+static bool
+all_utf8(const uint8_t *p)
+{
+ size_t len = strlen ((char *) p);
+ for (size_t ofs = 0, mblen; ofs < len; ofs += mblen)
+ {
+ ucs4_t uc;
+
+ mblen = u8_mbtouc (&uc, p + ofs, len - ofs);
+ if (uc < 32 || uc == 127 || uc == 0xfffd)
+ return false;
+ }
+ return true;
+}
+