str.empty())
@@ -62,26 +62,31 @@ bool AddPythonDLLToSearchPath() {
 #endif
 
 #ifdef LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME
-bool IsPythonDLLInPath() {
+std::optional<std::string> GetPythonDLLPath() {
 #define WIDEN2(x) L##x
 #define WIDEN(x) WIDEN2(x)
   HMODULE h = LoadLibraryW(WIDEN(LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME));
   if (!h)
-    return false;
+    return std::nullopt;
+
+  std::string path = GetModulePath(h);
   FreeLibrary(h);
-  return true;
+
+  return path;
 #undef WIDEN2
 #undef WIDEN
 }
 #endif
 
-llvm::Error SetupPythonRuntimeLibrary() {
+llvm::Expected<std::string> SetupPythonRuntimeLibrary() {
 #ifdef LLDB_PYTHON_RUNTIME_LIBRARY_FILENAME
-  if (IsPythonDLLInPath())
-    return Error::success();
+  if (std::optional<std::string> python_path = GetPythonDLLPath())
+    return *python_path;
 #ifdef LLDB_PYTHON_DLL_RELATIVE_PATH
-  if (AddPythonDLLToSearchPath() && IsPythonDLLInPath())
-    return Error::success();
+  if (AddPythonDLLToSearchPath()) {
+    if (std::optional<std::string> python_path = GetPythonDLLPath())
+      return *python_path;
+  }
 #endif
   return createStringError(
       inconvertibleErrorCode(),
@@ -91,7 +96,7 @@ llvm::Error SetupPythonRuntimeLibrary() {
     return createStringError(inconvertibleErrorCode(),
                              "unable to find the Python runtime library");
 #endif
-  return Error::success();
+  return "";
 }
 
 // BEGIN SWIFT

lldb/tools/driver/Driver.cpp

@@ -741,8 +741,10 @@ int main(int argc, char const *argv[]) {
 #endif
 
 #ifdef _WIN32
-  if (llvm::Error error = SetupPythonRuntimeLibrary()) {
-    llvm::WithColor::error() << llvm::toString(std::move(error)) << '\n';
+  auto python_path_or_err = SetupPythonRuntimeLibrary();
+  if (!python_path_or_err) {
+    llvm::WithColor::error()
+        << llvm::toString(std::move(python_path_or_err.takeError())) << '\n';
     // BEGIN SWIFT
     llvm::WithColor::note() << g_python_installation_note;
     return 1;

lldb/tools/lldb-dap/src-ts/debug-configuration-provider.ts

@@ -1,6 +1,7 @@
 import * as vscode from "vscode";
 import * as child_process from "child_process";
 import * as util from "util";
+import * as os from "os";
 import { LLDBDapServer } from "./lldb-dap-server";
 import { createDebugAdapterExecutable } from "./debug-adapter-factory";
 import { ConfigureButton, showErrorMessage } from "./ui/show-error-message";
@@ -70,8 +71,7 @@ const configurations: Record<string, DefaultConfig> = {
 };
 
 export class LLDBDapConfigurationProvider
-  implements vscode.DebugConfigurationProvider
-{
+  implements vscode.DebugConfigurationProvider {
   constructor(
     private readonly server: LLDBDapServer,
     private readonly logger: vscode.LogOutputChannel,
@@ -110,7 +110,7 @@ export class LLDBDapConfigurationProvider
     );
     this.logger.debug(
       "Initial debug configuration:\n" +
-        JSON.stringify(debugConfiguration, undefined, 2),
+      JSON.stringify(debugConfiguration, undefined, 2),
     );
     let config = vscode.workspace.getConfiguration("lldb-dap");
     for (const [key, cfg] of Object.entries(configurations)) {
@@ -195,6 +195,22 @@ export class LLDBDapConfigurationProvider
           return undefined;
         }
 
+        if (os.platform() === "win32") {
+          const pythonCheckProcess = child_process.spawnSync(executable.command, [
+            "--check-python",
+          ]);
+          if (pythonCheckProcess.status !== 0) {
+            await vscode.window.showErrorMessage(
+              "Python is not installed correctly. Please install it to use lldb-dap.",
+              {
+                modal: true,
+                detail: pythonCheckProcess.stderr?.toString() ?? "",
+              },
+            );
+            return undefined;
+          }
+        }
+
         // Server mode needs to be handled here since DebugAdapterDescriptorFactory
         // will show an unhelpful error if it returns undefined. We'd rather show a
         // nicer error message here and allow stopping the debug session gracefully.
@@ -222,7 +238,7 @@ export class LLDBDapConfigurationProvider
 
       this.logger.info(
         "Resolved debug configuration:\n" +
-          JSON.stringify(debugConfiguration, undefined, 2),
+        JSON.stringify(debugConfiguration, undefined, 2),
       );
 
       return debugConfiguration;

lldb/tools/lldb-dap/tool/Options.td

@@ -17,6 +17,10 @@ def: Flag<["-"], "v">,
   Alias<version>,
   HelpText<"Alias for --version">;
 
+def check_python : F<"check-python">,
+                   HelpText<"Prints the path to the resolved Python DLL. "
+                            "(Windows only).">;
+
 def wait_for_debugger: F<"wait-for-debugger">,
   HelpText<"Pause the program at startup.">;
 def: Flag<["-"], "g">,

lldb/tools/lldb-dap/tool/lldb-dap.cpp

@@ -475,16 +475,6 @@ int main(int argc, char *argv[]) {
                         "~/Library/Logs/DiagnosticReports/.\n");
 #endif
 
-#ifdef _WIN32
-  if (llvm::Error error = SetupPythonRuntimeLibrary()) {
-    llvm::WithColor::error() << llvm::toString(std::move(error)) << '\n';
-    // BEGIN SWIFT
-    llvm::WithColor::note() << g_python_installation_note;
-    return 1;
-    // END SWIFT
-  }
-#endif
-
   llvm::SmallString<256> program_path(argv[0]);
   llvm::sys::fs::make_absolute(program_path);
   DAP::debug_adapter_path = program_path;
@@ -504,6 +494,39 @@ int main(int argc, char *argv[]) {
     return EXIT_SUCCESS;
   }
 
+#ifdef _WIN32
+  if (input_args.hasArg(OPT_check_python)) {
+#ifndef LLDB_ENABLE_PYTHON
+    llvm::errs() << "lldb-dap was not built with Python support" << '\n';
+    return EXIT_SUCCESS;
+#endif
+    auto python_path_or_err = SetupPythonRuntimeLibrary();
+    if (!python_path_or_err) {
+      llvm::WithColor::error()
+          << llvm::toString(python_path_or_err.takeError()) << '\n';
+      return EXIT_FAILURE;
+    }
+    std::string python_path = *python_path_or_err;
+    if (python_path.empty()) {
+      llvm::WithColor::error()
+          << "unable to look for the Python shared library" << '\n';
+      return EXIT_FAILURE;
+    }
+    llvm::outs() << python_path << '\n';
+    return EXIT_SUCCESS;
+  }
+
+  auto python_path_or_err = SetupPythonRuntimeLibrary();
+  if (!python_path_or_err) {
+    llvm::WithColor::error()
+        << llvm::toString(std::move(python_path_or_err.takeError())) << '\n';
+    // BEGIN SWIFT
+    llvm::WithColor::note() << g_python_installation_note;
+    return 1;
+    // END SWIFT
+  }
+#endif
+
   ReplMode default_repl_mode = ReplMode::Auto;
   if (input_args.hasArg(OPT_repl_mode)) {
     llvm::opt::Arg *repl_mode = input_args.getLastArg(OPT_repl_mode);