Revert and patch "[Python] Remove readline module"

Fix https://bugs.llvm.org/show_bug.cgi?id=43830 while avoiding polluting the
global Python namespace.

This both reverts r357277 to rebundle a version of Python's readline module
based on libedit.

However, this patch also provides two improvements over the previous
implementation:

1. use PyMem_RawMalloc instead of PyMem_Malloc, as expected by PyOS_Readline
   (prevents to segfault upon exit of interactive session)
2. patch the readline module upon embedded interpreter loading, instead of
   patching it globally, which should prevent any side effect on other
   modules/packages
3. only activate the patched module if libedit is actually linked in lldb

Differential Revision: https://reviews.llvm.org/D69793

1 files changed, 26 insertions, 0 deletions

diff --git a/lldb/source/Plugins/ScriptInterpreter/Python/PythonReadline.h b/lldb/source/Plugins/ScriptInterpreter/Python/PythonReadline.h
new file mode 100644
index 00000000000..20242e2324d
--- /dev/null
+++ b/lldb/source/Plugins/ScriptInterpreter/Python/PythonReadline.h
@@ -0,0 +1,26 @@
+//===-- PythonReadline.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_PYTHONREADLINE_H
+#define LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONREADLINE_H
+
+#if !defined(LLDB_DISABLE_LIBEDIT) && !defined(__APPLE__)
+// NOTE: Since Python may define some pre-processor definitions which affect the
+// standard headers on some systems, you must include Python.h before any
+// standard headers are included.
+#include "Python.h"
+
+// no need to hack into Python's readline module if libedit isn't used.
+//
+#define LLDB_USE_LIBEDIT_READLINE_COMPAT_MODULE 1
+
+extern "C" PyMODINIT_FUNC initlldb_readline(void);
+
+#endif
+
+#endif // LLDB_PLUGINS_SCRIPTINTERPRETER_PYTHON_PYTHONREADLINE_H