Restore signal.SIGINT handler between prompts

Author: tornaria

src/prompt_toolkit/application/application.py

@@ -17,6 +17,7 @@
     sleep,
 )
 from contextlib import ExitStack, contextmanager
+from ctypes import c_int, c_void_p, pythonapi
 from subprocess import Popen
 from traceback import format_tb
 from typing import (
@@ -102,6 +103,21 @@
 _SIGTSTP = getattr(signal, "SIGTSTP", None)
 
 
+# The following functions are part of the stable ABI since python 3.2
+# See: https://docs.python.org/3/c-api/sys.html#c.PyOS_getsig
+
+# PyOS_sighandler_t PyOS_getsig(int i)
+pythonapi.PyOS_getsig.restype = c_void_p
+pythonapi.PyOS_getsig.argtypes = (c_int,)
+
+# PyOS_sighandler_t PyOS_setsig(int i, PyOS_sighandler_t h)
+pythonapi.PyOS_setsig.restype = c_void_p
+pythonapi.PyOS_setsig.argtypes = (
+    c_int,
+    c_void_p,
+)
+
+
 class Application(Generic[_AppResult]):
     """
     The main Application class!
@@ -807,6 +823,10 @@ def set_is_running() -> Iterator[None]:
         @contextmanager
         def set_handle_sigint(loop: AbstractEventLoop) -> Iterator[None]:
             if handle_sigint:
+                # save sigint handlers (python and os level)
+                # See: https://github.com/prompt-toolkit/python-prompt-toolkit/issues/1576
+                sigint = signal.getsignal(signal.SIGINT)
+                sigint_os = pythonapi.PyOS_getsig(signal.SIGINT)
                 loop.add_signal_handler(
                     signal.SIGINT,
                     lambda *_: loop.call_soon_threadsafe(
@@ -817,6 +837,8 @@ def set_handle_sigint(loop: AbstractEventLoop) -> Iterator[None]:
                     yield
                 finally:
                     loop.remove_signal_handler(signal.SIGINT)
+                    signal.signal(signal.SIGINT, sigint)
+                    pythonapi.PyOS_setsig(signal.SIGINT, sigint_os)
             else:
                 yield