GNU bug report logs - #15285
url-data not working for base64-encoded data

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Klaus Straubinger <KSNetz <at> UseNet.ArcorNews.DE>
Subject: bug#15285: closed (Re: bug#15285: url-data not working for
 base64-encoded data)
Date: Mon, 16 Sep 2013 21:32:03 +0000

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Your bug report

#15285: url-data not working for base64-encoded data

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 15285 <at> debbugs.gnu.org.

-- 
15285: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15285
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Glenn Morris <rgm <at> gnu.org>
To: 15285-done <at> debbugs.gnu.org
Subject: Re: bug#15285: url-data not working for base64-encoded data
Date: Mon, 16 Sep 2013 17:31:54 -0400

Version: 24.4

Thanks for the clear report.
(I needed to add a "(require 'mm-view)" to the test-case).

I think this fixes it:

*** lisp/url/url-misc.el	2013-01-02 16:13:04 +0000
--- lisp/url/url-misc.el	2013-09-16 21:28:11 +0000
***************
*** 89,107 ****
      (save-excursion
        (if (not (string-match "\\([^,]*\\)?," desc))
  	  (error "Malformed data URL: %s" desc)
! 	(setq mediatype (match-string 1 desc))
  	(if (and mediatype (string-match ";base64\\'" mediatype))
  	    (setq mediatype (substring mediatype 0 (match-beginning 0))
  		  encoding "base64"))
  	(if (or (null mediatype)
  		(eq ?\; (aref mediatype 0)))
! 	  (setq mediatype (concat "text/plain" mediatype)))
! 	(setq data (url-unhex-string (substring desc (match-end 0)))))
        (set-buffer (generate-new-buffer " *url-data*"))
        (mm-disable-multibyte)
        (insert (format "Content-Length: %d\n" (length data))
  	      "Content-Type: " mediatype "\n"
! 	      "Content-Encoding: " encoding "\n"
  	      "\n")
        (if data (insert data))
        (current-buffer))))
--- 88,106 ----
      (save-excursion
        (if (not (string-match "\\([^,]*\\)?," desc))
  	  (error "Malformed data URL: %s" desc)
! 	(setq mediatype (match-string 1 desc)
! 	      data (url-unhex-string (substring desc (match-end 0))))
  	(if (and mediatype (string-match ";base64\\'" mediatype))
  	    (setq mediatype (substring mediatype 0 (match-beginning 0))
  		  encoding "base64"))
  	(if (or (null mediatype)
  		(eq ?\; (aref mediatype 0)))
! 	  (setq mediatype (concat "text/plain" mediatype))))
        (set-buffer (generate-new-buffer " *url-data*"))
        (mm-disable-multibyte)
        (insert (format "Content-Length: %d\n" (length data))
  	      "Content-Type: " mediatype "\n"
! 	      "Content-Transfer-Encoding: " encoding "\n"
  	      "\n")
        (if data (insert data))
        (current-buffer))))

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From: Klaus Straubinger <KSNetz <at> UseNet.ArcorNews.DE>
To: bug-gnu-emacs <at> gnu.org
Subject: url-data not working for base64-encoded data
Date: Fri, 6 Sep 2013 11:22:59 +0200 (Mitteleuropäische
 Sommerzeit)

In GNU Emacs 24.3.1 (i386-mingw-nt6.1.7601),
evaluating

    (require 'mm-decode)
    (require 'url)
    (mm-display-part
     (with-current-buffer
         (url-retrieve-synchronously
          "data:image/x-portable-bitmap;base64,UDQKMTQgMTAK//zgHJAkiESHhItEkCSgFMAM//w=")
       (mm-dissect-buffer t)))

should insert a letter image into the current buffer, but this does not work.

The cause is that in the function url-data (defined in url-misc.el)
the handling of the base64 parameter moves the match end and so the
starting "," character gets into the data, making them invalid.

Furthermore, instead of inserting the header "Content-Encoding" (that
should be used for encodings like "gzip") the code should insert the
header "Content-Transfer-Encoding" (the correct one for "8bit" or "base64").

-- 
Klaus Straubinger

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