[PATCH] chgserver: remove Python 2 file descriptor logic

[Gregory Szorc]

I installed @ and am now seeing the following with `alias hg=chg`:

$ hg version
Mercurial Distributed SCM (version 6.1+hg145.469b9ee336a6)
(see https://mercurial-scm.org for more information)

Copyright (C) 2005-2022 Olivia Mackall and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
gps at ubuntu-vm-main:~/src/hg (@)$ Traceback (most recent call last):
  File "/home/gps/lib/python/mercurial/commandserver.py", line 509, in
_serverequest
    sv.cleanup()
  File "/home/gps/lib/python/mercurial/chgserver.py", line 382, in cleanup
    self._restoreio()
  File "/home/gps/lib/python/mercurial/chgserver.py", line 454, in
_restoreio
    os.dup2(fd, fp.fileno())
ValueError: I/O operation on closed file
Traceback (most recent call last):
  File "/home/gps/lib/python/mercurial/commandserver.py", line 693, in
_acceptnewconnection
    self._runworker(conn)
  File "/home/gps/lib/python/mercurial/commandserver.py", line 739, in
_runworker
    _serverequest(
  File "/home/gps/lib/python/mercurial/commandserver.py", line 509, in
_serverequest
    sv.cleanup()
  File "/home/gps/lib/python/mercurial/chgserver.py", line 382, in cleanup
    self._restoreio()
  File "/home/gps/lib/python/mercurial/chgserver.py", line 454, in
_restoreio
    os.dup2(fd, fp.fileno())
ValueError: I/O operation on closed file

I didn't bisect. So the regression could be another patch. But it certainly
looks like chg isn't working properly on @.

On Wed, Mar 9, 2022 at 3:02 AM Raphaël Gomès <raphael.gomes at octobus.net>
wrote:

> Queued, thanks!
>
> On 3/4/22 03:12, Yuya Nishihara wrote:
> > # HG changeset patch
> > # User Yuya Nishihara <yuya at tcha.org>
> > # Date 1646357326 -32400
> > #      Fri Mar 04 10:28:46 2022 +0900
> > # Node ID 3a9729bead90ef7caaf4d25138680c83a888be78
> > # Parent  46b3ecfb16e2781ede9752d972dc22f0e1dfea87
> > chgserver: remove Python 2 file descriptor logic
> >
> > Follows up 0bb28b7736bc "chgserver: remove Python 2 support code."
> >
> > On Python 2, we had to close newfp prior to restoring the original file
> > description since "delete newfp" would otherwise close the file
> descriptor
> > shared with the long-lived fp:
> >
> >    in attachio():
> >      newfp = os.fdopen(fp.fileno(), mode, bufsize)
> >    in _restoreio():
> >      newfp.close()  # temporarily close newfp.fileno() (= fp.fileno())
> >      os.dup2(fd, fp.fileno())  # reopen fp.fileno() with original fd
> >
> > On the other hand, we shouldn't call newfp.close() on Python 3 since
> > any function calls are proxied to the underlying file object by
> > procutil.LineBufferedWrapper.
> >
> > diff --git a/mercurial/chgserver.py b/mercurial/chgserver.py
> > --- a/mercurial/chgserver.py
> > +++ b/mercurial/chgserver.py
> > @@ -438,14 +438,8 @@ class chgcmdserver(commandserver.server)
> >           nullfd = os.open(os.devnull, os.O_WRONLY)
> >           ui = self.ui
> >           for (ch, fp, fd), (cn, fn, mode) in zip(self._oldios,
> _iochannels):
> > -            newfp = getattr(ui, fn)
> > -            # On Python 3, newfp is just a wrapper around fp even if
> newfp is
> > -            # not fp, so deleting newfp is safe.
> > -            if newfp is not fp:
> > -                newfp.close()
> > -            # restore original fd: fp is open again
> >               try:
> > -                if newfp is fp and 'w' in mode:
> > +                if 'w' in mode:
> >                       # Discard buffered data which couldn't be flushed
> because
> >                       # of EPIPE. The data should belong to the current
> session
> >                       # and should never persist.
> >
> > _______________________________________________
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> > Mercurial-devel at mercurial-scm.org
> > https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel
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