* crypto: implement automagic decryption when so requested

(mainly by adding some smartness to various part_foreach functions, adding
  mu_msg_(get|set)_auto_decrypt to mark a message for auto-decryption)

lib/mu-msg-priv.h

@@ -44,6 +44,9 @@ struct _MuMsgFile {
 	char		 _path    [PATH_MAX + 1];
 	char		 _maildir [PATH_MAX + 1];
 
+	/* whether to attemp to automagically decrypt encrypted parts */
+	gboolean         _auto_decrypt;
+
 	/* list where we push allocated strings so we can
 	 * free them when the struct gets destroyed
 	 */
@@ -97,15 +100,25 @@ gboolean mu_msg_part_mime_save_object (GMimeObject *obj, const char *fullpath,
  * get the MIME part that's probably the body of the message (heuristic)
  *
  * @param self a MuMsg
+ * @param decrypt whether decryption should be attempted, if needed
  * @param want_html whether it should be a html type of body
  *
  * @return the MIME part, or NULL in case of error.
  */
-GMimePart* mu_msg_mime_get_body_part (GMimeMessage *msg, gboolean want_html);
-
-
+GMimePart* mu_msg_mime_get_body_part (GMimeMessage *msg, gboolean decrypt,
+				      gboolean want_html);
 
 
+/**
+ * Like g_mime_message_foreach, but will recurse into encrypted parts
+ *
+ * @param msg
+ * @param decrypt whether to try to automatically decrypt
+ * @param func
+ * @param user_data
+ */
+void mu_mime_message_foreach (GMimeMessage *msg, gboolean decrypt,
+			      GMimeObjectForeachFunc func, gpointer user_data);
 
 #ifdef BUILD_CRYPTO
 /**
@@ -136,6 +149,18 @@ char* mu_msg_mime_decrypt (GMimeMultipartEncrypted *encpart,
 			   MuMsgOptions opts, GError **err);
 
 
+
+/**
+ * decrypt the given encrypted mime multipart
+ *
+ * @param enc encrypted part
+ * @param opts options
+ * @param err receives error data
+ *
+ * @return the decrypted part, or NULL in case of error
+ */
+GMimeObject* mu_msg_crypto_decrypt_part (GMimeMultipartEncrypted *enc, MuMsgOptions opts,
+					 GError **err);
 #endif /*BUILD_CRYPTO*/
 
 G_END_DECLS