QLockFile: Don't deadlock if the lock file has a mtime in the future

Stale Lock files in the future can happen in some situations. For exemple
two computers with different clocks access the same file system. It could
be that one of the timestamp is totaly off (several years into the future).

[ChangeLog][QtCore][QLockFile] Fixed a deadlock occurring if a corrupted
lock file's modification time is in the future.

Change-Id: I8dac98a0e898c76bcef67f8c195e126c996b6add
Reviewed-by: David Faure <david.faure@kdab.com>

1 files changed, 28 insertions, 0 deletions

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);