bug#8035: Processing of .. in a file path after going thru symlink

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: slpnabble@blackberry-hill.com,  8035@debbugs.gnu.org
> Date: Thu, 26 Aug 2021 19:03:24 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> I'm guessing it's calling expand-file-name here to resolve "~"?
> >
> > No, because we always must call expand-file-name before invoking a
> > libc function that accesses files -- to support file names relative to
> > their buffer's default-directory.
> 
> These are absolute file names, though.  I can understand expanding if
> they're not.

You asked why expand-file-name is there in general, so I gave a
general explanation.

expand-file-name also normalizes file names, though.  Which is also
needed in some use cases, e.g. when the /foo/bar/ isn't accessible,
but /foo/ is, in which case failing to normalize /foo/bar/../quux
could fail some file I/O function.