Re: pgnus-0.31: invoke external MIME stuff

[Jan Vroonhof <vroonhof@math.ethz.ch>]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> > > No -- base64 throws errors is the region in question isn't a valid
> > > base64 file, if I recall correctly.
> > 
> > Shouldn't you be catching JUST that error?
> 
> How does one catch an error thrown by `error' and no other errors?

One fixes the library (in this case base-64.el) to signal a more
specialised error, like this

 (condition-case ()
    (base64-decode-region (point-min) (point-max))
      (mime-conversion-error nil))


diff -u /u/scratch/vroonhof/xemacs/gnus/pgnus-0.32/lisp/base64.el~ /u/scratch/vroonhof/xemacs/gnus/pgnus-0.32/lisp/base64.el
--- /u/scratch/vroonhof/xemacs/gnus/pgnus-0.32/lisp/base64.el~	Fri Sep 25 13:14:06 1998
+++ /u/scratch/vroonhof/xemacs/gnus/pgnus-0.32/lisp/base64.el	Fri Sep 25 13:14:06 1998
@@ -29,6 +29,16 @@
 (if (not (fboundp 'char-int))
     (fset 'char-int 'identity))
 
+(define-error 'mime-conversion-error "Error in coverting encoded data.")
+; As data we return  (list <number of> <units>) where units is 'bits
+(define-error 'mime-short-coding-string
+  "The encoded string is short"
+  'mime-conversion-error)
+(define-error 'mime-external-program-error
+  "External conversion program error"
+  'mime-conversion-error)
+
+
 (defvar base64-alphabet
   "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
 
@@ -134,7 +144,7 @@
 				   base64-decoder-program
 				   base64-decoder-switches)))
 		(if (not (eq status t))
-		    (error "%s" (cdr status))))
+		    (signal-error 'mime-external-program-error (cdr status))))
 	    (goto-char start)
 	    (skip-chars-forward non-data-chars end)
 	    (while (not done)
@@ -159,13 +169,13 @@
 	      (cond
 	       ((= (point) end)
 		(if (not (zerop counter))
-		    (error "at least %d bits missing at end of base64 encoding"
-			   (* (- 4 counter) 6)))
+		    (signal-error 'mime-short-coding-string
+			   (list (* (- 4 counter) 6) 'bits)))
 		(setq done t))
 	       ((= (char-after (point)) ?=)
 		(setq done t)
 		(cond ((= counter 1)
-		       (error "at least 2 bits missing at end of base64 encoding"))
+		       (signal-error 'mime-short-coding-string '(2 bits))
 		      ((= counter 2)
 		       (base64-insert-char (lsh bits -10) 1 nil work-buffer))
 		      ((= counter 3)
@@ -201,7 +211,7 @@
 				   base64-encoder-program
 				   base64-encoder-switches)))
 		(if (not (eq status t))
-		    (error "%s" (cdr status))))
+		    (signal-error 'mime-external-program-error (list (cdr status)))))
 	    (setq inputpos start)
 	    (while (< inputpos end)
 	      (setq bits (+ bits (char-int (char-after inputpos))))