+
+char *utf16_to_utf8(const void *s, size_t length) {
+ char *r;
+ const uint8_t *f;
+ uint8_t *t;
+
+ r = new(char, (length*3+1)/2 + 1);
+ if (!r)
+ return NULL;
+
+ t = (uint8_t*) r;
+
+ for (f = s; f < (const uint8_t*) s + length; f += 2) {
+ uint16_t c;
+
+ c = (f[1] << 8) | f[0];
+
+ if (c == 0) {
+ *t = 0;
+ return r;
+ } else if (c < 0x80) {
+ *(t++) = (uint8_t) c;
+ } else if (c < 0x800) {
+ *(t++) = (uint8_t) (0xc0 | (c >> 6));
+ *(t++) = (uint8_t) (0x80 | (c & 0x3f));
+ } else {
+ *(t++) = (uint8_t) (0xe0 | (c >> 12));
+ *(t++) = (uint8_t) (0x80 | ((c >> 6) & 0x3f));
+ *(t++) = (uint8_t) (0x80 | (c & 0x3f));
+ }
+ }
+
+ *t = 0;
+
+ return r;
+}
+
+/* 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;
+}
+
+/* validate one encoded unicode char and return its length */
+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 (!is_unicode_valid(unichar))
+ return -1;
+
+ return len;
+}
+
+int is_utf8_encoding_whitelisted(char c, const char *white) {
+ if ((c >= '0' && c <= '9') ||
+ (c >= 'A' && c <= 'Z') ||
+ (c >= 'a' && c <= 'z') ||
+ strchr("#+-.:=@_", c) != NULL ||
+ (white != NULL && strchr(white, c) != NULL))
+ return 1;
+ return 0;
+}
+
+int udev_encode_string(const char *str, char *str_enc, size_t len) {
+ size_t i, j;
+
+ if (str == NULL || str_enc == NULL)
+ return -1;
+
+ for (i = 0, j = 0; str[i] != '\0'; i++) {
+ int seqlen;
+
+ seqlen = utf8_encoded_valid_unichar(&str[i]);
+ if (seqlen > 1) {
+ if (len-j < (size_t)seqlen)
+ goto err;
+ memcpy(&str_enc[j], &str[i], seqlen);
+ j += seqlen;
+ i += (seqlen-1);
+ } else if (str[i] == '\\' || !is_utf8_encoding_whitelisted(str[i], NULL)) {
+ if (len-j < 4)
+ goto err;
+ sprintf(&str_enc[j], "\\x%02x", (unsigned char) str[i]);
+ j += 4;
+ } else {
+ if (len-j < 1)
+ goto err;
+ str_enc[j] = str[i];
+ j++;
+ }
+ }
+ if (len-j < 1)
+ goto err;
+ str_enc[j] = '\0';
+ return 0;
+err:
+ return -1;
+}