+static int invalid_attr_name(const char *name, int namelen)
+{
+ /*
+ * Attribute name cannot begin with '-' and from
+ * [-A-Za-z0-9_.]. We'd specifically exclude '=' for now,
+ * as we might later want to allow non-binary value for
+ * attributes, e.g. "*.svg merge=special-merge-program-for-svg"
+ */
+ if (*name == '-')
+ return -1;
+ while (namelen--) {
+ char ch = *name++;
+ if (! (ch == '-' || ch == '.' || ch == '_' ||
+ ('0' <= ch && ch <= '9') ||
+ ('a' <= ch && ch <= 'z') ||
+ ('A' <= ch && ch <= 'Z')) )
+ return -1;
+ }
+ return 0;
+}
+