* [Bug #311316] Allow sane_open() to be called with empty (zero-length)

device name to select first available one (see special case described in
  SANE API Documentation, s. 4.3.4).

backend/hp5590.c

@@ -72,7 +72,7 @@
 }
 
 /* #define HAS_WORKING_COLOR_48 */
-#define BUILD 		3
+#define BUILD 		4
 #define USB_TIMEOUT	30 * 1000
 
 static SANE_Word
@@ -424,9 +424,14 @@ sane_open (SANE_String_Const devicename, SANE_Handle * handle)
   if (!handle)
     return SANE_STATUS_INVAL;
 
+  /* Allow to open the first available device by specifying zero-length name */
+  if (!devicename || !devicename[0]) {
+    ptr = scanners_list;
+  } else {
     for (ptr = scanners_list;
 	 ptr && strcmp (ptr->sane.name, devicename) != 0;
 	 ptr = ptr->next);
+  }
 
   if (!ptr)
     return SANE_STATUS_INVAL;