[lldb/Interpreter] Introduce ScriptedStopHook{,Python}Interface & make use of it (#105449)

This patch introduces new `ScriptedStopHook{,Python}Interface` classes
that make use of the Scripted Interface infrastructure and makes use of
it in `StopHookScripted`.

It also relax the requirement on the number of argument for initializing
scripting extension if the size of the interface parameter pack contains
1 less element than the extension maximum number of positional arguments
for this initializer.
This addresses the cases where the embedded interpreter session
dictionary is passed to the extension initializer which is not used most
of the time.

---------

Signed-off-by: Med Ismail Bennani <[email protected]>

Author: medismailben

lldb/bindings/python/python-wrapper.swig

@@ -301,104 +301,6 @@ unsigned int lldb_private::python::SWIGBridge::LLDBSwigPythonCallBreakpointResol
   return ret_val;
 }
 
-PythonObject lldb_private::python::SWIGBridge::LLDBSwigPythonCreateScriptedStopHook(
-    lldb::TargetSP target_sp, const char *python_class_name,
-    const char *session_dictionary_name, const StructuredDataImpl &args_impl,
-    Status &error) {
-  if (python_class_name == NULL || python_class_name[0] == '\0') {
-    error = Status::FromErrorString("Empty class name.");
-    return PythonObject();
-  }
-  if (!session_dictionary_name) {
-    error = Status::FromErrorString("No session dictionary");
-    return PythonObject();
-  }
-
-  PyErr_Cleaner py_err_cleaner(true);
-
-  auto dict = PythonModule::MainModule().ResolveName<PythonDictionary>(
-      session_dictionary_name);
-  auto pfunc = PythonObject::ResolveNameWithDictionary<PythonCallable>(
-      python_class_name, dict);
-
-  if (!pfunc.IsAllocated()) {
-    error = Status::FromErrorStringWithFormat("Could not find class: %s.",
-                                   python_class_name);
-    return PythonObject();
-  }
-
-  PythonObject result =
-      pfunc(SWIGBridge::ToSWIGWrapper(target_sp), SWIGBridge::ToSWIGWrapper(args_impl), dict);
-
-  if (result.IsAllocated()) {
-    // Check that the handle_stop callback is defined:
-    auto callback_func = result.ResolveName<PythonCallable>("handle_stop");
-    if (callback_func.IsAllocated()) {
-      if (auto args_info = callback_func.GetArgInfo()) {
-        size_t num_args = (*args_info).max_positional_args;
-        if (num_args != 2) {
-          error = Status::FromErrorStringWithFormat(
-              "Wrong number of args for "
-              "handle_stop callback, should be 2 (excluding self), got: %zu",
-              num_args);
-          return PythonObject();
-        } else
-          return result;
-      } else {
-        error = Status::FromErrorString(
-            "Couldn't get num arguments for handle_stop "
-            "callback.");
-        return PythonObject();
-      }
-      return result;
-    } else {
-      error = Status::FromErrorStringWithFormat(
-          "Class \"%s\" is missing the required "
-          "handle_stop callback.",
-          python_class_name);
-    }
-  }
-  return PythonObject();
-}
-
-bool lldb_private::python::SWIGBridge::LLDBSwigPythonStopHookCallHandleStop(
-    void *implementor, lldb::ExecutionContextRefSP exc_ctx_sp,
-    lldb::StreamSP stream) {
-  // handle_stop will return a bool with the meaning "should_stop"...
-  // If you return nothing we'll assume we are going to stop.
-  // Also any errors should return true, since we should stop on error.
-
-  PyErr_Cleaner py_err_cleaner(false);
-  PythonObject self(PyRefType::Borrowed, static_cast<PyObject *>(implementor));
-  auto pfunc = self.ResolveName<PythonCallable>("handle_stop");
-
-  if (!pfunc.IsAllocated())
-    return true;
-
-  std::shared_ptr<lldb::SBStream> sb_stream = std::make_shared<lldb::SBStream>();
-  PythonObject sb_stream_arg = SWIGBridge::ToSWIGWrapper(sb_stream);
-  PythonObject result =
-      pfunc(SWIGBridge::ToSWIGWrapper(std::move(exc_ctx_sp)), sb_stream_arg);
-
-  if (PyErr_Occurred()) {
-    stream->PutCString("Python error occurred handling stop-hook.");
-    PyErr_Print();
-    PyErr_Clear();
-    return true;
-  }
-
-  // Now add the result to the output stream.  SBStream only
-  // makes an internally help StreamString which I can't interpose, so I
-  // have to copy it over here.
-  stream->PutCString(sb_stream->GetData());
-  sb_stream_arg.release();
-
-  if (result.get() == Py_False)
-    return false;
-  else
-    return true;
-}
-
 // wrapper that calls an optional instance member of an object taking no
 // arguments
 static PyObject *LLDBSwigPython_CallOptionalMember(
@@ -677,6 +579,19 @@ void *lldb_private::python::LLDBSWIGPython_CastPyObjectToSBMemoryRegionInfo(PyOb
   return sb_ptr;
 }
 
+void *lldb_private::python::LLDBSWIGPython_CastPyObjectToSBExecutionContext(PyObject *
+                                                                    data) {
+  lldb::SBExecutionContext *sb_ptr = NULL;
+
+  int valid_cast = SWIG_ConvertPtr(data, (void **)&sb_ptr,
+                                   SWIGTYPE_p_lldb__SBExecutionContext, 0);
+
+  if (valid_cast == -1)
+    return NULL;
+
+  return sb_ptr;
+}
+
 bool lldb_private::python::SWIGBridge::LLDBSwigPythonCallCommand(
     const char *python_function_name, const char *session_dictionary_name,
     lldb::DebuggerSP debugger, const char *args,

lldb/include/lldb/API/SBExecutionContext.h

@@ -16,6 +16,7 @@
 #include <vector>
 
 namespace lldb_private {
+class ScriptInterpreter;
 namespace python {
 class SWIGBridge;
 }
@@ -55,6 +56,7 @@ class LLDB_API SBExecutionContext {
 
 protected:
   friend class lldb_private::python::SWIGBridge;
+  friend class lldb_private::ScriptInterpreter;
 
   lldb_private::ExecutionContextRef *get() const;
 

lldb/include/lldb/Interpreter/Interfaces/ScriptedStopHookInterface.h

@@ -0,0 +1,33 @@
+//===-- ScriptedStopHookInterface.h -----------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLDB_INTERPRETER_INTERFACES_SCRIPTEDSTOPHOOKINTERFACE_H
+#define LLDB_INTERPRETER_INTERFACES_SCRIPTEDSTOPHOOKINTERFACE_H
+
+#include "lldb/lldb-private.h"
+
+#include "ScriptedInterface.h"
+
+namespace lldb_private {
+class ScriptedStopHookInterface : public ScriptedInterface {
+public:
+  virtual llvm::Expected<StructuredData::GenericSP>
+  CreatePluginObject(llvm::StringRef class_name, lldb::TargetSP target_sp,
+                     const StructuredDataImpl &args_sp) = 0;
+
+  /// "handle_stop" will return a bool with the meaning "should_stop"...
+  /// If nothing is returned, we'll assume we are going to stop.
+  /// Also any errors should return true, since we should stop on error.
+  virtual llvm::Expected<bool> HandleStop(ExecutionContext &exe_ctx,
+                                          lldb::StreamSP output_sp) {
+    return true;
+  }
+};
+} // namespace lldb_private
+
+#endif // LLDB_INTERPRETER_INTERFACES_SCRIPTEDSTOPHOOKINTERFACE_H

lldb/include/lldb/Interpreter/ScriptInterpreter.h

@@ -14,6 +14,7 @@
 #include "lldb/API/SBData.h"
 #include "lldb/API/SBError.h"
 #include "lldb/API/SBEvent.h"
+#include "lldb/API/SBExecutionContext.h"
 #include "lldb/API/SBLaunchInfo.h"
 #include "lldb/API/SBMemoryRegionInfo.h"
 #include "lldb/API/SBStream.h"
@@ -271,24 +272,6 @@ class ScriptInterpreter : public PluginInterface {
     return lldb::eSearchDepthModule;
   }
 
-  virtual StructuredData::GenericSP
-  CreateScriptedStopHook(lldb::TargetSP target_sp, const char *class_name,
-                         const StructuredDataImpl &args_data, Status &error) {
-    error =
-        Status::FromErrorString("Creating scripted stop-hooks with the current "
-                                "script interpreter is not supported.");
-    return StructuredData::GenericSP();
-  }
-
-  // This dispatches to the handle_stop method of the stop-hook class.  It
-  // returns a "should_stop" bool.
-  virtual bool
-  ScriptedStopHookHandleStop(StructuredData::GenericSP implementor_sp,
-                             ExecutionContext &exc_ctx,
-                             lldb::StreamSP stream_sp) {
-    return true;
-  }
-
   virtual StructuredData::ObjectSP
   LoadPluginModule(const FileSpec &file_spec, lldb_private::Status &error) {
     return StructuredData::ObjectSP();
@@ -561,6 +544,10 @@ class ScriptInterpreter : public PluginInterface {
     return {};
   }
 
+  virtual lldb::ScriptedStopHookInterfaceSP CreateScriptedStopHookInterface() {
+    return {};
+  }
+
   virtual StructuredData::ObjectSP
   CreateStructuredDataFromScriptObject(ScriptObject obj) {
     return {};
@@ -587,6 +574,9 @@ class ScriptInterpreter : public PluginInterface {
   std::optional<MemoryRegionInfo> GetOpaqueTypeFromSBMemoryRegionInfo(
       const lldb::SBMemoryRegionInfo &mem_region) const;
 
+  lldb::ExecutionContextRefSP GetOpaqueTypeFromSBExecutionContext(
+      const lldb::SBExecutionContext &exe_ctx) const;
+
 protected:
   Debugger &m_debugger;
   lldb::ScriptLanguage m_script_lang;

lldb/include/lldb/Target/Target.h

@@ -1391,8 +1391,7 @@ class Target : public std::enable_shared_from_this<Target>,
     /// This holds the dictionary of keys & values that can be used to
     /// parametrize any given callback's behavior.
     StructuredDataImpl m_extra_args;
-    /// This holds the python callback object.
-    StructuredData::GenericSP m_implementation_sp;
+    lldb::ScriptedStopHookInterfaceSP m_interface_sp;
 
     /// Use CreateStopHook to make a new empty stop hook. The GetCommandPointer
     /// and fill it with commands, and SetSpecifier to set the specifier shared

lldb/include/lldb/lldb-forward.h

@@ -190,6 +190,7 @@ class ScriptInterpreterLocker;
 class ScriptedMetadata;
 class ScriptedPlatformInterface;
 class ScriptedProcessInterface;
+class ScriptedStopHookInterface;
 class ScriptedThreadInterface;
 class ScriptedThreadPlanInterface;
 class ScriptedSyntheticChildren;
@@ -408,6 +409,8 @@ typedef std::unique_ptr<lldb_private::ScriptedPlatformInterface>
     ScriptedPlatformInterfaceUP;
 typedef std::unique_ptr<lldb_private::ScriptedProcessInterface>
     ScriptedProcessInterfaceUP;
+typedef std::shared_ptr<lldb_private::ScriptedStopHookInterface>
+    ScriptedStopHookInterfaceSP;
 typedef std::shared_ptr<lldb_private::ScriptedThreadInterface>
     ScriptedThreadInterfaceSP;
 typedef std::shared_ptr<lldb_private::ScriptedThreadPlanInterface>

lldb/source/Interpreter/ScriptInterpreter.cpp

@@ -125,6 +125,12 @@ ScriptInterpreter::GetOpaqueTypeFromSBMemoryRegionInfo(
   return *mem_region.m_opaque_up.get();
 }
 
+lldb::ExecutionContextRefSP
+ScriptInterpreter::GetOpaqueTypeFromSBExecutionContext(
+    const lldb::SBExecutionContext &exe_ctx) const {
+  return exe_ctx.m_exe_ctx_sp;
+}
+
 lldb::ScriptLanguage
 ScriptInterpreter::StringToLanguage(const llvm::StringRef &language) {
   if (language.equals_insensitive(LanguageToString(eScriptLanguageNone)))

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/CMakeLists.txt

@@ -25,6 +25,7 @@ add_lldb_library(lldbPluginScriptInterpreterPythonInterfaces PLUGIN
   ScriptedPlatformPythonInterface.cpp
   ScriptedProcessPythonInterface.cpp
   ScriptedPythonInterface.cpp
+  ScriptedStopHookPythonInterface.cpp
   ScriptedThreadPlanPythonInterface.cpp
   ScriptedThreadPythonInterface.cpp
 

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptInterpreterPythonInterfaces.cpp

@@ -28,13 +28,15 @@ void ScriptInterpreterPythonInterfaces::Initialize() {
   OperatingSystemPythonInterface::Initialize();
   ScriptedPlatformPythonInterface::Initialize();
   ScriptedProcessPythonInterface::Initialize();
+  ScriptedStopHookPythonInterface::Initialize();
   ScriptedThreadPlanPythonInterface::Initialize();
 }
 
 void ScriptInterpreterPythonInterfaces::Terminate() {
   OperatingSystemPythonInterface::Terminate();
   ScriptedPlatformPythonInterface::Terminate();
   ScriptedProcessPythonInterface::Terminate();
+  ScriptedStopHookPythonInterface::Terminate();
   ScriptedThreadPlanPythonInterface::Terminate();
 }
 

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptInterpreterPythonInterfaces.h

@@ -18,6 +18,7 @@
 #include "OperatingSystemPythonInterface.h"
 #include "ScriptedPlatformPythonInterface.h"
 #include "ScriptedProcessPythonInterface.h"
+#include "ScriptedStopHookPythonInterface.h"
 #include "ScriptedThreadPlanPythonInterface.h"
 
 namespace lldb_private {

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedPythonInterface.cpp

@@ -159,4 +159,23 @@ ScriptedPythonInterface::ExtractValueFromPythonObject<
   return m_interpreter.GetOpaqueTypeFromSBMemoryRegionInfo(*sb_mem_reg_info);
 }
 
+template <>
+lldb::ExecutionContextRefSP
+ScriptedPythonInterface::ExtractValueFromPythonObject<
+    lldb::ExecutionContextRefSP>(python::PythonObject &p, Status &error) {
+
+  lldb::SBExecutionContext *sb_exe_ctx =
+      reinterpret_cast<lldb::SBExecutionContext *>(
+          python::LLDBSWIGPython_CastPyObjectToSBExecutionContext(p.get()));
+
+  if (!sb_exe_ctx) {
+    error = Status::FromErrorStringWithFormat(
+        "Couldn't cast lldb::SBExecutionContext to "
+        "lldb::ExecutionContextRefSP.");
+    return {};
+  }
+
+  return m_interpreter.GetOpaqueTypeFromSBExecutionContext(*sb_exe_ctx);
+}
+
 #endif

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedPythonInterface.h

@@ -180,12 +180,35 @@ class ScriptedPythonInterface : virtual public ScriptedInterface {
       llvm::Expected<PythonObject> expected_return_object =
           create_error("Resulting object is not initialized.");
 
-      std::apply(
-          [&init, &expected_return_object](auto &&...args) {
-            llvm::consumeError(expected_return_object.takeError());
-            expected_return_object = init(args...);
-          },
-          transformed_args);
+      // This relax the requirement on the number of argument for
+      // initializing scripting extension if the size of the interface
+      // parameter pack contains 1 less element than the extension maximum
+      // number of positional arguments for this initializer.
+      //
+      // This addresses the cases where the embedded interpreter session
+      // dictionary is passed to the extension initializer which is not used
+      // most of the time.
+      size_t num_args = sizeof...(Args);
+      if (num_args != arg_info->max_positional_args) {
+        if (num_args != arg_info->max_positional_args - 1)
+          return create_error("Passed arguments ({0}) doesn't match the number "
+                              "of expected arguments ({1}).",
+                              num_args, arg_info->max_positional_args);
+
+        std::apply(
+            [&init, &expected_return_object](auto &&...args) {
+              llvm::consumeError(expected_return_object.takeError());
+              expected_return_object = init(args...);
+            },
+            std::tuple_cat(transformed_args, std::make_tuple(dict)));
+      } else {
+        std::apply(
+            [&init, &expected_return_object](auto &&...args) {
+              llvm::consumeError(expected_return_object.takeError());
+              expected_return_object = init(args...);
+            },
+            transformed_args);
+      }
 
       if (!expected_return_object)
         return expected_return_object.takeError();
@@ -405,6 +428,10 @@ class ScriptedPythonInterface : virtual public ScriptedInterface {
     return python::SWIGBridge::ToSWIGWrapper(arg);
   }
 
+  python::PythonObject Transform(lldb::TargetSP arg) {
+    return python::SWIGBridge::ToSWIGWrapper(arg);
+  }
+
   python::PythonObject Transform(lldb::ProcessSP arg) {
     return python::SWIGBridge::ToSWIGWrapper(arg);
   }
@@ -557,6 +584,11 @@ std::optional<MemoryRegionInfo>
 ScriptedPythonInterface::ExtractValueFromPythonObject<
     std::optional<MemoryRegionInfo>>(python::PythonObject &p, Status &error);
 
+template <>
+lldb::ExecutionContextRefSP
+ScriptedPythonInterface::ExtractValueFromPythonObject<
+    lldb::ExecutionContextRefSP>(python::PythonObject &p, Status &error);
+
 } // namespace lldb_private
 
 #endif // LLDB_ENABLE_PYTHON