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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qqmldomfilewriter_p.h"
#include <QtCore/QRandomGenerator>
#include <QtCore/QScopeGuard>
QT_BEGIN_NAMESPACE
namespace QQmlJS {
namespace Dom {
FileWriter::Status FileWriter::write(const QString &tFile, function_ref<bool(QTextStream &)> write,
int nBk)
{
if (shouldRemoveTempFile)
tempFile.remove();
tempFile.close();
shouldRemoveTempFile = false;
Q_ASSERT(status != Status::ShouldWrite);
status = Status::ShouldWrite;
targetFile = tFile;
newBkFiles.clear();
warnings.clear();
int i = 0;
const int maxAttempts = 20;
for (; i < maxAttempts; ++i) {
tempFile.setFileName(targetFile
+ QString::number(QRandomGenerator::global()->generate(), 16).mid(0, 8)
+ QStringLiteral(u".tmp"));
if (tempFile.open(QIODevice::ReadWrite | QIODevice::NewOnly))
break;
}
if (i == maxAttempts) {
warnings.append(tr("Could not create temp file for %1").arg(targetFile));
status = FileWriter::Status::SkippedDueToFailure;
return status;
}
shouldRemoveTempFile = true;
bool success = false;
QTextStream inF(&tempFile);
QT_TRY
{
auto cleanup = qScopeGuard([this, &inF, &success, nBk] {
inF.flush();
tempFile.flush();
tempFile.close();
if (success) {
if (QFile::exists(targetFile)) {
// compareFiles
if (tempFile.open(QIODevice::ReadOnly)) {
auto closeTmpF = qScopeGuard([this] { tempFile.close(); });
QFile oldF(targetFile);
if (oldF.open(QIODevice::ReadOnly)) {
bool same = true;
while (!tempFile.atEnd() && !oldF.atEnd()) {
QByteArray l1 = tempFile.readLine();
QByteArray l2 = oldF.readLine();
if (l1 != l2)
same = false;
}
if (tempFile.atEnd() && oldF.atEnd() && same) {
tempFile.remove();
shouldRemoveTempFile = false;
status = Status::SkippedEqual;
return;
}
}
}
}
// move to target
int i = 0;
const int maxAttempts = 10;
for (; i < maxAttempts; ++i) {
if (QFile::exists(targetFile)) {
// make place for targetFile
QString bkFileName;
if (nBk < 1) {
QFile::remove(targetFile);
} else if (nBk == 1) {
QString bkFileName = targetFile + QStringLiteral(u"~");
QFile::remove(bkFileName);
QFile::rename(targetFile, bkFileName);
} else {
// f~ is the oldest, further backups at f1~ .. f<nBk>~
// keeping an empty place for the "next" backup
// f~ is never overwritten
int iBk = 0;
QString bkFileName = targetFile + QStringLiteral(u"~");
while (++iBk < nBk) {
if (QFile::exists(bkFileName))
bkFileName = targetFile + QString::number(iBk)
+ QStringLiteral(u"~");
}
if (iBk == nBk)
QFile::remove(targetFile + QStringLiteral(u"1~"));
else
QFile::remove(targetFile + QString::number(++iBk)
+ QStringLiteral(u"~"));
QFile::remove(bkFileName);
QFile::rename(targetFile, bkFileName);
}
if (!bkFileName.isEmpty() && QFile::rename(targetFile, bkFileName))
newBkFiles.append(bkFileName);
}
if (tempFile.rename(targetFile)) {
status = Status::DidWrite;
shouldRemoveTempFile = false;
return;
}
}
warnings.append(
tr("Rename of file %1 to %2 failed").arg(tempFile.fileName(), targetFile));
status = Status::SkippedDueToFailure;
} else {
warnings.append(tr("Error while writing"));
}
});
success = write(inF);
}
QT_CATCH(...)
{
warnings.append(tr("Exception trying to write file %1").arg(targetFile));
status = FileWriter::Status::SkippedDueToFailure;
}
if (status == Status::ShouldWrite)
status = Status::SkippedDueToFailure;
return status;
}
} // namespace Dom
} // namespace QQmlJS
QT_END_NAMESPACE
#include "moc_qqmldomfilewriter_p.cpp"
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