Added implementation of a data source for reading from drives.

libisoburn/isoburn.h

@@ -123,6 +123,15 @@ int isoburn_find_emulator(struct isoburn **pt,
 */
 int isoburn_set_start_byte(struct isoburn *o, off_t value, int flag);
 
+/** Get a data source suitable for read from a drive using burn_read_data()
+    function.
+    @param d drive to read from. Must be grabbed.
+    @return the data source, NULL on error. Must be freed with libisofs
+            data_source_free() function. Note that that doesn't release the
+            drive.
+*/
+static struct data_source *
+isoburn_data_source_new(struct burn_drive *d);
 
 #endif /* Isoburn_includeD */