support: Add error checking to close system calls [BZ #21244]

diff --git a/support/Makefile b/support/Makefile
index db7bb13..1f33fa0 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -53,6 +53,7 @@  libsupport-routines = \
   xasprintf \
   xbind \
   xcalloc \
+  xclose \
   xconnect \
   xfclose \
   xfopen \
diff --git a/support/resolv_test.c b/support/resolv_test.c
index 2d0ea3c..9fc5d5b 100644
--- a/support/resolv_test.c
+++ b/support/resolv_test.c
@@ -32,6 +32,7 @@ 
 #include <support/test-driver.h>
 #include <support/xsocket.h>
 #include <support/xthread.h>
+#include <support/xunistd.h>
 #include <unistd.h>
 
 /* Response builder. */
@@ -860,7 +861,7 @@  server_thread_tcp_client (void *arg)
         break;
     }
 
-  close (closure->client_socket);
+  xclose (closure->client_socket);
   free (closure);
   return NULL;
 }
@@ -881,7 +882,7 @@  server_thread_tcp (struct resolv_test *obj, int server_index)
       if (obj->termination_requested)
         {
           xpthread_mutex_unlock (&obj->lock);
-          close (client_socket);
+          xclose (client_socket);
           break;
         }
       xpthread_mutex_unlock (&obj->lock);
@@ -941,8 +942,8 @@  make_server_sockets (struct resolv_test_server *server)
              next local UDP address randomly.  */
           if (errno == EADDRINUSE)
             {
-              close (server->socket_udp);
-              close (server->socket_tcp);
+              xclose (server->socket_udp);
+              xclose (server->socket_tcp);
               continue;
             }
           FAIL_EXIT1 ("TCP bind: %m");
@@ -1025,7 +1026,7 @@  resolv_test_start (struct resolv_redirect_config config)
       struct resolv_test_server *server = obj->servers + server_index;
       if (config.servers[server_index].disable_udp)
         {
-          close (server->socket_udp);
+          xclose (server->socket_udp);
           server->socket_udp = -1;
         }
       else if (!config.single_thread_udp)
@@ -1033,7 +1034,7 @@  resolv_test_start (struct resolv_redirect_config config)
                                                   server_thread_udp);
       if (config.servers[server_index].disable_tcp)
         {
-          close (server->socket_tcp);
+          xclose (server->socket_tcp);
           server->socket_tcp = -1;
         }
       else
@@ -1114,7 +1115,7 @@  resolv_test_end (struct resolv_test *obj)
           xsendto (sock, "", 1, 0,
                    (struct sockaddr *) &obj->servers[server_index].address,
                    sizeof (obj->servers[server_index].address));
-          close (sock);
+          xclose (sock);
         }
       if (!obj->config.servers[server_index].disable_tcp)
         {
@@ -1122,7 +1123,7 @@  resolv_test_end (struct resolv_test *obj)
           xconnect (sock,
                     (struct sockaddr *) &obj->servers[server_index].address,
                     sizeof (obj->servers[server_index].address));
-          close (sock);
+          xclose (sock);
         }
     }
 
@@ -1137,12 +1138,12 @@  resolv_test_end (struct resolv_test *obj)
         {
           if (!obj->config.single_thread_udp)
             xpthread_join (obj->servers[server_index].thread_udp);
-          close (obj->servers[server_index].socket_udp);
+          xclose (obj->servers[server_index].socket_udp);
         }
       if (!obj->config.servers[server_index].disable_tcp)
         {
           xpthread_join (obj->servers[server_index].thread_tcp);
-          close (obj->servers[server_index].socket_tcp);
+          xclose (obj->servers[server_index].socket_tcp);
         }
     }
 
diff --git a/support/support_enter_network_namespace.c b/support/support_enter_network_namespace.c
index d2e78fe..28b0ee2 100644
--- a/support/support_enter_network_namespace.c
+++ b/support/support_enter_network_namespace.c
@@ -23,9 +23,10 @@ 
 #include <stdio.h>
 #include <string.h>
 #include <support/check.h>
+#include <support/xsocket.h>
+#include <support/xunistd.h>
 #include <sys/ioctl.h>
 #include <unistd.h>
-#include <xsocket.h>
 
 static bool in_uts_namespace;
 
@@ -58,7 +59,7 @@  support_enter_network_namespace (void)
           req.ifr_flags |= IFF_UP | IFF_RUNNING;
           TEST_VERIFY_EXIT (ioctl (fd, SIOCSIFFLAGS, &req) == 0);
         }
-      close (fd);
+      xclose (fd);
 
       return !already_up;
     }
diff --git a/support/support_run_diff.c b/support/support_run_diff.c
index 3085037..f5155de 100644
--- a/support/support_run_diff.c
+++ b/support/support_run_diff.c
@@ -24,8 +24,8 @@ 
 #include <support/check.h>
 #include <support/support.h>
 #include <support/temp_file.h>
+#include <support/xunistd.h>
 #include <sys/wait.h>
-#include <xunistd.h>
 
 static char *
 write_to_temp_file (const char *prefix, const char *str)
@@ -36,7 +36,7 @@  write_to_temp_file (const char *prefix, const char *str)
   TEST_VERIFY_EXIT (fd >= 0);
   free (template);
   xwrite (fd, str, strlen (str));
-  TEST_VERIFY_EXIT (close (fd) == 0);
+  xclose (fd);
   return name;
 }
 
diff --git a/support/xclose.c b/support/xclose.c
new file mode 100644
index 0000000..c931e08
--- /dev/null
+++ b/support/xclose.c
@@ -0,0 +1,28 @@ 
+/* close with error checking.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <support/xunistd.h>
+#include <support/check.h>
+#include <errno.h>
+
+void
+xclose (int fd)
+{
+  if (close (fd) < 0 && errno != EINTR)
+    FAIL_EXIT1 ("close of descriptor %d failed: %m", fd);
+}
diff --git a/support/xunistd.h b/support/xunistd.h
index a83b1f4..3c34a85 100644
--- a/support/xunistd.h
+++ b/support/xunistd.h
@@ -30,6 +30,10 @@  __BEGIN_DECLS
 pid_t xfork (void);
 pid_t xwaitpid (pid_t, int *status, int flags);
 
+/* Close the file descriptor.  Ignore EINTR errors, but terminate the
+   process on other errors. */
+void xclose (int);
+
 /* Write the buffer.  Retry on short writes.  */
 void xwrite (int, const void *, size_t);