From: TODOROKI Shin-ichi <todoroki.s@gmail.com>

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1075457#14

Index: ruby-eb-2.6/eb.c
===================================================================
--- ruby-eb-2.6.orig/eb.c
+++ ruby-eb-2.6/eb.c
@@ -401,7 +401,7 @@ reb_setsubbook(VALUE obj, VALUE sbook)
 }
 
 static VALUE
-reb_getsubbook(VALUE obj, VALUE sbook)
+reb_getsubbook(VALUE obj)
 {
     EB_Book *eb;
     int r;
@@ -1097,7 +1097,7 @@ read_binary(EB_Book * eb, long maxlen, i
                 break;
         }
     }
-    rb_obj_taint(robj);
+    rb_obj_id(robj);
 
     return iterateflag ? INT2NUM(readbytes) : robj;
 }
@@ -1368,7 +1368,7 @@ font2bitmapformat(struct ExtFont *font,
     };
 
     (*conv_func) (font->bitmap, width, height, buffer, &size);
-    robj = rb_tainted_str_new(buffer, size);
+    robj = rb_str_new(buffer, size);
     free(buffer);
     return robj;
 }