Revamp the CLOEXEC support in Qt

The pipe2/dup3/accept4 functions and SOCK_CLOEXEC are quite old nowadays
on Linux. They were introduced on Linux 2.6.28 and glibc 2.10, all from
2008. They were also picked up by uClibc in 2011 and FreeBSD as of
version 10.0. So we no longer need the runtime detection of whether the
feature is available.

Instead, if the libc has support for it, use it unconditionally and fail
at runtime if the syscall isn't implemented.

Change-Id: Ib056b47dde3341ef9a52ffff13efcc39ef8dff7d
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

2 files changed, 52 insertions, 0 deletions

diff --git a/config.tests/unix/cloexec/cloexec.cpp b/config.tests/unix/cloexec/cloexec.cpp
new file mode 100644
index 0000000000..3f127d8d3f
--- /dev/null
+++ b/config.tests/unix/cloexec/cloexec.cpp
@@ -0,0 +1,49 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 Intel Corporation.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the configuration module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#define _GNU_SOURCE 1
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+int main()
+{
+    int pipes[2];
+    (void) pipe2(pipes, O_CLOEXEC | O_NONBLOCK);
+    (void) fcntl(0, F_DUPFD_CLOEXEC, 0);
+    (void) dup3(0, 3, O_CLOEXEC);
+    (void) accept4(0, 0, 0, SOCK_CLOEXEC | SOCK_NONBLOCK);
+    return 0;
+}
diff --git a/config.tests/unix/cloexec/cloexec.pro b/config.tests/unix/cloexec/cloexec.pro
new file mode 100644
index 0000000000..bc735f9b1f
--- /dev/null
+++ b/config.tests/unix/cloexec/cloexec.pro
@@ -0,0 +1,3 @@
+SOURCES = cloexec.cpp
+CONFIG -= qt
+QT =