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QSaveFile: follow symbolic links

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[ChangeLog][QtCore][QSaveFile] Now follows symbolic links while writing to
a link instead of replacing the link with the contents.

Change-Id: I5afd519cb9f96ae68fa4c23c33a18de75671a301
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: David Faure <david.faure@kdab.com>
This commit is contained in:
Olivier Goffart 2014-05-28 22:53:57 +02:00 committed by The Qt Project
parent e747324f68
commit 7e5e7eeaa1
3 changed files with 130 additions and 3 deletions
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18
src/corelib/io/qsavefile.cpp
View File

@ -205,14 +205,26 @@ bool QSaveFile::open(OpenMode mode)
d->writeError = QFileDevice::WriteError;
return false;
}
d->fileEngine = new QTemporaryFileEngine(d->fileName);
// Resolve symlinks. Don't use QFileInfo::canonicalFilePath so it still give the expected
// target even if the file does not exist
d->finalFileName = d->fileName;
if (existingFile.isSymLink()) {
int maxDepth = 128;
while (--maxDepth && existingFile.isSymLink())
existingFile.setFile(existingFile.symLinkTarget());
if (maxDepth > 0)
d->finalFileName = existingFile.filePath();
}
d->fileEngine = new QTemporaryFileEngine(d->finalFileName);
// Same as in QFile: QIODevice provides the buffering, so there's no need to request it from the file engine.
if (!d->fileEngine->open(mode | QIODevice::Unbuffered)) {
QFileDevice::FileError err = d->fileEngine->error();
#ifdef Q_OS_UNIX
if (d->directWriteFallback && err == QFileDevice::OpenError && errno == EACCES) {
delete d->fileEngine;
d->fileEngine = QAbstractFileEngine::create(d->fileName);
d->fileEngine = QAbstractFileEngine::create(d->finalFileName);
if (d->fileEngine->open(mode | QIODevice::Unbuffered)) {
d->useTemporaryFile = false;
QFileDevice::open(mode);
@ -285,7 +297,7 @@ bool QSaveFile::commit()
// atomically replace old file with new file
// Can't use QFile::rename for that, must use the file engine directly
Q_ASSERT(d->fileEngine);
if (!d->fileEngine->renameOverwrite(d->fileName)) {
if (!d->fileEngine->renameOverwrite(d->finalFileName)) {
d->setError(d->fileEngine->error(), d->fileEngine->errorString());
d->fileEngine->remove();
delete d->fileEngine;

1
src/corelib/io/qsavefile_p.h
View File

@ -70,6 +70,7 @@ protected:
~QSaveFilePrivate();
QString fileName;
QString finalFileName; // fileName with symbolic links resolved
QFileDevice::FileError writeError;

114
tests/auto/corelib/io/qsavefile/tst_qsavefile.cpp
View File

@ -93,6 +93,7 @@ private slots:
void transactionalWriteNoPermissionsOnFile();
void transactionalWriteCanceled();
void transactionalWriteErrorRenaming();
void symlink();
};
static inline QByteArray msgCannotOpen(const QFileDevice &f)
@ -340,5 +341,118 @@ void tst_QSaveFile::transactionalWriteErrorRenaming()
QCOMPARE(file.error(), QFile::RenameError);
}
void tst_QSaveFile::symlink()
{
#ifdef Q_OS_UNIX
QByteArray someData = "some data";
QTemporaryDir dir;
QVERIFY(dir.isValid());
const QString targetFile = dir.path() + QLatin1String("/outfile");
const QString linkFile = dir.path() + QLatin1String("/linkfile");
{
QFile file(targetFile);
QVERIFY2(file.open(QIODevice::WriteOnly), msgCannotOpen(file).constData());
QCOMPARE(file.write("Hello"), Q_INT64_C(5));
file.close();
}
QVERIFY(QFile::link(targetFile, linkFile));
QString canonical = QFileInfo(linkFile).canonicalFilePath();
QCOMPARE(canonical, QFileInfo(targetFile).canonicalFilePath());
// Try saving into it
{
QSaveFile saveFile(linkFile);
QVERIFY(saveFile.open(QIODevice::WriteOnly));
QCOMPARE(saveFile.write(someData), someData.size());
saveFile.commit();
//Check that the linkFile is still a link and still has the same canonical path
QFileInfo info(linkFile);
QVERIFY(info.isSymLink());
QCOMPARE(QFileInfo(linkFile).canonicalFilePath(), canonical);
QFile file(targetFile);
QVERIFY2(file.open(QIODevice::ReadOnly), msgCannotOpen(file).constData());
QCOMPARE(file.readAll(), someData);
file.remove();
}
// Save into a symbolic link that point to a removed file
someData = "more stuff";
{
QSaveFile saveFile(linkFile);
QVERIFY(saveFile.open(QIODevice::WriteOnly));
QCOMPARE(saveFile.write(someData), someData.size());
saveFile.commit();
QFileInfo info(linkFile);
QVERIFY(info.isSymLink());
QCOMPARE(QFileInfo(linkFile).canonicalFilePath(), canonical);
QFile file(targetFile);
QVERIFY2(file.open(QIODevice::ReadOnly), msgCannotOpen(file).constData());
QCOMPARE(file.readAll(), someData);
}
// link to a link in another directory
QTemporaryDir dir2;
QVERIFY(dir2.isValid());
const QString linkFile2 = dir2.path() + QLatin1String("/linkfile");
QVERIFY(QFile::link(linkFile, linkFile2));
QCOMPARE(QFileInfo(linkFile2).canonicalFilePath(), canonical);
someData = "hello everyone";
{
QSaveFile saveFile(linkFile2);
QVERIFY(saveFile.open(QIODevice::WriteOnly));
QCOMPARE(saveFile.write(someData), someData.size());
saveFile.commit();
QFile file(targetFile);
QVERIFY2(file.open(QIODevice::ReadOnly), msgCannotOpen(file).constData());
QCOMPARE(file.readAll(), someData);
}
//cyclic link
const QString cyclicLink = dir.path() + QLatin1String("/cyclic");
QVERIFY(QFile::link(cyclicLink, cyclicLink));
{
QSaveFile saveFile(cyclicLink);
QVERIFY(saveFile.open(QIODevice::WriteOnly));
QCOMPARE(saveFile.write(someData), someData.size());
saveFile.commit();
QFile file(cyclicLink);
QVERIFY2(file.open(QIODevice::ReadOnly), msgCannotOpen(file).constData());
QCOMPARE(file.readAll(), someData);
}
//cyclic link2
QVERIFY(QFile::link(cyclicLink + QLatin1Char('1'), cyclicLink + QLatin1Char('2')));
QVERIFY(QFile::link(cyclicLink + QLatin1Char('2'), cyclicLink + QLatin1Char('1')));
{
QSaveFile saveFile(cyclicLink + QLatin1Char('1'));
QVERIFY(saveFile.open(QIODevice::WriteOnly));
QCOMPARE(saveFile.write(someData), someData.size());
saveFile.commit();
// the explicit file becomes a file instead of a link
QVERIFY(!QFileInfo(cyclicLink + QLatin1Char('1')).isSymLink());
QVERIFY(QFileInfo(cyclicLink + QLatin1Char('2')).isSymLink());
QFile file(cyclicLink + QLatin1Char('1'));
QVERIFY2(file.open(QIODevice::ReadOnly), msgCannotOpen(file).constData());
QCOMPARE(file.readAll(), someData);
}
#endif
}
QTEST_MAIN(tst_QSaveFile)
#include "tst_qsavefile.moc"