file-attributes inconsistent w. stat when .. or . symlinked

[Vivek Dasmohapatra <vivek@zeus.com>]

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In GNU Emacs 21.3.1 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2003-06-06 on arachne, modified by Debian
configured using `configure  i386-linux --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info --mandir=/usr/share/man --with-pop=yes --with-x=yes --with-x-toolkit=athena --without-gif'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: ja_JP
  value of $LC_CTYPE: ja_JP
  value of $LC_MESSAGES: en_GB
  value of $LC_MONETARY: en_GB
  value of $LC_NUMERIC: en_GB
  value of $LC_TIME: en_GB
  value of $LANG: ja_JP
  locale-coding-system: japanese-iso-8bit
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

If (for example) "/usr/src/linux" is a symlink, then stat 
and file-attributes differ in their treatment of "." in 
/usr/src/linux:

Using the stat command:
vivek@arachne:/usr/src/linux$ stat /usr/src/linux/.
  File: "/usr/src/linux/."
  Size: 4096            Blocks: 8          IO Block: 4096   Directory
Device: 303h/771d       Inode: 49090       Links: 14   
Access: (0755/drwxr-xr-x)  Uid: ( 1046/x-royston)   Gid: (  101/ telnetd)
Access: Tue Sep  2 15:34:49 2003
Modify: Mon Aug  4 17:28:57 2003
Change: Mon Aug  4 17:28:57 2003

vivek@arachne:/usr/src/linux$ stat /usr/src/linux  
  File: "/usr/src/linux" -> "kernel-source-2.4.7"
  Size: 19              Blocks: 0          IO Block: 4096   Symbolic Link
Device: 303h/771d       Inode: 35387       Links: 1    
Access: (0777/lrwxrwxrwx)  Uid: (    0/    root)   Gid: (   40/     src)
Access: Tue Sep  2 15:39:03 2003
Modify: Mon Aug  4 17:26:20 2003
Change: Mon Aug  4 17:26:20 2003

However, using file-attributes:

This one is Ok, as expected:

M-: (insert (pp (file-attributes "/usr/src/linux")))
("kernel-source-2.4.7" 1 0 40
 (16212 43914)
 (16174 35116)
 (16174 35116)
 19 "lrwxrwxrwx" t 35387 771)

This is not so good:

M-: (insert (pp (file-attributes "/usr/src/linux/.")))
("kernel-source-2.4.7" 1 0 40
 (16212 43991)
 (16174 35116)
 (16174 35116)
 19 "lrwxrwxrwx" t 35387 771)

And neither is this:

M-: (progn (cd "/usr/src/linux") (insert (pp (file-attributes "."))))
("kernel-source-2.4.7" 1 0 40
 (16212 44166)
 (16174 35116)
 (16174 35116)
 19 "lrwxrwxrwx" t 35387 771)

Which has the nasty effect of returning duff symlink data, especially 
when considering ls-lisp output:

  /usr/src/linux:
  total 2660  free 418244
  drwxrwsr-x   3 0        40           4096 Aug  4 17:26 ..
  drwxr-xr-x  27 1046     telnetd      4096 Jul 20  2001 Documentation
  .
  .
  .
  lrwxrwxrwx   1 0        40             19 Aug  4 17:26 . -> kernel-source-2.4.7

This is also a problem one level down:

  /usr/src/linux/fs:
  total 1232  free 418244
  drwxr-xr-x  40 1046     telnetd      4096 Aug  2  2001 .
  drwxr-xr-x   2 1046     telnetd      4096 Jul 30  2001 adfs
  .
  .
  .
  lrwxrwxrwx   1 0        40             19 Aug  4 17:26 .. -> kernel-source-2.4.7

Again, stat does not consider ".." to be a symlink, but file-attributes
and similar in emacs do.

I submitted a patch to ls-lisp earlier, based on my assumption that 
it was ls-lisp that was at fault: However, it does look like 
file-attributes and directory-files-and-attributes is feeding it
bad values when the "." or ".." by which we arrived in a directory 
(from the current path's perspective) was a symlink.

Actually, thinking about it, that patch [see below] stands, imo, 
it just doesn't cover the `.. in our path was a symlink' case.

If file-attributes isn't likely to change, "." and ".." can be 
special cased in the chunk of code below as well, which fixes 
ls-lisp in any case.

--- dist/ls-lisp.el	Wed Dec  4 12:38:27 2002
+++ patched/ls-lisp.el	Mon Jul 14 15:46:44 2003
@@ -384,9 +384,13 @@
   ;; ordering, and reverse whole list.  cadr of each element of
   ;; `file-alist' is t for directory, string (name linked to) for
   ;; symbolic link, or nil.
-      (let (el dirs files)
+      (let (el dirs files dir-or-link)
 	(while file-alist
-	  (if (eq (cadr (setq el (car file-alist))) t) ; directory
+          (setq el          (car  file-alist)
+                dir-or-link (cadr el        ))
+	  (if (and dir-or-link
+                   (or (eq dir-or-link   t)             ; directory
+                       (file-directory-p dir-or-link))) ; symlink to dir
 	      (setq dirs (cons el dirs))
 	    (setq files (cons el files)))
 	  (setq file-alist (cdr file-alist)))