Subject: bug#49283: [PATCH] 27.2; `(call-process "program" null-device ...)' fails over TRAMP from local MS Windows

From: Eli Zaretskii <[email-masked]>
Date: Fri, 02 Jul 2021 09:37:49 +0300

> From: Jim Porter <[email-masked]>
> Date: Thu, 1 Jul 2021 12:45:42 -0700
> Cc: Michael Albinus <[email-masked]>, Lars Ingebrigtsen <[email-masked]>, [email-masked]
> 
> > encode_current_directory returns an encoded file name.  So if we make
> > this change, we should avoid calling ENCODE_FILE on it (doing so is a
> > no-op, but it's still unclean).
> 
> I'd considered that when writing my initial patch to `call-process',
> but I wasn't sure what the most-correct way to avoid that would be. It
> seems we want an encoded path before returning from
> `encode_current_directory' in order to check that our result is
> actually accessible. But then that encoded dir gets passed in to
> `expand-file-name'. If INFILE is an un-encoded absolute path, wouldn't
> `expand-file-name' be un-encoded as well?

expand-file-name is not a problem, it can deal with encoded file
names.  The problem is the calls to remove_slash_colon and
report_file_error: they should receive file names in their internal
representation.

> Maybe a better way would be to get the cwd *without* encoding it (see
> the attached patch). However, maybe there's a simpler answer to all of
> this that I just don't know about since I'm not very familiar with how
> Emacs encodes file names.

How about adding a 'bool' argument to encode_current_directory, so
that the caller could control whether or not it encodes the directory
file name?  Then you could in this case tell encode_current_directory
not to encode the directory file name.