1 files changed, 87 insertions, 11 deletions

diff --git a/src/corelib/io/qlockfile.cpp b/src/corelib/io/qlockfile.cpp
index 48317d07e0..aa84ce6bc1 100644
--- a/src/corelib/io/qlockfile.cpp
+++ b/src/corelib/io/qlockfile.cpp
@@ -2,6 +2,7 @@
 **
 ** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org>
 ** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2017 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -42,12 +43,36 @@
 #include "qlockfile_p.h"
 
 #include <QtCore/qthread.h>
+#include <QtCore/qcoreapplication.h>
 #include <QtCore/qdeadlinetimer.h>
 #include <QtCore/qdatetime.h>
 #include <QtCore/qfileinfo.h>
 
 QT_BEGIN_NAMESPACE
 
+namespace {
+struct LockFileInfo
+{
+    qint64 pid;
+    QString appname;
+    QString hostname;
+    QByteArray hostid;
+    QByteArray bootid;
+};
+}
+
+static bool getLockInfo_helper(const QString &fileName, LockFileInfo *info);
+
+static QString machineName()
+{
+#ifdef Q_OS_WIN
+    // we don't use QSysInfo because it tries to do name resolution
+    return qEnvironmentVariable("COMPUTERNAME");
+#else
+    return QSysInfo::machineHostName();
+#endif
+}
+
 /*!
     \class QLockFile
     \inmodule QtCore
@@ -291,13 +316,32 @@ bool QLockFile::tryLock(int timeout)
 bool QLockFile::getLockInfo(qint64 *pid, QString *hostname, QString *appname) const
 {
     Q_D(const QLockFile);
-    return d->getLockInfo(pid, hostname, appname);
+    LockFileInfo info;
+    if (!getLockInfo_helper(d->fileName, &info))
+        return false;
+    if (pid)
+        *pid = info.pid;
+    if (hostname)
+        *hostname = info.hostname;
+    if (appname)
+        *appname = info.appname;
+    return true;
+}
+
+QByteArray QLockFilePrivate::lockFileContents() const
+{
+    // Use operator% from the fast builder to avoid multiple memory allocations.
+    return QByteArray::number(QCoreApplication::applicationPid()) % '\n'
+            % processNameByPid(QCoreApplication::applicationPid()).toUtf8() % '\n'
+            % machineName().toUtf8() % '\n'
+            % QSysInfo::machineUniqueId() % '\n'
+            % QSysInfo::bootUniqueId() % '\n';
 }
 
-bool QLockFilePrivate::getLockInfo(qint64 *pid, QString *hostname, QString *appname) const
+static bool getLockInfo_helper(const QString &fileName, LockFileInfo *info)
 {
     QFile reader(fileName);
-    if (!reader.open(QIODevice::ReadOnly))
+    if (!reader.open(QIODevice::ReadOnly | QIODevice::Text))
         return false;
 
     QByteArray pidLine = reader.readLine();
@@ -309,14 +353,46 @@ bool QLockFilePrivate::getLockInfo(qint64 *pid, QString *hostname, QString *appn
     QByteArray hostNameLine = reader.readLine();
     hostNameLine.chop(1);
 
-    qint64 thePid = pidLine.toLongLong();
-    if (pid)
-        *pid = thePid;
-    if (appname)
-        *appname = QString::fromUtf8(appNameLine);
-    if (hostname)
-        *hostname = QString::fromUtf8(hostNameLine);
-    return thePid > 0;
+    // prior to Qt 5.10, only the lines above were recorded
+    QByteArray hostId = reader.readLine();
+    hostId.chop(1);
+    QByteArray bootId = reader.readLine();
+    bootId.chop(1);
+
+    bool ok;
+    info->appname = QString::fromUtf8(appNameLine);
+    info->hostname = QString::fromUtf8(hostNameLine);
+    info->hostid = hostId;
+    info->bootid = bootId;
+    info->pid = pidLine.toLongLong(&ok);
+    return ok && info->pid > 0;
+}
+
+bool QLockFilePrivate::isApparentlyStale() const
+{
+    LockFileInfo info;
+    if (getLockInfo_helper(fileName, &info)) {
+        bool sameHost = info.hostname.isEmpty() || info.hostname == machineName();
+        if (!info.hostid.isEmpty()) {
+            // Override with the host ID, if we know it.
+            QByteArray ourHostId = QSysInfo::machineUniqueId();
+            if (!ourHostId.isEmpty())
+                sameHost = (ourHostId == info.hostid);
+        }
+
+        if (sameHost) {
+            if (!info.bootid.isEmpty()) {
+                // If we've rebooted, then the lock is definitely stale.
+                if (info.bootid != QSysInfo::bootUniqueId())
+                    return true;
+            }
+            if (!isProcessRunning(info.pid, info.appname))
+                return true;
+        }
+    }
+
+    const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTimeUtc());
+    return staleLockTime > 0 && qAbs(age) > staleLockTime;
 }
 
 /*!