The iconv function converts characters in the buffer pointed
    to by inbuf to characters in another code set. The resulting
    characters are stored in the buffer pointed to by outbuf. The
    conversion type is specified by the conversion descriptor cd.
    This descriptor is returned from a successful call to iconv_open.

    If an invalid character is found in the input buffer, the
    conversion stops after the last successful conversion. The
    variable pointed to by inbytesleft is updated to reflect the
    number of bytes in the input buffer that are not converted. The
    variable pointed to by outbytesleft is updated to reflect the
    number of bytes remaining in the output buffer.