Vendor import of stripped lldb trunk r375505, the last commit before thevendor/lldb/lldb-trunk-r375505vendor/lldb

upstream Subversion repository was made read-only, and the LLVM project
migrated to GitHub:

https://llvm.org/svn/llvm-project/lldb/trunk@375505

8 files changed, 1617 insertions, 1101 deletions

diff --git a/source/Plugins/ScriptInterpreter/None/ScriptInterpreterNone.cpp b/source/Plugins/ScriptInterpreter/None/ScriptInterpreterNone.cpp
index 7b9598379553..3517f831970d 100644
--- a/source/Plugins/ScriptInterpreter/None/ScriptInterpreterNone.cpp
+++ b/source/Plugins/ScriptInterpreter/None/ScriptInterpreterNone.cpp
@@ -28,13 +28,13 @@ ScriptInterpreterNone::~ScriptInterpreterNone() {}
 bool ScriptInterpreterNone::ExecuteOneLine(llvm::StringRef command,
                                            CommandReturnObject *,
                                            const ExecuteScriptOptions &) {
-  m_debugger.GetErrorFile()->PutCString(
+  m_debugger.GetErrorStream().PutCString(
       "error: there is no embedded script interpreter in this mode.\n");
   return false;
 }
 
 void ScriptInterpreterNone::ExecuteInterpreterLoop() {
-  m_debugger.GetErrorFile()->PutCString(
+  m_debugger.GetErrorStream().PutCString(
       "error: there is no embedded script interpreter in this mode.\n");
 }
 
diff --git a/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp b/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
index 29dd037efd86..70d93424fdec 100644
--- a/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
+++ b/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.cpp
@@ -18,9 +18,11 @@
 #include "lldb/Host/File.h"
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Interpreter/ScriptInterpreter.h"
+#include "lldb/Utility/Log.h"
 #include "lldb/Utility/Stream.h"
 
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/ConvertUTF.h"
 #include "llvm/Support/Errno.h"
 
@@ -28,9 +30,41 @@
 
 using namespace lldb_private;
 using namespace lldb;
+using namespace lldb_private::python;
+using llvm::cantFail;
+using llvm::Error;
+using llvm::Expected;
+using llvm::Twine;
 
-void StructuredPythonObject::Dump(Stream &s, bool pretty_print) const {
-  s << "Python Obj: 0x" << GetValue();
+template <> Expected<bool> python::As<bool>(Expected<PythonObject> &&obj) {
+  if (!obj)
+    return obj.takeError();
+  return obj.get().IsTrue();
+}
+
+template <>
+Expected<long long> python::As<long long>(Expected<PythonObject> &&obj) {
+  if (!obj)
+    return obj.takeError();
+  return obj.get().AsLongLong();
+}
+
+template <>
+Expected<std::string> python::As<std::string>(Expected<PythonObject> &&obj) {
+  if (!obj)
+    return obj.takeError();
+  PyObject *str_obj = PyObject_Str(obj.get().get());
+  if (!obj)
+    return llvm::make_error<PythonException>();
+  auto str = Take<PythonString>(str_obj);
+  auto utf8 = str.AsUTF8();
+  if (!utf8)
+    return utf8.takeError();
+  return utf8.get();
+}
+
+void StructuredPythonObject::Serialize(llvm::json::OStream &s) const {
+  s.value(llvm::formatv("Python Obj: {0:X}", GetValue()).str());
 }
 
 // PythonObject
@@ -167,12 +201,6 @@ PythonObject PythonObject::GetAttributeValue(llvm::StringRef attr) const {
                       PyObject_GetAttr(m_py_obj, py_attr.get()));
 }
 
-bool PythonObject::IsNone() const { return m_py_obj == Py_None; }
-
-bool PythonObject::IsValid() const { return m_py_obj != nullptr; }
-
-bool PythonObject::IsAllocated() const { return IsValid() && !IsNone(); }
-
 StructuredData::ObjectSP PythonObject::CreateStructuredObject() const {
   switch (GetObjectType()) {
   case PyObjectType::Dictionary:
@@ -201,43 +229,19 @@ StructuredData::ObjectSP PythonObject::CreateStructuredObject() const {
 }
 
 // PythonString
-PythonBytes::PythonBytes() : PythonObject() {}
 
-PythonBytes::PythonBytes(llvm::ArrayRef<uint8_t> bytes) : PythonObject() {
-  SetBytes(bytes);
-}
+PythonBytes::PythonBytes(llvm::ArrayRef<uint8_t> bytes) { SetBytes(bytes); }
 
-PythonBytes::PythonBytes(const uint8_t *bytes, size_t length) : PythonObject() {
+PythonBytes::PythonBytes(const uint8_t *bytes, size_t length) {
   SetBytes(llvm::ArrayRef<uint8_t>(bytes, length));
 }
 
-PythonBytes::PythonBytes(PyRefType type, PyObject *py_obj) : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a string
-}
-
-PythonBytes::~PythonBytes() {}
-
 bool PythonBytes::Check(PyObject *py_obj) {
   if (!py_obj)
     return false;
   return PyBytes_Check(py_obj);
 }
 
-void PythonBytes::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonBytes::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 llvm::ArrayRef<uint8_t> PythonBytes::GetBytes() const {
   if (!IsValid())
     return llvm::ArrayRef<uint8_t>();
@@ -257,8 +261,7 @@ size_t PythonBytes::GetSize() const {
 
 void PythonBytes::SetBytes(llvm::ArrayRef<uint8_t> bytes) {
   const char *data = reinterpret_cast<const char *>(bytes.data());
-  PyObject *py_bytes = PyBytes_FromStringAndSize(data, bytes.size());
-  PythonObject::Reset(PyRefType::Owned, py_bytes);
+  *this = Take<PythonBytes>(PyBytes_FromStringAndSize(data, bytes.size()));
 }
 
 StructuredData::StringSP PythonBytes::CreateStructuredString() const {
@@ -275,39 +278,15 @@ PythonByteArray::PythonByteArray(llvm::ArrayRef<uint8_t> bytes)
 
 PythonByteArray::PythonByteArray(const uint8_t *bytes, size_t length) {
   const char *str = reinterpret_cast<const char *>(bytes);
-  Reset(PyRefType::Owned, PyByteArray_FromStringAndSize(str, length));
-}
-
-PythonByteArray::PythonByteArray(PyRefType type, PyObject *o) {
-  Reset(type, o);
+  *this = Take<PythonByteArray>(PyByteArray_FromStringAndSize(str, length));
 }
 
-PythonByteArray::PythonByteArray(const PythonBytes &object)
-    : PythonObject(object) {}
-
-PythonByteArray::~PythonByteArray() {}
-
 bool PythonByteArray::Check(PyObject *py_obj) {
   if (!py_obj)
     return false;
   return PyByteArray_Check(py_obj);
 }
 
-void PythonByteArray::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonByteArray::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 llvm::ArrayRef<uint8_t> PythonByteArray::GetBytes() const {
   if (!IsValid())
     return llvm::ArrayRef<uint8_t>();
@@ -334,21 +313,18 @@ StructuredData::StringSP PythonByteArray::CreateStructuredString() const {
 
 // PythonString
 
-PythonString::PythonString(PyRefType type, PyObject *py_obj) : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a string
-}
-
-PythonString::PythonString(llvm::StringRef string) : PythonObject() {
-  SetString(string);
-}
-
-PythonString::PythonString(const char *string) : PythonObject() {
-  SetString(llvm::StringRef(string));
+Expected<PythonString> PythonString::FromUTF8(llvm::StringRef string) {
+#if PY_MAJOR_VERSION >= 3
+  PyObject *str = PyUnicode_FromStringAndSize(string.data(), string.size());
+#else
+  PyObject *str = PyString_FromStringAndSize(string.data(), string.size());
+#endif
+  if (!str)
+    return llvm::make_error<PythonException>();
+  return Take<PythonString>(str);
 }
 
-PythonString::PythonString() : PythonObject() {}
-
-PythonString::~PythonString() {}
+PythonString::PythonString(llvm::StringRef string) { SetString(string); }
 
 bool PythonString::Check(PyObject *py_obj) {
   if (!py_obj)
@@ -363,30 +339,40 @@ bool PythonString::Check(PyObject *py_obj) {
   return false;
 }
 
-void PythonString::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonString::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
+void PythonString::Convert(PyRefType &type, PyObject *&py_obj) {
 #if PY_MAJOR_VERSION < 3
   // In Python 2, Don't store PyUnicode objects directly, because we need
   // access to their underlying character buffers which Python 2 doesn't
   // provide.
-  if (PyUnicode_Check(py_obj))
-    result.Reset(PyRefType::Owned, PyUnicode_AsUTF8String(result.get()));
+  if (PyUnicode_Check(py_obj)) {
+    PyObject *s = PyUnicode_AsUTF8String(py_obj);
+    if (s == nullptr) {
+      PyErr_Clear();
+      if (type == PyRefType::Owned)
+        Py_DECREF(py_obj);
+      return;
+    }
+    if (type == PyRefType::Owned)
+      Py_DECREF(py_obj);
+    else
+      type = PyRefType::Owned;
+    py_obj = s;
+  }
 #endif
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
 }
 
 llvm::StringRef PythonString::GetString() const {
+  auto s = AsUTF8();
+  if (!s) {
+    llvm::consumeError(s.takeError());
+    return llvm::StringRef("");
+  }
+  return s.get();
+}
+
+Expected<llvm::StringRef> PythonString::AsUTF8() const {
   if (!IsValid())
-    return llvm::StringRef();
+    return nullDeref();
 
   Py_ssize_t size;
   const char *data;
@@ -394,10 +380,16 @@ llvm::StringRef PythonString::GetString() const {
 #if PY_MAJOR_VERSION >= 3
   data = PyUnicode_AsUTF8AndSize(m_py_obj, &size);
 #else
-  char *c;
-  PyString_AsStringAndSize(m_py_obj, &c, &size);
+  char *c = NULL;
+  int r = PyString_AsStringAndSize(m_py_obj, &c, &size);
+  if (r < 0)
+    c = NULL;
   data = c;
 #endif
+
+  if (!data)
+    return exception();
+
   return llvm::StringRef(data, size);
 }
 
@@ -413,13 +405,13 @@ size_t PythonString::GetSize() const {
 }
 
 void PythonString::SetString(llvm::StringRef string) {
-#if PY_MAJOR_VERSION >= 3
-  PyObject *unicode = PyUnicode_FromStringAndSize(string.data(), string.size());
-  PythonObject::Reset(PyRefType::Owned, unicode);
-#else
-  PyObject *str = PyString_FromStringAndSize(string.data(), string.size());
-  PythonObject::Reset(PyRefType::Owned, str);
-#endif
+  auto s = FromUTF8(string);
+  if (!s) {
+    llvm::consumeError(s.takeError());
+    Reset();
+  } else {
+    *this = std::move(s.get());
+  }
 }
 
 StructuredData::StringSP PythonString::CreateStructuredString() const {
@@ -430,18 +422,7 @@ StructuredData::StringSP PythonString::CreateStructuredString() const {
 
 // PythonInteger
 
-PythonInteger::PythonInteger() : PythonObject() {}
-
-PythonInteger::PythonInteger(PyRefType type, PyObject *py_obj)
-    : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a integer type
-}
-
-PythonInteger::PythonInteger(int64_t value) : PythonObject() {
-  SetInteger(value);
-}
-
-PythonInteger::~PythonInteger() {}
+PythonInteger::PythonInteger(int64_t value) { SetInteger(value); }
 
 bool PythonInteger::Check(PyObject *py_obj) {
   if (!py_obj)
@@ -456,16 +437,7 @@ bool PythonInteger::Check(PyObject *py_obj) {
 #endif
 }
 
-void PythonInteger::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonInteger::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
+void PythonInteger::Convert(PyRefType &type, PyObject *&py_obj) {
 #if PY_MAJOR_VERSION < 3
   // Always store this as a PyLong, which makes interoperability between Python
   // 2.x and Python 3.x easier.  This is only necessary in 2.x, since 3.x
@@ -474,16 +446,23 @@ void PythonInteger::Reset(PyRefType type, PyObject *py_obj) {
     // Since we converted the original object to a different type, the new
     // object is an owned object regardless of the ownership semantics
     // requested by the user.
-    result.Reset(PyRefType::Owned, PyLong_FromLongLong(PyInt_AsLong(py_obj)));
+    long long value = PyInt_AsLong(py_obj);
+    PyObject *l = nullptr;
+    if (!PyErr_Occurred())
+      l = PyLong_FromLongLong(value);
+    if (l == nullptr) {
+      PyErr_Clear();
+      if (type == PyRefType::Owned)
+        Py_DECREF(py_obj);
+      return;
+    }
+    if (type == PyRefType::Owned)
+      Py_DECREF(py_obj);
+    else
+      type = PyRefType::Owned;
+    py_obj = l;
   }
 #endif
-
-  assert(PyLong_Check(result.get()) &&
-         "Couldn't get a PyLong from this PyObject");
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
 }
 
 int64_t PythonInteger::GetInteger() const {
@@ -506,7 +485,7 @@ int64_t PythonInteger::GetInteger() const {
 }
 
 void PythonInteger::SetInteger(int64_t value) {
-  PythonObject::Reset(PyRefType::Owned, PyLong_FromLongLong(value));
+  *this = Take<PythonInteger>(PyLong_FromLongLong(value));
 }
 
 StructuredData::IntegerSP PythonInteger::CreateStructuredInteger() const {
@@ -517,11 +496,6 @@ StructuredData::IntegerSP PythonInteger::CreateStructuredInteger() const {
 
 // PythonBoolean
 
-PythonBoolean::PythonBoolean(PyRefType type, PyObject *py_obj)
-    : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a boolean type
-}
-
 PythonBoolean::PythonBoolean(bool value) {
   SetValue(value);
 }
@@ -530,27 +504,12 @@ bool PythonBoolean::Check(PyObject *py_obj) {
   return py_obj ? PyBool_Check(py_obj) : false;
 }
 
-void PythonBoolean::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonBoolean::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 bool PythonBoolean::GetValue() const {
   return m_py_obj ? PyObject_IsTrue(m_py_obj) : false;
 }
 
 void PythonBoolean::SetValue(bool value) {
-  PythonObject::Reset(PyRefType::Owned, PyBool_FromLong(value));
+  *this = Take<PythonBoolean>(PyBool_FromLong(value));
 }
 
 StructuredData::BooleanSP PythonBoolean::CreateStructuredBoolean() const {
@@ -561,42 +520,21 @@ StructuredData::BooleanSP PythonBoolean::CreateStructuredBoolean() const {
 
 // PythonList
 
-PythonList::PythonList(PyInitialValue value) : PythonObject() {
+PythonList::PythonList(PyInitialValue value) {
   if (value == PyInitialValue::Empty)
-    Reset(PyRefType::Owned, PyList_New(0));
-}
-
-PythonList::PythonList(int list_size) : PythonObject() {
-  Reset(PyRefType::Owned, PyList_New(list_size));
+    *this = Take<PythonList>(PyList_New(0));
 }
 
-PythonList::PythonList(PyRefType type, PyObject *py_obj) : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a list
+PythonList::PythonList(int list_size) {
+  *this = Take<PythonList>(PyList_New(list_size));
 }
 
-PythonList::~PythonList() {}
-
 bool PythonList::Check(PyObject *py_obj) {
   if (!py_obj)
     return false;
   return PyList_Check(py_obj);
 }
 
-void PythonList::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonList::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 uint32_t PythonList::GetSize() const {
   if (IsValid())
     return PyList_GET_SIZE(m_py_obj);
@@ -638,17 +576,13 @@ StructuredData::ArraySP PythonList::CreateStructuredArray() const {
 
 // PythonTuple
 
-PythonTuple::PythonTuple(PyInitialValue value) : PythonObject() {
+PythonTuple::PythonTuple(PyInitialValue value) {
   if (value == PyInitialValue::Empty)
-    Reset(PyRefType::Owned, PyTuple_New(0));
-}
-
-PythonTuple::PythonTuple(int tuple_size) : PythonObject() {
-  Reset(PyRefType::Owned, PyTuple_New(tuple_size));
+    *this = Take<PythonTuple>(PyTuple_New(0));
 }
 
-PythonTuple::PythonTuple(PyRefType type, PyObject *py_obj) : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a tuple
+PythonTuple::PythonTuple(int tuple_size) {
+  *this = Take<PythonTuple>(PyTuple_New(tuple_size));
 }
 
 PythonTuple::PythonTuple(std::initializer_list<PythonObject> objects) {
@@ -674,29 +608,12 @@ PythonTuple::PythonTuple(std::initializer_list<PyObject *> objects) {
   }
 }
 
-PythonTuple::~PythonTuple() {}
-
 bool PythonTuple::Check(PyObject *py_obj) {
   if (!py_obj)
     return false;
   return PyTuple_Check(py_obj);
 }
 
-void PythonTuple::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonTuple::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 uint32_t PythonTuple::GetSize() const {
   if (IsValid())
     return PyTuple_GET_SIZE(m_py_obj);
@@ -730,18 +647,11 @@ StructuredData::ArraySP PythonTuple::CreateStructuredArray() const {
 
 // PythonDictionary
 
-PythonDictionary::PythonDictionary(PyInitialValue value) : PythonObject() {
+PythonDictionary::PythonDictionary(PyInitialValue value) {
   if (value == PyInitialValue::Empty)
-    Reset(PyRefType::Owned, PyDict_New());
+    *this = Take<PythonDictionary>(PyDict_New());
 }
 
-PythonDictionary::PythonDictionary(PyRefType type, PyObject *py_obj)
-    : PythonObject() {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a dictionary
-}
-
-PythonDictionary::~PythonDictionary() {}
-
 bool PythonDictionary::Check(PyObject *py_obj) {
   if (!py_obj)
     return false;
@@ -749,21 +659,6 @@ bool PythonDictionary::Check(PyObject *py_obj) {
   return PyDict_Check(py_obj);
 }
 
-void PythonDictionary::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonDictionary::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 uint32_t PythonDictionary::GetSize() const {
   if (IsValid())
     return PyDict_Size(m_py_obj);
@@ -777,16 +672,66 @@ PythonList PythonDictionary::GetKeys() const {
 }
 
 PythonObject PythonDictionary::GetItemForKey(const PythonObject &key) const {
-  if (IsAllocated() && key.IsValid())
-    return PythonObject(PyRefType::Borrowed,
-                        PyDict_GetItem(m_py_obj, key.get()));
-  return PythonObject();
+  auto item = GetItem(key);
+  if (!item) {
+    llvm::consumeError(item.takeError());
+    return PythonObject();
+  }
+  return std::move(item.get());
+}
+
+Expected<PythonObject>
+PythonDictionary::GetItem(const PythonObject &key) const {
+  if (!IsValid())
+    return nullDeref();
+#if PY_MAJOR_VERSION >= 3
+  PyObject *o = PyDict_GetItemWithError(m_py_obj, key.get());
+  if (PyErr_Occurred())
+    return exception();
+#else
+  PyObject *o = PyDict_GetItem(m_py_obj, key.get());
+#endif
+  if (!o)
+    return keyError();
+  return Retain<PythonObject>(o);
+}
+
+Expected<PythonObject> PythonDictionary::GetItem(const Twine &key) const {
+  if (!IsValid())
+    return nullDeref();
+  PyObject *o = PyDict_GetItemString(m_py_obj, NullTerminated(key));
+  if (PyErr_Occurred())
+    return exception();
+  if (!o)
+    return keyError();
+  return Retain<PythonObject>(o);
+}
+
+Error PythonDictionary::SetItem(const PythonObject &key,
+                                const PythonObject &value) const {
+  if (!IsValid() || !value.IsValid())
+    return nullDeref();
+  int r = PyDict_SetItem(m_py_obj, key.get(), value.get());
+  if (r < 0)
+    return exception();
+  return Error::success();
+}
+
+Error PythonDictionary::SetItem(const Twine &key,
+                                const PythonObject &value) const {
+  if (!IsValid() || !value.IsValid())
+    return nullDeref();
+  int r = PyDict_SetItemString(m_py_obj, NullTerminated(key), value.get());
+  if (r < 0)
+    return exception();
+  return Error::success();
 }
 
 void PythonDictionary::SetItemForKey(const PythonObject &key,
                                      const PythonObject &value) {
-  if (IsAllocated() && key.IsValid() && value.IsValid())
-    PyDict_SetItem(m_py_obj, key.get(), value.get());
+  Error error = SetItem(key, value);
+  if (error)
+    llvm::consumeError(std::move(error));
 }
 
 StructuredData::DictionarySP
@@ -803,14 +748,6 @@ PythonDictionary::CreateStructuredDictionary() const {
   return result;
 }
 
-PythonModule::PythonModule() : PythonObject() {}
-
-PythonModule::PythonModule(PyRefType type, PyObject *py_obj) {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a module
-}
-
-PythonModule::~PythonModule() {}
-
 PythonModule PythonModule::BuiltinsModule() {
 #if PY_MAJOR_VERSION >= 3
   return AddModule("builtins");
@@ -826,9 +763,23 @@ PythonModule PythonModule::AddModule(llvm::StringRef module) {
   return PythonModule(PyRefType::Borrowed, PyImport_AddModule(str.c_str()));
 }
 
-PythonModule PythonModule::ImportModule(llvm::StringRef module) {
-  std::string str = module.str();
-  return PythonModule(PyRefType::Owned, PyImport_ImportModule(str.c_str()));
+Expected<PythonModule> PythonModule::Import(const Twine &name) {
+  PyObject *mod = PyImport_ImportModule(NullTerminated(name));
+  if (!mod)
+    return exception();
+  return Take<PythonModule>(mod);
+}
+
+Expected<PythonObject> PythonModule::Get(const Twine &name) {
+  if (!IsValid())
+    return nullDeref();
+  PyObject *dict = PyModule_GetDict(m_py_obj);
+  if (!dict)
+    return exception();
+  PyObject *item = PyDict_GetItemString(dict, NullTerminated(name));
+  if (!item)
+    return exception();
+  return Retain<PythonObject>(item);
 }
 
 bool PythonModule::Check(PyObject *py_obj) {
@@ -838,33 +789,12 @@ bool PythonModule::Check(PyObject *py_obj) {
   return PyModule_Check(py_obj);
 }
 
-void PythonModule::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonModule::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
-  }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
-}
-
 PythonDictionary PythonModule::GetDictionary() const {
-  return PythonDictionary(PyRefType::Borrowed, PyModule_GetDict(m_py_obj));
-}
-
-PythonCallable::PythonCallable() : PythonObject() {}
-
-PythonCallable::PythonCallable(PyRefType type, PyObject *py_obj) {
-  Reset(type, py_obj); // Use "Reset()" to ensure that py_obj is a callable
+  if (!IsValid())
+    return PythonDictionary();
+  return Retain<PythonDictionary>(PyModule_GetDict(m_py_obj));
 }
 
-PythonCallable::~PythonCallable() {}
-
 bool PythonCallable::Check(PyObject *py_obj) {
   if (!py_obj)
     return false;
@@ -872,32 +802,80 @@ bool PythonCallable::Check(PyObject *py_obj) {
   return PyCallable_Check(py_obj);
 }
 
-void PythonCallable::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonCallable::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
+PythonCallable::ArgInfo PythonCallable::GetNumInitArguments() const {
+  auto arginfo = GetInitArgInfo();
+  if (!arginfo) {
+    llvm::consumeError(arginfo.takeError());
+    return ArgInfo{};
   }
-
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
+  return arginfo.get();
 }
 
-PythonCallable::ArgInfo PythonCallable::GetNumArguments() const {
-  ArgInfo result = {0, false, false, false};
+Expected<PythonCallable::ArgInfo> PythonCallable::GetInitArgInfo() const {
   if (!IsValid())
-    return result;
+    return nullDeref();
+  auto init = As<PythonCallable>(GetAttribute("__init__"));
+  if (!init)
+    return init.takeError();
+  return init.get().GetArgInfo();
+}
+
+#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
+static const char get_arg_info_script[] = R"(
+from inspect import signature, Parameter, ismethod
+from collections import namedtuple
+ArgInfo = namedtuple('ArgInfo', ['count', 'has_varargs', 'is_bound_method'])
+def main(f):
+    count = 0
+    varargs = False
+    for parameter in signature(f).parameters.values():
+        kind = parameter.kind
+        if kind in (Parameter.POSITIONAL_ONLY,
+                    Parameter.POSITIONAL_OR_KEYWORD):
+            count += 1
+        elif kind == Parameter.VAR_POSITIONAL:
+            varargs = True
+        elif kind in (Parameter.KEYWORD_ONLY,
+                      Parameter.VAR_KEYWORD):
+            pass
+        else:
+            raise Exception(f'unknown parameter kind: {kind}')
+    return ArgInfo(count, varargs, ismethod(f))
+)";
+#endif
+
+Expected<PythonCallable::ArgInfo> PythonCallable::GetArgInfo() const {
+  ArgInfo result = {};
+  if (!IsValid())
+    return nullDeref();
+
+#if PY_MAJOR_VERSION >= 3 && PY_MINOR_VERSION >= 3
+
+  // no need to synchronize access to this global, we already have the GIL
+  static PythonScript get_arg_info(get_arg_info_script);
+  Expected<PythonObject> pyarginfo = get_arg_info(*this);
+  if (!pyarginfo)
+    return pyarginfo.takeError();
+  result.count = cantFail(As<long long>(pyarginfo.get().GetAttribute("count")));
+  result.has_varargs =
+      cantFail(As<bool>(pyarginfo.get().GetAttribute("has_varargs")));
+  bool is_method =
+      cantFail(As<bool>(pyarginfo.get().GetAttribute("is_bound_method")));
+  result.max_positional_args =
+      result.has_varargs ? ArgInfo::UNBOUNDED : result.count;
+
+  // FIXME emulate old broken behavior
+  if (is_method)
+    result.count++;
 
+#else
+  bool is_bound_method = false;
   PyObject *py_func_obj = m_py_obj;
   if (PyMethod_Check(py_func_obj)) {
     py_func_obj = PyMethod_GET_FUNCTION(py_func_obj);
     PythonObject im_self = GetAttributeValue("im_self");
     if (im_self.IsValid() && !im_self.IsNone())
-      result.is_bound_method = true;
+      is_bound_method = true;
   } else {
     // see if this is a callable object with an __call__ method
     if (!PyFunction_Check(py_func_obj)) {
@@ -906,9 +884,9 @@ PythonCallable::ArgInfo PythonCallable::GetNumArguments() const {
         auto __callable__ = __call__.AsType<PythonCallable>();
         if (__callable__.IsValid()) {
           py_func_obj = PyMethod_GET_FUNCTION(__callable__.get());
-          PythonObject im_self = GetAttributeValue("im_self");
+          PythonObject im_self = __callable__.GetAttributeValue("im_self");
           if (im_self.IsValid() && !im_self.IsNone())
-            result.is_bound_method = true;
+            is_bound_method = true;
         }
       }
     }
@@ -923,10 +901,27 @@ PythonCallable::ArgInfo PythonCallable::GetNumArguments() const {
 
   result.count = code->co_argcount;
   result.has_varargs = !!(code->co_flags & CO_VARARGS);
-  result.has_kwargs = !!(code->co_flags & CO_VARKEYWORDS);
+  result.max_positional_args = result.has_varargs
+                                   ? ArgInfo::UNBOUNDED
+                                   : (result.count - (int)is_bound_method);
+
+#endif
+
   return result;
 }
 
+constexpr unsigned
+    PythonCallable::ArgInfo::UNBOUNDED; // FIXME delete after c++17
+
+PythonCallable::ArgInfo PythonCallable::GetNumArguments() const {
+  auto arginfo = GetArgInfo();
+  if (!arginfo) {
+    llvm::consumeError(arginfo.takeError());
+    return ArgInfo{};
+  }
+  return arginfo.get();
+}
+
 PythonObject PythonCallable::operator()() {
   return PythonObject(PyRefType::Owned, PyObject_CallObject(m_py_obj, nullptr));
 }
@@ -945,21 +940,9 @@ operator()(std::initializer_list<PythonObject> args) {
                       PyObject_CallObject(m_py_obj, arg_tuple.get()));
 }
 
-PythonFile::PythonFile() : PythonObject() {}
-
-PythonFile::PythonFile(File &file, const char *mode) { Reset(file, mode); }
-
-PythonFile::PythonFile(const char *path, const char *mode) {
-  lldb_private::File file;
-  FileSystem::Instance().Open(file, FileSpec(path), GetOptionsFromMode(mode));
-  Reset(file, mode);
-}
-
-PythonFile::PythonFile(PyRefType type, PyObject *o) { Reset(type, o); }
-
-PythonFile::~PythonFile() {}
-
 bool PythonFile::Check(PyObject *py_obj) {
+  if (!py_obj)
+    return false;
 #if PY_MAJOR_VERSION < 3
   return PyFile_Check(py_obj);
 #else
@@ -967,86 +950,633 @@ bool PythonFile::Check(PyObject *py_obj) {
   // first-class object type anymore.  `PyFile_FromFd` is just a thin wrapper
   // over `io.open()`, which returns some object derived from `io.IOBase`. As a
   // result, the only way to detect a file in Python 3 is to check whether it
-  // inherits from `io.IOBase`.  Since it is possible for non-files to also
-  // inherit from `io.IOBase`, we additionally verify that it has the `fileno`
-  // attribute, which should guarantee that it is backed by the file system.
-  PythonObject io_module(PyRefType::Owned, PyImport_ImportModule("io"));
-  PythonDictionary io_dict(PyRefType::Borrowed,
-                           PyModule_GetDict(io_module.get()));
-  PythonObject io_base_class = io_dict.GetItemForKey(PythonString("IOBase"));
-
-  PythonObject object_type(PyRefType::Owned, PyObject_Type(py_obj));
-
-  if (1 != PyObject_IsSubclass(object_type.get(), io_base_class.get()))
+  // inherits from `io.IOBase`.
+  auto io_module = PythonModule::Import("io");
+  if (!io_module) {
+    llvm::consumeError(io_module.takeError());
     return false;
-  if (!object_type.HasAttribute("fileno"))
+  }
+  auto iobase = io_module.get().Get("IOBase");
+  if (!iobase) {
+    llvm::consumeError(iobase.takeError());
     return false;
-
-  return true;
+  }
+  int r = PyObject_IsInstance(py_obj, iobase.get().get());
+  if (r < 0) {
+    llvm::consumeError(exception()); // clear the exception and log it.
+    return false;
+  }
+  return !!r;
 #endif
 }
 
-void PythonFile::Reset(PyRefType type, PyObject *py_obj) {
-  // Grab the desired reference type so that if we end up rejecting `py_obj` it
-  // still gets decremented if necessary.
-  PythonObject result(type, py_obj);
-
-  if (!PythonFile::Check(py_obj)) {
-    PythonObject::Reset();
-    return;
+namespace {
+class GIL {
+public:
+  GIL() {
+    m_state = PyGILState_Ensure();
+    assert(!PyErr_Occurred());
   }
+  ~GIL() { PyGILState_Release(m_state); }
+
+protected:
+  PyGILState_STATE m_state;
+};
+} // namespace
+
+const char *PythonException::toCString() const {
+  if (!m_repr_bytes)
+    return "unknown exception";
+  return PyBytes_AS_STRING(m_repr_bytes);
+}
+
+PythonException::PythonException(const char *caller) {
+  assert(PyErr_Occurred());
+  m_exception_type = m_exception = m_traceback = m_repr_bytes = NULL;
+  PyErr_Fetch(&m_exception_type, &m_exception, &m_traceback);
+  PyErr_NormalizeException(&m_exception_type, &m_exception, &m_traceback);
+  PyErr_Clear();
+  if (m_exception) {
+    PyObject *repr = PyObject_Repr(m_exception);
+    if (repr) {
+      m_repr_bytes = PyUnicode_AsEncodedString(repr, "utf-8", nullptr);
+      if (!m_repr_bytes) {
+        PyErr_Clear();
+      }
+      Py_XDECREF(repr);
+    } else {
+      PyErr_Clear();
+    }
+  }
+  Log *log = GetLogIfAllCategoriesSet(LIBLLDB_LOG_SCRIPT);
+  if (caller)
+    LLDB_LOGF(log, "%s failed with exception: %s", caller, toCString());
+  else
+    LLDB_LOGF(log, "python exception: %s", toCString());
+}
+void PythonException::Restore() {
+  if (m_exception_type && m_exception) {
+    PyErr_Restore(m_exception_type, m_exception, m_traceback);
+  } else {
+    PyErr_SetString(PyExc_Exception, toCString());
+  }
+  m_exception_type = m_exception = m_traceback = NULL;
+}
 
-  // Calling PythonObject::Reset(const PythonObject&) will lead to stack
-  // overflow since it calls back into the virtual implementation.
-  PythonObject::Reset(PyRefType::Borrowed, result.get());
+PythonException::~PythonException() {
+  Py_XDECREF(m_exception_type);
+  Py_XDECREF(m_exception);
+  Py_XDECREF(m_traceback);
+  Py_XDECREF(m_repr_bytes);
 }
 
-void PythonFile::Reset(File &file, const char *mode) {
-  if (!file.IsValid()) {
-    Reset();
-    return;
+void PythonException::log(llvm::raw_ostream &OS) const { OS << toCString(); }
+
+std::error_code PythonException::convertToErrorCode() const {
+  return llvm::inconvertibleErrorCode();
+}
+
+bool PythonException::Matches(PyObject *exc) const {
+  return PyErr_GivenExceptionMatches(m_exception_type, exc);
+}
+
+const char read_exception_script[] = R"(
+import sys
+from traceback import print_exception
+if sys.version_info.major < 3:
+  from StringIO import StringIO
+else:
+  from io import StringIO
+def main(exc_type, exc_value, tb):
+  f = StringIO()
+  print_exception(exc_type, exc_value, tb, file=f)
+  return f.getvalue()
+)";
+
+std::string PythonException::ReadBacktrace() const {
+
+  if (!m_traceback)
+    return toCString();
+
+  // no need to synchronize access to this global, we already have the GIL
+  static PythonScript read_exception(read_exception_script);
+
+  Expected<std::string> backtrace = As<std::string>(
+      read_exception(m_exception_type, m_exception, m_traceback));
+
+  if (!backtrace) {
+    std::string message =
+        std::string(toCString()) + "\n" +
+        "Traceback unavailble, an error occurred while reading it:\n";
+    return (message + llvm::toString(backtrace.takeError()));
   }
 
-  char *cmode = const_cast<char *>(mode);
+  return std::move(backtrace.get());
+}
+
+char PythonException::ID = 0;
+
+llvm::Expected<File::OpenOptions>
+GetOptionsForPyObject(const PythonObject &obj) {
 #if PY_MAJOR_VERSION >= 3
-  Reset(PyRefType::Owned, PyFile_FromFd(file.GetDescriptor(), nullptr, cmode,
-                                        -1, nullptr, "ignore", nullptr, 0));
+  auto options = File::OpenOptions(0);
+  auto readable = As<bool>(obj.CallMethod("readable"));
+  if (!readable)
+    return readable.takeError();
+  auto writable = As<bool>(obj.CallMethod("writable"));
+  if (!writable)
+    return writable.takeError();
+  if (readable.get())
+    options |= File::eOpenOptionRead;
+  if (writable.get())
+    options |= File::eOpenOptionWrite;
+  return options;
 #else
-  // Read through the Python source, doesn't seem to modify these strings
-  Reset(PyRefType::Owned,
-        PyFile_FromFile(file.GetStream(), const_cast<char *>(""), cmode,
-                        nullptr));
+  PythonString py_mode = obj.GetAttributeValue("mode").AsType<PythonString>();
+  return File::GetOptionsFromMode(py_mode.GetString());
 #endif
 }
 
-uint32_t PythonFile::GetOptionsFromMode(llvm::StringRef mode) {
-  if (mode.empty())
-    return 0;
+// Base class template for python files.   All it knows how to do
+// is hold a reference to the python object and close or flush it
+// when the File is closed.
+namespace {
+template <typename Base> class OwnedPythonFile : public Base {
+public:
+  template <typename... Args>
+  OwnedPythonFile(const PythonFile &file, bool borrowed, Args... args)
+      : Base(args...), m_py_obj(file), m_borrowed(borrowed) {
+    assert(m_py_obj);
+  }
+
+  ~OwnedPythonFile() override {
+    assert(m_py_obj);
+    GIL takeGIL;
+    Close();
+    // we need to ensure the python object is released while we still
+    // hold the GIL
+    m_py_obj.Reset();
+  }
+
+  bool IsPythonSideValid() const {
+    GIL takeGIL;
+    auto closed = As<bool>(m_py_obj.GetAttribute("closed"));
+    if (!closed) {
+      llvm::consumeError(closed.takeError());
+      return false;
+    }
+    return !closed.get();
+  }
+
+  bool IsValid() const override {
+    return IsPythonSideValid() && Base::IsValid();
+  }
+
+  Status Close() override {
+    assert(m_py_obj);
+    Status py_error, base_error;
+    GIL takeGIL;
+    if (!m_borrowed) {
+      auto r = m_py_obj.CallMethod("close");
+      if (!r)
+        py_error = Status(r.takeError());
+    }
+    base_error = Base::Close();
+    if (py_error.Fail())
+      return py_error;
+    return base_error;
+  };
+
+  PyObject *GetPythonObject() const {
+    assert(m_py_obj.IsValid());
+    return m_py_obj.get();
+  }
+
+  static bool classof(const File *file) = delete;
+
+protected:
+  PythonFile m_py_obj;
+  bool m_borrowed;
+};
+} // namespace
+
+// A SimplePythonFile is a OwnedPythonFile that just does all I/O as
+// a NativeFile
+namespace {
+class SimplePythonFile : public OwnedPythonFile<NativeFile> {
+public:
+  SimplePythonFile(const PythonFile &file, bool borrowed, int fd,
+                   File::OpenOptions options)
+      : OwnedPythonFile(file, borrowed, fd, options, false) {}
+
+  static char ID;
+  bool isA(const void *classID) const override {
+    return classID == &ID || NativeFile::isA(classID);
+  }
+  static bool classof(const File *file) { return file->isA(&ID); }
+};
+char SimplePythonFile::ID = 0;
+} // namespace
+
+#if PY_MAJOR_VERSION >= 3
+
+namespace {
+class PythonBuffer {
+public:
+  PythonBuffer &operator=(const PythonBuffer &) = delete;
+  PythonBuffer(const PythonBuffer &) = delete;
+
+  static Expected<PythonBuffer> Create(PythonObject &obj,
+                                       int flags = PyBUF_SIMPLE) {
+    Py_buffer py_buffer = {};
+    PyObject_GetBuffer(obj.get(), &py_buffer, flags);
+    if (!py_buffer.obj)
+      return llvm::make_error<PythonException>();
+    return PythonBuffer(py_buffer);
+  }
+
+  PythonBuffer(PythonBuffer &&other) {
+    m_buffer = other.m_buffer;
+    other.m_buffer.obj = nullptr;
+  }
 
-  return llvm::StringSwitch<uint32_t>(mode.str())
-      .Case("r", File::eOpenOptionRead)
-      .Case("w", File::eOpenOptionWrite)
-      .Case("a", File::eOpenOptionWrite | File::eOpenOptionAppend |
-                     File::eOpenOptionCanCreate)
-      .Case("r+", File::eOpenOptionRead | File::eOpenOptionWrite)
-      .Case("w+", File::eOpenOptionRead | File::eOpenOptionWrite |
-                      File::eOpenOptionCanCreate | File::eOpenOptionTruncate)
-      .Case("a+", File::eOpenOptionRead | File::eOpenOptionWrite |
-                      File::eOpenOptionAppend | File::eOpenOptionCanCreate)
-      .Default(0);
+  ~PythonBuffer() {
+    if (m_buffer.obj)
+      PyBuffer_Release(&m_buffer);
+  }
+
+  Py_buffer &get() { return m_buffer; }
+
+private:
+  // takes ownership of the buffer.
+  PythonBuffer(const Py_buffer &py_buffer) : m_buffer(py_buffer) {}
+  Py_buffer m_buffer;
+};
+} // namespace
+
+// Shared methods between TextPythonFile and BinaryPythonFile
+namespace {
+class PythonIOFile : public OwnedPythonFile<File> {
+public:
+  PythonIOFile(const PythonFile &file, bool borrowed)
+      : OwnedPythonFile(file, borrowed) {}
+
+  ~PythonIOFile() override { Close(); }
+
+  bool IsValid() const override { return IsPythonSideValid(); }
+
+  Status Close() override {
+    assert(m_py_obj);
+    GIL takeGIL;
+    if (m_borrowed)
+      return Flush();
+    auto r = m_py_obj.CallMethod("close");
+    if (!r)
+      return Status(r.takeError());
+    return Status();
+  }
+
+  Status Flush() override {
+    GIL takeGIL;
+    auto r = m_py_obj.CallMethod("flush");
+    if (!r)
+      return Status(r.takeError());
+    return Status();
+  }
+
+  Expected<File::OpenOptions> GetOptions() const override {
+    GIL takeGIL;
+    return GetOptionsForPyObject(m_py_obj);
+  }
+
+  static char ID;
+  bool isA(const void *classID) const override {
+    return classID == &ID || File::isA(classID);
+  }
+  static bool classof(const File *file) { return file->isA(&ID); }
+};
+char PythonIOFile::ID = 0;
+} // namespace
+
+namespace {
+class BinaryPythonFile : public PythonIOFile {
+protected:
+  int m_descriptor;
+
+public:
+  BinaryPythonFile(int fd, const PythonFile &file, bool borrowed)
+      : PythonIOFile(file, borrowed),
+        m_descriptor(File::DescriptorIsValid(fd) ? fd
+                                                 : File::kInvalidDescriptor) {}
+
+  int GetDescriptor() const override { return m_descriptor; }
+
+  Status Write(const void *buf, size_t &num_bytes) override {
+    GIL takeGIL;
+    PyObject *pybuffer_p = PyMemoryView_FromMemory(
+        const_cast<char *>((const char *)buf), num_bytes, PyBUF_READ);
+    if (!pybuffer_p)
+      return Status(llvm::make_error<PythonException>());
+    auto pybuffer = Take<PythonObject>(pybuffer_p);
+    num_bytes = 0;
+    auto bytes_written = As<long long>(m_py_obj.CallMethod("write", pybuffer));
+    if (!bytes_written)
+      return Status(bytes_written.takeError());
+    if (bytes_written.get() < 0)
+      return Status(".write() method returned a negative number!");
+    static_assert(sizeof(long long) >= sizeof(size_t), "overflow");
+    num_bytes = bytes_written.get();
+    return Status();
+  }
+
+  Status Read(void *buf, size_t &num_bytes) override {
+    GIL takeGIL;
+    static_assert(sizeof(long long) >= sizeof(size_t), "overflow");
+    auto pybuffer_obj =
+        m_py_obj.CallMethod("read", (unsigned long long)num_bytes);
+    if (!pybuffer_obj)
+      return Status(pybuffer_obj.takeError());
+    num_bytes = 0;
+    if (pybuffer_obj.get().IsNone()) {
+      // EOF
+      num_bytes = 0;
+      return Status();
+    }
+    auto pybuffer = PythonBuffer::Create(pybuffer_obj.get());
+    if (!pybuffer)
+      return Status(pybuffer.takeError());
+    memcpy(buf, pybuffer.get().get().buf, pybuffer.get().get().len);
+    num_bytes = pybuffer.get().get().len;
+    return Status();
+  }
+};
+} // namespace
+
+namespace {
+class TextPythonFile : public PythonIOFile {
+protected:
+  int m_descriptor;
+
+public:
+  TextPythonFile(int fd, const PythonFile &file, bool borrowed)
+      : PythonIOFile(file, borrowed),
+        m_descriptor(File::DescriptorIsValid(fd) ? fd
+                                                 : File::kInvalidDescriptor) {}
+
+  int GetDescriptor() const override { return m_descriptor; }
+
+  Status Write(const void *buf, size_t &num_bytes) override {
+    GIL takeGIL;
+    auto pystring =
+        PythonString::FromUTF8(llvm::StringRef((const char *)buf, num_bytes));
+    if (!pystring)
+      return Status(pystring.takeError());
+    num_bytes = 0;
+    auto bytes_written =
+        As<long long>(m_py_obj.CallMethod("write", pystring.get()));
+    if (!bytes_written)
+      return Status(bytes_written.takeError());
+    if (bytes_written.get() < 0)
+      return Status(".write() method returned a negative number!");
+    static_assert(sizeof(long long) >= sizeof(size_t), "overflow");
+    num_bytes = bytes_written.get();
+    return Status();
+  }
+
+  Status Read(void *buf, size_t &num_bytes) override {
+    GIL takeGIL;
+    size_t num_chars = num_bytes / 6;
+    size_t orig_num_bytes = num_bytes;
+    num_bytes = 0;
+    if (orig_num_bytes < 6) {
+      return Status("can't read less than 6 bytes from a utf8 text stream");
+    }
+    auto pystring = As<PythonString>(
+        m_py_obj.CallMethod("read", (unsigned long long)num_chars));
+    if (!pystring)
+      return Status(pystring.takeError());
+    if (pystring.get().IsNone()) {
+      // EOF
+      return Status();
+    }
+    auto stringref = pystring.get().AsUTF8();
+    if (!stringref)
+      return Status(stringref.takeError());
+    num_bytes = stringref.get().size();
+    memcpy(buf, stringref.get().begin(), num_bytes);
+    return Status();
+  }
+};
+} // namespace
+
+#endif
+
+llvm::Expected<FileSP> PythonFile::ConvertToFile(bool borrowed) {
+  if (!IsValid())
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "invalid PythonFile");
+
+  int fd = PyObject_AsFileDescriptor(m_py_obj);
+  if (fd < 0) {
+    PyErr_Clear();
+    return ConvertToFileForcingUseOfScriptingIOMethods(borrowed);
+  }
+  auto options = GetOptionsForPyObject(*this);
+  if (!options)
+    return options.takeError();
+
+  // LLDB and python will not share I/O buffers.  We should probably
+  // flush the python buffers now.
+  auto r = CallMethod("flush");
+  if (!r)
+    return r.takeError();
+
+  FileSP file_sp;
+  if (borrowed) {
+    // In this case we we don't need to retain the python
+    // object at all.
+    file_sp = std::make_shared<NativeFile>(fd, options.get(), false);
+  } else {
+    file_sp = std::static_pointer_cast<File>(
+        std::make_shared<SimplePythonFile>(*this, borrowed, fd, options.get()));
+  }
+  if (!file_sp->IsValid())
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "invalid File");
+
+  return file_sp;
 }
 
-bool PythonFile::GetUnderlyingFile(File &file) const {
+llvm::Expected<FileSP>
+PythonFile::ConvertToFileForcingUseOfScriptingIOMethods(bool borrowed) {
+
+  assert(!PyErr_Occurred());
+
   if (!IsValid())
-    return false;
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "invalid PythonFile");
+
+#if PY_MAJOR_VERSION < 3
+
+  return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                 "not supported on python 2");
+
+#else
+
+  int fd = PyObject_AsFileDescriptor(m_py_obj);
+  if (fd < 0) {
+    PyErr_Clear();
+    fd = File::kInvalidDescriptor;
+  }
+
+  auto io_module = PythonModule::Import("io");
+  if (!io_module)
+    return io_module.takeError();
+  auto textIOBase = io_module.get().Get("TextIOBase");
+  if (!textIOBase)
+    return textIOBase.takeError();
+  auto rawIOBase = io_module.get().Get("RawIOBase");
+  if (!rawIOBase)
+    return rawIOBase.takeError();
+  auto bufferedIOBase = io_module.get().Get("BufferedIOBase");
+  if (!bufferedIOBase)
+    return bufferedIOBase.takeError();
+
+  FileSP file_sp;
+
+  auto isTextIO = IsInstance(textIOBase.get());
+  if (!isTextIO)
+    return isTextIO.takeError();
+  if (isTextIO.get())
+    file_sp = std::static_pointer_cast<File>(
+        std::make_shared<TextPythonFile>(fd, *this, borrowed));
+
+  auto isRawIO = IsInstance(rawIOBase.get());
+  if (!isRawIO)
+    return isRawIO.takeError();
+  auto isBufferedIO = IsInstance(bufferedIOBase.get());
+  if (!isBufferedIO)
+    return isBufferedIO.takeError();
+
+  if (isRawIO.get() || isBufferedIO.get()) {
+    file_sp = std::static_pointer_cast<File>(
+        std::make_shared<BinaryPythonFile>(fd, *this, borrowed));
+  }
+
+  if (!file_sp)
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "python file is neither text nor binary");
+
+  if (!file_sp->IsValid())
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "invalid File");
+
+  return file_sp;
+
+#endif
+}
+
+Expected<PythonFile> PythonFile::FromFile(File &file, const char *mode) {
+  if (!file.IsValid())
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "invalid file");
+
+  if (auto *simple = llvm::dyn_cast<SimplePythonFile>(&file))
+    return Retain<PythonFile>(simple->GetPythonObject());
+#if PY_MAJOR_VERSION >= 3
+  if (auto *pythonio = llvm::dyn_cast<PythonIOFile>(&file))
+    return Retain<PythonFile>(pythonio->GetPythonObject());
+#endif
+
+  if (!mode) {
+    auto m = file.GetOpenMode();
+    if (!m)
+      return m.takeError();
+    mode = m.get();
+  }
+
+  PyObject *file_obj;
+#if PY_MAJOR_VERSION >= 3
+  file_obj = PyFile_FromFd(file.GetDescriptor(), nullptr, mode, -1, nullptr,
+                           "ignore", nullptr, 0);
+#else
+  // Read through the Python source, doesn't seem to modify these strings
+  char *cmode = const_cast<char *>(mode);
+  // We pass ::flush instead of ::fclose here so we borrow the FILE* --
+  // the lldb_private::File still owns it.
+  file_obj =
+      PyFile_FromFile(file.GetStream(), const_cast<char *>(""), cmode, ::fflush);
+#endif
+
+  if (!file_obj)
+    return exception();
+
+  return Take<PythonFile>(file_obj);
+}
+
+Error PythonScript::Init() {
+  if (function.IsValid())
+    return Error::success();
+
+  PythonDictionary globals(PyInitialValue::Empty);
+  auto builtins = PythonModule::BuiltinsModule();
+  if (Error error = globals.SetItem("__builtins__", builtins))
+    return error;
+  PyObject *o =
+      PyRun_String(script, Py_file_input, globals.get(), globals.get());
+  if (!o)
+    return exception();
+  Take<PythonObject>(o);
+  auto f = As<PythonCallable>(globals.GetItem("main"));
+  if (!f)
+    return f.takeError();
+  function = std::move(f.get());
+
+  return Error::success();
+}
+
+llvm::Expected<PythonObject>
+python::runStringOneLine(const llvm::Twine &string,
+                         const PythonDictionary &globals,
+                         const PythonDictionary &locals) {
+  if (!globals.IsValid() || !locals.IsValid())
+    return nullDeref();
+
+  PyObject *code =
+      Py_CompileString(NullTerminated(string), "<string>", Py_eval_input);
+  if (!code) {
+    PyErr_Clear();
+    code =
+        Py_CompileString(NullTerminated(string), "<string>", Py_single_input);
+  }
+  if (!code)
+    return exception();
+  auto code_ref = Take<PythonObject>(code);
+
+#if PY_MAJOR_VERSION < 3
+  PyObject *result =
+      PyEval_EvalCode((PyCodeObject *)code, globals.get(), locals.get());
+#else
+  PyObject *result = PyEval_EvalCode(code, globals.get(), locals.get());
+#endif
+
+  if (!result)
+    return exception();
+
+  return Take<PythonObject>(result);
+}
 
-  file.Close();
-  // We don't own the file descriptor returned by this function, make sure the
-  // File object knows about that.
-  file.SetDescriptor(PyObject_AsFileDescriptor(m_py_obj), false);
-  PythonString py_mode = GetAttributeValue("mode").AsType<PythonString>();
-  file.SetOptions(PythonFile::GetOptionsFromMode(py_mode.GetString()));
-  return file.IsValid();
+llvm::Expected<PythonObject>
+python::runStringMultiLine(const llvm::Twine &string,
+                           const PythonDictionary &globals,
+                           const PythonDictionary &locals) {
+  if (!globals.IsValid() || !locals.IsValid())
+    return nullDeref();
+  PyObject *result = PyRun_String(NullTerminated(string), Py_file_input,
+                                  globals.get(), locals.get());
+  if (!result)
+    return exception();
+  return Take<PythonObject>(result);
 }
 
 #endif
diff --git a/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h b/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
index 049ce90bb1b1..373d3212697d 100644
--- a/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
+++ b/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h
@@ -6,6 +6,45 @@
 //
 //===----------------------------------------------------------------------===//
 
+//
+// !! FIXME FIXME FIXME !!
+//
+// Python APIs nearly all can return an exception.   They do this
+// by returning NULL, or -1, or some such value and setting
+// the exception state with PyErr_Set*().   Exceptions must be
+// handled before further python API functions are called.   Failure
+// to do so will result in asserts on debug builds of python.
+// It will also sometimes, but not usually result in crashes of
+// release builds.
+//
+// Nearly all the code in this header does not handle python exceptions
+// correctly.  It should all be converted to return Expected<> or
+// Error types to capture the exception.
+//
+// Everything in this file except functions that return Error or
+// Expected<> is considered deprecated and should not be
+// used in new code.  If you need to use it, fix it first.
+//
+//
+// TODOs for this file
+//
+// * Make all methods safe for exceptions.
+//
+// * Eliminate method signatures that must translate exceptions into
+//   empty objects or NULLs.   Almost everything here should return
+//   Expected<>.   It should be acceptable for certain operations that
+//   can never fail to assert instead, such as the creation of
+//   PythonString from a string literal.
+//
+// * Elimintate Reset(), and make all non-default constructors private.
+//   Python objects should be created with Retain<> or Take<>, and they
+//   should be assigned with operator=
+//
+// * Eliminate default constructors, make python objects always
+//   nonnull, and use optionals where necessary.
+//
+
+
 #ifndef LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONDATAOBJECTS_H
 #define LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONDATAOBJECTS_H
 
@@ -20,12 +59,15 @@
 #include "llvm/ADT/ArrayRef.h"
 
 namespace lldb_private {
+namespace python {
 
+class PythonObject;
 class PythonBytes;
 class PythonString;
 class PythonList;
 class PythonDictionary;
 class PythonInteger;
+class PythonException;
 
 class StructuredPythonObject : public StructuredData::Generic {
 public:
@@ -43,7 +85,7 @@ public:
 
   bool IsValid() const override { return GetValue() && GetValue() != Py_None; }
 
-  void Dump(Stream &s, bool pretty_print = true) const override;
+  void Serialize(llvm::json::OStream &s) const override;
 
 private:
   DISALLOW_COPY_AND_ASSIGN(StructuredPythonObject);
@@ -72,61 +114,137 @@ enum class PyRefType {
             // not call Py_INCREF.
 };
 
-enum class PyInitialValue { Invalid, Empty };
 
-class PythonObject {
-public:
-  PythonObject() : m_py_obj(nullptr) {}
+// Take a reference that you already own, and turn it into
+// a PythonObject.
+//
+// Most python API methods will return a +1 reference
+// if they succeed or NULL if and only if
+// they set an exception.   Use this to collect such return
+// values, after checking for NULL.
+//
+// If T is not just PythonObject, then obj must be already be
+// checked to be of the correct type.
+template <typename T> T Take(PyObject *obj) {
+  assert(obj);
+  assert(!PyErr_Occurred());
+  T thing(PyRefType::Owned, obj);
+  assert(thing.IsValid());
+  return std::move(thing);
+}
+
+// Retain a reference you have borrowed, and turn it into
+// a PythonObject.
+//
+// A minority of python APIs return a borrowed reference
+// instead of a +1.   They will also return NULL if and only
+// if they set an exception.   Use this to collect such return
+// values, after checking for NULL.
+//
+// If T is not just PythonObject, then obj must be already be
+// checked to be of the correct type.
+template <typename T> T Retain(PyObject *obj) {
+  assert(obj);
+  assert(!PyErr_Occurred());
+  T thing(PyRefType::Borrowed, obj);
+  assert(thing.IsValid());
+  return std::move(thing);
+}
+
+// This class can be used like a utility function to convert from
+// a llvm-friendly Twine into a null-terminated const char *,
+// which is the form python C APIs want their strings in.
+//
+// Example:
+// const llvm::Twine &some_twine;
+// PyFoo_Bar(x, y, z, NullTerminated(some_twine));
+//
+// Why a class instead of a function?  If the twine isn't already null
+// terminated, it will need a temporary buffer to copy the string
+// into.   We need that buffer to stick around for the lifetime of the
+// statement.
+class NullTerminated {
+  const char *str;
+  llvm::SmallString<32> storage;
 
-  PythonObject(PyRefType type, PyObject *py_obj) : m_py_obj(nullptr) {
-    Reset(type, py_obj);
+public:
+  NullTerminated(const llvm::Twine &twine) {
+    llvm::StringRef ref = twine.toNullTerminatedStringRef(storage);
+    str = ref.begin();
   }
+  operator const char *() { return str; }
+};
 
-  PythonObject(const PythonObject &rhs) : m_py_obj(nullptr) { Reset(rhs); }
+inline llvm::Error nullDeref() {
+  return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                 "A NULL PyObject* was dereferenced");
+}
 
-  virtual ~PythonObject() { Reset(); }
+inline llvm::Error exception(const char *s = nullptr) {
+  return llvm::make_error<PythonException>(s);
+}
 
-  void Reset() {
-    // Avoid calling the virtual method since it's not necessary
-    // to actually validate the type of the PyObject if we're
-    // just setting to null.
-    if (Py_IsInitialized())
-      Py_XDECREF(m_py_obj);
-    m_py_obj = nullptr;
-  }
+inline llvm::Error keyError() {
+  return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                 "key not in dict");
+}
 
-  void Reset(const PythonObject &rhs) {
-    // Avoid calling the virtual method if it's not necessary
-    // to actually validate the type of the PyObject.
-    if (!rhs.IsValid())
-      Reset();
-    else
-      Reset(PyRefType::Borrowed, rhs.m_py_obj);
-  }
+enum class PyInitialValue { Invalid, Empty };
 
-  // PythonObject is implicitly convertible to PyObject *, which will call the
-  // wrong overload.  We want to explicitly disallow this, since a PyObject
-  // *always* owns its reference.  Therefore the overload which takes a
-  // PyRefType doesn't make sense, and the copy constructor should be used.
-  void Reset(PyRefType type, const PythonObject &ref) = delete;
+template <typename T, typename Enable = void> struct PythonFormat;
 
-  virtual void Reset(PyRefType type, PyObject *py_obj) {
-    if (py_obj == m_py_obj)
-      return;
+template <> struct PythonFormat<unsigned long long> {
+  static constexpr char format = 'K';
+  static auto get(unsigned long long value) { return value; }
+};
 
-    if (Py_IsInitialized())
-      Py_XDECREF(m_py_obj);
+template <> struct PythonFormat<long long> {
+  static constexpr char format = 'L';
+  static auto get(long long value) { return value; }
+};
 
-    m_py_obj = py_obj;
+template <> struct PythonFormat<PyObject *> {
+  static constexpr char format = 'O';
+  static auto get(PyObject *value) { return value; }
+};
+
+template <typename T>
+struct PythonFormat<
+    T, typename std::enable_if<std::is_base_of<PythonObject, T>::value>::type> {
+  static constexpr char format = 'O';
+  static auto get(const T &value) { return value.get(); }
+};
+
+class PythonObject {
+public:
+  PythonObject() : m_py_obj(nullptr) {}
 
+  PythonObject(PyRefType type, PyObject *py_obj) {
+    m_py_obj = py_obj;
     // If this is a borrowed reference, we need to convert it to
     // an owned reference by incrementing it.  If it is an owned
     // reference (for example the caller allocated it with PyDict_New()
     // then we must *not* increment it.
-    if (Py_IsInitialized() && type == PyRefType::Borrowed)
+    if (m_py_obj && Py_IsInitialized() && type == PyRefType::Borrowed)
       Py_XINCREF(m_py_obj);
   }
 
+  PythonObject(const PythonObject &rhs)
+      : PythonObject(PyRefType::Borrowed, rhs.m_py_obj) {}
+
+  PythonObject(PythonObject &&rhs) {
+    m_py_obj = rhs.m_py_obj;
+    rhs.m_py_obj = nullptr;
+  }
+
+  ~PythonObject() { Reset(); }
+
+  void Reset() {
+    if (m_py_obj && Py_IsInitialized())
+      Py_DECREF(m_py_obj);
+    m_py_obj = nullptr;
+  }
+
   void Dump() const {
     if (m_py_obj)
       _PyObject_Dump(m_py_obj);
@@ -144,8 +262,9 @@ public:
     return result;
   }
 
-  PythonObject &operator=(const PythonObject &other) {
-    Reset(PyRefType::Borrowed, other.get());
+  PythonObject &operator=(PythonObject other) {
+    Reset();
+    m_py_obj = std::exchange(other.m_py_obj, nullptr);
     return *this;
   }
 
@@ -174,11 +293,13 @@ public:
 
   PythonObject GetAttributeValue(llvm::StringRef attribute) const;
 
-  bool IsValid() const;
+  bool IsNone() const { return m_py_obj == Py_None; }
+
+  bool IsValid() const { return m_py_obj != nullptr; }
 
-  bool IsAllocated() const;
+  bool IsAllocated() const { return IsValid() && !IsNone(); }
 
-  bool IsNone() const;
+  explicit operator bool() const { return IsValid() && !IsNone(); }
 
   template <typename T> T AsType() const {
     if (!T::Check(m_py_obj))
@@ -189,24 +310,125 @@ public:
   StructuredData::ObjectSP CreateStructuredObject() const;
 
 protected:
+
+#if PY_MAJOR_VERSION < 3
+  // The python 2 API declares some arguments as char* that should
+  // be const char *, but it doesn't actually modify them.
+  static char *py2_const_cast(const char *s) { return const_cast<char *>(s); }
+#else
+  static const char *py2_const_cast(const char *s) { return s; }
+#endif
+
+public:
+  template <typename... T>
+  llvm::Expected<PythonObject> CallMethod(const char *name,
+                                          const T &... t) const {
+    const char format[] = {'(', PythonFormat<T>::format..., ')', 0};
+    PyObject *obj =
+        PyObject_CallMethod(m_py_obj, py2_const_cast(name),
+                            py2_const_cast(format), PythonFormat<T>::get(t)...);
+    if (!obj)
+      return exception();
+    return python::Take<PythonObject>(obj);
+  }
+
+  template <typename... T>
+  llvm::Expected<PythonObject> Call(const T &... t) const {
+    const char format[] = {'(', PythonFormat<T>::format..., ')', 0};
+    PyObject *obj = PyObject_CallFunction(m_py_obj, py2_const_cast(format),
+                                          PythonFormat<T>::get(t)...);
+    if (!obj)
+      return exception();
+    return python::Take<PythonObject>(obj);
+  }
+
+  llvm::Expected<PythonObject> GetAttribute(const llvm::Twine &name) const {
+    if (!m_py_obj)
+      return nullDeref();
+    PyObject *obj = PyObject_GetAttrString(m_py_obj, NullTerminated(name));
+    if (!obj)
+      return exception();
+    return python::Take<PythonObject>(obj);
+  }
+
+  llvm::Expected<bool> IsTrue() {
+    if (!m_py_obj)
+      return nullDeref();
+    int r = PyObject_IsTrue(m_py_obj);
+    if (r < 0)
+      return exception();
+    return !!r;
+  }
+
+  llvm::Expected<long long> AsLongLong() {
+    if (!m_py_obj)
+      return nullDeref();
+    assert(!PyErr_Occurred());
+    long long r = PyLong_AsLongLong(m_py_obj);
+    if (PyErr_Occurred())
+      return exception();
+    return r;
+  }
+
+  llvm::Expected<bool> IsInstance(const PythonObject &cls) {
+    if (!m_py_obj || !cls.IsValid())
+      return nullDeref();
+    int r = PyObject_IsInstance(m_py_obj, cls.get());
+    if (r < 0)
+      return exception();
+    return !!r;
+  }
+
+protected:
   PyObject *m_py_obj;
 };
 
-class PythonBytes : public PythonObject {
+
+// This is why C++ needs monads.
+template <typename T> llvm::Expected<T> As(llvm::Expected<PythonObject> &&obj) {
+  if (!obj)
+    return obj.takeError();
+  if (!T::Check(obj.get().get()))
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "type error");
+  return T(PyRefType::Borrowed, std::move(obj.get().get()));
+}
+
+template <> llvm::Expected<bool> As<bool>(llvm::Expected<PythonObject> &&obj);
+
+template <>
+llvm::Expected<long long> As<long long>(llvm::Expected<PythonObject> &&obj);
+
+template <>
+llvm::Expected<std::string> As<std::string>(llvm::Expected<PythonObject> &&obj);
+
+
+template <class T> class TypedPythonObject : public PythonObject {
 public:
-  PythonBytes();
-  explicit PythonBytes(llvm::ArrayRef<uint8_t> bytes);
-  PythonBytes(const uint8_t *bytes, size_t length);
-  PythonBytes(PyRefType type, PyObject *o);
+  // override to perform implicit type conversions on Reset
+  // This can be eliminated once we drop python 2 support.
+  static void Convert(PyRefType &type, PyObject *&py_obj) {}
 
-  ~PythonBytes() override;
+  TypedPythonObject(PyRefType type, PyObject *py_obj) {
+    if (!py_obj)
+      return;
+    T::Convert(type, py_obj);
+    if (T::Check(py_obj))
+      PythonObject::operator=(PythonObject(type, py_obj));
+    else if (type == PyRefType::Owned)
+      Py_DECREF(py_obj);
+  }
 
-  static bool Check(PyObject *py_obj);
+  TypedPythonObject() {}
+};
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
+class PythonBytes : public TypedPythonObject<PythonBytes> {
+public:
+  using TypedPythonObject::TypedPythonObject;
+  explicit PythonBytes(llvm::ArrayRef<uint8_t> bytes);
+  PythonBytes(const uint8_t *bytes, size_t length);
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
+  static bool Check(PyObject *py_obj);
 
   llvm::ArrayRef<uint8_t> GetBytes() const;
 
@@ -217,23 +439,15 @@ public:
   StructuredData::StringSP CreateStructuredString() const;
 };
 
-class PythonByteArray : public PythonObject {
+class PythonByteArray : public TypedPythonObject<PythonByteArray> {
 public:
-  PythonByteArray();
+  using TypedPythonObject::TypedPythonObject;
   explicit PythonByteArray(llvm::ArrayRef<uint8_t> bytes);
   PythonByteArray(const uint8_t *bytes, size_t length);
-  PythonByteArray(PyRefType type, PyObject *o);
   PythonByteArray(const PythonBytes &object);
 
-  ~PythonByteArray() override;
-
   static bool Check(PyObject *py_obj);
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
-
-  void Reset(PyRefType type, PyObject *py_obj) override;
-
   llvm::ArrayRef<uint8_t> GetBytes() const;
 
   size_t GetSize() const;
@@ -243,45 +457,39 @@ public:
   StructuredData::StringSP CreateStructuredString() const;
 };
 
-class PythonString : public PythonObject {
+class PythonString : public TypedPythonObject<PythonString> {
 public:
-  PythonString();
-  explicit PythonString(llvm::StringRef string);
-  explicit PythonString(const char *string);
-  PythonString(PyRefType type, PyObject *o);
+  using TypedPythonObject::TypedPythonObject;
+  static llvm::Expected<PythonString> FromUTF8(llvm::StringRef string);
 
-  ~PythonString() override;
+  PythonString() : TypedPythonObject() {} // MSVC requires this for some reason
 
-  static bool Check(PyObject *py_obj);
+  explicit PythonString(llvm::StringRef string); // safe, null on error
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
+  static bool Check(PyObject *py_obj);
+  static void Convert(PyRefType &type, PyObject *&py_obj);
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
+  llvm::StringRef GetString() const; // safe, empty string on error
 
-  llvm::StringRef GetString() const;
+  llvm::Expected<llvm::StringRef> AsUTF8() const;
 
   size_t GetSize() const;
 
-  void SetString(llvm::StringRef string);
+  void SetString(llvm::StringRef string); // safe, null on error
 
   StructuredData::StringSP CreateStructuredString() const;
 };
 
-class PythonInteger : public PythonObject {
+class PythonInteger : public TypedPythonObject<PythonInteger> {
 public:
-  PythonInteger();
-  explicit PythonInteger(int64_t value);
-  PythonInteger(PyRefType type, PyObject *o);
-
-  ~PythonInteger() override;
+  using TypedPythonObject::TypedPythonObject;
 
-  static bool Check(PyObject *py_obj);
+  PythonInteger() : TypedPythonObject() {} // MSVC requires this for some reason
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
+  explicit PythonInteger(int64_t value);
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
+  static bool Check(PyObject *py_obj);
+  static void Convert(PyRefType &type, PyObject *&py_obj);
 
   int64_t GetInteger() const;
 
@@ -290,21 +498,14 @@ public:
   StructuredData::IntegerSP CreateStructuredInteger() const;
 };
 
-class PythonBoolean : public PythonObject {
+class PythonBoolean : public TypedPythonObject<PythonBoolean> {
 public:
-  PythonBoolean() = default;
-  explicit PythonBoolean(bool value);
-  PythonBoolean(PyRefType type, PyObject *o);
+  using TypedPythonObject::TypedPythonObject;
 
-  ~PythonBoolean() override = default;
+  explicit PythonBoolean(bool value);
 
   static bool Check(PyObject *py_obj);
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
-
-  void Reset(PyRefType type, PyObject *py_obj) override;
-
   bool GetValue() const;
 
   void SetValue(bool value);
@@ -312,22 +513,17 @@ public:
   StructuredData::BooleanSP CreateStructuredBoolean() const;
 };
 
-class PythonList : public PythonObject {
+class PythonList : public TypedPythonObject<PythonList> {
 public:
-  PythonList() {}
+  using TypedPythonObject::TypedPythonObject;
+
+  PythonList() : TypedPythonObject() {} // MSVC requires this for some reason
+
   explicit PythonList(PyInitialValue value);
   explicit PythonList(int list_size);
-  PythonList(PyRefType type, PyObject *o);
-
-  ~PythonList() override;
 
   static bool Check(PyObject *py_obj);
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
-
-  void Reset(PyRefType type, PyObject *py_obj) override;
-
   uint32_t GetSize() const;
 
   PythonObject GetItemAtIndex(uint32_t index) const;
@@ -339,24 +535,17 @@ public:
   StructuredData::ArraySP CreateStructuredArray() const;
 };
 
-class PythonTuple : public PythonObject {
+class PythonTuple : public TypedPythonObject<PythonTuple> {
 public:
-  PythonTuple() {}
+  using TypedPythonObject::TypedPythonObject;
+
   explicit PythonTuple(PyInitialValue value);
   explicit PythonTuple(int tuple_size);
-  PythonTuple(PyRefType type, PyObject *o);
   PythonTuple(std::initializer_list<PythonObject> objects);
   PythonTuple(std::initializer_list<PyObject *> objects);
 
-  ~PythonTuple() override;
-
   static bool Check(PyObject *py_obj);
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
-
-  void Reset(PyRefType type, PyObject *py_obj) override;
-
   uint32_t GetSize() const;
 
   PythonObject GetItemAtIndex(uint32_t index) const;
@@ -366,37 +555,35 @@ public:
   StructuredData::ArraySP CreateStructuredArray() const;
 };
 
-class PythonDictionary : public PythonObject {
+class PythonDictionary : public TypedPythonObject<PythonDictionary> {
 public:
-  PythonDictionary() {}
-  explicit PythonDictionary(PyInitialValue value);
-  PythonDictionary(PyRefType type, PyObject *o);
+  using TypedPythonObject::TypedPythonObject;
 
-  ~PythonDictionary() override;
-
-  static bool Check(PyObject *py_obj);
+  PythonDictionary() : TypedPythonObject() {} // MSVC requires this for some reason
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
+  explicit PythonDictionary(PyInitialValue value);
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
+  static bool Check(PyObject *py_obj);
 
   uint32_t GetSize() const;
 
   PythonList GetKeys() const;
 
-  PythonObject GetItemForKey(const PythonObject &key) const;
-  void SetItemForKey(const PythonObject &key, const PythonObject &value);
+  PythonObject GetItemForKey(const PythonObject &key) const; // DEPRECATED
+  void SetItemForKey(const PythonObject &key,
+                     const PythonObject &value); // DEPRECATED
+
+  llvm::Expected<PythonObject> GetItem(const PythonObject &key) const;
+  llvm::Expected<PythonObject> GetItem(const llvm::Twine &key) const;
+  llvm::Error SetItem(const PythonObject &key, const PythonObject &value) const;
+  llvm::Error SetItem(const llvm::Twine &key, const PythonObject &value) const;
 
   StructuredData::DictionarySP CreateStructuredDictionary() const;
 };
 
-class PythonModule : public PythonObject {
+class PythonModule : public TypedPythonObject<PythonModule> {
 public:
-  PythonModule();
-  PythonModule(PyRefType type, PyObject *o);
-
-  ~PythonModule() override;
+  using TypedPythonObject::TypedPythonObject;
 
   static bool Check(PyObject *py_obj);
 
@@ -406,38 +593,57 @@ public:
 
   static PythonModule AddModule(llvm::StringRef module);
 
-  static PythonModule ImportModule(llvm::StringRef module);
+  // safe, returns invalid on error;
+  static PythonModule ImportModule(llvm::StringRef name) {
+    std::string s = name;
+    auto mod = Import(s.c_str());
+    if (!mod) {
+      llvm::consumeError(mod.takeError());
+      return PythonModule();
+    }
+    return std::move(mod.get());
+  }
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
+  static llvm::Expected<PythonModule> Import(const llvm::Twine &name);
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
+  llvm::Expected<PythonObject> Get(const llvm::Twine &name);
 
   PythonDictionary GetDictionary() const;
 };
 
-class PythonCallable : public PythonObject {
+class PythonCallable : public TypedPythonObject<PythonCallable> {
 public:
+  using TypedPythonObject::TypedPythonObject;
+
   struct ArgInfo {
-    size_t count;
-    bool is_bound_method : 1;
-    bool has_varargs : 1;
-    bool has_kwargs : 1;
+    /* the largest number of positional arguments this callable
+     * can accept, or UNBOUNDED, ie UINT_MAX if it's a varargs
+     * function and can accept an arbitrary number */
+    unsigned max_positional_args;
+    static constexpr unsigned UNBOUNDED = UINT_MAX; // FIXME c++17 inline
+    /* the number of positional arguments, including optional ones,
+     * and excluding varargs.  If this is a bound method, then the
+     * count will still include a +1 for self.
+     *
+     * FIXME. That's crazy.  This should be replaced with
+     * an accurate min and max for positional args.
+     */
+    int count;
+    /* does the callable have positional varargs? */
+    bool has_varargs : 1; // FIXME delete this
   };
 
-  PythonCallable();
-  PythonCallable(PyRefType type, PyObject *o);
-
-  ~PythonCallable() override;
-
   static bool Check(PyObject *py_obj);
 
-  // Bring in the no-argument base class version
-  using PythonObject::Reset;
+  llvm::Expected<ArgInfo> GetArgInfo() const;
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
+  llvm::Expected<ArgInfo> GetInitArgInfo() const;
 
-  ArgInfo GetNumArguments() const;
+  ArgInfo GetNumArguments() const; // DEPRECATED
+
+  // If the callable is a Py_Class, then find the number of arguments
+  // of the __init__ method.
+  ArgInfo GetNumInitArguments() const; // DEPRECATED
 
   PythonObject operator()();
 
@@ -451,27 +657,123 @@ public:
   }
 };
 
-class PythonFile : public PythonObject {
+class PythonFile : public TypedPythonObject<PythonFile> {
 public:
-  PythonFile();
-  PythonFile(File &file, const char *mode);
-  PythonFile(const char *path, const char *mode);
-  PythonFile(PyRefType type, PyObject *o);
+  using TypedPythonObject::TypedPythonObject;
 
-  ~PythonFile() override;
+  PythonFile() : TypedPythonObject() {} // MSVC requires this for some reason
 
   static bool Check(PyObject *py_obj);
 
-  using PythonObject::Reset;
+  static llvm::Expected<PythonFile> FromFile(File &file,
+                                             const char *mode = nullptr);
 
-  void Reset(PyRefType type, PyObject *py_obj) override;
-  void Reset(File &file, const char *mode);
+  llvm::Expected<lldb::FileSP> ConvertToFile(bool borrowed = false);
+  llvm::Expected<lldb::FileSP>
+  ConvertToFileForcingUseOfScriptingIOMethods(bool borrowed = false);
+};
 
-  static uint32_t GetOptionsFromMode(llvm::StringRef mode);
+class PythonException : public llvm::ErrorInfo<PythonException> {
+private:
+  PyObject *m_exception_type, *m_exception, *m_traceback;
+  PyObject *m_repr_bytes;
 
-  bool GetUnderlyingFile(File &file) const;
+public:
+  static char ID;
+  const char *toCString() const;
+  PythonException(const char *caller = nullptr);
+  void Restore();
+  ~PythonException();
+  void log(llvm::raw_ostream &OS) const override;
+  std::error_code convertToErrorCode() const override;
+  bool Matches(PyObject *exc) const;
+  std::string ReadBacktrace() const;
+};
+
+// This extracts the underlying T out of an Expected<T> and returns it.
+// If the Expected is an Error instead of a T, that error will be converted
+// into a python exception, and this will return a default-constructed T.
+//
+// This is appropriate for use right at the boundary of python calling into
+// C++, such as in a SWIG typemap.   In such a context you should simply
+// check if the returned T is valid, and if it is, return a NULL back
+// to python.   This will result in the Error being raised as an exception
+// from python code's point of view.
+//
+// For example:
+// ```
+// Expected<Foo *> efoop = some_cpp_function();
+// Foo *foop = unwrapOrSetPythonException(efoop);
+// if (!foop)
+//    return NULL;
+// do_something(*foop);
+//
+// If the Error returned was itself created because a python exception was
+// raised when C++ code called into python, then the original exception
+// will be restored.   Otherwise a simple string exception will be raised.
+template <typename T> T unwrapOrSetPythonException(llvm::Expected<T> expected) {
+  if (expected)
+    return expected.get();
+  llvm::handleAllErrors(
+      expected.takeError(), [](PythonException &E) { E.Restore(); },
+      [](const llvm::ErrorInfoBase &E) {
+        PyErr_SetString(PyExc_Exception, E.message().c_str());
+      });
+  return T();
+}
+
+// This is only here to help incrementally migrate old, exception-unsafe
+// code.
+template <typename T> T unwrapIgnoringErrors(llvm::Expected<T> expected) {
+  if (expected)
+    return std::move(expected.get());
+  llvm::consumeError(expected.takeError());
+  return T();
+}
+
+llvm::Expected<PythonObject> runStringOneLine(const llvm::Twine &string,
+                                              const PythonDictionary &globals,
+                                              const PythonDictionary &locals);
+
+llvm::Expected<PythonObject> runStringMultiLine(const llvm::Twine &string,
+                                                const PythonDictionary &globals,
+                                                const PythonDictionary &locals);
+
+// Sometimes the best way to interact with a python interpreter is
+// to run some python code.   You construct a PythonScript with
+// script string.   The script assigns some function to `_function_`
+// and you get a C++ callable object that calls the python function.
+//
+// Example:
+//
+// const char script[] = R"(
+// def main(x, y):
+//    ....
+// )";
+//
+// Expected<PythonObject> cpp_foo_wrapper(PythonObject x, PythonObject y) {
+//   // no need to synchronize access to this global, we already have the GIL
+//   static PythonScript foo(script)
+//   return  foo(x, y);
+// }
+class PythonScript {
+  const char *script;
+  PythonCallable function;
+
+  llvm::Error Init();
+
+public:
+  PythonScript(const char *script) : script(script), function() {}
+
+  template <typename... Args>
+  llvm::Expected<PythonObject> operator()(Args &&... args) {
+    if (llvm::Error error = Init())
+      return std::move(error);
+    return function.Call(std::forward<Args>(args)...);
+  }
 };
 
+} // namespace python
 } // namespace lldb_private
 
 #endif
diff --git a/source/Plugins/ScriptInterpreter/Python/PythonExceptionState.cpp b/source/Plugins/ScriptInterpreter/Python/PythonExceptionState.cpp
deleted file mode 100644
index c9d834ce6868..000000000000
--- a/source/Plugins/ScriptInterpreter/Python/PythonExceptionState.cpp
+++ /dev/null
@@ -1,169 +0,0 @@
-//===-- PythonExceptionState.cpp --------------------------------*- 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_DISABLE_PYTHON
-
-// LLDB Python header must be included first
-#include "lldb-python.h"
-
-#include "PythonExceptionState.h"
-
-#include "llvm/ADT/StringRef.h"
-#include "llvm/Support/raw_ostream.h"
-
-using namespace lldb_private;
-
-PythonExceptionState::PythonExceptionState(bool restore_on_exit)
-    : m_restore_on_exit(restore_on_exit) {
-  Acquire(restore_on_exit);
-}
-
-PythonExceptionState::~PythonExceptionState() {
-  if (m_restore_on_exit)
-    Restore();
-}
-
-void PythonExceptionState::Acquire(bool restore_on_exit) {
-  // If a state is already acquired, the user needs to decide whether they want
-  // to discard or restore it.  Don't allow the potential silent loss of a
-  // valid state.
-  assert(!IsError());
-
-  if (!HasErrorOccurred())
-    return;
-
-  PyObject *py_type = nullptr;
-  PyObject *py_value = nullptr;
-  PyObject *py_traceback = nullptr;
-  PyErr_Fetch(&py_type, &py_value, &py_traceback);
-  // PyErr_Fetch clears the error flag.
-  assert(!HasErrorOccurred());
-
-  // Ownership of the objects returned by `PyErr_Fetch` is transferred to us.
-  m_type.Reset(PyRefType::Owned, py_type);
-  m_value.Reset(PyRefType::Owned, py_value);
-  m_traceback.Reset(PyRefType::Owned, py_traceback);
-  m_restore_on_exit = restore_on_exit;
-}
-
-void PythonExceptionState::Restore() {
-  if (m_type.IsValid()) {
-    // The documentation for PyErr_Restore says "Do not pass a null type and
-    // non-null value or traceback.  So only restore if type was non-null to
-    // begin with.  In this case we're passing ownership back to Python so
-    // release them all.
-    PyErr_Restore(m_type.release(), m_value.release(), m_traceback.release());
-  }
-
-  // After we restore, we should not hold onto the exception state.  Demand
-  // that it be re-acquired.
-  Discard();
-}
-
-void PythonExceptionState::Discard() {
-  m_type.Reset();
-  m_value.Reset();
-  m_traceback.Reset();
-}
-
-void PythonExceptionState::Reset() {
-  if (m_restore_on_exit)
-    Restore();
-  else
-    Discard();
-}
-
-bool PythonExceptionState::HasErrorOccurred() { return PyErr_Occurred(); }
-
-bool PythonExceptionState::IsError() const {
-  return m_type.IsValid() || m_value.IsValid() || m_traceback.IsValid();
-}
-
-PythonObject PythonExceptionState::GetType() const { return m_type; }
-
-PythonObject PythonExceptionState::GetValue() const { return m_value; }
-
-PythonObject PythonExceptionState::GetTraceback() const { return m_traceback; }
-
-std::string PythonExceptionState::Format() const {
-  // Don't allow this function to modify the error state.
-  PythonExceptionState state(true);
-
-  std::string backtrace = ReadBacktrace();
-  if (!IsError())
-    return std::string();
-
-  // It's possible that ReadPythonBacktrace generated another exception. If
-  // this happens we have to clear the exception, because otherwise
-  // PyObject_Str() will assert below.  That's why we needed to do the save /
-  // restore at the beginning of this function.
-  PythonExceptionState bt_error_state(false);
-
-  std::string error_string;
-  llvm::raw_string_ostream error_stream(error_string);
-  error_stream << m_value.Str().GetString() << "\n";
-
-  if (!bt_error_state.IsError()) {
-    // If we were able to read the backtrace, just append it.
-    error_stream << backtrace << "\n";
-  } else {
-    // Otherwise, append some information about why we were unable to obtain
-    // the backtrace.
-    PythonString bt_error = bt_error_state.GetValue().Str();
-    error_stream << "An error occurred while retrieving the backtrace: "
-                 << bt_error.GetString() << "\n";
-  }
-  return error_stream.str();
-}
-
-std::string PythonExceptionState::ReadBacktrace() const {
-  std::string retval("backtrace unavailable");
-
-  auto traceback_module = PythonModule::ImportModule("traceback");
-#if PY_MAJOR_VERSION >= 3
-  auto stringIO_module = PythonModule::ImportModule("io");
-#else
-  auto stringIO_module = PythonModule::ImportModule("StringIO");
-#endif
-  if (!m_traceback.IsAllocated())
-    return retval;
-
-  if (!traceback_module.IsAllocated() || !stringIO_module.IsAllocated())
-    return retval;
-
-  auto stringIO_builder =
-      stringIO_module.ResolveName<PythonCallable>("StringIO");
-  if (!stringIO_builder.IsAllocated())
-    return retval;
-
-  auto stringIO_buffer = stringIO_builder();
-  if (!stringIO_buffer.IsAllocated())
-    return retval;
-
-  auto printTB = traceback_module.ResolveName<PythonCallable>("print_tb");
-  if (!printTB.IsAllocated())
-    return retval;
-
-  auto printTB_result =
-      printTB(m_traceback.get(), Py_None, stringIO_buffer.get());
-  auto stringIO_getvalue =
-      stringIO_buffer.ResolveName<PythonCallable>("getvalue");
-  if (!stringIO_getvalue.IsAllocated())
-    return retval;
-
-  auto printTB_string = stringIO_getvalue().AsType<PythonString>();
-  if (!printTB_string.IsAllocated())
-    return retval;
-
-  llvm::StringRef string_data(printTB_string.GetString());
-  retval.assign(string_data.data(), string_data.size());
-
-  return retval;
-}
-
-#endif
diff --git a/source/Plugins/ScriptInterpreter/Python/PythonExceptionState.h b/source/Plugins/ScriptInterpreter/Python/PythonExceptionState.h
deleted file mode 100644
index 3a88aa037776..000000000000
--- a/source/Plugins/ScriptInterpreter/Python/PythonExceptionState.h
+++ /dev/null
@@ -1,56 +0,0 @@
-//===-- PythonExceptionState.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_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONEXCEPTIONSTATE_H
-#define LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONEXCEPTIONSTATE_H
-
-#ifndef LLDB_DISABLE_PYTHON
-
-#include "PythonDataObjects.h"
-
-namespace lldb_private {
-
-class PythonExceptionState {
-public:
-  explicit PythonExceptionState(bool restore_on_exit);
-  ~PythonExceptionState();
-
-  void Acquire(bool restore_on_exit);
-
-  void Restore();
-
-  void Discard();
-
-  void Reset();
-
-  static bool HasErrorOccurred();
-
-  bool IsError() const;
-
-  PythonObject GetType() const;
-
-  PythonObject GetValue() const;
-
-  PythonObject GetTraceback() const;
-
-  std::string Format() const;
-
-private:
-  std::string ReadBacktrace() const;
-
-  bool m_restore_on_exit;
-
-  PythonObject m_type;
-  PythonObject m_value;
-  PythonObject m_traceback;
-};
-}
-
-#endif
-
-#endif
diff --git a/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp b/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
index 2d2b68ceaaa6..3eee52184142 100644
--- a/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
+++ b/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp
@@ -16,7 +16,6 @@
 #include "lldb-python.h"
 
 #include "PythonDataObjects.h"
-#include "PythonExceptionState.h"
 #include "ScriptInterpreterPythonImpl.h"
 
 #include "lldb/API/SBFrame.h"
@@ -45,6 +44,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FormatAdapters.h"
 
 #include <memory>
 #include <mutex>
@@ -54,6 +54,8 @@
 
 using namespace lldb;
 using namespace lldb_private;
+using namespace lldb_private::python;
+using llvm::Expected;
 
 // Defined in the SWIG source file
 #if PY_MAJOR_VERSION >= 3
@@ -96,6 +98,8 @@ LLDBSwigPythonCreateCommandObject(const char *python_class_name,
 
 extern "C" void *LLDBSwigPythonCreateScriptedThreadPlan(
     const char *python_class_name, const char *session_dictionary_name,
+    StructuredDataImpl *args_data,
+    std::string &error_string,
     const lldb::ThreadPlanSP &thread_plan_sp);
 
 extern "C" bool LLDBSWIGPythonCallThreadPlan(void *implementor,
@@ -302,39 +306,26 @@ void ScriptInterpreterPython::ComputePythonDirForApple(
   auto rend = llvm::sys::path::rend(path_ref);
   auto framework = std::find(rbegin, rend, "LLDB.framework");
   if (framework == rend) {
-    ComputePythonDirForPosix(path);
+    ComputePythonDir(path);
     return;
   }
   path.resize(framework - rend);
   llvm::sys::path::append(path, style, "LLDB.framework", "Resources", "Python");
 }
 
-void ScriptInterpreterPython::ComputePythonDirForPosix(
+void ScriptInterpreterPython::ComputePythonDir(
     llvm::SmallVectorImpl<char> &path) {
-  auto style = llvm::sys::path::Style::posix;
-#if defined(LLDB_PYTHON_RELATIVE_LIBDIR)
   // Build the path by backing out of the lib dir, then building with whatever
   // the real python interpreter uses.  (e.g. lib for most, lib64 on RHEL
-  // x86_64).
-  llvm::sys::path::remove_filename(path, style);
-  llvm::sys::path::append(path, style, LLDB_PYTHON_RELATIVE_LIBDIR);
-#else
-  llvm::sys::path::append(path, style,
-                          "python" + llvm::Twine(PY_MAJOR_VERSION) + "." +
-                              llvm::Twine(PY_MINOR_VERSION),
-                          "site-packages");
-#endif
-}
-
-void ScriptInterpreterPython::ComputePythonDirForWindows(
-    llvm::SmallVectorImpl<char> &path) {
-  auto style = llvm::sys::path::Style::windows;
-  llvm::sys::path::remove_filename(path, style);
-  llvm::sys::path::append(path, style, "lib", "site-packages");
+  // x86_64, or bin on Windows).
+  llvm::sys::path::remove_filename(path);
+  llvm::sys::path::append(path, LLDB_PYTHON_RELATIVE_LIBDIR);
 
+#if defined(_WIN32)
   // This will be injected directly through FileSpec.GetDirectory().SetString(),
   // so we need to normalize manually.
   std::replace(path.begin(), path.end(), '\\', '/');
+#endif
 }
 
 FileSpec ScriptInterpreterPython::GetPythonDir() {
@@ -347,10 +338,8 @@ FileSpec ScriptInterpreterPython::GetPythonDir() {
 
 #if defined(__APPLE__)
     ComputePythonDirForApple(path);
-#elif defined(_WIN32)
-    ComputePythonDirForWindows(path);
 #else
-    ComputePythonDirForPosix(path);
+    ComputePythonDir(path);
 #endif
     spec.GetDirectory().SetString(path);
     return spec;
@@ -382,7 +371,7 @@ void ScriptInterpreterPython::Terminate() {}
 
 ScriptInterpreterPythonImpl::Locker::Locker(
     ScriptInterpreterPythonImpl *py_interpreter, uint16_t on_entry,
-    uint16_t on_leave, FILE *in, FILE *out, FILE *err)
+    uint16_t on_leave, FileSP in, FileSP out, FileSP err)
     : ScriptInterpreterLocker(),
       m_teardown_session((on_leave & TearDownSession) == TearDownSession),
       m_python_interpreter(py_interpreter) {
@@ -412,8 +401,8 @@ bool ScriptInterpreterPythonImpl::Locker::DoAcquireLock() {
 }
 
 bool ScriptInterpreterPythonImpl::Locker::DoInitSession(uint16_t on_entry_flags,
-                                                        FILE *in, FILE *out,
-                                                        FILE *err) {
+                                                        FileSP in, FileSP out,
+                                                        FileSP err) {
   if (!m_python_interpreter)
     return false;
   return m_python_interpreter->EnterSession(on_entry_flags, in, out, err);
@@ -448,9 +437,9 @@ ScriptInterpreterPythonImpl::ScriptInterpreterPythonImpl(Debugger &debugger)
       m_sys_module_dict(PyInitialValue::Invalid), m_run_one_line_function(),
       m_run_one_line_str_global(),
       m_dictionary_name(m_debugger.GetInstanceName().AsCString()),
-      m_terminal_state(), m_active_io_handler(eIOHandlerNone),
-      m_session_is_active(false), m_pty_slave_is_open(false),
-      m_valid_session(true), m_lock_count(0), m_command_thread_state(nullptr) {
+      m_active_io_handler(eIOHandlerNone), m_session_is_active(false),
+      m_pty_slave_is_open(false), m_valid_session(true), m_lock_count(0),
+      m_command_thread_state(nullptr) {
   InitializePrivate();
 
   m_dictionary_name.append("_dict");
@@ -535,7 +524,7 @@ def function (frame, bp_loc, internal_dict):
   }
 
   if (instructions) {
-    StreamFileSP output_sp(io_handler.GetOutputStreamFile());
+    StreamFileSP output_sp(io_handler.GetOutputStreamFileSP());
     if (output_sp && interactive) {
       output_sp->PutCString(instructions);
       output_sp->Flush();
@@ -558,7 +547,7 @@ void ScriptInterpreterPythonImpl::IOHandlerInputComplete(IOHandler &io_handler,
       if (!bp_options)
         continue;
 
-      auto data_up = llvm::make_unique<CommandDataPython>();
+      auto data_up = std::make_unique<CommandDataPython>();
       if (!data_up)
         break;
       data_up->user_source.SplitIntoLines(data);
@@ -571,7 +560,7 @@ void ScriptInterpreterPythonImpl::IOHandlerInputComplete(IOHandler &io_handler,
         bp_options->SetCallback(
             ScriptInterpreterPythonImpl::BreakpointCallbackFunction, baton_sp);
       } else if (!batch_mode) {
-        StreamFileSP error_sp = io_handler.GetErrorStreamFile();
+        StreamFileSP error_sp = io_handler.GetErrorStreamFileSP();
         if (error_sp) {
           error_sp->Printf("Warning: No command attached to breakpoint.\n");
           error_sp->Flush();
@@ -583,7 +572,7 @@ void ScriptInterpreterPythonImpl::IOHandlerInputComplete(IOHandler &io_handler,
   case eIOHandlerWatchpoint: {
     WatchpointOptions *wp_options =
         (WatchpointOptions *)io_handler.GetUserData();
-    auto data_up = llvm::make_unique<WatchpointOptions::CommandData>();
+    auto data_up = std::make_unique<WatchpointOptions::CommandData>();
     data_up->user_source.SplitIntoLines(data);
 
     if (GenerateWatchpointCommandCallbackData(data_up->user_source,
@@ -593,7 +582,7 @@ void ScriptInterpreterPythonImpl::IOHandlerInputComplete(IOHandler &io_handler,
       wp_options->SetCallback(
           ScriptInterpreterPythonImpl::WatchpointCallbackFunction, baton_sp);
     } else if (!batch_mode) {
-      StreamFileSP error_sp = io_handler.GetErrorStreamFile();
+      StreamFileSP error_sp = io_handler.GetErrorStreamFileSP();
       if (error_sp) {
         error_sp->Printf("Warning: No command attached to breakpoint.\n");
         error_sp->Flush();
@@ -609,29 +598,15 @@ ScriptInterpreterPythonImpl::CreateInstance(Debugger &debugger) {
   return std::make_shared<ScriptInterpreterPythonImpl>(debugger);
 }
 
-void ScriptInterpreterPythonImpl::ResetOutputFileHandle(FILE *fh) {}
-
-void ScriptInterpreterPythonImpl::SaveTerminalState(int fd) {
-  // Python mucks with the terminal state of STDIN. If we can possibly avoid
-  // this by setting the file handles up correctly prior to entering the
-  // interpreter we should. For now we save and restore the terminal state on
-  // the input file handle.
-  m_terminal_state.Save(fd, false);
-}
-
-void ScriptInterpreterPythonImpl::RestoreTerminalState() {
-  // Python mucks with the terminal state of STDIN. If we can possibly avoid
-  // this by setting the file handles up correctly prior to entering the
-  // interpreter we should. For now we save and restore the terminal state on
-  // the input file handle.
-  m_terminal_state.Restore();
-}
-
 void ScriptInterpreterPythonImpl::LeaveSession() {
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SCRIPT));
   if (log)
     log->PutCString("ScriptInterpreterPythonImpl::LeaveSession()");
 
+  // Unset the LLDB global variables.
+  PyRun_SimpleString("lldb.debugger = None; lldb.target = None; lldb.process "
+                     "= None; lldb.thread = None; lldb.frame = None");
+
   // checking that we have a valid thread state - since we use our own
   // threading and locking in some (rare) cases during cleanup Python may end
   // up believing we have no thread state and PyImport_AddModule will crash if
@@ -662,45 +637,52 @@ void ScriptInterpreterPythonImpl::LeaveSession() {
   m_session_is_active = false;
 }
 
-bool ScriptInterpreterPythonImpl::SetStdHandle(File &file, const char *py_name,
-                                               PythonFile &save_file,
+bool ScriptInterpreterPythonImpl::SetStdHandle(FileSP file_sp,
+                                               const char *py_name,
+                                               PythonObject &save_file,
                                                const char *mode) {
-  if (file.IsValid()) {
-    // Flush the file before giving it to python to avoid interleaved output.
-    file.Flush();
+  if (!file_sp || !*file_sp) {
+    save_file.Reset();
+    return false;
+  }
+  File &file = *file_sp;
 
-    PythonDictionary &sys_module_dict = GetSysModuleDictionary();
+  // Flush the file before giving it to python to avoid interleaved output.
+  file.Flush();
 
-    save_file = sys_module_dict.GetItemForKey(PythonString(py_name))
-                    .AsType<PythonFile>();
+  PythonDictionary &sys_module_dict = GetSysModuleDictionary();
 
-    PythonFile new_file(file, mode);
-    sys_module_dict.SetItemForKey(PythonString(py_name), new_file);
-    return true;
-  } else
-    save_file.Reset();
-  return false;
+  auto new_file = PythonFile::FromFile(file, mode);
+  if (!new_file) {
+    llvm::consumeError(new_file.takeError());
+    return false;
+  }
+
+  save_file = sys_module_dict.GetItemForKey(PythonString(py_name));
+
+  sys_module_dict.SetItemForKey(PythonString(py_name), new_file.get());
+  return true;
 }
 
 bool ScriptInterpreterPythonImpl::EnterSession(uint16_t on_entry_flags,
-                                               FILE *in, FILE *out, FILE *err) {
+                                               FileSP in_sp, FileSP out_sp,
+                                               FileSP err_sp) {
   // If we have already entered the session, without having officially 'left'
   // it, then there is no need to 'enter' it again.
   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_SCRIPT));
   if (m_session_is_active) {
-    if (log)
-      log->Printf(
-          "ScriptInterpreterPythonImpl::EnterSession(on_entry_flags=0x%" PRIx16
-          ") session is already active, returning without doing anything",
-          on_entry_flags);
+    LLDB_LOGF(
+        log,
+        "ScriptInterpreterPythonImpl::EnterSession(on_entry_flags=0x%" PRIx16
+        ") session is already active, returning without doing anything",
+        on_entry_flags);
     return false;
   }
 
-  if (log)
-    log->Printf(
-        "ScriptInterpreterPythonImpl::EnterSession(on_entry_flags=0x%" PRIx16
-        ")",
-        on_entry_flags);
+  LLDB_LOGF(
+      log,
+      "ScriptInterpreterPythonImpl::EnterSession(on_entry_flags=0x%" PRIx16 ")",
+      on_entry_flags);
 
   m_session_is_active = true;
 
@@ -733,33 +715,29 @@ bool ScriptInterpreterPythonImpl::EnterSession(uint16_t on_entry_flags,
 
   PythonDictionary &sys_module_dict = GetSysModuleDictionary();
   if (sys_module_dict.IsValid()) {
-    File in_file(in, false);
-    File out_file(out, false);
-    File err_file(err, false);
-
-    lldb::StreamFileSP in_sp;
-    lldb::StreamFileSP out_sp;
-    lldb::StreamFileSP err_sp;
-    if (!in_file.IsValid() || !out_file.IsValid() || !err_file.IsValid())
-      m_debugger.AdoptTopIOHandlerFilesIfInvalid(in_sp, out_sp, err_sp);
+    lldb::FileSP top_in_sp;
+    lldb::StreamFileSP top_out_sp, top_err_sp;
+    if (!in_sp || !out_sp || !err_sp || !*in_sp || !*out_sp || !*err_sp)
+      m_debugger.AdoptTopIOHandlerFilesIfInvalid(top_in_sp, top_out_sp,
+                                                 top_err_sp);
 
     if (on_entry_flags & Locker::NoSTDIN) {
       m_saved_stdin.Reset();
     } else {
-      if (!SetStdHandle(in_file, "stdin", m_saved_stdin, "r")) {
-        if (in_sp)
-          SetStdHandle(in_sp->GetFile(), "stdin", m_saved_stdin, "r");
+      if (!SetStdHandle(in_sp, "stdin", m_saved_stdin, "r")) {
+        if (top_in_sp)
+          SetStdHandle(top_in_sp, "stdin", m_saved_stdin, "r");
       }
     }
 
-    if (!SetStdHandle(out_file, "stdout", m_saved_stdout, "w")) {
-      if (out_sp)
-        SetStdHandle(out_sp->GetFile(), "stdout", m_saved_stdout, "w");
+    if (!SetStdHandle(out_sp, "stdout", m_saved_stdout, "w")) {
+      if (top_out_sp)
+        SetStdHandle(top_out_sp->GetFileSP(), "stdout", m_saved_stdout, "w");
     }
 
-    if (!SetStdHandle(err_file, "stderr", m_saved_stderr, "w")) {
-      if (err_sp)
-        SetStdHandle(err_sp->GetFile(), "stderr", m_saved_stderr, "w");
+    if (!SetStdHandle(err_sp, "stderr", m_saved_stderr, "w")) {
+      if (top_err_sp)
+        SetStdHandle(top_err_sp->GetFileSP(), "stderr", m_saved_stderr, "w");
     }
   }
 
@@ -769,9 +747,9 @@ bool ScriptInterpreterPythonImpl::EnterSession(uint16_t on_entry_flags,
   return true;
 }
 
-PythonObject &ScriptInterpreterPythonImpl::GetMainModule() {
+PythonModule &ScriptInterpreterPythonImpl::GetMainModule() {
   if (!m_main_module.IsValid())
-    m_main_module.Reset(PyRefType::Borrowed, PyImport_AddModule("__main__"));
+    m_main_module = unwrapIgnoringErrors(PythonModule::Import("__main__"));
   return m_main_module;
 }
 
@@ -788,19 +766,16 @@ PythonDictionary &ScriptInterpreterPythonImpl::GetSessionDictionary() {
   if (!main_dict.IsValid())
     return m_session_dict;
 
-  PythonObject item = main_dict.GetItemForKey(PythonString(m_dictionary_name));
-  m_session_dict.Reset(PyRefType::Borrowed, item.get());
+  m_session_dict = unwrapIgnoringErrors(
+      As<PythonDictionary>(main_dict.GetItem(m_dictionary_name)));
   return m_session_dict;
 }
 
 PythonDictionary &ScriptInterpreterPythonImpl::GetSysModuleDictionary() {
   if (m_sys_module_dict.IsValid())
     return m_sys_module_dict;
-
-  PythonObject sys_module(PyRefType::Borrowed, PyImport_AddModule("sys"));
-  if (sys_module.IsValid())
-    m_sys_module_dict.Reset(PyRefType::Borrowed,
-                            PyModule_GetDict(sys_module.get()));
+  PythonModule sys_module = unwrapIgnoringErrors(PythonModule::Import("sys"));
+  m_sys_module_dict = sys_module.GetDictionary();
   return m_sys_module_dict;
 }
 
@@ -867,7 +842,7 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
     // directly down to Python.
     Debugger &debugger = m_debugger;
 
-    StreamFileSP input_file_sp;
+    FileSP input_file_sp;
     StreamFileSP output_file_sp;
     StreamFileSP error_file_sp;
     Communication output_comm(
@@ -875,7 +850,7 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
     bool join_read_thread = false;
     if (options.GetEnableIO()) {
       if (result) {
-        input_file_sp = debugger.GetInputFile();
+        input_file_sp = debugger.GetInputFileSP();
         // Set output to a temporary file so we can forward the results on to
         // the result object
 
@@ -906,9 +881,9 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
               ::setbuf(outfile_handle, nullptr);
 
             result->SetImmediateOutputFile(
-                debugger.GetOutputFile()->GetFile().GetStream());
+                debugger.GetOutputStream().GetFileSP());
             result->SetImmediateErrorFile(
-                debugger.GetErrorFile()->GetFile().GetStream());
+                debugger.GetErrorStream().GetFileSP());
           }
         }
       }
@@ -916,22 +891,26 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
         debugger.AdoptTopIOHandlerFilesIfInvalid(input_file_sp, output_file_sp,
                                                  error_file_sp);
     } else {
-      input_file_sp = std::make_shared<StreamFile>();
-      FileSystem::Instance().Open(input_file_sp->GetFile(),
+      auto nullin = FileSystem::Instance().Open(
                                   FileSpec(FileSystem::DEV_NULL),
                                   File::eOpenOptionRead);
-
-      output_file_sp = std::make_shared<StreamFile>();
-      FileSystem::Instance().Open(output_file_sp->GetFile(),
+      auto nullout = FileSystem::Instance().Open(
                                   FileSpec(FileSystem::DEV_NULL),
                                   File::eOpenOptionWrite);
-
-      error_file_sp = output_file_sp;
+      if (!nullin) {
+        result->AppendErrorWithFormatv("failed to open /dev/null: {0}\n",
+                                       llvm::fmt_consume(nullin.takeError()));
+        return false;
+      }
+      if (!nullout) {
+        result->AppendErrorWithFormatv("failed to open /dev/null: {0}\n",
+                                       llvm::fmt_consume(nullout.takeError()));
+        return false;
+      }
+      input_file_sp = std::move(nullin.get());
+      error_file_sp = output_file_sp = std::make_shared<StreamFile>(std::move(nullout.get()));
     }
 
-    FILE *in_file = input_file_sp->GetFile().GetStream();
-    FILE *out_file = output_file_sp->GetFile().GetStream();
-    FILE *err_file = error_file_sp->GetFile().GetStream();
     bool success = false;
     {
       // WARNING!  It's imperative that this RAII scope be as tight as
@@ -947,8 +926,8 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
           Locker::AcquireLock | Locker::InitSession |
               (options.GetSetLLDBGlobals() ? Locker::InitGlobals : 0) |
               ((result && result->GetInteractive()) ? 0 : Locker::NoSTDIN),
-          Locker::FreeAcquiredLock | Locker::TearDownSession, in_file, out_file,
-          err_file);
+          Locker::FreeAcquiredLock | Locker::TearDownSession, input_file_sp,
+          output_file_sp->GetFileSP(), error_file_sp->GetFileSP());
 
       // Find the correct script interpreter dictionary in the main module.
       PythonDictionary &session_dict = GetSessionDictionary();
@@ -975,9 +954,8 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLine(
       }
 
       // Flush our output and error file handles
-      ::fflush(out_file);
-      if (out_file != err_file)
-        ::fflush(err_file);
+      output_file_sp->Flush();
+      error_file_sp->Flush();
     }
 
     if (join_read_thread) {
@@ -1020,7 +998,7 @@ void ScriptInterpreterPythonImpl::ExecuteInterpreterLoop() {
   // a running interpreter loop inside the already running Python interpreter
   // loop, so we won't do it.
 
-  if (!debugger.GetInputFile()->GetFile().IsValid())
+  if (!debugger.GetInputFile().IsValid())
     return;
 
   IOHandlerSP io_handler_sp(new IOHandlerPythonInterpreter(debugger, this));
@@ -1040,19 +1018,19 @@ bool ScriptInterpreterPythonImpl::Interrupt() {
       long tid = state->thread_id;
       PyThreadState_Swap(state);
       int num_threads = PyThreadState_SetAsyncExc(tid, PyExc_KeyboardInterrupt);
-      if (log)
-        log->Printf("ScriptInterpreterPythonImpl::Interrupt() sending "
-                    "PyExc_KeyboardInterrupt (tid = %li, num_threads = %i)...",
-                    tid, num_threads);
+      LLDB_LOGF(log,
+                "ScriptInterpreterPythonImpl::Interrupt() sending "
+                "PyExc_KeyboardInterrupt (tid = %li, num_threads = %i)...",
+                tid, num_threads);
       return true;
     }
   }
-  if (log)
-    log->Printf(
-        "ScriptInterpreterPythonImpl::Interrupt() python code not running, "
-        "can't interrupt");
+  LLDB_LOGF(log,
+            "ScriptInterpreterPythonImpl::Interrupt() python code not running, "
+            "can't interrupt");
   return false;
 }
+
 bool ScriptInterpreterPythonImpl::ExecuteOneLineWithReturn(
     llvm::StringRef in_string, ScriptInterpreter::ScriptReturnType return_type,
     void *ret_value, const ExecuteScriptOptions &options) {
@@ -1063,152 +1041,111 @@ bool ScriptInterpreterPythonImpl::ExecuteOneLineWithReturn(
                     Locker::NoSTDIN,
                 Locker::FreeAcquiredLock | Locker::TearDownSession);
 
-  PythonObject py_return;
-  PythonObject &main_module = GetMainModule();
-  PythonDictionary globals(PyRefType::Borrowed,
-                           PyModule_GetDict(main_module.get()));
-  PythonObject py_error;
-  bool ret_success = false;
-  int success;
+  PythonModule &main_module = GetMainModule();
+  PythonDictionary globals = main_module.GetDictionary();
 
   PythonDictionary locals = GetSessionDictionary();
-
-  if (!locals.IsValid()) {
-    locals.Reset(
-        PyRefType::Owned,
-        PyObject_GetAttrString(globals.get(), m_dictionary_name.c_str()));
-  }
-
+  if (!locals.IsValid())
+    locals = unwrapIgnoringErrors(
+        As<PythonDictionary>(globals.GetAttribute(m_dictionary_name)));
   if (!locals.IsValid())
     locals = globals;
 
-  py_error.Reset(PyRefType::Borrowed, PyErr_Occurred());
-  if (py_error.IsValid())
-    PyErr_Clear();
-
-  std::string as_string = in_string.str();
-  { // scope for PythonInputReaderManager
-    // PythonInputReaderManager py_input(options.GetEnableIO() ? this : NULL);
-    py_return.Reset(PyRefType::Owned,
-                    PyRun_String(as_string.c_str(), Py_eval_input,
-                                 globals.get(), locals.get()));
-    if (!py_return.IsValid()) {
-      py_error.Reset(PyRefType::Borrowed, PyErr_Occurred());
-      if (py_error.IsValid())
-        PyErr_Clear();
-
-      py_return.Reset(PyRefType::Owned,
-                      PyRun_String(as_string.c_str(), Py_single_input,
-                                   globals.get(), locals.get()));
-    }
+  Expected<PythonObject> maybe_py_return =
+      runStringOneLine(in_string, globals, locals);
+
+  if (!maybe_py_return) {
+    llvm::handleAllErrors(
+        maybe_py_return.takeError(),
+        [&](PythonException &E) {
+          E.Restore();
+          if (options.GetMaskoutErrors()) {
+            if (E.Matches(PyExc_SyntaxError)) {
+              PyErr_Print();
+            }
+            PyErr_Clear();
+          }
+        },
+        [](const llvm::ErrorInfoBase &E) {});
+    return false;
   }
 
-  if (py_return.IsValid()) {
-    switch (return_type) {
-    case eScriptReturnTypeCharPtr: // "char *"
-    {
-      const char format[3] = "s#";
-      success = PyArg_Parse(py_return.get(), format, (char **)ret_value);
-      break;
-    }
-    case eScriptReturnTypeCharStrOrNone: // char* or NULL if py_return ==
-                                         // Py_None
-    {
-      const char format[3] = "z";
-      success = PyArg_Parse(py_return.get(), format, (char **)ret_value);
-      break;
-    }
-    case eScriptReturnTypeBool: {
-      const char format[2] = "b";
-      success = PyArg_Parse(py_return.get(), format, (bool *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeShortInt: {
-      const char format[2] = "h";
-      success = PyArg_Parse(py_return.get(), format, (short *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeShortIntUnsigned: {
-      const char format[2] = "H";
-      success =
-          PyArg_Parse(py_return.get(), format, (unsigned short *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeInt: {
-      const char format[2] = "i";
-      success = PyArg_Parse(py_return.get(), format, (int *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeIntUnsigned: {
-      const char format[2] = "I";
-      success = PyArg_Parse(py_return.get(), format, (unsigned int *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeLongInt: {
-      const char format[2] = "l";
-      success = PyArg_Parse(py_return.get(), format, (long *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeLongIntUnsigned: {
-      const char format[2] = "k";
-      success =
-          PyArg_Parse(py_return.get(), format, (unsigned long *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeLongLong: {
-      const char format[2] = "L";
-      success = PyArg_Parse(py_return.get(), format, (long long *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeLongLongUnsigned: {
-      const char format[2] = "K";
-      success =
-          PyArg_Parse(py_return.get(), format, (unsigned long long *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeFloat: {
-      const char format[2] = "f";
-      success = PyArg_Parse(py_return.get(), format, (float *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeDouble: {
-      const char format[2] = "d";
-      success = PyArg_Parse(py_return.get(), format, (double *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeChar: {
-      const char format[2] = "c";
-      success = PyArg_Parse(py_return.get(), format, (char *)ret_value);
-      break;
-    }
-    case eScriptReturnTypeOpaqueObject: {
-      success = true;
-      PyObject *saved_value = py_return.get();
-      Py_XINCREF(saved_value);
-      *((PyObject **)ret_value) = saved_value;
-      break;
-    }
-    }
+  PythonObject py_return = std::move(maybe_py_return.get());
+  assert(py_return.IsValid());
 
-    ret_success = success;
+  switch (return_type) {
+  case eScriptReturnTypeCharPtr: // "char *"
+  {
+    const char format[3] = "s#";
+    return PyArg_Parse(py_return.get(), format, (char **)ret_value);
+  }
+  case eScriptReturnTypeCharStrOrNone: // char* or NULL if py_return ==
+                                       // Py_None
+  {
+    const char format[3] = "z";
+    return PyArg_Parse(py_return.get(), format, (char **)ret_value);
+  }
+  case eScriptReturnTypeBool: {
+    const char format[2] = "b";
+    return PyArg_Parse(py_return.get(), format, (bool *)ret_value);
+  }
+  case eScriptReturnTypeShortInt: {
+    const char format[2] = "h";
+    return PyArg_Parse(py_return.get(), format, (short *)ret_value);
+  }
+  case eScriptReturnTypeShortIntUnsigned: {
+    const char format[2] = "H";
+    return PyArg_Parse(py_return.get(), format, (unsigned short *)ret_value);
+  }
+  case eScriptReturnTypeInt: {
+    const char format[2] = "i";
+    return PyArg_Parse(py_return.get(), format, (int *)ret_value);
+  }
+  case eScriptReturnTypeIntUnsigned: {
+    const char format[2] = "I";
+    return PyArg_Parse(py_return.get(), format, (unsigned int *)ret_value);
+  }
+  case eScriptReturnTypeLongInt: {
+    const char format[2] = "l";
+    return PyArg_Parse(py_return.get(), format, (long *)ret_value);
+  }
+  case eScriptReturnTypeLongIntUnsigned: {
+    const char format[2] = "k";
+    return PyArg_Parse(py_return.get(), format, (unsigned long *)ret_value);
+  }
+  case eScriptReturnTypeLongLong: {
+    const char format[2] = "L";
+    return PyArg_Parse(py_return.get(), format, (long long *)ret_value);
+  }
+  case eScriptReturnTypeLongLongUnsigned: {
+    const char format[2] = "K";
+    return PyArg_Parse(py_return.get(), format,
+                       (unsigned long long *)ret_value);
+  }
+  case eScriptReturnTypeFloat: {
+    const char format[2] = "f";
+    return PyArg_Parse(py_return.get(), format, (float *)ret_value);
+  }
+  case eScriptReturnTypeDouble: {
+    const char format[2] = "d";
+    return PyArg_Parse(py_return.get(), format, (double *)ret_value);
+  }
+  case eScriptReturnTypeChar: {
+    const char format[2] = "c";
+    return PyArg_Parse(py_return.get(), format, (char *)ret_value);
+  }
+  case eScriptReturnTypeOpaqueObject: {
+    *((PyObject **)ret_value) = py_return.release();
+    return true;
   }
-
-  py_error.Reset(PyRefType::Borrowed, PyErr_Occurred());
-  if (py_error.IsValid()) {
-    ret_success = false;
-    if (options.GetMaskoutErrors()) {
-      if (PyErr_GivenExceptionMatches(py_error.get(), PyExc_SyntaxError))
-        PyErr_Print();
-      PyErr_Clear();
-    }
   }
-
-  return ret_success;
 }
 
 Status ScriptInterpreterPythonImpl::ExecuteMultipleLines(
     const char *in_string, const ExecuteScriptOptions &options) {
-  Status error;
+
+  if (in_string == nullptr)
+    return Status();
 
   Locker locker(this,
                 Locker::AcquireLock | Locker::InitSession |
@@ -1216,52 +1153,32 @@ Status ScriptInterpreterPythonImpl::ExecuteMultipleLines(
                     Locker::NoSTDIN,
                 Locker::FreeAcquiredLock | Locker::TearDownSession);
 
-  PythonObject return_value;
-  PythonObject &main_module = GetMainModule();
-  PythonDictionary globals(PyRefType::Borrowed,
-                           PyModule_GetDict(main_module.get()));
-  PythonObject py_error;
+  PythonModule &main_module = GetMainModule();
+  PythonDictionary globals = main_module.GetDictionary();
 
   PythonDictionary locals = GetSessionDictionary();
-
   if (!locals.IsValid())
-    locals.Reset(
-        PyRefType::Owned,
-        PyObject_GetAttrString(globals.get(), m_dictionary_name.c_str()));
-
+    locals = unwrapIgnoringErrors(
+        As<PythonDictionary>(globals.GetAttribute(m_dictionary_name)));
   if (!locals.IsValid())
     locals = globals;
 
-  py_error.Reset(PyRefType::Borrowed, PyErr_Occurred());
-  if (py_error.IsValid())
-    PyErr_Clear();
+  Expected<PythonObject> return_value =
+      runStringMultiLine(in_string, globals, locals);
 
-  if (in_string != nullptr) {
-    PythonObject code_object;
-    code_object.Reset(PyRefType::Owned,
-                      Py_CompileString(in_string, "temp.py", Py_file_input));
-
-    if (code_object.IsValid()) {
-// In Python 2.x, PyEval_EvalCode takes a PyCodeObject, but in Python 3.x, it
-// takes a PyObject.  They are convertible (hence the function
-// PyCode_Check(PyObject*), so we have to do the cast for Python 2.x
-#if PY_MAJOR_VERSION >= 3
-      PyObject *py_code_obj = code_object.get();
-#else
-      PyCodeObject *py_code_obj =
-          reinterpret_cast<PyCodeObject *>(code_object.get());
-#endif
-      return_value.Reset(
-          PyRefType::Owned,
-          PyEval_EvalCode(py_code_obj, globals.get(), locals.get()));
-    }
+  if (!return_value) {
+    llvm::Error error =
+        llvm::handleErrors(return_value.takeError(), [&](PythonException &E) {
+          llvm::Error error = llvm::createStringError(
+              llvm::inconvertibleErrorCode(), E.ReadBacktrace());
+          if (!options.GetMaskoutErrors())
+            E.Restore();
+          return error;
+        });
+    return Status(std::move(error));
   }
 
-  PythonExceptionState exception_state(!options.GetMaskoutErrors());
-  if (exception_state.IsError())
-    error.SetErrorString(exception_state.Format().c_str());
-
-  return error;
+  return Status();
 }
 
 void ScriptInterpreterPythonImpl::CollectDataForBreakpointCommandCallback(
@@ -1308,7 +1225,7 @@ Status ScriptInterpreterPythonImpl::SetBreakpointCommandCallback(
 // Set a Python one-liner as the callback for the breakpoint.
 Status ScriptInterpreterPythonImpl::SetBreakpointCommandCallback(
     BreakpointOptions *bp_options, const char *command_body_text) {
-  auto data_up = llvm::make_unique<CommandDataPython>();
+  auto data_up = std::make_unique<CommandDataPython>();
 
   // Split the command_body_text into lines, and pass that to
   // GenerateBreakpointCommandCallbackData.  That will wrap the body in an
@@ -1331,7 +1248,7 @@ Status ScriptInterpreterPythonImpl::SetBreakpointCommandCallback(
 // Set a Python one-liner as the callback for the watchpoint.
 void ScriptInterpreterPythonImpl::SetWatchpointCommandCallback(
     WatchpointOptions *wp_options, const char *oneliner) {
-  auto data_up = llvm::make_unique<WatchpointOptions::CommandData>();
+  auto data_up = std::make_unique<WatchpointOptions::CommandData>();
 
   // It's necessary to set both user_source and script_source to the oneliner.
   // The former is used to generate callback description (as in watchpoint
@@ -1853,12 +1770,14 @@ StructuredData::DictionarySP ScriptInterpreterPythonImpl::OSPlugin_CreateThread(
 }
 
 StructuredData::ObjectSP ScriptInterpreterPythonImpl::CreateScriptedThreadPlan(
-    const char *class_name, lldb::ThreadPlanSP thread_plan_sp) {
+    const char *class_name, StructuredDataImpl *args_data,
+    std::string &error_str, 
+    lldb::ThreadPlanSP thread_plan_sp) {
   if (class_name == nullptr || class_name[0] == '\0')
     return StructuredData::ObjectSP();
 
   if (!thread_plan_sp.get())
-    return StructuredData::ObjectSP();
+    return {};
 
   Debugger &debugger = thread_plan_sp->GetTarget().GetDebugger();
   ScriptInterpreter *script_interpreter = debugger.GetScriptInterpreter();
@@ -1866,17 +1785,18 @@ StructuredData::ObjectSP ScriptInterpreterPythonImpl::CreateScriptedThreadPlan(
       static_cast<ScriptInterpreterPythonImpl *>(script_interpreter);
 
   if (!script_interpreter)
-    return StructuredData::ObjectSP();
+    return {};
 
   void *ret_val;
 
   {
     Locker py_lock(this,
                    Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
-
     ret_val = LLDBSwigPythonCreateScriptedThreadPlan(
         class_name, python_interpreter->m_dictionary_name.c_str(),
-        thread_plan_sp);
+        args_data, error_str, thread_plan_sp);
+    if (!ret_val)
+      return {};
   }
 
   return StructuredData::ObjectSP(new StructuredPythonObject(ret_val));
@@ -2052,15 +1972,22 @@ StructuredData::DictionarySP ScriptInterpreterPythonImpl::GetDynamicSettings(
   if (!generic)
     return StructuredData::DictionarySP();
 
-  PythonObject reply_pyobj;
   Locker py_lock(this,
                  Locker::AcquireLock | Locker::InitSession | Locker::NoSTDIN);
   TargetSP target_sp(target->shared_from_this());
-  reply_pyobj.Reset(PyRefType::Owned,
-                    (PyObject *)LLDBSWIGPython_GetDynamicSetting(
-                        generic->GetValue(), setting_name, target_sp));
 
-  PythonDictionary py_dict(PyRefType::Borrowed, reply_pyobj.get());
+  auto setting = (PyObject *)LLDBSWIGPython_GetDynamicSetting(
+      generic->GetValue(), setting_name, target_sp);
+
+  if (!setting)
+    return StructuredData::DictionarySP();
+
+  PythonDictionary py_dict =
+      unwrapIgnoringErrors(As<PythonDictionary>(Take<PythonObject>(setting)));
+
+  if (!py_dict)
+    return StructuredData::DictionarySP();
+
   return py_dict.CreateStructuredDictionary();
 }
 
@@ -2230,18 +2157,6 @@ bool ScriptInterpreterPythonImpl::GetScriptedSummary(
   return ret_val;
 }
 
-void ScriptInterpreterPythonImpl::Clear() {
-  // Release any global variables that might have strong references to
-  // LLDB objects when clearing the python script interpreter.
-  Locker locker(this, Locker::AcquireLock, Locker::FreeAcquiredLock);
-
-  // This may be called as part of Py_Finalize.  In that case the modules are
-  // destroyed in random order and we can't guarantee that we can access these.
-  if (Py_IsInitialized())
-    PyRun_SimpleString("lldb.debugger = None; lldb.target = None; lldb.process "
-                       "= None; lldb.thread = None; lldb.frame = None");
-}
-
 bool ScriptInterpreterPythonImpl::BreakpointCallbackFunction(
     void *baton, StoppointCallbackContext *context, user_id_t break_id,
     user_id_t break_loc_id) {
diff --git a/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.h b/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.h
index 24941ec77452..33ae308041b2 100644
--- a/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.h
+++ b/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.h
@@ -48,8 +48,7 @@ public:
 
 protected:
   static void ComputePythonDirForApple(llvm::SmallVectorImpl<char> &path);
-  static void ComputePythonDirForPosix(llvm::SmallVectorImpl<char> &path);
-  static void ComputePythonDirForWindows(llvm::SmallVectorImpl<char> &path);
+  static void ComputePythonDir(llvm::SmallVectorImpl<char> &path);
 };
 } // namespace lldb_private
 
diff --git a/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPythonImpl.h b/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPythonImpl.h
index a9993c4068a2..929567e579d8 100644
--- a/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPythonImpl.h
+++ b/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPythonImpl.h
@@ -78,6 +78,8 @@ public:
 
   StructuredData::ObjectSP
   CreateScriptedThreadPlan(const char *class_name,
+                           StructuredDataImpl *args_data,
+                           std::string &error_str,
                            lldb::ThreadPlanSP thread_plan) override;
 
   bool ScriptedThreadPlanExplainsStop(StructuredData::ObjectSP implementor_sp,
@@ -188,8 +190,6 @@ public:
                           const TypeSummaryOptions &options,
                           std::string &retval) override;
 
-  void Clear() override;
-
   bool GetDocumentationForItem(const char *item, std::string &dest) override;
 
   bool GetShortHelpForCommandObject(StructuredData::GenericSP cmd_obj_sp,
@@ -256,8 +256,6 @@ public:
   void SetWatchpointCommandCallback(WatchpointOptions *wp_options,
                                     const char *oneliner) override;
 
-  void ResetOutputFileHandle(FILE *new_fh) override;
-
   const char *GetDictionaryName() { return m_dictionary_name.c_str(); }
 
   PyThreadState *GetThreadState() { return m_command_thread_state; }
@@ -296,17 +294,19 @@ public:
       TearDownSession = 0x0004
     };
 
-    Locker(ScriptInterpreterPythonImpl *py_interpreter = nullptr,
+    Locker(ScriptInterpreterPythonImpl *py_interpreter,
            uint16_t on_entry = AcquireLock | InitSession,
-           uint16_t on_leave = FreeLock | TearDownSession, FILE *in = nullptr,
-           FILE *out = nullptr, FILE *err = nullptr);
+           uint16_t on_leave = FreeLock | TearDownSession,
+           lldb::FileSP in = nullptr, lldb::FileSP out = nullptr,
+           lldb::FileSP err = nullptr);
 
     ~Locker() override;
 
   private:
     bool DoAcquireLock();
 
-    bool DoInitSession(uint16_t on_entry_flags, FILE *in, FILE *out, FILE *err);
+    bool DoInitSession(uint16_t on_entry_flags, lldb::FileSP in,
+                       lldb::FileSP out, lldb::FileSP err);
 
     bool DoFreeLock();
 
@@ -314,7 +314,6 @@ public:
 
     bool m_teardown_session;
     ScriptInterpreterPythonImpl *m_python_interpreter;
-    //    	FILE*                    m_tmp_fh;
     PyGILState_STATE m_GILState;
   };
 
@@ -343,14 +342,11 @@ public:
 
   static void AddToSysPath(AddLocation location, std::string path);
 
-  bool EnterSession(uint16_t on_entry_flags, FILE *in, FILE *out, FILE *err);
+  bool EnterSession(uint16_t on_entry_flags, lldb::FileSP in, lldb::FileSP out,
+                    lldb::FileSP err);
 
   void LeaveSession();
 
-  void SaveTerminalState(int fd);
-
-  void RestoreTerminalState();
-
   uint32_t IsExecutingPython() const { return m_lock_count > 0; }
 
   uint32_t IncrementLockCount() { return ++m_lock_count; }
@@ -367,27 +363,26 @@ public:
     eIOHandlerWatchpoint
   };
 
-  PythonObject &GetMainModule();
+  python::PythonModule &GetMainModule();
 
-  PythonDictionary &GetSessionDictionary();
+  python::PythonDictionary &GetSessionDictionary();
 
-  PythonDictionary &GetSysModuleDictionary();
+  python::PythonDictionary &GetSysModuleDictionary();
 
   bool GetEmbeddedInterpreterModuleObjects();
 
-  bool SetStdHandle(File &file, const char *py_name, PythonFile &save_file,
-                    const char *mode);
-
-  PythonFile m_saved_stdin;
-  PythonFile m_saved_stdout;
-  PythonFile m_saved_stderr;
-  PythonObject m_main_module;
-  PythonDictionary m_session_dict;
-  PythonDictionary m_sys_module_dict;
-  PythonObject m_run_one_line_function;
-  PythonObject m_run_one_line_str_global;
+  bool SetStdHandle(lldb::FileSP file, const char *py_name,
+                    python::PythonObject &save_file, const char *mode);
+
+  python::PythonObject m_saved_stdin;
+  python::PythonObject m_saved_stdout;
+  python::PythonObject m_saved_stderr;
+  python::PythonModule m_main_module;
+  python::PythonDictionary m_session_dict;
+  python::PythonDictionary m_sys_module_dict;
+  python::PythonObject m_run_one_line_function;
+  python::PythonObject m_run_one_line_str_global;
   std::string m_dictionary_name;
-  TerminalState m_terminal_state;
   ActiveIOHandler m_active_io_handler;
   bool m_session_is_active;
   bool m_pty_slave_is_open;