[lldb] Move ScriptedProcess private state update to implementation

While debugging a Scripted Process, in order to update its state and
work nicely with lldb's execution model, it needs to toggle its private
state from running to stopped, which will result in broadcasting a
process state changed event to the debugger listener.

Originally, this state update was done systematically in the Scripted
Process C++ plugin, however in order to make scripted process
interactive, we need to be able to update their state dynamically.

This patch makes use of the recent addition of the
SBProcess::ForceScriptedState to programatically, and moves the
process private state update to the python implementation of the resume
method instead of doing it in ScriptedProcess::DoResume.

This patch also removes the unused ShouldStop & Stop scripted
process APIs, and adds new ScriptedInterface transform methods for
boolean arguments. This allow the user to programmatically decide if
after running the process, we should stop it (which is the default setting).

Differential Revision: https://reviews.llvm.org/D145295

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

Author: medismailben

lldb/examples/python/scripted_process/scripted_process.py

@@ -160,30 +160,25 @@ def attach(self, attach_info):
         """
         return lldb.SBError()
 
-    def resume(self):
+    def resume(self, should_stop=True):
         """ Simulate the scripted process resume.
 
-        Returns:
-            lldb.SBError: An `lldb.SBError` with error code 0.
-        """
-        return lldb.SBError()
-
-    @abstractmethod
-    def should_stop(self):
-        """ Check if the scripted process plugin should produce the stop event.
-
-        Returns:
-            bool: True if scripted process should broadcast a stop event.
-                  False otherwise.
-        """
-        pass
-
-    def stop(self):
-        """ Trigger the scripted process stop.
+        Args:
+            should_stop (bool): If True, resume will also force the process
+            state to stopped after running it.
 
         Returns:
             lldb.SBError: An `lldb.SBError` with error code 0.
         """
+        process = self.target.GetProcess()
+        if not process:
+            error = lldb.SBError()
+            error.SetErrorString("Invalid process.")
+            return error
+
+        process.ForceScriptedState(lldb.eStateRunning);
+        if (should_stop):
+            process.ForceScriptedState(lldb.eStateStopped);
         return lldb.SBError()
 
     @abstractmethod

lldb/include/lldb/Interpreter/ScriptedProcessInterface.h

@@ -37,10 +37,6 @@ class ScriptedProcessInterface : virtual public ScriptedInterface {
 
   virtual Status Resume() { return Status("ScriptedProcess did not resume"); }
 
-  virtual bool ShouldStop() { return true; }
-
-  virtual Status Stop() { return Status("ScriptedProcess did not stop"); }
-
   virtual llvm::Optional<MemoryRegionInfo>
   GetMemoryRegionContainingAddress(lldb::addr_t address, Status &error) {
     error.SetErrorString("ScriptedProcess have no memory region.");

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

@@ -150,22 +150,15 @@ Status ScriptedProcess::DoLoadCore() {
 
 Status ScriptedProcess::DoLaunch(Module *exe_module,
                                  ProcessLaunchInfo &launch_info) {
-  /* FIXME: This doesn't reflect how lldb actually launches a process.
-           In reality, it attaches to debugserver, then resume the process. */
+  LLDB_LOGF(GetLog(LLDBLog::Process), "ScriptedProcess::%s launching process", __FUNCTION__);
+  
+  /* MARK: This doesn't reflect how lldb actually launches a process.
+           In reality, it attaches to debugserver, then resume the process.
+           That's not true in all cases.  If debugserver is remote, lldb
+           asks debugserver to launch the process for it. */
   Status error = GetInterface().Launch();
-  SetPrivateState(eStateRunning);
-
-  if (error.Fail())
-    return error;
-
-  // TODO: Fetch next state from stopped event queue then send stop event
-  //  const StateType state = SetThreadStopInfo(response);
-  //  if (state != eStateInvalid) {
-  //    SetPrivateState(state);
-
   SetPrivateState(eStateStopped);
-
-  return {};
+  return error;
 }
 
 void ScriptedProcess::DidLaunch() {
@@ -174,25 +167,9 @@ void ScriptedProcess::DidLaunch() {
 }
 
 Status ScriptedProcess::DoResume() {
-  Log *log = GetLog(LLDBLog::Process);
-  // FIXME: Fetch data from thread.
-  const StateType thread_resume_state = eStateRunning;
-  LLDB_LOGF(log, "ScriptedProcess::%s thread_resume_state = %s", __FUNCTION__,
-            StateAsCString(thread_resume_state));
-
-  bool resume = (thread_resume_state == eStateRunning);
-  assert(thread_resume_state == eStateRunning && "invalid thread resume state");
+  LLDB_LOGF(GetLog(LLDBLog::Process), "ScriptedProcess::%s resuming process", __FUNCTION__);
 
-  Status error;
-  if (resume) {
-    LLDB_LOGF(log, "ScriptedProcess::%s sending resume", __FUNCTION__);
-
-    SetPrivateState(eStateRunning);
-    SetPrivateState(eStateStopped);
-    error = GetInterface().Resume();
-  }
-
-  return error;
+  return GetInterface().Resume();
 }
 
 Status ScriptedProcess::DoAttach(const ProcessAttachInfo &attach_info) {
@@ -223,19 +200,6 @@ void ScriptedProcess::DidAttach(ArchSpec &process_arch) {
   process_arch = GetArchitecture();
 }
 
-Status ScriptedProcess::DoStop() {
-  Log *log = GetLog(LLDBLog::Process);
-
-  if (GetInterface().ShouldStop()) {
-    SetPrivateState(eStateStopped);
-    LLDB_LOGF(log, "ScriptedProcess::%s Immediate stop", __FUNCTION__);
-    return {};
-  }
-
-  LLDB_LOGF(log, "ScriptedProcess::%s Delayed stop", __FUNCTION__);
-  return GetInterface().Stop();
-}
-
 Status ScriptedProcess::DoDestroy() { return Status(); }
 
 bool ScriptedProcess::IsAlive() { return GetInterface().IsAlive(); }

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

@@ -96,8 +96,6 @@ class ScriptedProcess : public Process {
   ScriptedProcess(lldb::TargetSP target_sp, lldb::ListenerSP listener_sp,
                   const ScriptedMetadata &scripted_metadata, Status &error);
 
-  Status DoStop();
-
   void Clear();
 
   bool DoUpdateThreadList(ThreadList &old_thread_list,

lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h

@@ -201,6 +201,7 @@ template <> struct PythonFormat<short> : PassthroughFormat<short, 'h'> {};
 template <>
 struct PythonFormat<unsigned short> : PassthroughFormat<unsigned short, 'H'> {};
 template <> struct PythonFormat<int> : PassthroughFormat<int, 'i'> {};
+template <> struct PythonFormat<bool> : PassthroughFormat<bool, 'p'> {};
 template <>
 struct PythonFormat<unsigned int> : PassthroughFormat<unsigned int, 'I'> {};
 template <> struct PythonFormat<long> : PassthroughFormat<long, 'l'> {};

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedProcessPythonInterface.cpp

@@ -80,21 +80,8 @@ Status ScriptedProcessPythonInterface::Launch() {
 }
 
 Status ScriptedProcessPythonInterface::Resume() {
-  return GetStatusFromMethod("resume");
-}
-
-bool ScriptedProcessPythonInterface::ShouldStop() {
-  Status error;
-  StructuredData::ObjectSP obj = Dispatch("is_alive", error);
-
-  if (!CheckStructuredDataObject(LLVM_PRETTY_FUNCTION, obj, error))
-    return {};
-
-  return obj->GetBooleanValue();
-}
-
-Status ScriptedProcessPythonInterface::Stop() {
-  return GetStatusFromMethod("stop");
+  // When calling ScriptedProcess.Resume from lldb we should always stop.
+  return GetStatusFromMethod("resume", /*should_stop=*/true);
 }
 
 llvm::Optional<MemoryRegionInfo>

lldb/source/Plugins/ScriptInterpreter/Python/ScriptedProcessPythonInterface.h

@@ -36,10 +36,6 @@ class ScriptedProcessPythonInterface : public ScriptedProcessInterface,
 
   Status Resume() override;
 
-  bool ShouldStop() override;
-
-  Status Stop() override;
-
   llvm::Optional<MemoryRegionInfo>
   GetMemoryRegionContainingAddress(lldb::addr_t address,
                                    Status &error) override;

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

@@ -112,6 +112,11 @@ class ScriptedPythonInterface : virtual public ScriptedInterface {
     return {object};
   }
 
+  python::PythonObject Transform(bool arg) {
+    // Boolean arguments need to be turned into python objects.
+    return python::PythonBoolean(arg);
+  }
+
   python::PythonObject Transform(Status arg) {
     return python::ToSWIGWrapper(arg);
   }
@@ -140,6 +145,19 @@ class ScriptedPythonInterface : virtual public ScriptedInterface {
     original_arg = ExtractValueFromPythonObject<T>(transformed_arg, error);
   }
 
+  template <>
+  void ReverseTransform(bool &original_arg,
+                        python::PythonObject transformed_arg, Status &error) {
+    python::PythonBoolean boolean_arg = python::PythonBoolean(
+        python::PyRefType::Borrowed, transformed_arg.get());
+    if (boolean_arg.IsValid())
+      original_arg = boolean_arg.GetValue();
+    else
+      error.SetErrorString(
+          llvm::formatv("{}: Invalid boolean argument.", LLVM_PRETTY_FUNCTION)
+              .str());
+  }
+
   template <std::size_t... I, typename... Args>
   auto TransformTuple(const std::tuple<Args...> &args,
                       std::index_sequence<I...>) {