Converts hostname to its canonical presentation form; a UTF-8 string in Unicode normalization form C, containing no
uppercase letters, no forbidden characters, and no ASCII-encoded segments, and not ending with a trailing dot.
Of course if hostname is not an internationalized hostname, then the canonical presentation form will be entirely ASCII.
| hostname |
a valid UTF-8 or ASCII hostname |
|
a UTF-8 hostname, which must be freed, or null if |