io: add a trivial type reader for fds

io.hpp

@@ -148,6 +148,17 @@ namespace cruft {
     }
 
 
+    template <typename ValueT>
+    requires (std::is_trivial_v<ValueT>)
+    ValueT
+    read (cruft::posix::fd &src)
+    {
+        ValueT res;
+        read (src, cruft::make_byte_view<u08> (res));
+        return res;
+    }
+
+
     ///////////////////////////////////////////////////////////////////////////
     class indenter : public std::streambuf {
     protected: