4 files changed, 33 insertions, 2 deletions
diff --git a/src/corelib/io/qlockfile.cpp b/src/corelib/io/qlockfile.cpp
index cb1ff93ad3..48317d07e0 100644
--- a/src/corelib/io/qlockfile.cpp
+++ b/src/corelib/io/qlockfile.cpp
@@ -44,6 +44,7 @@
 #include <QtCore/qthread.h>
 #include <QtCore/qdeadlinetimer.h>
 #include <QtCore/qdatetime.h>
+#include <QtCore/qfileinfo.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -226,6 +227,8 @@ bool QLockFile::tryLock(int timeout)
             return false;
         case LockFailedError:
             if (!d->isLocked && d->isApparentlyStale()) {
+                if (Q_UNLIKELY(QFileInfo(d->fileName).lastModified() > QDateTime::currentDateTime()))
+                    qInfo("QLockFile: Lock file '%ls' has a modification time in the future", qUtf16Printable(d->fileName));
                 // Stale lock from another thread/process
                 // Ensure two processes don't remove it at the same time
                 QLockFile rmlock(d->fileName + QLatin1String(".rmlock"));
diff --git a/src/corelib/io/qlockfile_unix.cpp b/src/corelib/io/qlockfile_unix.cpp
index 3a80014c00..5a02741727 100644
--- a/src/corelib/io/qlockfile_unix.cpp
+++ b/src/corelib/io/qlockfile_unix.cpp
@@ -247,7 +247,7 @@ bool QLockFilePrivate::isApparentlyStale() const
         }
     }
     const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTime());
-    return staleLockTime > 0 && age > staleLockTime;
+    return staleLockTime > 0 && qAbs(age) > staleLockTime;
 }
 
 QString QLockFilePrivate::processNameByPid(qint64 pid)
diff --git a/src/corelib/io/qlockfile_win.cpp b/src/corelib/io/qlockfile_win.cpp
index baaff8da17..4b43181686 100644
--- a/src/corelib/io/qlockfile_win.cpp
+++ b/src/corelib/io/qlockfile_win.cpp
@@ -160,7 +160,7 @@ bool QLockFilePrivate::isApparentlyStale() const
     Q_UNUSED(appname);
 #endif // Q_OS_WINRT
     const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTime());
-    return staleLockTime > 0 && age > staleLockTime;
+    return staleLockTime > 0 && qAbs(age) > staleLockTime;
 }
 
 QString QLockFilePrivate::processNameByPid(qint64 pid)
diff --git a/tests/auto/corelib/io/qlockfile/tst_qlockfile.cpp b/tests/auto/corelib/io/qlockfile/tst_qlockfile.cpp
index a13ff0358a..d2f345feb5 100644
--- a/tests/auto/corelib/io/qlockfile/tst_qlockfile.cpp
+++ b/tests/auto/corelib/io/qlockfile/tst_qlockfile.cpp
@@ -34,6 +34,7 @@
 #include <qsysinfo.h>
 #if defined(Q_OS_UNIX) && !defined(Q_OS_VXWORKS)
 #include <unistd.h>
+#include <sys/time.h>
 #elif defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
 #  include <qt_windows.h>
 #endif
@@ -59,6 +60,7 @@ private slots:
     void noPermissions();
     void noPermissionsWindows();
     void corruptedLockFile();
+    void corruptedLockFileInTheFuture();
 
 private:
     static bool overwritePidInLockFile(const QString &filePath, qint64 pid);
@@ -521,6 +523,32 @@ void tst_QLockFile::corruptedLockFile()
     QCOMPARE(int(secondLock.error()), int(QLockFile::NoError));
 }
 
+void tst_QLockFile::corruptedLockFileInTheFuture()
+{
+#if !defined(Q_OS_UNIX)
+    QSKIP("This tests needs utimes");
+#else
+    // This test is the same as the previous one, but the corruption was so there is a corrupted
+    // .rmlock whose timestamp is in the future
+
+    const QString fileName = dir.path() + "/corruptedLockFile.rmlock";
+
+    {
+        QFile file(fileName);
+        QVERIFY(file.open(QFile::WriteOnly));
+    }
+
+    struct timeval times[2];
+    gettimeofday(times, 0);
+    times[1].tv_sec = (times[0].tv_sec += 600);
+    times[1].tv_usec = times[0].tv_usec;
+    utimes(fileName.toLocal8Bit(), times);
+
+    QTest::ignoreMessage(QtInfoMsg, "QLockFile: Lock file '" + fileName.toUtf8() + "' has a modification time in the future");
+    corruptedLockFile();
+#endif
+}
+
 bool tst_QLockFile::overwritePidInLockFile(const QString &filePath, qint64 pid)
 {
     QFile f(filePath);