-/* count of characters used to encode one unicode char */
-static int utf8_encoded_expected_len(const char *str)
-{
- unsigned char c = (unsigned char)str[0];
-
- if (c < 0x80)
- return 1;
- if ((c & 0xe0) == 0xc0)
- return 2;
- if ((c & 0xf0) == 0xe0)
- return 3;
- if ((c & 0xf8) == 0xf0)
- return 4;
- if ((c & 0xfc) == 0xf8)
- return 5;
- if ((c & 0xfe) == 0xfc)
- return 6;
- return 0;
-}
-
-/* decode one unicode char */
-static int utf8_encoded_to_unichar(const char *str)
-{
- int unichar;
- int len;
- int i;
-
- len = utf8_encoded_expected_len(str);
- switch (len) {
- case 1:
- return (int)str[0];
- case 2:
- unichar = str[0] & 0x1f;
- break;
- case 3:
- unichar = (int)str[0] & 0x0f;
- break;
- case 4:
- unichar = (int)str[0] & 0x07;
- break;
- case 5:
- unichar = (int)str[0] & 0x03;
- break;
- case 6:
- unichar = (int)str[0] & 0x01;
- break;
- default:
- return -1;
- }
-
- for (i = 1; i < len; i++) {
- if (((int)str[i] & 0xc0) != 0x80)
- return -1;
- unichar <<= 6;
- unichar |= (int)str[i] & 0x3f;
- }
-
- return unichar;
-}
-
-/* expected size used to encode one unicode char */
-static int utf8_unichar_to_encoded_len(int unichar)
-{
- if (unichar < 0x80)
- return 1;
- if (unichar < 0x800)
- return 2;
- if (unichar < 0x10000)
- return 3;
- if (unichar < 0x200000)
- return 4;
- if (unichar < 0x4000000)
- return 5;
- return 6;
-}
-
-/* check if unicode char has a valid numeric range */
-static int utf8_unichar_valid_range(int unichar)
-{
- if (unichar > 0x10ffff)
- return 0;
- if ((unichar & 0xfffff800) == 0xd800)
- return 0;
- if ((unichar > 0xfdcf) && (unichar < 0xfdf0))
- return 0;
- if ((unichar & 0xffff) == 0xffff)
- return 0;
- return 1;
-}
-
-/* validate one encoded unicode char and return its length */
-static int utf8_encoded_valid_unichar(const char *str)
-{
- int len;
- int unichar;
- int i;
-
- len = utf8_encoded_expected_len(str);
- if (len == 0)
- return -1;
-
- /* ascii is valid */
- if (len == 1)
- return 1;
-
- /* check if expected encoded chars are available */
- for (i = 0; i < len; i++)
- if ((str[i] & 0x80) != 0x80)
- return -1;
-
- unichar = utf8_encoded_to_unichar(str);
-
- /* check if encoded length matches encoded value */
- if (utf8_unichar_to_encoded_len(unichar) != len)
- return -1;
-
- /* check if value has valid range */
- if (!utf8_unichar_valid_range(unichar))
- return -1;
-
- return len;
-}
-