qfile.cpp

Go to the documentation of this file.

/****************************************************************************
**
** Copyright (C) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/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 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qplatformdefs.h"
#include "qdebug.h"
#include "qfile.h"
#include "qfsfileengine.h"
#include "qtemporaryfile.h"
#include "qlist.h"
#include "qfileinfo.h"
#include "private/qiodevice_p.h"
#include "private/qfile_p.h"
#include "private/qsystemerror_p.h"
#if defined(QT_BUILD_CORE_LIB)
# include "qcoreapplication.h"
#endif

#ifdef QT_NO_QOBJECT
#define tr(X) QString::fromLatin1(X)
#endif

QT_BEGIN_NAMESPACE

static const int QFILE_WRITEBUFFER_SIZE = 16384;

static QByteArray locale_encode(const QString &f)
{
#if defined(Q_OS_DARWIN)
    // Mac always expects UTF-8... and decomposed...
    return f.normalized(QString::NormalizationForm_D).toUtf8();
#elif defined(Q_OS_SYMBIAN)
    return f.toUtf8();
#else
    return f.toLocal8Bit();
#endif
}

static QString locale_decode(const QByteArray &f)
{
#if defined(Q_OS_DARWIN)
    // Mac always gives us UTF-8 and decomposed, we want that composed...
    return QString::fromUtf8(f).normalized(QString::NormalizationForm_C);
#elif defined(Q_OS_SYMBIAN)
    return QString::fromUtf8(f);
#else
    return QString::fromLocal8Bit(f);
#endif
}

//************* QFilePrivate
QFile::EncoderFn QFilePrivate::encoder = locale_encode;
QFile::DecoderFn QFilePrivate::decoder = locale_decode;

QFilePrivate::QFilePrivate()
    : fileEngine(0), lastWasWrite(false),
      writeBuffer(QFILE_WRITEBUFFER_SIZE), error(QFile::NoError),
      cachedSize(0)
{
}

QFilePrivate::~QFilePrivate()
{
    delete fileEngine;
    fileEngine = 0;
}

bool
QFilePrivate::openExternalFile(int flags, int fd, QFile::FileHandleFlags handleFlags)
{
#ifdef QT_NO_FSFILEENGINE
    Q_UNUSED(flags);
    Q_UNUSED(fd);
    return false;
#else
    delete fileEngine;
    fileEngine = 0;
    QFSFileEngine *fe = new QFSFileEngine;
    fileEngine = fe;
    return fe->open(QIODevice::OpenMode(flags), fd, handleFlags);
#endif
}

bool
QFilePrivate::openExternalFile(int flags, FILE *fh, QFile::FileHandleFlags handleFlags)
{
#ifdef QT_NO_FSFILEENGINE
    Q_UNUSED(flags);
    Q_UNUSED(fh);
    return false;
#else
    delete fileEngine;
    fileEngine = 0;
    QFSFileEngine *fe = new QFSFileEngine;
    fileEngine = fe;
    return fe->open(QIODevice::OpenMode(flags), fh, handleFlags);
#endif
}

#ifdef Q_OS_SYMBIAN
bool QFilePrivate::openExternalFile(int flags, const RFile &f, QFile::FileHandleFlags handleFlags)
{
#ifdef QT_NO_FSFILEENGINE
    Q_UNUSED(flags);
    Q_UNUSED(fh);
    return false;
#else
    delete fileEngine;
    fileEngine = 0;
    QFSFileEngine *fe = new QFSFileEngine;
    fileEngine = fe;
    return fe->open(QIODevice::OpenMode(flags), f, handleFlags);
#endif
}
#endif

inline bool QFilePrivate::ensureFlushed() const
{
    // This function ensures that the write buffer has been flushed (const
    // because certain const functions need to call it.
    if (lastWasWrite) {
        const_cast<QFilePrivate *>(this)->lastWasWrite = false;
        if (!const_cast<QFile *>(q_func())->flush())
            return false;
    }
    return true;
}

void
QFilePrivate::setError(QFile::FileError err)
{
    error = err;
    errorString.clear();
}

void
QFilePrivate::setError(QFile::FileError err, const QString &errStr)
{
    error = err;
    errorString = errStr;
}

void
QFilePrivate::setError(QFile::FileError err, int errNum)
{
    error = err;
    errorString = qt_error_string(errNum);
}

//************* QFile

#ifdef QT3_SUPPORT

#endif

#ifdef QT_NO_QOBJECT
QFile::QFile()
    : QIODevice(*new QFilePrivate)
{
}
QFile::QFile(const QString &name)
    : QIODevice(*new QFilePrivate)
{
    d_func()->fileName = name;
}
QFile::QFile(QFilePrivate &dd)
    : QIODevice(dd)
{
}
#else

QFile::QFile()
    : QIODevice(*new QFilePrivate, 0)
{
}
QFile::QFile(QObject *parent)
    : QIODevice(*new QFilePrivate, parent)
{
}
QFile::QFile(const QString &name)
    : QIODevice(*new QFilePrivate, 0)
{
    Q_D(QFile);
    d->fileName = name;
}
QFile::QFile(const QString &name, QObject *parent)
    : QIODevice(*new QFilePrivate, parent)
{
    Q_D(QFile);
    d->fileName = name;
}
QFile::QFile(QFilePrivate &dd, QObject *parent)
    : QIODevice(dd, parent)
{
}
#endif

QFile::~QFile()
{
    close();
}

QString QFile::fileName() const
{
    return fileEngine()->fileName(QAbstractFileEngine::DefaultName);
}

void
QFile::setFileName(const QString &name)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::setFileName: File (%s) is already opened",
                 qPrintable(fileName()));
        close();
    }
    if(d->fileEngine) { //get a new file engine later
        delete d->fileEngine;
        d->fileEngine = 0;
    }
    d->fileName = name;
}

QByteArray
QFile::encodeName(const QString &fileName)
{
    return (*QFilePrivate::encoder)(fileName);
}

QString
QFile::decodeName(const QByteArray &localFileName)
{
    return (*QFilePrivate::decoder)(localFileName);
}

void
QFile::setEncodingFunction(EncoderFn f)
{
    if (!f)
        f = locale_encode;
    QFilePrivate::encoder = f;
}

void
QFile::setDecodingFunction(DecoderFn f)
{
    if (!f)
        f = locale_decode;
    QFilePrivate::decoder = f;
}

bool
QFile::exists() const
{
    // 0x1000000 = QAbstractFileEngine::Refresh, forcing an update
    return (fileEngine()->fileFlags(QAbstractFileEngine::FlagsMask
                                    | QAbstractFileEngine::FileFlag(0x1000000)) & QAbstractFileEngine::ExistsFlag);
}

bool
QFile::exists(const QString &fileName)
{
    return QFileInfo(fileName).exists();
}

QString
QFile::readLink() const
{
    return fileEngine()->fileName(QAbstractFileEngine::LinkName);
}

QString
QFile::readLink(const QString &fileName)
{
    return QFileInfo(fileName).readLink();
}

bool
QFile::remove()
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::remove: Empty or null file name");
        return false;
    }
    unsetError();
    close();
    if(error() == QFile::NoError) {
        if(fileEngine()->remove()) {
            unsetError();
            return true;
        }
        d->setError(QFile::RemoveError, d->fileEngine->errorString());
    }
    return false;
}

bool
QFile::remove(const QString &fileName)
{
    return QFile(fileName).remove();
}

bool
QFile::rename(const QString &newName)
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::rename: Empty or null file name");
        return false;
    }
    if (QFile(newName).exists()) {
        // ### Race condition. If a file is moved in after this, it /will/ be
        // overwritten. On Unix, the proper solution is to use hardlinks:
        // return ::link(old, new) && ::remove(old);
        d->setError(QFile::RenameError, tr("Destination file exists"));
        return false;
    }
    unsetError();
    close();
    if(error() == QFile::NoError) {
        if (fileEngine()->rename(newName)) {
            unsetError();
            // engine was able to handle the new name so we just reset it
            d->fileEngine->setFileName(newName);
            d->fileName = newName;
            return true;
        }

        if (isSequential()) {
            d->setError(QFile::RenameError, tr("Will not rename sequential file using block copy"));
            return false;
        }

        QFile out(newName);
        if (open(QIODevice::ReadOnly)) {
            if (out.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
                bool error = false;
                char block[4096];
                qint64 bytes;
                while ((bytes = read(block, sizeof(block))) > 0) {
                    if (bytes != out.write(block, bytes)) {
                        d->setError(QFile::RenameError, out.errorString());
                        error = true;
                        break;
                    }
                }
                if (bytes == -1) {
                    d->setError(QFile::RenameError, errorString());
                    error = true;
                }
                if(!error) {
                    if (!remove()) {
                        d->setError(QFile::RenameError, tr("Cannot remove source file"));
                        error = true;
                    }
                }
                if (error) {
                    out.remove();
                } else {
                    d->fileEngine->setFileName(newName);
                    setPermissions(permissions());
                    unsetError();
                    setFileName(newName);
                }
                close();
                return !error;
            }
            close();
        }
        d->setError(QFile::RenameError, out.isOpen() ? errorString() : out.errorString());
    }
    return false;
}

bool
QFile::rename(const QString &oldName, const QString &newName)
{
    return QFile(oldName).rename(newName);
}

bool
QFile::link(const QString &linkName)
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::link: Empty or null file name");
        return false;
    }
    QFileInfo fi(linkName);
    if(fileEngine()->link(fi.absoluteFilePath())) {
        unsetError();
        return true;
    }
    d->setError(QFile::RenameError, d->fileEngine->errorString());
    return false;
}

bool
QFile::link(const QString &fileName, const QString &linkName)
{
    return QFile(fileName).link(linkName);
}

bool
QFile::copy(const QString &newName)
{
    Q_D(QFile);
    if (d->fileName.isEmpty()) {
        qWarning("QFile::copy: Empty or null file name");
        return false;
    }
    if (QFile(newName).exists()) {
        // ### Race condition. If a file is moved in after this, it /will/ be
        // overwritten. On Unix, the proper solution is to use hardlinks:
        // return ::link(old, new) && ::remove(old); See also rename().
        d->setError(QFile::CopyError, tr("Destination file exists"));
        return false;
    }
    unsetError();
    close();
    if(error() == QFile::NoError) {
        if(fileEngine()->copy(newName)) {
            unsetError();
            return true;
        } else {
            bool error = false;
            if(!open(QFile::ReadOnly)) {
                error = true;
                d->setError(QFile::CopyError, tr("Cannot open %1 for input").arg(d->fileName));
            } else {
                QString fileTemplate = QLatin1String("%1/qt_temp.XXXXXX");
#ifdef QT_NO_TEMPORARYFILE
                QFile out(fileTemplate.arg(QFileInfo(newName).path()));
                if (!out.open(QIODevice::ReadWrite))
                    error = true;
#else
                QTemporaryFile out(fileTemplate.arg(QFileInfo(newName).path()));
                if (!out.open()) {
                    out.setFileTemplate(fileTemplate.arg(QDir::tempPath()));
                    if (!out.open())
                        error = true;
                }
#endif
                if (error) {
                    out.close();
                    close();
                    d->setError(QFile::CopyError, tr("Cannot open for output"));
                } else {
                    char block[4096];
                    qint64 totalRead = 0;
                    while(!atEnd()) {
                        qint64 in = read(block, sizeof(block));
                        if (in <= 0)
                            break;
                        totalRead += in;
                        if(in != out.write(block, in)) {
                            close();
                            d->setError(QFile::CopyError, tr("Failure to write block"));
                            error = true;
                            break;
                        }
                    }

                    if (totalRead != size()) {
                        // Unable to read from the source. The error string is
                        // already set from read().
                        error = true;
                    }
                    if (!error && !out.rename(newName)) {
                        error = true;
                        close();
                        d->setError(QFile::CopyError, tr("Cannot create %1 for output").arg(newName));
                    }
#ifdef QT_NO_TEMPORARYFILE
                    if (error)
                        out.remove();
#else
                    if (!error)
                        out.setAutoRemove(false);
#endif
                }
            }
            if(!error) {
                QFile::setPermissions(newName, permissions());
                close();
                unsetError();
                return true;
            }
        }
    }
    return false;
}

bool
QFile::copy(const QString &fileName, const QString &newName)
{
    return QFile(fileName).copy(newName);
}

bool QFile::isSequential() const
{
    Q_D(const QFile);
    return d->fileEngine && d->fileEngine->isSequential();
}

bool QFile::open(OpenMode mode)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;

    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QIODevice::open: File access not specified");
        return false;
    }

#ifdef Q_OS_SYMBIAN
    // For symbian, the unbuffered flag is used to control write-behind cache behaviour
    if (fileEngine()->open(mode))
#else
    // QIODevice provides the buffering, so there's no need to request it from the file engine.
    if (fileEngine()->open(mode | QIODevice::Unbuffered))
#endif
    {
        QIODevice::open(mode);
        if (mode & Append) {
            //The file engine should have done this in open(),
            //this is a workaround for backward compatibility
            fileEngine()->seek(size());
        }
        return true;
    }
    QFile::FileError err = d->fileEngine->error();
    if(err == QFile::UnspecifiedError)
        err = QFile::OpenError;
    d->setError(err, d->fileEngine->errorString());
    return false;
}

// ### Qt5: merge this into new overload with a default parameter
bool QFile::open(FILE *fh, OpenMode mode)
{
    return open(fh, mode, DontCloseHandle);
}

bool QFile::open(FILE *fh, OpenMode mode, FileHandleFlags handleFlags)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;
    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QFile::open: File access not specified");
        return false;
    }
    if (d->openExternalFile(mode, fh, handleFlags)) {
        QIODevice::open(mode);
        if (mode & Append) {
            seek(size());
        } else {
            qint64 pos = (qint64)QT_FTELL(fh);
            if (pos != -1)
                seek(pos);
        }
        return true;
    }
    return false;
}

// ### Qt5: merge this into new overload with a default parameter
bool QFile::open(int fd, OpenMode mode)
{
    return open(fd, mode, DontCloseHandle);
}

bool QFile::open(int fd, OpenMode mode, FileHandleFlags handleFlags)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;
    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QFile::open: File access not specified");
        return false;
    }
    if (d->openExternalFile(mode, fd, handleFlags)) {
        QIODevice::open(mode);
        if (mode & Append) {
            seek(size());
        } else {
            qint64 pos = (qint64)QT_LSEEK(fd, QT_OFF_T(0), SEEK_CUR);
            if (pos != -1)
                seek(pos);
        }
        return true;
    }
    return false;
}

#ifdef Q_OS_SYMBIAN

bool QFile::open(const RFile &f, OpenMode mode, FileHandleFlags handleFlags)
{
    Q_D(QFile);
    if (isOpen()) {
        qWarning("QFile::open: File (%s) already open", qPrintable(fileName()));
        return false;
    }
    if (mode & Append)
        mode |= WriteOnly;
    unsetError();
    if ((mode & (ReadOnly | WriteOnly)) == 0) {
        qWarning("QFile::open: File access not specified");
        return false;
    }
    if (d->openExternalFile(mode, f, handleFlags)) {
        bool ok = QIODevice::open(mode);
        if (ok) {
            if (mode & Append) {
                ok = seek(size());
            } else {
                qint64 pos = 0;
                TInt err;
#ifdef SYMBIAN_ENABLE_64_BIT_FILE_SERVER_API
                err = static_cast<const RFile64&>(f).Seek(ESeekCurrent, pos);
#else
                TInt pos32 = 0;
                err = f.Seek(ESeekCurrent, pos32);
                pos = pos32;
#endif
                ok = ok && (err == KErrNone);
                ok = ok && seek(pos);
            }
        }
        return ok;
    }
    return false;
}
#endif

int
QFile::handle() const
{
    Q_D(const QFile);
    if (!isOpen() || !d->fileEngine)
        return -1;

    return d->fileEngine->handle();
}

uchar *QFile::map(qint64 offset, qint64 size, MemoryMapFlags flags)
{
    Q_D(QFile);
    if (fileEngine()
            && d->fileEngine->supportsExtension(QAbstractFileEngine::MapExtension)) {
        unsetError();
        uchar *address = d->fileEngine->map(offset, size, flags);
        if (address == 0)
            d->setError(d->fileEngine->error(), d->fileEngine->errorString());
        return address;
    }
    return 0;
}

bool QFile::unmap(uchar *address)
{
    Q_D(QFile);
    if (fileEngine()
        && d->fileEngine->supportsExtension(QAbstractFileEngine::UnMapExtension)) {
        unsetError();
        bool success = d->fileEngine->unmap(address);
        if (!success)
            d->setError(d->fileEngine->error(), d->fileEngine->errorString());
        return success;
    }
    d->setError(PermissionsError, tr("No file engine available or engine does not support UnMapExtension"));
    return false;
}

bool
QFile::resize(qint64 sz)
{
    Q_D(QFile);
    if (!d->ensureFlushed())
        return false;
    fileEngine();
    if (isOpen() && d->fileEngine->pos() > sz)
        seek(sz);
    if(d->fileEngine->setSize(sz)) {
        unsetError();
        d->cachedSize = sz;
        return true;
    }
    d->cachedSize = 0;
    d->setError(QFile::ResizeError, d->fileEngine->errorString());
    return false;
}

bool
QFile::resize(const QString &fileName, qint64 sz)
{
    return QFile(fileName).resize(sz);
}

QFile::Permissions
QFile::permissions() const
{
    QAbstractFileEngine::FileFlags perms = fileEngine()->fileFlags(QAbstractFileEngine::PermsMask) & QAbstractFileEngine::PermsMask;
    return QFile::Permissions((int)perms); //ewww
}

QFile::Permissions
QFile::permissions(const QString &fileName)
{
    return QFile(fileName).permissions();
}

bool
QFile::setPermissions(Permissions permissions)
{
    Q_D(QFile);
    if(fileEngine()->setPermissions(permissions)) {
        unsetError();
        return true;
    }
    d->setError(QFile::PermissionsError, d->fileEngine->errorString());
    return false;
}

bool
QFile::setPermissions(const QString &fileName, Permissions permissions)
{
    return QFile(fileName).setPermissions(permissions);
}

static inline qint64 _qfile_writeData(QAbstractFileEngine *engine, QRingBuffer *buffer)
{
    qint64 ret = engine->write(buffer->readPointer(), buffer->nextDataBlockSize());
    if (ret > 0)
        buffer->free(ret);
    return ret;
}

bool
QFile::flush()
{
    Q_D(QFile);
    if (!d->fileEngine) {
        qWarning("QFile::flush: No file engine. Is IODevice open?");
        return false;
    }

    if (!d->writeBuffer.isEmpty()) {
        qint64 size = d->writeBuffer.size();
        if (_qfile_writeData(d->fileEngine, &d->writeBuffer) != size) {
            QFile::FileError err = d->fileEngine->error();
            if(err == QFile::UnspecifiedError)
                err = QFile::WriteError;
            d->setError(err, d->fileEngine->errorString());
            return false;
        }
    }

    if (!d->fileEngine->flush()) {
        QFile::FileError err = d->fileEngine->error();
        if(err == QFile::UnspecifiedError)
            err = QFile::WriteError;
        d->setError(err, d->fileEngine->errorString());
        return false;
    }
    return true;
}

void
QFile::close()
{
    Q_D(QFile);
    if(!isOpen())
        return;
    bool flushed = flush();
    QIODevice::close();

    // reset write buffer
    d->lastWasWrite = false;
    d->writeBuffer.clear();

    // keep earlier error from flush
    if (d->fileEngine->close() && flushed)
        unsetError();
    else if (flushed)
        d->setError(d->fileEngine->error(), d->fileEngine->errorString());
}

qint64 QFile::size() const
{
    Q_D(const QFile);
    if (!d->ensureFlushed())
        return 0;
    d->cachedSize = fileEngine()->size();
    return d->cachedSize;
}

qint64 QFile::pos() const
{
    return QIODevice::pos();
}

bool QFile::atEnd() const
{
    Q_D(const QFile);

    // If there's buffered data left, we're not at the end.
    if (!d->buffer.isEmpty())
        return false;

    if (!isOpen())
        return true;

    if (!d->ensureFlushed())
        return false;

    // If the file engine knows best, say what it says.
    if (d->fileEngine->supportsExtension(QAbstractFileEngine::AtEndExtension)) {
        // Check if the file engine supports AtEndExtension, and if it does,
        // check if the file engine claims to be at the end.
        return d->fileEngine->atEnd();
    }

    // if it looks like we are at the end, or if size is not cached,
    // fall through to bytesAvailable() to make sure.
    if (pos() < d->cachedSize)
        return false;

    // Fall back to checking how much is available (will stat files).
    return bytesAvailable() == 0;
}

bool QFile::seek(qint64 off)
{
    Q_D(QFile);
    if (!isOpen()) {
        qWarning("QFile::seek: IODevice is not open");
        return false;
    }

    if (off == d->pos && off == d->devicePos)
        return true; //avoid expensive flush for NOP seek to current position

    if (!d->ensureFlushed())
        return false;

    if (!d->fileEngine->seek(off) || !QIODevice::seek(off)) {
        QFile::FileError err = d->fileEngine->error();
        if(err == QFile::UnspecifiedError)
            err = QFile::PositionError;
        d->setError(err, d->fileEngine->errorString());
        return false;
    }
    unsetError();
    return true;
}

qint64 QFile::readLineData(char *data, qint64 maxlen)
{
    Q_D(QFile);
    if (!d->ensureFlushed())
        return -1;

    qint64 read;
    if (d->fileEngine->supportsExtension(QAbstractFileEngine::FastReadLineExtension)) {
        read = d->fileEngine->readLine(data, maxlen);
    } else {
        // Fall back to QIODevice's readLine implementation if the engine
        // cannot do it faster.
        read = QIODevice::readLineData(data, maxlen);
    }

    if (read < maxlen) {
        // failed to read all requested, may be at the end of file, stop caching size so that it's rechecked
        d->cachedSize = 0;
    }

    return read;
}

qint64 QFile::readData(char *data, qint64 len)
{
    Q_D(QFile);
    unsetError();
    if (!d->ensureFlushed())
        return -1;

    qint64 read = d->fileEngine->read(data, len);
    if(read < 0) {
        QFile::FileError err = d->fileEngine->error();
        if(err == QFile::UnspecifiedError)
            err = QFile::ReadError;
        d->setError(err, d->fileEngine->errorString());
    }

    if (read < len) {
        // failed to read all requested, may be at the end of file, stop caching size so that it's rechecked
        d->cachedSize = 0;
    }

    return read;
}

bool QFilePrivate::putCharHelper(char c)
{
#ifdef QT_NO_QOBJECT
    return QIODevicePrivate::putCharHelper(c);
#else

    // Cutoff for code that doesn't only touch the buffer.
    int writeBufferSize = writeBuffer.size();
    if ((openMode & QIODevice::Unbuffered) || writeBufferSize + 1 >= QFILE_WRITEBUFFER_SIZE
#ifdef Q_OS_WIN
        || ((openMode & QIODevice::Text) && c == '\n' && writeBufferSize + 2 >= QFILE_WRITEBUFFER_SIZE)
#endif
        ) {
        return QIODevicePrivate::putCharHelper(c);
    }

    if (!(openMode & QIODevice::WriteOnly)) {
        if (openMode == QIODevice::NotOpen)
            qWarning("QIODevice::putChar: Closed device");
        else
            qWarning("QIODevice::putChar: ReadOnly device");
        return false;
    }

    // Make sure the device is positioned correctly.
    const bool sequential = isSequential();
    if (pos != devicePos && !sequential && !q_func()->seek(pos))
        return false;

    lastWasWrite = true;

    int len = 1;
#ifdef Q_OS_WIN
    if ((openMode & QIODevice::Text) && c == '\n') {
        ++len;
        *writeBuffer.reserve(1) = '\r';
    }
#endif

    // Write to buffer.
    *writeBuffer.reserve(1) = c;

    if (!sequential) {
        pos += len;
        devicePos += len;
        if (!buffer.isEmpty())
            buffer.skip(len);
    }

    return true;
#endif
}

qint64
QFile::writeData(const char *data, qint64 len)
{
    Q_D(QFile);
    unsetError();
    d->lastWasWrite = true;
    bool buffered = !(d->openMode & Unbuffered);

    // Flush buffered data if this read will overflow.
    if (buffered && (d->writeBuffer.size() + len) > QFILE_WRITEBUFFER_SIZE) {
        if (!flush())
            return -1;
    }

    // Write directly to the engine if the block size is larger than
    // the write buffer size.
    if (!buffered || len > QFILE_WRITEBUFFER_SIZE) {
        qint64 ret = d->fileEngine->write(data, len);
        if(ret < 0) {
            QFile::FileError err = d->fileEngine->error();
            if(err == QFile::UnspecifiedError)
                err = QFile::WriteError;
            d->setError(err, d->fileEngine->errorString());
        }
        return ret;
    }

    // Write to the buffer.
    char *writePointer = d->writeBuffer.reserve(len);
    if (len == 1)
        *writePointer = *data;
    else
        ::memcpy(writePointer, data, len);
    return len;
}

QAbstractFileEngine *QFile::fileEngine() const
{
    Q_D(const QFile);
    if(!d->fileEngine)
        d->fileEngine = QAbstractFileEngine::create(d->fileName);
    return d->fileEngine;
}

QFile::FileError
QFile::error() const
{
    Q_D(const QFile);
    return d->error;
}

void
QFile::unsetError()
{
    Q_D(QFile);
    d->setError(QFile::NoError);
}

QT_END_NAMESPACE