Fix build on GNU/Hurd [supports openat()]. Bug 2608

diff --git a/src/OS/os.h-GNU b/src/OS/os.h-GNU
index 59130ef1054c85e99b16a8d1e52f2969bd8862e7..2c3b7b5f557bafd16ee92ccf731d4da82aca47e4 100644 (file)
--- a/src/OS/os.h-GNU
+++ b/src/OS/os.h-GNU
@@ -1,6 +1,8 @@
 /* Exim: OS-specific C header file for GNU/Hurd */
 /* Copyright (c) The Exim Maintainers 2020 */
 
+#include <features.h>
+
 #define CRYPT_H
 #define GLIBC_IP_OPTIONS
 #define HAVE_BSD_GETLOADAVG
@@ -25,4 +27,8 @@ typedef struct flock flock_t;
 as well as any supplementary groups*/
 #define OS_SETGROUPS_ZERO_DROPS_ALL
 
+#if _POSIX_C_SOURCE >= 200809L || _ATFILE_SOURCE
+# define EXIM_HAVE_OPENAT
+#endif
+
 /* End */