+static int isurlschemechar(int first_flag, int ch)
+{
+ /*
+ * The set of valid URL schemes, as per STD66 (RFC3986) is
+ * '[A-Za-z][A-Za-z0-9+.-]*'. But use sightly looser check
+ * of '[A-Za-z0-9][A-Za-z0-9+.-]*' because earlier version
+ * of check used '[A-Za-z0-9]+' so not to break any remote
+ * helpers.
+ */
+ int alphanumeric, special;
+ alphanumeric = ch > 0 && isalnum(ch);
+ special = ch == '+' || ch == '-' || ch == '.';
+ return alphanumeric || (!first_flag && special);
+}
+