GNU bug report logs - #28156
Emacs quietly munges symlink contents

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Message #20 received at 28156 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Eli Zaretskii <eliz <at> gnu.org>, Philipp Stephani <p.stephani2 <at> gmail.com>
Cc: michael.albinus <at> gmx.de, 28156 <at> debbugs.gnu.org
Subject: Re: bug#28156: Emacs quietly munges symlink contents
Date: Sun, 20 Aug 2017 10:54:45 -0700

[Message part 1 (text/plain, inline)]

Eli Zaretskii wrote:

> We have quoting for these cases.

Quoting does not work for these cases. If I try to rename a symlink to the 
literal string '~eggert' on my machine, Emacs will misbehave as described and 
there is no way to quote the string naming the symlink to fix this.

> doesn't Emacs behave here like Unix shell commands do?

They differ in many ways. Two examples. First, the Unix shell command 'ln -s 
~/$$ def' expands both the "~" and the "$$", whereas (make-symbolic-link "~/$$" 
"def") expands only the "~". Second, the Unix shell command "ln -s def" creates 
a symlink to itself, whereas (make-symbolic-link "def") is an error. Briefly, 
the Unix shell commands are higher-level than the Emacs primitives.

The main points here are (1) Emacs functions should let users create and 
manipulate whatever symlinks they want to, and (2) the documentation has long 
said that symlinks are not expanded.

> If make-symbolic-link would create a link like this:
> 
>   ttt -> ~/bin/etags
> 
> (which is what your proposed change does, right?), then programs which
> follow the link will probably fail

Yes, they will fail unless there is a directory named '~'. That is the intent. 
If I want to create a symlink to my home directory, I can use expand-file-name 
on the link target, before calling make-symbolic-link.

> this text should be clarified.

Sure, that's easy. Revised patch attached.

[0001-Do-not-munge-contents-of-local-symbolic-links.patch (text/x-patch, attachment)]

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