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/****************************************************************************
**
** Copyright (C) 2013 David Faure <faure+bluesystems@kde.org>
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtCore 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.
**
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef _UNICODE
#define _UNICODE
#endif
#ifndef UNICODE
#define UNICODE
#endif
#include "qlockfile_p.h"
#include <qt_windows.h>
#include <QCoreApplication>
#include <QDir>
#include <QFileInfo>
#include <QDateTime>
#include <QDebug>
QT_BEGIN_NAMESPACE
static inline QByteArray localHostName()
{
return qgetenv("COMPUTERNAME");
}
static inline bool fileExists(const wchar_t *fileName)
{
WIN32_FILE_ATTRIBUTE_DATA data;
return GetFileAttributesEx(fileName, GetFileExInfoStandard, &data);
}
QLockFile::LockError QLockFilePrivate::tryLock_sys()
{
const ushort* nativePath = QDir::toNativeSeparators(fileName).utf16();
// When writing, allow others to read.
// When reading, QFile will allow others to read and write, all good.
// Adding FILE_SHARE_DELETE would allow forceful deletion of stale files,
// but Windows doesn't allow recreating it while this handle is open anyway,
// so this would only create confusion (can't lock, but no lock file to read from).
const DWORD dwShareMode = FILE_SHARE_READ;
#ifndef Q_OS_WINRT
SECURITY_ATTRIBUTES securityAtts = { sizeof(SECURITY_ATTRIBUTES), NULL, FALSE };
HANDLE fh = CreateFile((const wchar_t*)nativePath,
GENERIC_WRITE,
dwShareMode,
&securityAtts,
CREATE_NEW, // error if already exists
FILE_ATTRIBUTE_NORMAL,
NULL);
#else // !Q_OS_WINRT
HANDLE fh = CreateFile2((const wchar_t*)nativePath,
GENERIC_WRITE,
dwShareMode,
CREATE_NEW, // error if already exists
NULL);
#endif // Q_OS_WINRT
if (fh == INVALID_HANDLE_VALUE) {
const DWORD lastError = GetLastError();
switch (lastError) {
case ERROR_SHARING_VIOLATION:
case ERROR_ALREADY_EXISTS:
case ERROR_FILE_EXISTS:
return QLockFile::LockFailedError;
case ERROR_ACCESS_DENIED:
// readonly file, or file still in use by another process.
// Assume the latter if the file exists, since we don't create it readonly.
return fileExists((const wchar_t*)nativePath)
? QLockFile::LockFailedError
: QLockFile::PermissionError;
default:
qWarning() << "Got unexpected locking error" << lastError;
return QLockFile::UnknownError;
}
}
// We hold the lock, continue.
fileHandle = fh;
// Assemble data, to write in a single call to write
// (otherwise we'd have to check every write call)
QByteArray fileData;
fileData += QByteArray::number(QCoreApplication::applicationPid());
fileData += '\n';
fileData += QCoreApplication::applicationName().toUtf8();
fileData += '\n';
fileData += localHostName();
fileData += '\n';
DWORD bytesWritten = 0;
QLockFile::LockError error = QLockFile::NoError;
if (!WriteFile(fh, fileData.constData(), fileData.size(), &bytesWritten, NULL) || !FlushFileBuffers(fh))
error = QLockFile::UnknownError; // partition full
return error;
}
bool QLockFilePrivate::removeStaleLock()
{
// QFile::remove fails on Windows if the other process is still using the file, so it's not stale.
return QFile::remove(fileName);
}
bool QLockFilePrivate::isApparentlyStale() const
{
qint64 pid;
QString hostname, appname;
// On WinRT there seems to be no way of obtaining information about other
// processes due to sandboxing
#ifndef Q_OS_WINRT
if (getLockInfo(&pid, &hostname, &appname)) {
if (hostname.isEmpty() || hostname == QString::fromLocal8Bit(localHostName())) {
HANDLE procHandle = ::OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, pid);
if (!procHandle)
return true;
// We got a handle but check if process is still alive
DWORD dwR = ::WaitForSingleObject(procHandle, 0);
::CloseHandle(procHandle);
if (dwR == WAIT_TIMEOUT)
return true;
const QString processName = processNameByPid(pid);
if (!processName.isEmpty() && processName != appname)
return true; // PID got reused by a different application.
}
}
#else // !Q_OS_WINRT
Q_UNUSED(pid);
Q_UNUSED(hostname);
Q_UNUSED(appname);
#endif // Q_OS_WINRT
const qint64 age = QFileInfo(fileName).lastModified().msecsTo(QDateTime::currentDateTime());
return staleLockTime > 0 && age > staleLockTime;
}
QString QLockFilePrivate::processNameByPid(qint64 pid)
{
#if !defined(Q_OS_WINRT) && !defined(Q_OS_WINCE)
typedef DWORD (WINAPI *GetModuleFileNameExFunc)(HANDLE, HMODULE, LPTSTR, DWORD);
HMODULE hPsapi = LoadLibraryA("psapi");
if (!hPsapi)
return QString();
GetModuleFileNameExFunc qGetModuleFileNameEx
= (GetModuleFileNameExFunc)GetProcAddress(hPsapi, "GetModuleFileNameExW");
if (!qGetModuleFileNameEx) {
FreeLibrary(hPsapi);
return QString();
}
HANDLE hProcess = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, FALSE, DWORD(pid));
if (!hProcess) {
FreeLibrary(hPsapi);
return QString();
}
wchar_t buf[MAX_PATH];
const DWORD length = qGetModuleFileNameEx(hProcess, NULL, buf, sizeof(buf) / sizeof(wchar_t));
CloseHandle(hProcess);
FreeLibrary(hPsapi);
if (!length)
return QString();
QString name = QString::fromWCharArray(buf, length);
int i = name.lastIndexOf(QLatin1Char('\\'));
if (i >= 0)
name.remove(0, i + 1);
i = name.lastIndexOf(QLatin1Char('.'));
if (i >= 0)
name.truncate(i);
return name;
#else
Q_UNUSED(pid);
return QString();
#endif
}
void QLockFile::unlock()
{
Q_D(QLockFile);
if (!d->isLocked)
return;
CloseHandle(d->fileHandle);
int attempts = 0;
static const int maxAttempts = 500; // 500ms
while (!QFile::remove(d->fileName) && ++attempts < maxAttempts) {
// Someone is reading the lock file right now (on Windows this prevents deleting it).
QLockFileThread::msleep(1);
}
if (attempts == maxAttempts) {
qWarning() << "Could not remove our own lock file" << d->fileName << ". Either other users of the lock file are reading it constantly for 500 ms, or we (no longer) have permissions to delete the file";
// This is bad because other users of this lock file will now have to wait for the stale-lock-timeout...
}
d->lockError = QLockFile::NoError;
d->isLocked = false;
}
QT_END_NAMESPACE
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