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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
#include "savefile.h"
#include "filepath.h"
#include "qtcassert.h"
#include <QTemporaryFile>
#ifdef Q_OS_WIN
# include <windows.h>
# include <io.h>
#else
# include <unistd.h>
# include <sys/stat.h>
#endif
namespace Utils {
static QFile::Permissions m_umask;
SaveFile::SaveFile(const QString &filename) :
m_finalFileName(filename)
{
}
SaveFile::~SaveFile()
{
QTC_ASSERT(m_finalized, rollback());
}
bool SaveFile::open(OpenMode flags)
{
QTC_ASSERT(!m_finalFileName.isEmpty(), return false);
QFile ofi(m_finalFileName);
// Check whether the existing file is writable
if (ofi.exists() && !ofi.open(QIODevice::ReadWrite)) {
setErrorString(ofi.errorString());
return false;
}
m_tempFile = std::make_unique<QTemporaryFile>(m_finalFileName);
m_tempFile->setAutoRemove(false);
if (!m_tempFile->open())
return false;
setFileName(m_tempFile->fileName());
if (!QFile::open(flags))
return false;
m_finalized = false; // needs clean up in the end
if (ofi.exists()) {
setPermissions(ofi.permissions()); // Ignore errors
} else {
Permissions permAll = QFile::ReadOwner
| QFile::ReadGroup
| QFile::ReadOther
| QFile::WriteOwner
| QFile::WriteGroup
| QFile::WriteOther;
// set permissions with respect to the current umask
setPermissions(permAll & ~m_umask);
}
return true;
}
void SaveFile::rollback()
{
close();
if (m_tempFile)
m_tempFile->remove();
m_finalized = true;
}
bool SaveFile::commit()
{
QTC_ASSERT(!m_finalized && m_tempFile, return false;);
m_finalized = true;
if (!flush()) {
close();
m_tempFile->remove();
return false;
}
#ifdef Q_OS_WIN
FlushFileBuffers(reinterpret_cast<HANDLE>(_get_osfhandle(handle())));
#elif _POSIX_SYNCHRONIZED_IO > 0
fdatasync(handle());
#else
fsync(handle());
#endif
close();
m_tempFile->close();
if (error() != NoError) {
m_tempFile->remove();
return false;
}
QString finalFileName = FilePath::fromString(m_finalFileName).resolveSymlinks().toString();
#ifdef Q_OS_WIN
// Release the file lock
m_tempFile.reset();
bool result = ReplaceFile(finalFileName.toStdWString().data(),
fileName().toStdWString().data(),
nullptr, REPLACEFILE_IGNORE_MERGE_ERRORS, nullptr, nullptr);
if (!result) {
DWORD replaceErrorCode = GetLastError();
QString errorStr;
if (!QFile::exists(finalFileName)) {
// Replace failed because finalFileName does not exist, try rename.
if (!(result = rename(finalFileName)))
errorStr = errorString();
} else {
if (replaceErrorCode == ERROR_UNABLE_TO_REMOVE_REPLACED) {
// If we do not get the rights to remove the original final file we still might try
// to replace the file contents
result = MoveFileEx(fileName().toStdWString().data(),
finalFileName.toStdWString().data(),
MOVEFILE_COPY_ALLOWED
| MOVEFILE_REPLACE_EXISTING
| MOVEFILE_WRITE_THROUGH);
if (!result)
replaceErrorCode = GetLastError();
}
if (!result) {
wchar_t messageBuffer[256];
FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
nullptr, replaceErrorCode,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
messageBuffer, sizeof(messageBuffer), nullptr);
errorStr = QString::fromWCharArray(messageBuffer);
}
}
if (!result) {
remove();
setErrorString(errorStr);
}
}
return result;
#else
const QString backupName = finalFileName + '~';
// Back up current file.
// If it's opened by another application, the lock follows the move.
if (QFile::exists(finalFileName)) {
// Kill old backup. Might be useful if creator crashed before removing backup.
QFile::remove(backupName);
QFile finalFile(finalFileName);
if (!finalFile.rename(backupName)) {
m_tempFile->remove();
setErrorString(finalFile.errorString());
return false;
}
}
bool result = true;
if (!m_tempFile->rename(finalFileName)) {
// The case when someone else was able to create finalFileName after we've renamed it.
// Higher level call may try to save this file again but here we do nothing and
// return false while keeping the error string from last rename call.
const QString &renameError = m_tempFile->errorString();
m_tempFile->remove();
setErrorString(renameError);
QFile::rename(backupName, finalFileName); // rollback to backup if possible ...
return false; // ... or keep the backup copy at least
}
QFile::remove(backupName);
return result;
#endif
}
void SaveFile::initializeUmask()
{
#ifdef Q_OS_WIN
m_umask = QFile::WriteGroup | QFile::WriteOther;
#else
// Get the current process' file creation mask (umask)
// umask() is not thread safe so this has to be done by single threaded
// application initialization
mode_t mask = umask(0); // get current umask
umask(mask); // set it back
m_umask = ((mask & S_IRUSR) ? QFile::ReadOwner : QFlags<QFile::Permission>())
| ((mask & S_IWUSR) ? QFile::WriteOwner : QFlags<QFile::Permission>())
| ((mask & S_IXUSR) ? QFile::ExeOwner : QFlags<QFile::Permission>())
| ((mask & S_IRGRP) ? QFile::ReadGroup : QFlags<QFile::Permission>())
| ((mask & S_IWGRP) ? QFile::WriteGroup : QFlags<QFile::Permission>())
| ((mask & S_IXGRP) ? QFile::ExeGroup : QFlags<QFile::Permission>())
| ((mask & S_IROTH) ? QFile::ReadOther : QFlags<QFile::Permission>())
| ((mask & S_IWOTH) ? QFile::WriteOther : QFlags<QFile::Permission>())
| ((mask & S_IXOTH) ? QFile::ExeOther : QFlags<QFile::Permission>());
#endif
}
} // namespace Utils
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