Merge citrix branch into master.

[sliver-openvswitch.git] / lib / socket-util.c

diff --git a/lib/socket-util.c b/lib/socket-util.c
index fdd8e95..d537434 100644 (file)
--- a/lib/socket-util.c
+++ b/lib/socket-util.c
@@ -1,17 +1,17 @@
 /*
  * Copyright (c) 2008, 2009 Nicira Networks.
  *
- * Permission to use, copy, modify, and/or distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
  *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
  */
 
 #include <config.h>
@@ -466,6 +466,24 @@ exit:
     return error ? -error : fd;
 }
 
+/* Returns a readable and writable fd for /dev/null, if successful, otherwise
+ * a negative errno value.  The caller must not close the returned fd (because
+ * the same fd will be handed out to subsequent callers). */
+int
+get_null_fd(void)
+{
+    static int null_fd = -1;
+    if (null_fd < 0) {
+        null_fd = open("/dev/null", O_RDWR);
+        if (null_fd < 0) {
+            int error = errno;
+            VLOG_ERR("could not open /dev/null: %s", strerror(error));
+            return -error;
+        }
+    }
+    return null_fd;
+}
+
 int
 read_fully(int fd, void *p_, size_t size, size_t *bytes_read)
 {