CDRIVER-5901 support auto encryption in unified tests

src/libmongoc/src/mongoc/mongoc-util-private.h

@@ -100,6 +100,9 @@ mongoc_ends_with (const char *str, const char *suffix);
 void
 mongoc_lowercase (const char *src, char *buf /* OUT */);
 
+void
+mongoc_lowercase_inplace (char *src);
+
 bool
 mongoc_parse_port (uint16_t *port, const char *str);
 

src/libmongoc/src/mongoc/mongoc-util.c

@@ -526,6 +526,18 @@ mongoc_lowercase (const char *src, char *buf /* OUT */)
    }
 }
 
+void
+mongoc_lowercase_inplace (char *src)
+{
+   for (; *src; ++src) {
+      /* UTF8 non-ascii characters have a 1 at the leftmost bit. If this is the
+       * case, just copy */
+      if ((*src & (0x1 << 7)) == 0) {
+         *src = (char) tolower (*src);
+      }
+   }
+}
+
 bool
 mongoc_parse_port (uint16_t *port, const char *str)
 {