fd_util: support eventfd()

configure.ac

@@ -133,7 +133,7 @@ AC_SEARCH_LIBS([syslog], [bsd socket inet],
 AC_SEARCH_LIBS([socket], [socket])
 AC_SEARCH_LIBS([gethostbyname], [nsl])
 
-AC_CHECK_FUNCS(pipe2 accept4)
+AC_CHECK_FUNCS(pipe2 accept4 eventfd)
 
 AC_SEARCH_LIBS([exp], [m],,
 	[AC_MSG_ERROR([exp() not found])])

src/fd_util.c

@@ -49,6 +49,10 @@
 #include <sys/inotify.h>
 #endif
 
+#ifdef HAVE_EVENTFD
+#include <sys/eventfd.h>
+#endif
+
 #ifndef WIN32
 
 static int
@@ -328,6 +332,16 @@ inotify_init_cloexec(void)
 
 #endif
 
+#ifdef HAVE_EVENTFD
+
+int
+eventfd_cloexec_nonblock(unsigned initval, int flags)
+{
+	return eventfd(initval, flags | EFD_CLOEXEC | EFD_NONBLOCK);
+}
+
+#endif
+
 int
 close_socket(int fd)
 {

src/fd_util.h

@@ -144,6 +144,17 @@ inotify_init_cloexec(void);
 
 #endif
 
+#ifdef HAVE_EVENTFD
+
+/**
+ * Wrapper for eventfd() which sets the flags CLOEXEC and NONBLOCK
+ * flag (atomically if supported by the OS).
+ */
+int
+eventfd_cloexec_nonblock(unsigned initval, int flags);
+
+#endif
+
 /**
  * Portable wrapper for close(); use closesocket() on WIN32/WinSock.
  */