short-read (re-search-forward "^msgid" nil t)))
      (save-excursion
        (goto-char (point-max))
        (let ((pair (insert-file-contents-literally filename nil
                                                    (1- (point))
                                                    (1- (+ (point) 4096)))))
          (setq short-read (< (nth 1 pair) 4096)))))
    (cond ((re-search-forward charset-regexp nil t) (match-string 1))
          (short-read nil)
          ;; We've found the first msgid; maybe, only a part of the msgstr
          ;; value was loaded.  Load the next 1024 bytes; if charset still
          ;; isn't available, give up.
          (t (save-excursion
               (goto-char (point-max))
               (insert-file-contents-literally filename nil
                                               (1- (point))
                                               (1- (+ (point) 1024))))
             (if (re-search-forward charset-regexp nil t)
                 (match-string 1))))))

;;;###autoload (autoload 'po-find-file-coding-system "po-compat")

(defun po-find-file-coding-system-guts (operation filename)
  "\
Return a Mule (DECODING . ENCODING) pair, according to PO file charset.
Called through file-coding-system-alist, before the file is visited for real."
  (and (eq operation 'insert-file-contents)
       (file-exists-p filename)
       (with-temp-buffer
        (let* ((coding-system-for-read 'no-conversion)
               (charset (or (po-find-charset filename) "ascii"))
               (charset-upper (upcase charset))
               (charset-lower (downcase charset))
               (candidate
                (cdr (assoc charset-upper po-content-type-charset-alist)))
               (try-symbol (or candidate (intern-soft charset-lower)))
               (try-string
                (if try-symbol (symbol-name try-symbol) charset-lower)))
          (list (cond ((and try-symbol (coding-system-p try-symbol))
                       try-symbol)
                      ((and (not (string-lessp "23" emacs-version))
                            (string-match "\\`cp[1-9][0-9][0-9]?\\'"
                                          try-string)
                            (assoc (substring try-string 2)
                                   (cp-supported-codepages)))
                       (codepage-setup (substring try-string 2))
                       (intern try-string))
                      (t
                       'no-conversion)))))))

(defun po-find-file-coding-system (arg-list)
  "\
Return a Mule (DECODING . ENCODING) pair, according to PO file charset.
Called through file-coding-system-alist, before the file is visited for real."
  (po-find-file-coding-system-guts (car arg-list) (car (cdr arg-list))))

(provide 'po-compat)

;;; Testing this file:

;; For each pofile in {
;;   cs.po           ; gettext/po/cs.el, charset=ISO-8859-2
;;   cs-modified.po  ; gettext/po/cs.el, charset=ISO_8859-2
;;   de.po           ; gettext/po/de.el, charset=UTF-8, if $emacsimpl = emacs
;; } do
;;   Start $emacsimpl
;;   M-x load-file  po-compat.el RET
;;   C-x C-f  $pofile RET
;;   Verify charset marker in status line ('2' = ISO-8859-2, 'u' = UTF-8).

;;; po-compat.el ends here