fastcgi: using accept4 on connections accept when possible.

saving 1/2 fcntl calls in the process and possibly safer than doing so
in 1 operation (possible race condition in between accept/fcntl parts).

Author: devnexen

configure.ac

@@ -525,6 +525,7 @@ dnl Checks for library functions.
 dnl ----------------------------------------------------------------------------
 
 AC_CHECK_FUNCS(m4_normalize([
+  accept4
   alphasort
   asctime_r
   asprintf

ext/sockets/config.m4

@@ -4,7 +4,7 @@ PHP_ARG_ENABLE([sockets],
     [Enable sockets support])])
 
 if test "$PHP_SOCKETS" != "no"; then
-  AC_CHECK_FUNCS([hstrerror if_nametoindex if_indextoname sockatmark accept4])
+  AC_CHECK_FUNCS([hstrerror if_nametoindex if_indextoname sockatmark])
   AC_CHECK_HEADERS([sys/sockio.h linux/filter.h linux/if_packet.h linux/if_ether.h linux/udp.h])
   AC_DEFINE([HAVE_SOCKETS], [1],
     [Define to 1 if the PHP extension 'sockets' is available.])

main/fastcgi.c

@@ -1394,7 +1394,11 @@ int fcgi_accept_request(fcgi_request *req)
 					socklen_t len = sizeof(sa);
 
 					FCGI_LOCK(req->listen_socket);
+#if defined(HAVE_ACCEPT4)
+					req->fd = accept4(listen_socket, (struct sockaddr *)&sa, &len, SOCK_CLOEXEC);
+#else
 					req->fd = accept(listen_socket, (struct sockaddr *)&sa, &len);
+#endif
 					FCGI_UNLOCK(req->listen_socket);
 
 					client_sa = sa;
@@ -1414,7 +1418,8 @@ int fcgi_accept_request(fcgi_request *req)
 					return -1;
 				}
 
-#if defined(F_SETFD) && defined(FD_CLOEXEC)
+// TODO once we drop support for older solaris (i.e < 11.4) we could drop this block
+#if defined(F_SETFD) && defined(FD_CLOEXEC) && !defined(HAVE_ACCEPT4)
 				int fd_attrs = fcntl(req->fd, F_GETFD);
 				if (0 > fd_attrs) {
 					fcgi_log(FCGI_WARNING, "failed to get attributes of the connection socket");