GNU bug report logs - #76943
30.1; comint-interrupt-subjob does not interrupt process in inferior-python

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From: Eli Zaretskii <eliz <at> gnu.org>
To: mattias.engdegard <at> gmail.com, kobarity <kobarity <at> gmail.com>
Cc: 76943 <at> debbugs.gnu.org, eggert <at> cs.ucla.edu, garidzorigoo <at> gmail.com
Subject: bug#76943: 30.1; comint-interrupt-subjob does not interrupt process in inferior-python
Date: Sat, 05 Apr 2025 11:30:02 +0300

Ping!  Mattias, could you please try the proposed patch?

> Date: Thu, 20 Mar 2025 20:43:26 +0900
> From: kobarity <kobarity <at> gmail.com>
> Cc: Paul Eggert <eggert <at> cs.ucla.edu>,
> 	garidzorigoo <at> gmail.com,
> 	76943 <at> debbugs.gnu.org
> 
> Eli Zaretskii wrote:
> > 
> > > Date: Fri, 14 Mar 2025 01:13:29 +0900
> > > From: kobarity <kobarity <at> gmail.com>
> > > Cc: Garid Zorigoo <garidzorigoo <at> gmail.com>,
> > > 	76943 <at> debbugs.gnu.org
> > > 
> > > Eli Zaretskii wrote:
> > > > 
> > > > > From: Garid Zorigoo <garidzorigoo <at> gmail.com>
> > > > > Date: Thu, 13 Mar 2025 11:04:23 +0900
> > > > > 
> > > > > 
> > > > > I found a work around, not sure how & why.
> > > > > Changing the value of comint-ptyp seems to make comint-interrupt-subjob work:
> > > > > 
> > > > >  (setq comint-ptyp nil)
> > > > > 
> > > > > Hope this helps.
> > > > > 
> > > > > I believe that inferior-python should be able to interrupt subjobs
> > > > > by default (i.e. without the user changing the above variable value).
> > > > 
> > > > kobarity, any comments or suggestions?
> > > 
> > > This turned out to be an effect of the setting to make the tty RAW,
> > > which Mattias and I did as part of #68559.
> > > 
> > > (defconst python-shell-setup-code
> > >   "\
> > > try:
> > >     import tty
> > > except ImportError:
> > >     pass
> > > else:
> > >     tty.setraw(0)"
> > >   "Code used to setup the inferior Python processes.")
> > > 
> > > This is to disable echo back on MacOS, so there is a workaround to
> > > limit this setting to MacOS only.  That would not solve the
> > > `comint-interrupt-subjob' problem on MacOS, though.
> > > 
> > > `comint-ptyp' is passed as the CURRENT-GROUP argument of
> > > `interrupt-process' function.  It is finally processed by the
> > > process_send_signal function in process.c.  If CURRENT-GROUP is
> > > non-nil, it first try to send the control character instead of sending
> > > the signal.  However, I believe the control character is ignored
> > > because tty is set to RAW by the above code.
> > > 
> > > I feel it would be better for process_send_signal to check if the tty
> > > is RAW, but I am not sure if that is appropriate.
> > 
> > Paul, WDYT about this?
> > 
> > > Since process_send_signal checks whether control characters such as
> > > VINTR are valid, we can also avoid this problem by disabling VINTR as
> > > follows.
> > > 
> > > (defconst python-shell-setup-code
> > >   "\
> > > try:
> > >     import tty
> > >     import termios
> > > except ImportError:
> > >     pass
> > > else:
> > >     tty.setraw(0)
> > >     attr = termios.tcgetattr(0)
> > >     attr[-1][termios.VINTR] = b'\x00'
> > >     termios.tcsetattr(0, termios.TCSANOW, attr)"
> > >   "Code used to setup the inferior Python processes.")
> > > 
> > > In summary, there are at least four possible options.
> > > 
> > > 1. Set `comint-ptyp' to nil.
> > > 2. Improve process_send_signal to check if tty is RAW.
> > > 3. Disable VINTR in addition to making the tty RAW.
> > > 4. Do not set tty to RAW except on MacOS.
> > > 
> > > If we choose 4, I believe MacOS requires one of 1-3.
> > 
> > Thanks.
> > 
> > Let's see what Paul thinks about this, and take it from there.
> 
> I have been thinking about it some more too.
> 
> > > 1. Set `comint-ptyp' to nil.
> 
> This method does not seem to be a solution.  `comint-ptyp' determines
> which process group to signal.  For example, when `comint-ptyp' is t,
> the foreground process is interrupted instead of Python as follows.
> 
> >>> import pty
> >>> pty.spawn("/bin/bash")
> $ sleep 10
> sleep 10
>   C-c C-c^C
> $
> 
> However, when `comint-ptyp' is nil, the Python process is interrupted.
> 
> >>> import pty
> >>> pty.spawn("/bin/bash")
> $ sleep 10
> sleep 10
>   C-c C-cTraceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/usr/lib/python3.12/pty.py", line 205, in spawn
>     _copy(master_fd, master_read, stdin_read)
>   File "/usr/lib/python3.12/pty.py", line 133, in _copy
>     _copy(master_fd, master_read=master_read, stdin_read=stdin_read)
>   File "/usr/lib/python3.12/pty.py", line 155, in _copy
>     rfds, wfds, _xfds = select(rfds, wfds, [])
>                         ^^^^^^^^^^^^^^^^^^^^^^
> KeyboardInterrupt
> >>>
> 
> So I think the interrupt should work whether `comint-ptyp' is t or
> nil.
> 
> > > 2. Improve process_send_signal to check if tty is RAW.
> 
> More precisely, it would be better to check ISIG of c_lflag.  However,
> it may be difficult to change the behavior for compatibility with
> previous behavior.
> 
> > > 3. Disable VINTR in addition to making the tty RAW.
> 
> Another option is to disable echo back only instead of making the tty
> raw.  As I mentioned in my earlier mail, `python-shell-setup-code' is
> for disabling echo back in MacOS.  Echo back must be disabled for
> completion to work, but it is not necessary to make the tty raw.  The
> attached patch is to disable echo back only.  Python on Windows is not
> affected by this patch because there is no termios module.
> 
> Mattias, could you try this patch on MacOS and confirm that completion
> works and that ERTs pass?

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