emacs 20 copy-part uncompress

[Kevin Ryde <user42@zip.com.au>]

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The change I'd made a while ago to gnus-mime-copy-part for jka-compr
auto-decompression never actually worked with emacs 20, it bombs
prompting for a coding system and then sending the wrong bytes out to
gzip.  Eg. press "c" on the foo.txt.gz below to see it happen.

I think the part contents have to be sent out from a unibyte buffer to
avoid conversions,

	* gnus-art.el (gnus-mime-jka-compr-maybe-uncompress): Take contents
	parameter, use a unibyte buffer for that data to get the right bytes
	out of call-process-region under emacs 20.
	(gnus-mime-copy-part): Pass contents parameter.


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--- gnus-art.el.~6.378.~	1970-01-01 10:00:01.000000000 +1000
+++ gnus-art.el	2003-11-23 08:46:48.000000000 +1000
@@ -4140,9 +4140,14 @@ (eval-when-compile
 ;; jka-compr.el uses a "sh -c" to direct stderr to err-file, but these days
 ;; emacs can do that itself.
 ;;
-(defun gnus-mime-jka-compr-maybe-uncompress ()
-  "Uncompress the current buffer if `auto-compression-mode' is enabled.
-The uncompress method used is derived from `buffer-file-name'."
+;; The temporary unibyte buffer used is necessary to get the right bytes out
+;; of call-process-region in Emacs 20.  In Emacs 21 unibyte data can be
+;; successfully sent via a multibyte buffer, but not in Emacs 20.
+;;
+(defun gnus-mime-jka-compr-maybe-uncompress (contents)
+  "Uncompress CONTENTS if `auto-compression-mode' is enabled.
+The uncompress method used is derived from `buffer-file-name'.
+CONTENTS should be a unibyte string."
   (when (and (fboundp 'jka-compr-installed-p)
              (jka-compr-installed-p))
     (let ((info (jka-compr-get-compression-info buffer-file-name)))
@@ -4151,18 +4156,22 @@ (defun gnus-mime-jka-compr-maybe-uncompr
               (args     (jka-compr-info-uncompress-args    info))
               (prog     (jka-compr-info-uncompress-program info))
               (message  (jka-compr-info-uncompress-message info))
-              (err-file (jka-compr-make-temp-name)))
+              (err-file (jka-compr-make-temp-name))
+              (out-buf  (current-buffer)))
+          (erase-buffer)
+          (mm-with-unibyte-buffer
+            (insert contents)
           (if message
               (message "%s %s..." message basename))
           (unwind-protect
               (unless (memq (apply 'call-process-region
                                    (point-min) (point-max)
                                    prog
-                                   t (list t err-file) nil
+                                   nil (list out-buf err-file) nil
                                    args)
                             jka-compr-acceptable-retval-list)
                 (jka-compr-error prog args basename message err-file))
-            (jka-compr-delete-temp-file err-file)))))))
+            (jka-compr-delete-temp-file err-file))))))))
 
 (defun gnus-mime-copy-part (&optional handle)
   "Put the MIME part under point into a new buffer.
@@ -4187,7 +4196,7 @@ (defun gnus-mime-copy-part (&optional ha
       (unwind-protect
 	  (progn
 	    (setq buffer-file-name (expand-file-name base))
-	    (gnus-mime-jka-compr-maybe-uncompress)
+	    (gnus-mime-jka-compr-maybe-uncompress contents)
 	    (normal-mode))
 	(setq buffer-file-name nil))
       (goto-char (point-min)))))

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