#include <fontconfig.h>
FcBool FcUtf8Len (FcChar8 *src, intlen, int *nchar, int *wchar);
Counts the number of Unicode chars in len bytes of src. Places that count in nchar. wchar contains 1, 2 or 4 depending on the number of bytes needed to hold the largest unicode char counted. The return value indicates whether src is a well-formed UTF8 string.
Fontconfig version 2.3.2