GLib.utf8_get_char_validated

function utf8_get_char_validated(p: String, max_len: Number(gssize)): String {
    // Gjs wrapper for g_utf8_get_char_validated()
}

Convert a sequence of bytes encoded as UTF-8 to a Unicode character. This function checks for incomplete characters, for invalid characters such as characters that are out of the range of Unicode, and for overlong encodings of valid characters.

p: a pointer to Unicode character encoded as UTF-8
max_len: the maximum number of bytes to read, or -1, for no maximum or if p is nul-terminated
Returns: the resulting character. If p points to a partial sequence at the end of a string that could begin a valid character (or if max_len is zero), returns (gunichar)-2; otherwise, if p does not point to a valid UTF-8 encoded Unicode character, returns (gunichar)-1.