Long live QLockFile

Locking between processes, implemented with open(O_EXCL) on Unix
and CreateFile(CREATE_NEW) on Windows.

Supports detecting stale lock files and deleting them.
Advisory locking is used to prevent deletion of files that are still in use.

Change-Id: Id00ee2a4e77a29483d869037c7047c59cb909339
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 91 insertions, 0 deletions

diff --git a/src/corelib/io/qlockfile.h b/src/corelib/io/qlockfile.h
new file mode 100644
index 0000000000..4c8b6bf31a
--- /dev/null
+++ b/src/corelib/io/qlockfile.h
@@ -0,0 +1,91 @@
+/****************************************************************************
+**
+** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org>
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the QtCore module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/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 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QLOCKFILE_H
+#define QLOCKFILE_H
+
+#include <QtCore/qstring.h>
+#include <QtCore/qscopedpointer.h>
+
+QT_BEGIN_HEADER
+
+QT_BEGIN_NAMESPACE
+
+class QLockFilePrivate;
+
+class Q_CORE_EXPORT QLockFile
+{
+public:
+    QLockFile(const QString &fileName);
+    ~QLockFile();
+
+    bool lock();
+    bool tryLock(int timeout = 0);
+    void unlock();
+
+    void setStaleLockTime(int);
+    int staleLockTime() const;
+
+    bool isLocked() const;
+    bool getLockInfo(qint64 *pid, QString *hostname, QString *appname) const;
+    bool removeStaleLockFile();
+
+    enum LockError {
+        NoError = 0,
+        LockFailedError = 1,
+        PermissionError = 2,
+        UnknownError = 3
+    };
+    LockError error() const;
+
+protected:
+    QScopedPointer<QLockFilePrivate> d_ptr;
+
+private:
+    Q_DECLARE_PRIVATE(QLockFile)
+    Q_DISABLE_COPY(QLockFile)
+};
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif // QLOCKFILE_H