cli: Add support for Python 3.13 enhanced REPL

Signed-off-by: Stephen Brennan <[email protected]>

docs/advanced_usage.rst

@@ -114,6 +114,13 @@ Some of drgn's behavior can be modified through environment variables:
     Whether drgn should use libkdumpfile for ELF vmcores (0 or 1). The default
     is 0. This functionality will be removed in the future.
 
+``DRGN_USE_PYREPL``
+    Whether drgn should attempt to use the improved REPL (pyrepl) from Python
+    3.13. This provides colored output and multiline editing, among other
+    features. The default is 1.  Unfortunately, Python has no public API to use
+    these features, so drgn must rely on internal implementation details. Set
+    this to 0 to disable this feature.
+
 ``DRGN_USE_SYS_MODULE``
     Whether drgn should use ``/sys/module`` to find information about loaded
     kernel modules for the running kernel instead of getting them from the core

drgn/cli.py

@@ -6,19 +6,18 @@
 
 import argparse
 import builtins
-import code
 import importlib
 import logging
 import os
 import os.path
 import pkgutil
-import readline
 import runpy
 import shutil
 import sys
 from typing import Any, Callable, Dict, Optional
 
 import drgn
+from drgn.internal.repl import interact, readline
 from drgn.internal.rlcompleter import Completer
 from drgn.internal.sudohelper import open_via_sudo
 
@@ -435,7 +434,7 @@ def run_interactive(
         drgn.set_default_prog(prog)
 
         try:
-            code.interact(banner=banner, exitmsg="", local=init_globals)
+            interact(init_globals, banner)
         finally:
             try:
                 readline.write_history_file(histfile)

drgn/internal/repl.py

@@ -0,0 +1,47 @@
+# Copyright (c) 2024, Oracle and/or its affiliates.
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+"""Compatibility shim between drgn and the pyrepl/code modules"""
+
+import os
+import sys
+from typing import Any, Dict
+
+__all__ = ("interact", "readline")
+
+# Python 3.13 introduces a new REPL implemented by the "_pyrepl" internal
+# module. It includes features such as colored output and multiline editing.
+# Unfortunately, there is no public API exposing these abilities to users, even
+# in the "code" module. We'd like to give the best experience possible, so we'll
+# detect _pyrepl and try to use it where possible.
+try:
+    # Since this mucks with internals, add a knob that can be used to disable it
+    # and use the traditional REPL.
+    if os.environ.get("DRGN_USE_PYREPL") in ("0", "n", "N", "false", "False"):
+        raise ModuleNotFoundError()
+
+    # Unfortunately, the typeshed library behind mypy explicitly removed type
+    # stubs for these modules. This makes sense as they are private APIs, but it
+    # means we need to disable mypy checks.
+    from _pyrepl import readline  # type: ignore
+    from _pyrepl.console import InteractiveColoredConsole  # type: ignore
+    from _pyrepl.simple_interact import (  # type: ignore
+        run_multiline_interactive_console,
+    )
+
+    # This _setup() function clobbers the readline completer, but it is
+    # protected so it only runs once. Call it early so that our overridden
+    # completer doesn't get clobbered.
+    readline._setup({})
+
+    def interact(local: Dict[str, Any], banner: str) -> None:
+        console = InteractiveColoredConsole(local)
+        print(banner, file=sys.stderr)
+        run_multiline_interactive_console(console)
+
+except (ModuleNotFoundError, ImportError):
+    import code
+    import readline
+
+    def interact(local: Dict[str, Any], banner: str) -> None:
+        code.interact(banner=banner, exitmsg="", local=local)

drgn/internal/rlcompleter.py

@@ -6,9 +6,10 @@
 import builtins
 import keyword
 import re
-import readline
 from typing import Any, Dict, List, Optional
 
+from drgn.internal.repl import readline
+
 _EXPR_RE = re.compile(
     r"""
 (