File::Clear() -> File::TakeStreamAndClear()

[lawrence_danna]

Summary

File::Clear() is an ugly function. It's only used in one place,
which is the swig typemaps for FILE*. This patch refactors and
renames that function to make it clear what it's really for and
why nobody else should use it.

Both File::TakeStreamAndClear() and the FILE* typemaps will be
removed in later patches after a suitable replacement is in place.

[labath]

Sounds good. If this were a more permanent interface, I'd argue that the function should be called TakeStream (in analogy with llvm::Expected::takeError), but for a temporary thing that does not matter...

lldb/source/Host/common/File.cpp

166–167

FILE *stream = GetStream() ?

[lawrence_danna]

review fix

[lawrence_danna]

lldb/source/Host/common/File.cpp

166–167

yea that's better.

lldb/include/lldb/Host/File.h

public:
   /// Get the file spec for this file.
   ///
   /// \return
   ///     A reference to the file specification object.
   Status GetFileSpec(FileSpec &file_spec) const;
 
   Status Close() override;
 
-  void Clear();
+  /// DEPRECATED! Extract the underlying FILE* and reset this File without closing it.
+  ///
+  /// This is only here to support legacy SB interfaces that need to convert scripting
+  /// language objects into FILE* streams.   That conversion is inherently sketchy and
+  /// doing so may cause the stream to be leaked.
+  ///
+  /// After calling this the File will be reset to its original state.  It will be
+  /// invalid and it will not hold on to any resources.
+  ///
+  /// \return
+  ///     The underlying FILE* stream from this File, if one exists and can be extracted,
+  ///     nullptr otherwise.
+  FILE *TakeStreamAndClear();
 
   int GetDescriptor() const;
 
   WaitableHandle GetWaitableHandle() override;
 
   FILE *GetStream();
 
   /// Read bytes from a file from the current file position.

lldb/scripts/Python/python-typemaps.swig

%typemap(in) (lldb::LogOutputCallback log_callback, void *baton) {
   $2 = $input;
 }
 
 %typemap(typecheck) (lldb::LogOutputCallback log_callback, void *baton) {
   $1 = $input == Py_None;
   $1 = $1 || PyCallable_Check(reinterpret_cast<PyObject*>($input));
 }
 
+// FIXME both of these paths wind up calling fdopen() with no provision for ever calling
+// fclose() on the result.  SB interfaces that use FILE* should be deprecated for scripting
+// use and this typemap should eventually be removed.
 %typemap(in) FILE * {
    using namespace lldb_private;
    if ($input == Py_None)
       $1 = nullptr;
    else if (!lldb_private::PythonFile::Check($input)) {
       int fd = PyObject_AsFileDescriptor($input);
       PythonObject py_input(PyRefType::Borrowed, $input);
       PythonString py_mode = py_input.GetAttributeValue("mode").AsType<PythonString>();
else if (!lldb_private::PythonFile::Check($input)) {
       }
    }
    else
    {
       PythonFile py_file(PyRefType::Borrowed, $input);
       lldb::FileUP file = py_file.GetUnderlyingFile();
       if (!file)
          return nullptr;
-      $1 = file->GetStream();
-      if ($1)
-         file->Clear();
+      $1 = file->TakeStreamAndClear();
     }
 }
 
 %typemap(out) FILE * {
    char mode[4] = {0};
 %#ifdef __APPLE__
    int i = 0;
    if ($1)

lldb/source/Host/common/File.cpp

Status File::Close() {
   m_options = 0;
   m_own_stream = false;
   m_own_descriptor = false;
   m_is_interactive = eLazyBoolCalculate;
   m_is_real_terminal = eLazyBoolCalculate;
   return error;
 }
 
-void File::Clear() {
-  m_stream = nullptr;
+FILE *File::TakeStreamAndClear() {
+  FILE *stream = GetStream();
+  m_stream = NULL;
   m_descriptor = kInvalidDescriptor;
   m_options = 0;
   m_own_stream = false;
+  m_own_descriptor = false;
   m_is_interactive = m_supports_colors = m_is_real_terminal =
       eLazyBoolCalculate;
+  return stream;
 }
 
 Status File::GetFileSpec(FileSpec &file_spec) const {
   Status error;
 #ifdef F_GETPATH
   if (IsValid()) {
     char path[PATH_MAX];
     if (::fcntl(GetDescriptor(), F_GETPATH, path) == -1)