small bugs.

taglib-ffi.rkt

@@ -263,8 +263,18 @@
   (when nul? (ptr-set! ptr _byte len 0))
   ptr)
 
+(define (string/bytes->malloc-cstring who v)
+  (define bs
+    (cond
+      [(bytes? v) v]
+      [(string? v) (string->bytes/utf-8 v)]
+      [(symbol? v) (string->bytes/utf-8 (symbol->string v))]
+      [(number? v) (string->bytes/utf-8 (number->string v))]
+      [else (raise-argument-error who "(or/c string? bytes? symbol? number?)" v)]))
+  (bytes->malloc-ptr bs #t))
+
 (define (string->malloc-cstring s)
-  (bytes->malloc-ptr (string->bytes/utf-8 s) #t))
+  (string/bytes->malloc-cstring 'string->malloc-cstring s))
 
 (define (picture->complex-property data size description mimetype picture-type)
   (define data-ptr (bytes->malloc-ptr data #f))