[lldb/Plugins] Add ScriptedProcess Process Plugin

This patch introduces Scripted Processes to lldb.

The goal, here, is to be able to attach in the debugger to fake processes
that are backed by script files (in Python, Lua, Swift, etc ...) and
inspect them statically.

Scripted Processes can be used in cooperative multithreading environments
like the XNU Kernel or other real-time operating systems, but it can
also help us improve the debugger testing infrastructure by writting
synthetic tests that simulates hard-to-reproduce process/thread states.

Although ScriptedProcess is not feature-complete at the moment, it has
basic execution capabilities and will improve in the following patches.

rdar://65508855

Differential Revision: https://reviews.llvm.org/D95713

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

Author: medismailben

lldb/bindings/python/CMakeLists.txt

@@ -111,6 +111,13 @@ function(finish_swig_python swig_target lldb_python_bindings_dir lldb_python_tar
     FILES
     "${LLDB_SOURCE_DIR}/examples/python/scripted_process/scripted_process.py")
 
+  create_python_package(
+    ${swig_target}
+    ${lldb_python_target_dir}
+    "plugins"
+    FILES
+    "${LLDB_SOURCE_DIR}/examples/python/scripted_process/scripted_process.py")
+
   if(APPLE)
     create_python_package(
       ${swig_target}

lldb/include/lldb/Target/Process.h

@@ -2561,8 +2561,6 @@ void PruneThreadPlans();
   virtual size_t DoReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
                               Status &error) = 0;
 
-  void SetState(lldb::EventSP &event_sp);
-
   lldb::StateType GetPrivateState();
 
   /// The "private" side of resuming a process.  This doesn't alter the state

lldb/source/Plugins/Process/CMakeLists.txt

@@ -12,6 +12,7 @@ elseif (CMAKE_SYSTEM_NAME MATCHES "Windows")
 elseif (CMAKE_SYSTEM_NAME MATCHES "Darwin")
   add_subdirectory(MacOSX-Kernel)
 endif()
+add_subdirectory(scripted)
 add_subdirectory(gdb-remote)
 add_subdirectory(Utility)
 add_subdirectory(elf-core)

lldb/source/Plugins/Process/scripted/CMakeLists.txt

@@ -0,0 +1,13 @@
+add_lldb_library(lldbPluginScriptedProcess PLUGIN
+  ScriptedProcess.cpp
+
+  LINK_LIBS
+    lldbCore
+    lldbTarget
+    lldbUtility
+    lldbPluginProcessUtility
+  LINK_COMPONENTS
+    BinaryFormat
+    Object
+    Support
+  )

lldb/source/Plugins/Process/scripted/ScriptedProcess.cpp

@@ -0,0 +1,242 @@
+//===-- ScriptedProcess.cpp -----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "ScriptedProcess.h"
+
+#include "lldb/Core/Debugger.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/PluginManager.h"
+
+#include "lldb/Host/OptionParser.h"
+
+#include "lldb/Interpreter/OptionArgParser.h"
+#include "lldb/Interpreter/OptionGroupBoolean.h"
+#include "lldb/Interpreter/ScriptInterpreter.h"
+#include "lldb/Target/MemoryRegionInfo.h"
+
+LLDB_PLUGIN_DEFINE(ScriptedProcess)
+
+using namespace lldb;
+using namespace lldb_private;
+
+ConstString ScriptedProcess::GetPluginNameStatic() {
+  static ConstString g_name("ScriptedProcess");
+  return g_name;
+}
+
+const char *ScriptedProcess::GetPluginDescriptionStatic() {
+  return "Scripted Process plug-in.";
+}
+
+lldb::ProcessSP ScriptedProcess::CreateInstance(lldb::TargetSP target_sp,
+                                                lldb::ListenerSP listener_sp,
+                                                const FileSpec *file,
+                                                bool can_connect) {
+  ScriptedProcess::LaunchInfo launch_info(target_sp->GetProcessLaunchInfo());
+
+  auto process_sp =
+      std::make_shared<ScriptedProcess>(target_sp, listener_sp, launch_info);
+
+  if (!process_sp || !process_sp->m_script_object_sp ||
+      !process_sp->m_script_object_sp->IsValid())
+    return nullptr;
+
+  return process_sp;
+}
+
+bool ScriptedProcess::CanDebug(lldb::TargetSP target_sp,
+                               bool plugin_specified_by_name) {
+  return true;
+}
+
+ScriptedProcess::ScriptedProcess(lldb::TargetSP target_sp,
+                                 lldb::ListenerSP listener_sp,
+                                 const ScriptedProcess::LaunchInfo &launch_info)
+    : Process(target_sp, listener_sp), m_launch_info(launch_info),
+      m_interpreter(nullptr), m_script_object_sp(nullptr) {
+  if (!target_sp)
+    return;
+
+  m_interpreter = target_sp->GetDebugger().GetScriptInterpreter();
+
+  if (!m_interpreter)
+    return;
+
+  StructuredData::ObjectSP object_sp = GetInterface().CreatePluginObject(
+      m_launch_info.GetClassName().c_str(), target_sp,
+      m_launch_info.GetDictionarySP());
+
+  if (object_sp && object_sp->IsValid())
+    m_script_object_sp = object_sp;
+}
+
+ScriptedProcess::~ScriptedProcess() {
+  Clear();
+  // We need to call finalize on the process before destroying ourselves to
+  // make sure all of the broadcaster cleanup goes as planned. If we destruct
+  // this class, then Process::~Process() might have problems trying to fully
+  // destroy the broadcaster.
+  Finalize();
+}
+
+void ScriptedProcess::Initialize() {
+  static llvm::once_flag g_once_flag;
+
+  llvm::call_once(g_once_flag, []() {
+    PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                  GetPluginDescriptionStatic(), CreateInstance);
+  });
+}
+
+void ScriptedProcess::Terminate() {
+  PluginManager::UnregisterPlugin(ScriptedProcess::CreateInstance);
+}
+
+ConstString ScriptedProcess::GetPluginName() { return GetPluginNameStatic(); }
+
+uint32_t ScriptedProcess::GetPluginVersion() { return 1; }
+
+Status ScriptedProcess::DoLoadCore() {
+  ProcessLaunchInfo launch_info = GetTarget().GetProcessLaunchInfo();
+
+  return DoLaunch(nullptr, launch_info);
+}
+
+Status ScriptedProcess::DoLaunch(Module *exe_module,
+                                 ProcessLaunchInfo &launch_info) {
+  if (!m_interpreter)
+    return Status("No interpreter.");
+
+  if (!m_script_object_sp)
+    return Status("No python object.");
+
+  Status status = GetInterface().Launch();
+
+  if (status.Success()) {
+    SetPrivateState(eStateRunning);
+    SetPrivateState(eStateStopped);
+  }
+
+  return status;
+};
+
+void ScriptedProcess::DidLaunch() {
+  if (m_interpreter)
+    m_pid = GetInterface().GetProcessID();
+}
+
+Status ScriptedProcess::DoResume() {
+  if (!m_interpreter)
+    return Status("No interpreter.");
+
+  if (!m_script_object_sp)
+    return Status("No python object.");
+
+  Status status = GetInterface().Resume();
+
+  if (status.Success()) {
+    SetPrivateState(eStateRunning);
+    SetPrivateState(eStateStopped);
+  }
+
+  return status;
+}
+
+Status ScriptedProcess::DoDestroy() { return Status(); }
+
+bool ScriptedProcess::IsAlive() {
+  if (!m_interpreter)
+    return false;
+
+  return GetInterface().IsAlive();
+}
+
+size_t ScriptedProcess::ReadMemory(lldb::addr_t addr, void *buf, size_t size,
+                                   Status &error) {
+  return DoReadMemory(addr, buf, size, error);
+}
+
+size_t ScriptedProcess::DoReadMemory(lldb::addr_t addr, void *buf, size_t size,
+                                     Status &error) {
+
+  auto error_with_message = [&error](llvm::StringRef message) {
+    error.SetErrorString(message);
+    return LLDB_INVALID_ADDRESS;
+  };
+
+  if (!m_interpreter)
+    return error_with_message("No interpreter.");
+
+  lldb::DataExtractorSP data_extractor_sp =
+      GetInterface().ReadMemoryAtAddress(addr, size, error);
+
+  if (!data_extractor_sp || error.Fail())
+    return LLDB_INVALID_ADDRESS;
+
+  if (data_extractor_sp->GetByteSize() != size)
+    return error_with_message("Failed to read requested memory size.");
+
+  if (data_extractor_sp->CopyData(0, size, buf) <= size)
+    return error_with_message("Failed to copy read memory to buffer.");
+
+  return size;
+}
+
+ArchSpec ScriptedProcess::GetArchitecture() {
+  return GetTarget().GetArchitecture();
+}
+
+Status ScriptedProcess::GetMemoryRegionInfo(lldb::addr_t load_addr,
+                                            MemoryRegionInfo &region) {
+  return Status();
+}
+
+Status ScriptedProcess::GetMemoryRegions(MemoryRegionInfos &region_list) {
+  Status error;
+
+  if (!m_interpreter) {
+    error.SetErrorString("No interpreter.");
+    return error;
+  }
+
+  lldb::addr_t address = 0;
+  lldb::MemoryRegionInfoSP mem_region_sp = nullptr;
+
+  while ((mem_region_sp =
+              GetInterface().GetMemoryRegionContainingAddress(address))) {
+    auto range = mem_region_sp->GetRange();
+    address += range.GetRangeBase() + range.GetByteSize();
+    region_list.push_back(*mem_region_sp.get());
+  }
+
+  return error;
+}
+
+void ScriptedProcess::Clear() { Process::m_thread_list.Clear(); }
+
+bool ScriptedProcess::DoUpdateThreadList(ThreadList &old_thread_list,
+                                         ThreadList &new_thread_list) {
+  return new_thread_list.GetSize(false) > 0;
+}
+
+bool ScriptedProcess::GetProcessInfo(ProcessInstanceInfo &info) {
+  info.Clear();
+  info.SetProcessID(GetID());
+  info.SetArchitecture(GetArchitecture());
+  lldb::ModuleSP module_sp = GetTarget().GetExecutableModule();
+  if (module_sp) {
+    const bool add_exe_file_as_first_arg = false;
+    info.SetExecutableFile(GetTarget().GetExecutableModule()->GetFileSpec(),
+                           add_exe_file_as_first_arg);
+  }
+  return true;
+}
+
+ScriptedProcessInterface &ScriptedProcess::GetInterface() const {
+  return m_interpreter->GetScriptedProcessInterface();
+}