Re: dired-do-copy may create infinite directory hierarchy, again

[Thierry Volpiatto <thierry.volpiatto@gmail.com>]

Hi Michael,

Michael Heerdegen <michael_heerdegen@web.de> writes:

> Hi,
>
> I had sent a reply to
>
>   bug#10489: 24.0.92; dired-do-copy may create infinite directory hierarchy
>
> after it had been closed, saying that there are still problems.
> Unfortunately I got no answer.  Since it was an important bug: Can
> please somebody have a look?  Thanks.
Thanks for this, you should open a new bug.

> This was my message:
>
>
>
> Hello again,
>
> I'm afraid there are still problems.  I encountered these two:
>
>
> 1. Creating symlinks to parent directories doesn't work anymore.
>
> E.g. if you have a directory "~/test/dir1/", open a dired for "~", go to
> "test/", hit S, enter "~/test/dir1/" and hit RET.  You get the error
>
>   dired-create-files: Cannot copy `/home/micha/test' into its
> subdirectory `/home/micha/test/dir1/test'
>
> But I only wanted a symlink...  This worked in Emacs 23.
>
Need to be fixed.

> 2. Symlinks to parent directories (still) lead to ininite loops when
> copying containing dir.
>
> To use the above example: just create this symlink from outside Emacs,
> so you get e.g. this:
>
>   /home/micha/test/dir1:
>   total used in directory 8,0K available 94267456
>   drwxr-xr-x 2 micha users 4,0K Mär 22 02:32 .
>   drwxr-xr-x 3 micha users 4,0K Mär 22 02:33 ..
>   lrwxrwxrwx 1 micha users   22 Mär 22 02:32 test -> /home/micha/test
>
>
> Now dired "~", and copy "~/test" to "~/test2".  You get a hierarchy
>
>   ~/test2/dir1/test/dir1/test/...
>
> again (the command terminates without error, btw).  And all these
> are real directories, and _not_ symlinks!
This is because the loop of copy-directory test the file it copy with
`file-directory-p' instead of testing if the car of its
`file-attributes' is non-nil.

--8<---------------cut here---------------start------------->8---
diff --git a/lisp/files.el b/lisp/files.el
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -5102,10 +5102,10 @@
 	       ;; We do not want to copy "." and "..".
 	       (directory-files directory 'full
 				directory-files-no-dot-files-regexp))
-	(if (file-directory-p file)
-	    (copy-directory file newname keep-time parents)
-	  (let ((target (expand-file-name (file-name-nondirectory file) newname))
-		(attrs (file-attributes file)))
+        (let ((target (expand-file-name (file-name-nondirectory file) newname))
+              (attrs (file-attributes file)))
+          (if (eq t (car attrs)) ; A directory but not a symlink.
+              (copy-directory file newname keep-time parents)
 	    (if (stringp (car attrs)) ; Symbolic link
 		(make-symbolic-link (car attrs) target t)
 	      (copy-file file target t keep-time)))))
--8<---------------cut here---------------end--------------->8---

This patch should fix it, but not fully tested, please have a look.

>
> I also wonder why dired doesn't copy the symlink itself, but copies the
> target instead?  This seems to be the case also in other examples.  If I
> copy a directory containing any symlinks with dired, copying always
> copies the targets of the symlinks.
The patch above should fix this.

>
> Michael
>
>

-- 
  Thierry
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