Re: Trouble getting archives to load as archives

[Kevin Rodgers <kevin.d.rodgers@gmail.com>]

Davin Pearson wrote:
> 2008/7/5 Peter Dyballa <Peter_Dyballa@web.de>:
>> How does it work when you invoke GNU Emacs as 'emacs -Q' or 'emacs -q' ?
>> With -Q neither the system's nor your own customisation is loaded, with -q
>> your's not loaded. In either both or in one case GNU Emacs should behave
>> correctly ...
> 
> With -q and -Q and the following:
> 
> (add-to-list 'auto-mode-alist
> '("\\.\\(arc\\|zip\\|tar\\|gz\\|lzh\\|zoo\\)\\'" . archive-mode))
> 
> Then loading a *.tar or *.gz file generates the following error messages:
> 
> File mode specification error: (error "Buffer format not recognized") [3 times]

That's because archive-mode does not support .tar or .gz files.  From
arc-mode.el (Emacs 22.2):

;; ARCHIVE TYPES: Currently only the archives below are handled, but the
;; structure for handling just about anything is in place.
;;
;;                        Arc     Lzh     Zip     Zoo
;;                        --------------------------------
;; View listing           Intern  Intern  Intern  Intern
;; Extract member         Y       Y       Y       Y
;; Save changed member    Y       Y       Y       Y
;; Add new member         N       N       N       N
;; Delete member          Y       Y       Y       Y
;; Rename member          Y       Y       N       N
;; Chmod                  -       Y       Y       -
;; Chown                  -       Y       -       -
;; Chgrp                  -       Y       -       -

...

(defun archive-find-type ()
   (widen)
   (goto-char (point-min))
   ;; The funny [] here make it unlikely that the .elc file will be treated
   ;; as an archive by other software.
   (let (case-fold-search)
     (cond ((looking-at "[P]K\003\004") 'zip)
	  ((looking-at "..-l[hz][0-9ds]-") 'lzh)
	  ((looking-at "....................[\334]\247\304\375") 'zoo)
	  ((and (looking-at "\C-z")	; signature too simple, IMHO
		(string-match "\\.[aA][rR][cC]$"
			      (or buffer-file-name (buffer-name))))
	   'arc)
           ;; This pattern modelled on the BSD/GNU+Linux `file' command.
           ;; Have seen capital "LHA's", and file has lower case "LHa's" 
too.
           ;; Note this regexp is also in archive-exe-p.
           ((looking-at "MZ\\(.\\|\n\\)\\{34\\}LH[aA]'s SFX ") 'lzh-exe)
	  (t (error "Buffer format not recognized")))))


-- 
Kevin Rodgers
Denver, Colorado, USA