Implement #1220212. Add os.kill support for Windows.

os.kill takes one of two newly added signals, CTRL_C_EVENT and
CTRL_BREAK_EVENT, or any integer value. The events are a special case
which work with subprocess console applications which implement a
special console control handler. Any other value but those two will
cause os.kill to use TerminateProcess, outright killing the process.

This change adds win_console_handler.py, which is a script to implement
SetConsoleCtrlHandler and applicable handler function, using ctypes.

subprocess also gets another attribute which is a necessary flag to
creationflags in Popen in order to send the CTRL events.

3 files changed, 25 insertions, 3 deletions

diff --git a/Doc/library/os.rst b/Doc/library/os.rst
index b4e39a4..11d9607 100644
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -1719,7 +1719,14 @@ written in Python, such as a mail server's external command delivery program.
 
    Send signal *sig* to the process *pid*.  Constants for the specific signals
    available on the host platform are defined in the :mod:`signal` module.
-   Availability: Unix.
+
+   Windows: The :data:`signal.CTRL_C_EVENT` and
+   :data:`signal.CTRL_BREAK_EVENT` signals are special signals which can
+   only be sent to console processes which share a common console window,
+   e.g., some subprocesses. Any other value for *sig* will cause the process
+   to be unconditionally killed by the TerminateProcess API, and the exit code
+   will be set to *sig*. The Windows version of :func:`kill` additionally takes
+   process handles to be killed.
 
 
 .. function:: killpg(pgid, sig)
diff --git a/Doc/library/signal.rst b/Doc/library/signal.rst
index 84f08b3..300c717 100644
--- a/Doc/library/signal.rst
+++ b/Doc/library/signal.rst
@@ -75,6 +75,20 @@ The variables defined in the :mod:`signal` module are:
    the system are defined by this module.
 
 
+.. data:: CTRL_C_EVENT
+
+   The signal corresponding to the CTRL+C keystroke event.
+
+   Availability: Windows.
+
+
+.. data:: CTRL_BREAK_EVENT
+
+   The signal corresponding to the CTRL+BREAK keystroke event.
+
+   Availability: Windows.
+
+
 .. data:: NSIG
 
    One more than the number of the highest signal number.
diff --git a/Doc/library/subprocess.rst b/Doc/library/subprocess.rst
index b557bcd..439a46d 100644
--- a/Doc/library/subprocess.rst
+++ b/Doc/library/subprocess.rst
@@ -320,8 +320,9 @@ Instances of the :class:`Popen` class have the following methods:
 
    .. note::
 
-      On Windows only SIGTERM is supported so far. It's an alias for
-      :meth:`terminate`.
+      On Windows, SIGTERM is an alias for :meth:`terminate`. CTRL_C_EVENT and
+      CTRL_BREAK_EVENT can be sent to processes started with a `creationflags`
+      parameter which includes `CREATE_NEW_PROCESS_GROUP`.
 
    .. versionadded:: 2.6