From bac4118d6873c5f5b15692d82561aeb80373a064 Mon Sep 17 00:00:00 2001
From: Martine Lenders <m.lenders@fu-berlin.de>
Date: Mon, 20 Mar 2017 09:43:55 +0100
Subject: [PATCH] posix: fix close() if fd_obj was closed already

---
 sys/posix/unistd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/posix/unistd.c b/sys/posix/unistd.c
index c7f2fe7d3..52a24cb8e 100644
--- a/sys/posix/unistd.c
+++ b/sys/posix/unistd.c
@@ -22,7 +22,7 @@ int close(int fildes)
 {
     fd_t *fd_obj = fd_get(fildes);
 
-    if (!fd_obj) {
+    if (!fd_obj || (fd_obj->close == NULL)) {
         errno = EBADF;
         return -1;
     }