Introduce a PythonFile object, and use it everywhere.

Python file handling got an overhaul in Python 3, and it affects
the way we have to interact with files.  Notably:

1) `PyFile_FromFile` no longer exists, and instead we have to use
   `PyFile_FromFd`.  This means having a way to get an fd from
   a FILE*.  For this we reuse the lldb_private::File class to
   convert between FILE*s and fds, since there are some subtleties
   regarding ownership rules when FILE*s and fds refer to the same
   file.
2) PyFile is no longer a builtin type, so there is no such thing as
   `PyFile_Check`.  Instead, files in Python 3 are just instances
   of `io.IOBase`.  So the logic for checking if something is a file
   in Python 3 is to check if it is a subclass of that module.

Additionally, some unit tests are added to verify that `PythonFile`
works as expected on Python 2 and Python 3, and
`ScriptInterpreterPython` is updated to use `PythonFile` instead of
manual calls to the various `PyFile_XXX` methods.

llvm-svn: 250444

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

@@ -19,6 +19,7 @@
 #include "lldb/Core/ConstString.h"
 #include "lldb/Core/StructuredData.h"
 #include "lldb/Core/Flags.h"
+#include "lldb/Host/File.h"
 #include "lldb/Interpreter/OptionValue.h"
 
 namespace lldb_private {
@@ -67,7 +68,8 @@ enum class PyObjectType
     Integer,
     Dictionary,
     List,
-    String
+    String,
+    File
 };
 
 enum class PyRefType
@@ -196,6 +198,9 @@ public:
         return *this;
     }
 
+    bool
+    HasAttribute(llvm::StringRef attribute) const;
+
     bool
     IsValid() const;
 
@@ -315,6 +320,21 @@ public:
     StructuredData::DictionarySP CreateStructuredDictionary() const;
 };
 
+class PythonFile : public PythonObject
+{
+  public:
+    explicit PythonFile(File &file, const char *mode);
+    PythonFile(PyRefType type, PyObject *o);
+    ~PythonFile() override;
+
+    static bool Check(PyObject *py_obj);
+
+    using PythonObject::Reset;
+
+    void Reset(PyRefType type, PyObject *py_obj) override;
+    void Reset(File &file, const char *mode);
+};
+
 } // namespace lldb_private
 
 #endif  // LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONDATAOBJECTS_H