new file mode 100644
--- /dev/null
+++ b/m4/idpriv.m4
@@ -0,0 +1,14 @@
+# idpriv.m4 serial 1
+dnl Copyright (C) 2009 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_IDPRIV],
+[
+  dnl Persuade glibc <unistd.h> to declare {get,set}res{uid,gid}.
+  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+
+  AC_CHECK_FUNCS_ONCE([getuid geteuid getresuid getgid getegid getresgid])
+  AC_CHECK_FUNCS_ONCE([setresuid setreuid seteuid setresgid setregid setegid])
+])