qiodevice.cpp

奇趣公司比较新的qt/emd版本

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//#define QIODEVICE_DEBUG

#include "qbytearray.h"
#include "qdebug.h"
#include "qiodevice_p.h"
#include "qfile.h"
#include "qstringlist.h"
#include <limits.h>

#ifdef QIODEVICE_DEBUG
void debugBinaryString(const QByteArray &input)
{
    QByteArray tmp;
    int startOffset = 0;
    for (int i = 0; i < input.size(); ++i) {
        tmp += input[i];

        if ((i % 16) == 15 || i == (input.size() - 1)) {
            printf("\n%15d:", startOffset);
            startOffset += tmp.size();

            for (int j = 0; j < tmp.size(); ++j)
                printf(" %02x", int(uchar(tmp[j])));
            for (int j = tmp.size(); j < 16 + 1; ++j)
                printf("   ");
            for (int j = 0; j < tmp.size(); ++j)
                printf("%c", isprint(int(uchar(tmp[j]))) ? tmp[j] : '.');
            tmp.clear();
        }
    }
    printf("\n\n");
}

void debugBinaryString(const char *data, qint64 maxlen)
{
    debugBinaryString(QByteArray(data, maxlen));
}
#endif

static const qint64 QIODEVICE_BUFFERSIZE = 16384;

#define Q_VOID

#define CHECK_MAXLEN(function, returnType) \
    do { \
        if (maxSize < 0) { \
            qWarning("QIODevice::"#function": Called with maxSize < 0"); \
            return returnType; \
        } \
    } while (0)

#define CHECK_WRITABLE(function, returnType) \
   do { \
       if ((d->openMode & WriteOnly) == 0) { \
           if (d->openMode == NotOpen) \
               return returnType; \
           qWarning("QIODevice::"#function": ReadOnly device"); \
           return returnType; \
       } \
   } while (0)

#define CHECK_READABLE(function, returnType) \
   do { \
       if ((d->openMode & ReadOnly) == 0) { \
           if (d->openMode == NotOpen) \
               return returnType; \
           qWarning("QIODevice::"#function": WriteOnly device"); \
           return returnType; \
       } \
   } while (0)

/*! \internal
 */
QIODevicePrivate::QIODevicePrivate()
    : openMode(QIODevice::NotOpen), buffer(QIODEVICE_BUFFERSIZE),
      pos(0), devicePos(0), accessMode(Unset)
{
}

/*! \internal
 */
QIODevicePrivate::~QIODevicePrivate()
{
}

/*!
    \class QIODevice
    \reentrant

    \brief The QIODevice class is the base interface class of all I/O
    devices in Qt.

    \ingroup io

    QIODevice provides both a common implementation and an abstract
    interface for devices that support reading and writing of blocks
    of data, such as QFile, QBuffer and QTcpSocket. QIODevice is
    abstract and can not be instantiated, but it is common to use the
    interface it defines to provide device-independent I/O features.
    For example, Qt's XML classes operate on a QIODevice pointer,
    allowing them to be used with various devices (such as files and
    buffers).

    Before accessing the device, open() must be called to set the
    correct OpenMode (such as ReadOnly or ReadWrite). You can then
    write to the device with write() or putChar(), and read by calling
    either read(), readLine(), or readAll(). Call close() when you are
    done with the device.

    QIODevice distinguishes between two types of devices:
    random-access devices and sequential devices.

    \list
    \o Random-access devices support seeking to arbitrary
    positions using seek(). The current position in the file is
    available by calling pos(). QFile and QBuffer are examples of
    random-access devices.

    \o Sequential devices don't support seeking to arbitrary
    positions. The data must be read in one pass. The functions
    pos() and size() don't work for sequential devices.
    QTcpSocket and QProcess are examples of sequential devices.
    \endlist

    You can use isSequential() to determine the type of device.

    QIODevice emits readyRead() when new data is available for
    reading; for example, if new data has arrived on the network or if
    additional data is appended to a file that you are reading
    from. You can call bytesAvailable() to determine the number of
    bytes that currently available for reading. It's common to use
    bytesAvailable() together with the readyRead() signal when
    programming with asynchronous devices such as QTcpSocket, where
    fragments of data can arrive at arbitrary points in
    time. QIODevice emits the bytesWritten() signal every time a
    payload of data has been written to the device. Use bytesToWrite()
    to determine the current amount of data waiting to be written.

    Certain subclasses of QIODevice, such as QTcpSocket and QProcess,
    are asynchronous. This means that I/O functions such as write()
    or read() always return immediately, while communication with the
    device itself may happen when control goes back to the event loop.
    QIODevice provides functions that allow you to force these
    operations to be performed immediately, while blocking the
    calling thread and without entering the event loop. This allows
    QIODevice subclasses to be used without an event loop, or in
    a separate thread:

    \list
    \o waitForReadyRead() - This function suspends operation in the
    calling thread until new data is available for reading.

    \o waitForBytesWritten() - This function suspends operation in the
    calling thread until one payload of data has been written to the
    device.

    \o waitFor....() - Subclasses of QIODevice implement blocking
    functions for device-specific operations. For example, QProcess
    has a function called waitForStarted() which suspends operation in
    the calling thread until the process has started.
    \endlist

    Calling these functions from the main, GUI thread, may cause your
    user interface to freeze. Example:

    \code
        QProcess gzip;
        gzip.start("gzip", QStringList() << "-c");
        if (!gzip.waitForStarted())
            return false;

        gzip.write("uncompressed data");

        QByteArray compressed;
        while (gzip.waitForReadyRead())
            compressed += gzip.readAll();
    \endcode

    By subclassing QIODevice, you can provide the same interface to
    your own I/O devices. Subclasses of QIODevice are only required to
    implement the protected readData() and writeData() functions.
    QIODevice uses these functions to implement all its convenience
    functions, such as getChar(), readLine() and write(). QIODevice
    also handles access control for you, so you can safely assume that
    the device is opened in write mode if writeData() is called.

    Some subclasses, such as QFile and QTcpSocket, are implemented
    using a memory buffer for intermediate storing of data. This
    reduces the number of required device accessing calls, which are
    often very slow. Buffering makes functions like getChar() and
    putChar() fast, as they can operate on the memory buffer instead
    of directly on the device itself. Certain I/O operations, however,
    don't work well with a buffer. For example, if several users open
    the same device and read it character by character, they may end
    up reading the same data when they meant to read a separate chunk
    each. For this reason, QIODevice allows you to bypass any
    buffering by passing the Unbuffered flag to open(). When
    subclassing QIODevice, remember to bypass any buffer you may use
    when the device is open in Unbuffered mode.

    \sa QBuffer QFile QTcpSocket
*/

/*!
    \typedef QIODevice::Offset
    \compat

    Use \c qint64 instead.
*/

/*!
    \typedef QIODevice::Status
    \compat

    Use QIODevice::OpenMode instead, or see the documentation for
    specific devices.
*/

/*!
    \enum QIODevice::OpenModeFlag

    This enum is used with open() to describe the mode in which a device
    is opened. It is also returned by openMode().

    \value NotOpen   The device is not open.
    \value ReadOnly  The device is open for reading.
    \value WriteOnly The device is open for writing.
    \value ReadWrite The device is open for reading and writing.
    \value Append    The device is opened in append mode, so that all data is
                     written to the end of the file.
    \value Truncate  If possible, the device is truncated before it is opened.
                     All earlier contents of the device are lost.
    \value Text      When reading, the end-of-line terminators are
                     translated to '\n'. When writing, the end-of-line
                     terminators are translated to the local encoding, for
                     example '\r\n' for Win32.
    \value Unbuffered Any buffer in the device is bypassed.

    Certain flags, such as \c Unbuffered and \c Truncate, are
    meaningless when used with some subclasses. Some of these
    restrictions are implied by the type of device that is represented
    by a subclass; for example, access to a QBuffer is always
    unbuffered. In other cases, the restriction may be due to the
    implementation, or may be imposed by the underlying platform; for
    example, QTcpSocket does not support \c Unbuffered mode, and
    limitations in the native API prevent QFile from supporting \c
    Unbuffered on Windows.
*/

/*!     \fn QIODevice::bytesWritten(qint64 bytes)

    This signal is emitted every time a payload of data has been
    written to the device. The \a bytes argument is set to the number
    of bytes that were written in this payload.

    bytesWritten() is not emitted recursively; if you reenter the event loop
    or call waitForBytesWritten() inside a slot connected to the
    bytesWritten() signal, the signal will not be reemitted (although
    waitForBytesWritten() may still return true).

    \sa readyRead()
*/

/*!
    \fn QIODevice::readyRead()

    This signal is emitted once every time new data is available for
    reading from the device. It will only be emitted again once new
    data is available, such as when a new payload of network data has
    arrived on your network socket, or when a new block of data has
    been appended to your device.

    readyRead() is not emitted recursively; if you reenter the event loop or
    call waitForReadyRead() inside a slot connected to the readyRead() signal,
    the signal will not be reemitted (although waitForReadyRead() may still
    return true).

    \sa bytesWritten()
*/

/*! \fn QIODevice::aboutToClose()

    This signal is emitted when the device is about to close. Connect
    this signal if you have operations that need to be performed
    before the device closes (e.g., if you have data in a separate
    buffer that needs to be written to the device).
*/

#ifdef QT_NO_QOBJECT
QIODevice::QIODevice()
    : d_ptr(new QIODevicePrivate)
{
    d_ptr->q_ptr = this;
}

/*! \internal
*/
QIODevice::QIODevice(QIODevicePrivate &dd)
    : d_ptr(&dd)
{
    d_ptr->q_ptr = this;
}
#else

/*!
    Constructs a QIODevice object.
*/

QIODevice::QIODevice()
    : QObject(*new QIODevicePrivate, 0)
{
#if defined QIODEVICE_DEBUG
    QFile *file = qobject_cast<QFile *>(this);
    printf("%p QIODevice::QIODevice(\"%s\") %s\n", this, className(),
           qPrintable(file ? file->fileName() : QString()));
#endif
}

/*!
    Constructs a QIODevice object with the given \a parent.
*/

QIODevice::QIODevice(QObject *parent)
    : QObject(*new QIODevicePrivate, parent)
{
#if defined QIODEVICE_DEBUG
    printf("%p QIODevice::QIODevice(%p \"%s\")\n", this, parent, className());
#endif
}

/*! \internal
*/
QIODevice::QIODevice(QIODevicePrivate &dd, QObject *parent)
    : QObject(dd, parent)
{
}
#endif


/*!
    Destructs the QIODevice object.
*/
QIODevice::~QIODevice()
{
#if defined QIODEVICE_DEBUG
    printf("%p QIODevice::~QIODevice()\n", this);
#endif
}

/*!
    Returns true if this device is sequential; otherwise returns
    false.

    Sequential devices, as opposed to a random-access devices, have no
    concept of a start, an end, a size, or a current position, and they
    do not support seeking. You can only read from the device when it
    reports that data is available. The most common example of a
    sequential device is a network socket. On Unix, special files such
    as /dev/zero and fifo pipes are sequential.

    Regular files, on the other hand, do support random access. They
    have both a size and a current position, and they also support
    seeking backwards and forwards in the data stream. Regular files
    are non-sequential.

    \sa bytesAvailable()
*/
bool QIODevice::isSequential() const
{
    return false;
}

/*!
    Returns the mode in which the device has been opened;
    i.e. ReadOnly or WriteOnly.

    \sa OpenMode
*/
QIODevice::OpenMode QIODevice::openMode() const
{
    return d_func()->openMode;
}

/*!
    Sets the OpenMode of the device to \a openMode. Call this
    function to set the open mode when reimplementing open().

    \sa openMode() OpenMode
*/
void QIODevice::setOpenMode(OpenMode openMode)
{
#if defined QIODEVICE_DEBUG
    printf("%p QIODevice::setOpenMode(0x%x)\n", this, int(openMode));
#endif