static JSON_Status verify_utf8_sequence()

in lib/parson.c [317:357]

• 33 lines of code
• 17 McCabe index (conditional complexity)

static JSON_Status verify_utf8_sequence(const unsigned char *string, int *len) {
    unsigned int cp = 0;
    *len = num_bytes_in_utf8_sequence(string[0]);

    if (*len == 1) {
        cp = string[0];
    } else if (*len == 2 && IS_CONT(string[1])) {
        cp = string[0] & 0x1F;
        cp = (cp << 6) | (string[1] & 0x3F);
    } else if (*len == 3 && IS_CONT(string[1]) && IS_CONT(string[2])) {
        cp = ((unsigned char)string[0]) & 0xF;
        cp = (cp << 6) | (string[1] & 0x3F);
        cp = (cp << 6) | (string[2] & 0x3F);
    } else if (*len == 4 && IS_CONT(string[1]) && IS_CONT(string[2]) && IS_CONT(string[3])) {
        cp = string[0] & 0x7;
        cp = (cp << 6) | (string[1] & 0x3F);
        cp = (cp << 6) | (string[2] & 0x3F);
        cp = (cp << 6) | (string[3] & 0x3F);
    } else {
        return JSONFailure;
    }

    /* overlong encodings */
    if ((cp < 0x80    && *len > 1) ||
        (cp < 0x800   && *len > 2) ||
        (cp < 0x10000 && *len > 3)) {
        return JSONFailure;
    }

    /* invalid unicode */
    if (cp > 0x10FFFF) {
        return JSONFailure;
    }

    /* surrogate halves */
    if (cp >= 0xD800 && cp <= 0xDFFF) {
        return JSONFailure;
    }

    return JSONSuccess;
}