a pointer to Unicode character encoded as UTF-8
the maximum number of bytes to read, or -1, for no maximum or if p is nul-terminated
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.
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.