qnoncontiguousbytedevice.cpp

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// Copyright (C) 2016 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 "qnoncontiguousbytedevice_p.h"
#include <qbuffer.h>
#include <qdebug.h>
#include <qfile.h>
 
#include <utility>
 
QT_BEGIN_NAMESPACE
 
QNonContiguousByteDevice::QNonContiguousByteDevice() : QObject((QObject*)nullptr)
{
}
 
QNonContiguousByteDevice::~QNonContiguousByteDevice()
{
}
 
QNonContiguousByteDeviceByteArrayImpl::QNonContiguousByteDeviceByteArrayImpl(QByteArray ba)
    : QNonContiguousByteDevice(), byteArray(std::move(ba)), view(byteArray)
{
}
 
QNonContiguousByteDeviceByteArrayImpl::QNonContiguousByteDeviceByteArrayImpl(QBuffer *buffer)
    : QNonContiguousByteDevice(),
      byteArray(buffer->buffer()),
      view(QByteArrayView(byteArray).sliced(buffer->pos(), buffer->size() - buffer->pos()))
{
}
 
QNonContiguousByteDeviceByteArrayImpl::~QNonContiguousByteDeviceByteArrayImpl()
{
}
 
const char* QNonContiguousByteDeviceByteArrayImpl::readPointer(qint64 maximumLength, qint64 &len)
{
    if (atEnd()) {
        len = -1;
        return nullptr;
    }
 
    if (maximumLength != -1)
        len = qMin(maximumLength, size() - currentPosition);
    else
        len = size() - currentPosition;
 
    return view.data() + currentPosition;
}
 
bool QNonContiguousByteDeviceByteArrayImpl::advanceReadPointer(qint64 amount)
{
    currentPosition += amount;
    emit readProgress(currentPosition, size());
    return true;
}
 
bool QNonContiguousByteDeviceByteArrayImpl::atEnd() const
{
    return currentPosition >= size();
}
 
bool QNonContiguousByteDeviceByteArrayImpl::reset()
{
    currentPosition = 0;
    return true;
}
 
qint64 QNonContiguousByteDeviceByteArrayImpl::size() const
{
    return view.size();
}
 
qint64 QNonContiguousByteDeviceByteArrayImpl::pos() const
{
    return currentPosition;
}
 
QNonContiguousByteDeviceRingBufferImpl::QNonContiguousByteDeviceRingBufferImpl(std::shared_ptr<QRingBuffer> rb)
    : QNonContiguousByteDevice(), ringBuffer(std::move(rb))
{
}
 
QNonContiguousByteDeviceRingBufferImpl::~QNonContiguousByteDeviceRingBufferImpl()
{
}
 
const char* QNonContiguousByteDeviceRingBufferImpl::readPointer(qint64 maximumLength, qint64 &len)
{
    if (atEnd()) {
        len = -1;
        return nullptr;
    }
 
    const char *returnValue = ringBuffer->readPointerAtPosition(currentPosition, len);
 
    if (maximumLength != -1)
        len = qMin(len, maximumLength);
 
    return returnValue;
}
 
bool QNonContiguousByteDeviceRingBufferImpl::advanceReadPointer(qint64 amount)
{
    currentPosition += amount;
    emit readProgress(currentPosition, size());
    return true;
}
 
bool QNonContiguousByteDeviceRingBufferImpl::atEnd() const
{
    return currentPosition >= size();
}
 
qint64 QNonContiguousByteDeviceRingBufferImpl::pos() const
{
    return currentPosition;
}
 
bool QNonContiguousByteDeviceRingBufferImpl::reset()
{
    currentPosition = 0;
    return true;
}
 
qint64 QNonContiguousByteDeviceRingBufferImpl::size() const
{
    return ringBuffer->size();
}
 
QNonContiguousByteDeviceIoDeviceImpl::QNonContiguousByteDeviceIoDeviceImpl(QIODevice *d)
    : QNonContiguousByteDevice(),
      device(d),
      currentReadBuffer(nullptr),
      currentReadBufferSize(16 * 1024),
      currentReadBufferAmount(0),
      currentReadBufferPosition(0),
      totalAdvancements(0),
      eof(false),
      initialPosition(d->pos())
{
    connect(device, &QIODevice::readyRead, this,
            &QNonContiguousByteDevice::readyRead);
    connect(device, &QIODevice::readChannelFinished, this,
            &QNonContiguousByteDevice::readyRead);
}
 
QNonContiguousByteDeviceIoDeviceImpl::~QNonContiguousByteDeviceIoDeviceImpl()
{
    delete currentReadBuffer;
}
 
const char *QNonContiguousByteDeviceIoDeviceImpl::readPointer(qint64 maximumLength, qint64 &len)
{
    if (eof) {
        len = -1;
        return nullptr;
    }
 
    if (currentReadBuffer == nullptr)
        currentReadBuffer = new QByteArray(currentReadBufferSize, '\0'); // lazy alloc
 
    if (maximumLength == -1)
        maximumLength = currentReadBufferSize;
 
    if (currentReadBufferAmount - currentReadBufferPosition > 0) {
        len = currentReadBufferAmount - currentReadBufferPosition;
        return currentReadBuffer->data() + currentReadBufferPosition;
    }
 
    qint64 haveRead = device->read(currentReadBuffer->data(),
                                   qMin(maximumLength, currentReadBufferSize));
 
    if ((haveRead == -1) || (haveRead == 0 && device->atEnd() && !device->isSequential())) {
        eof = true;
        len = -1;
        // size was unknown before, emit a readProgress with the final size
        if (size() == -1)
            emit readProgress(totalAdvancements, totalAdvancements);
        return nullptr;
    }
 
    currentReadBufferAmount = haveRead;
    currentReadBufferPosition = 0;
 
    len = haveRead;
    return currentReadBuffer->data();
}
 
bool QNonContiguousByteDeviceIoDeviceImpl::advanceReadPointer(qint64 amount)
{
    totalAdvancements += amount;
 
    // normal advancement
    currentReadBufferPosition += amount;
 
    if (size() == -1)
        emit readProgress(totalAdvancements, totalAdvancements);
    else
        emit readProgress(totalAdvancements, size());
 
    // advancing over that what has actually been read before
    if (currentReadBufferPosition > currentReadBufferAmount) {
        qint64 i = currentReadBufferPosition - currentReadBufferAmount;
        while (i > 0) {
            if (!device->getChar(nullptr)) {
                emit readProgress(totalAdvancements - i, size());
                return false; // ### FIXME handle eof
            }
            i--;
        }
 
        currentReadBufferPosition = 0;
        currentReadBufferAmount = 0;
    }
 
    return true;
}
 
bool QNonContiguousByteDeviceIoDeviceImpl::atEnd() const
{
    return eof;
}
 
bool QNonContiguousByteDeviceIoDeviceImpl::reset()
{
    bool reset = (initialPosition == 0) ? device->reset() : device->seek(initialPosition);
    if (reset) {
        eof = false; // assume eof is false, it will be true after a read has been attempted
        totalAdvancements = 0; // reset the progress counter
        if (currentReadBuffer) {
            delete currentReadBuffer;
            currentReadBuffer = nullptr;
        }
        currentReadBufferAmount = 0;
        currentReadBufferPosition = 0;
        return true;
    }
 
    return false;
}
 
qint64 QNonContiguousByteDeviceIoDeviceImpl::size() const
{
    // note that this is different from the size() implementation of QIODevice!
 
    if (device->isSequential())
        return -1;
 
    return device->size() - initialPosition;
}
 
qint64 QNonContiguousByteDeviceIoDeviceImpl::pos() const
{
    if (device->isSequential())
        return -1;
 
    return device->pos();
}
 
QByteDeviceWrappingIoDevice::QByteDeviceWrappingIoDevice(QNonContiguousByteDevice *bd)
    : QIODevice(nullptr), byteDevice(bd)
{
    connect(bd, &QNonContiguousByteDevice::readyRead, this, &QIODevice::readyRead);
 
    open(ReadOnly);
}
 
QByteDeviceWrappingIoDevice::~QByteDeviceWrappingIoDevice()
    = default;
 
bool QByteDeviceWrappingIoDevice::isSequential() const
{
    return (byteDevice->size() == -1);
}
 
bool QByteDeviceWrappingIoDevice::atEnd() const
{
    return byteDevice->atEnd();
}
 
bool QByteDeviceWrappingIoDevice::reset()
{
    return byteDevice->reset();
}
 
qint64 QByteDeviceWrappingIoDevice::size() const
{
    if (isSequential())
        return 0;
 
    return byteDevice->size();
}
 
qint64 QByteDeviceWrappingIoDevice::readData(char *data, qint64 maxSize)
{
    qint64 len;
    const char *readPointer = byteDevice->readPointer(maxSize, len);
    if (len == -1)
        return -1;
 
    memcpy(data, readPointer, len);
    byteDevice->advanceReadPointer(len);
    return len;
}
 
qint64 QByteDeviceWrappingIoDevice::writeData(const char *data, qint64 maxSize)
{
    Q_UNUSED(data);
    Q_UNUSED(maxSize);
    return -1;
}
 
QNonContiguousByteDevice *QNonContiguousByteDeviceFactory::create(QIODevice *device)
{
    // shortcut if it is a QBuffer
    if (QBuffer *buffer = qobject_cast<QBuffer *>(device)) {
        return new QNonContiguousByteDeviceByteArrayImpl(buffer);
    }
 
    // ### FIXME special case if device is a QFile that supports map()
    // then we can actually deal with the file without using read/peek
 
    // generic QIODevice
    return new QNonContiguousByteDeviceIoDeviceImpl(device); // FIXME
}
 
std::shared_ptr<QNonContiguousByteDevice> QNonContiguousByteDeviceFactory::createShared(QIODevice *device)
{
    // shortcut if it is a QBuffer
    if (QBuffer *buffer = qobject_cast<QBuffer*>(device))
        return std::make_shared<QNonContiguousByteDeviceByteArrayImpl>(buffer);
 
    // ### FIXME special case if device is a QFile that supports map()
    // then we can actually deal with the file without using read/peek
 
    // generic QIODevice
    return std::make_shared<QNonContiguousByteDeviceIoDeviceImpl>(device); // FIXME
}
 
QNonContiguousByteDevice *
QNonContiguousByteDeviceFactory::create(std::shared_ptr<QRingBuffer> ringBuffer)
{
    return new QNonContiguousByteDeviceRingBufferImpl(std::move(ringBuffer));
}
 
std::shared_ptr<QNonContiguousByteDevice>
QNonContiguousByteDeviceFactory::createShared(std::shared_ptr<QRingBuffer> ringBuffer)
{
    return std::make_shared<QNonContiguousByteDeviceRingBufferImpl>(std::move(ringBuffer));
}
 
QNonContiguousByteDevice* QNonContiguousByteDeviceFactory::create(const QByteArray &byteArray)
{
    return new QNonContiguousByteDeviceByteArrayImpl(byteArray);
}
 
std::shared_ptr<QNonContiguousByteDevice>
QNonContiguousByteDeviceFactory::createShared(const QByteArray &byteArray)
{
    return std::make_shared<QNonContiguousByteDeviceByteArrayImpl>(byteArray);
}
 
QIODevice *QNonContiguousByteDeviceFactory::wrap(QNonContiguousByteDevice *byteDevice)
{
    // ### FIXME if it already has been based on QIoDevice, we could that one out again
    // and save some calling
 
    // needed for FTP backend
 
    return new QByteDeviceWrappingIoDevice(byteDevice);
}
 
QT_END_NAMESPACE
 
#include "moc_qnoncontiguousbytedevice_p.cpp"