1 files changed, 57 insertions, 0 deletions
diff --git a/email/quoted-printable.scm b/email/quoted-printable.scm
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+++ b/email/quoted-printable.scm
@@ -0,0 +1,57 @@
+;;; guile-email --- Guile email parser
+;;; Copyright © 2018 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of guile-email.
+;;;
+;;; guile-email is free software; you can redistribute it and/or modify
+;;; it under the terms of the GNU Affero General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; guile-email is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; Affero General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU Affero General Public
+;;; License along with guile-email.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (email quoted-printable)
+  #:use-module (rnrs)
+  #:use-module (ice-9 match)
+  #:export (quoted-printable-decode
+	    q-encoding-decode))
+
+;; TODO: Error out on invalid quoted-printable input
+(define quoted-printable-decode
+  (match-lambda*
+    (((? string? str))
+     (call-with-input-string str quoted-printable-decode))
+    (((? port? in))
+     (let-values (((out get-bytevector)
+		   (open-bytevector-output-port)))
+       (quoted-printable-decode in out)
+       (get-bytevector)))
+    (((? port? in) (? port? out))
+     (let ((c (read-char in)))
+       (cond
+	((eof-object? c)
+	 out)
+	((char=? c #\=)
+	 ;; TODO: Support "\r\n" line ending
+	 (let ((c1 (read-char in)))
+	   (unless (char=? c1 #\Newline)
+	     (let ((c2 (read-char in)))
+	       (put-u8 out (string->number (string c1 c2) 16)))))
+	 (quoted-printable-decode in out))
+	(#t
+	 (put-u8 out (char->integer c))
+	 (quoted-printable-decode in out)))))))
+
+(define (q-encoding-decode str)
+  (quoted-printable-decode
+   (string-map
+    (lambda (c)
+      (if (char=? c #\_) #\Space c))
+    str)))