qlocalserver.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 "qlocalserver.h"
#include "qlocalserver_p.h"
#include "qlocalsocket.h"
 
#if defined(Q_OS_WIN) && !defined(QT_LOCALSOCKET_TCP)
#include <QtCore/qt_windows.h>
#endif
 
QT_BEGIN_NAMESPACE
 
using namespace Qt::StringLiterals;
 
/*!
    \class QLocalServer
    \since 4.4
    \inmodule QtNetwork
 
    \brief The QLocalServer class provides a local socket based server.
 
    This class makes it possible to accept incoming local socket
    connections.
 
    Call listen() to have the server start listening
    for incoming connections on a specified key.  The
    newConnection() signal is then emitted each time a client
    connects to the server.
 
    Call nextPendingConnection() to accept the pending connection
    as a connected QLocalSocket.  The function returns a pointer to a
    QLocalSocket that can be used for communicating with the client.
 
    If an error occurs, serverError() returns the type of error, and
    errorString() can be called to get a human readable description
    of what happened.
 
    When listening for connections, the name which the server is
    listening on is available through serverName().
 
    Calling close() makes QLocalServer stop listening for incoming connections.
 
    Although QLocalServer is designed for use with an event loop, it's possible
    to use it without one. In that case, you must use waitForNewConnection(),
    which blocks until either a connection is available or a timeout expires.
 
    \sa QLocalSocket, QTcpServer
*/
 
/*!
    \enum QLocalServer::SocketOption
    \since 5.0
 
    This enum describes the possible options that can be used to create the
    socket. This changes the access permissions on platforms (Linux, Windows)
    that support access permissions on the socket. Both GroupAccess and OtherAccess
    may vary slightly in meanings depending on the platform.
    On Linux and Android it is possible to use sockets with abstract addresses;
    socket permissions have no meaning for such sockets.
 
    \value NoOptions No access restrictions have been set.
    \value UserAccessOption
    Access is restricted to the same user as the process that created the socket.
    \value GroupAccessOption
    Access is restricted to the same group but not the user that created the socket on Linux.
    Access is restricted to the primary group of the process on Windows
    \value OtherAccessOption
    Access is available to everyone but the user and group that created the socket on Linux.
    Access is available to everyone on Windows.
    \value WorldAccessOption
    No access restrictions.
    \value AbstractNamespaceOption
    The listening socket will be created in the abstract namespace. This flag is specific to Linux.
    In case of other platforms, for the sake of code portability, this flag is equivalent
    to WorldAccessOption.
 
    \sa socketOptions
*/
 
 
/*!
    Create a new local socket server with the given \a parent.
 
    \sa listen()
 */
QLocalServer::QLocalServer(QObject *parent)
        : QObject(*new QLocalServerPrivate, parent)
{
    Q_D(QLocalServer);
    d->init();
}
 
/*!
    Destroys the QLocalServer object.  If the server is listening for
    connections, it is automatically closed.
 
    Any client QLocalSockets that are still connected must either
    disconnect or be reparented before the server is deleted.
 
    \sa close()
 */
QLocalServer::~QLocalServer()
{
    if (isListening())
        close();
}
 
/*!
    \property QLocalServer::socketOptions
    \since 5.0
 
    \brief the socket options that control how the socket operates.
 
    For example, the socket may restrict access to what user ids can
    connect to the socket.
 
    These options must be set before listen() is called.
 
    In some cases, such as with Unix domain sockets on Linux, the
    access to the socket will be determined by file system permissions,
    and are created based on the umask. Setting the access flags will
    override this and will restrict or permit access as specified.
 
    Other Unix-based operating systems, such as \macos, do not
    honor file permissions for Unix domain sockets and by default
    have WorldAccess and these permission flags will have no effect.
 
    On Windows, UserAccessOption is sufficient to allow a non
    elevated process to connect to a local server created by an
    elevated process run by the same user. GroupAccessOption
    refers to the primary group of the process (see TokenPrimaryGroup
    in the Windows documentation). OtherAccessOption refers to
    the well known "Everyone" group.
 
    On Linux platforms it is possible to create a socket in the abstract
    namespace, which is independent of the filesystem. Using this kind
    of socket implies ignoring permission options. On other platforms
    AbstractNamespaceOption is equivalent to WorldAccessOption.
 
    By default none of the flags are set, access permissions
    are the platform default.
 
    \sa listen()
*/
void QLocalServer::setSocketOptions(SocketOptions options)
{
    Q_D(QLocalServer);
 
    d->socketOptions = options;
}
 
/*!
    \since 5.0
    Returns the socket options set on the socket.
 
    \sa setSocketOptions()
 */
QLocalServer::SocketOptions QLocalServer::socketOptions() const
{
    Q_D(const QLocalServer);
    return d->socketOptions;
}
 
QBindable<QLocalServer::SocketOptions> QLocalServer::bindableSocketOptions()
{
    Q_D(QLocalServer);
    return &d->socketOptions;
}
 
/*!
    \since 5.10
    Returns the native socket descriptor the server uses to listen
    for incoming instructions, or -1 if the server is not listening.
 
    The type of the descriptor depends on the platform:
    \list
        \li On Windows, the returned value is a
        \l{Winsock 2 Socket Handle}.
 
        \li On INTEGRITY, the returned value is the
        QTcpServer socket descriptor and the type is defined by
        \l{QTcpServer::socketDescriptor}{socketDescriptor}.
 
        \li On all other UNIX-like operating systems, the type is
        a file descriptor representing a listening socket.
    \endlist
 
    \sa listen()
*/
qintptr QLocalServer::socketDescriptor() const
{
    Q_D(const QLocalServer);
    if (!isListening())
        return -1;
#if defined(QT_LOCALSOCKET_TCP)
    return d->tcpServer.socketDescriptor();
#elif defined(Q_OS_WIN)
    const auto handle = d->connectionEventNotifier->handle();
    return handle ? qintptr(handle) : -1;
#else
    return d->socketNotifier->socket();
#endif
}
 
/*!
    Stop listening for incoming connections.  Existing connections are not
    affected, but any new connections will be refused.
 
    \sa isListening(), listen()
 */
void QLocalServer::close()
{
    Q_D(QLocalServer);
    if (!isListening())
        return;
    qDeleteAll(d->pendingConnections);
    d->pendingConnections.clear();
    d->closeServer();
    d->serverName.clear();
    d->fullServerName.clear();
    d->errorString.clear();
    d->error = QAbstractSocket::UnknownSocketError;
}
 
/*!
    Returns the human-readable message appropriate to the current error
    reported by serverError(). If no suitable string is available, an empty
    string is returned.
 
    \sa serverError()
 */
QString QLocalServer::errorString() const
{
    Q_D(const QLocalServer);
    return d->errorString;
}
 
/*!
    Returns \c true if the server has a pending connection; otherwise
    returns \c false.
 
    \sa nextPendingConnection(), setMaxPendingConnections()
 */
bool QLocalServer::hasPendingConnections() const
{
    Q_D(const QLocalServer);
    return !(d->pendingConnections.isEmpty());
}
 
/*!
    This virtual function is called by QLocalServer when a new connection
    is available. \a socketDescriptor is the native socket descriptor for
    the accepted connection.
 
    The base implementation creates a QLocalSocket, sets the socket descriptor
    and then stores the QLocalSocket in an internal list of pending
    connections. Finally newConnection() is emitted.
 
    Reimplement this function to alter the server's behavior
    when a connection is available.
 
    \sa newConnection(), nextPendingConnection(),
    QLocalSocket::setSocketDescriptor()
 */
void QLocalServer::incomingConnection(quintptr socketDescriptor)
{
    QLocalSocket *socket = new QLocalSocket(this);
    socket->setSocketDescriptor(socketDescriptor);
    addPendingConnection(socket);
}
 
/*!
    This function is called by QLocalServer::incomingConnection()
    to add the \a socket to the list of pending incoming connections.
 
    \note Don't forget to call this member from reimplemented
    incomingConnection() if you do not want to break the
    Pending Connections mechanism. This function emits the
    newConnection() signal after the socket has been
    added.
 
    \sa incomingConnection(), newConnection()
    \since 6.8
*/
void QLocalServer::addPendingConnection(QLocalSocket *socket)
{
    Q_D(QLocalServer);
    d->pendingConnections.enqueue(socket);
    emit newConnection();
}
 
/*!
    Returns \c true if the server is listening for incoming connections
    otherwise false.
 
    \sa listen(), close()
 */
bool QLocalServer::isListening() const
{
    Q_D(const QLocalServer);
    return !(d->serverName.isEmpty());
}
 
/*!
    Tells the server to listen for incoming connections on \a name.
    If the server is currently listening then it will return false.
    Return true on success otherwise false.
 
    \a name can be a single name and QLocalServer will determine
    the correct platform specific path.  serverName() will return
    the name that is passed into listen.
 
    Usually you would just pass in a name like "foo", but on Unix this
    could also be a path such as "/tmp/foo" and on Windows this could
    be a pipe path such as "\\\\.\\pipe\\foo"
 
    \note On Unix if the server crashes without closing listen will fail
    with AddressInUseError.  To create a new server the file should be removed.
    On Windows two local servers can listen to the same pipe at the same
    time, but any connections will go to one of the server.
 
    \sa serverName(), isListening(), close()
 */
bool QLocalServer::listen(const QString &name)
{
    Q_D(QLocalServer);
    if (isListening()) {
        qWarning("QLocalServer::listen() called when already listening");
        return false;
    }
 
    if (name.isEmpty()) {
        d->error = QAbstractSocket::HostNotFoundError;
        QString function = "QLocalServer::listen"_L1;
        d->errorString = tr("%1: Name error").arg(function);
        return false;
    }
 
    if (!d->listen(name)) {
        d->serverName.clear();
        d->fullServerName.clear();
        return false;
    }
 
    d->serverName = name;
    return true;
}
 
/*!
    \since 5.0
 
    Instructs the server to listen for incoming connections on
    \a socketDescriptor. The property returns \c false if the server is
    currently listening. It returns \c true on success; otherwise,
    it returns \c false. The socket must be ready to accept
    new connections with no extra platform-specific functions
    called. The socket is set into non-blocking mode.
 
    serverName(), fullServerName() may return a string with
    a name if this option is supported by the platform;
    otherwise, they return an empty QString. In particular, the addresses
    of sockets in the abstract namespace supported by Linux will
    not yield useful names if they contain unprintable characters.
 
    \sa isListening(), close()
 */
bool QLocalServer::listen(qintptr socketDescriptor)
{
    Q_D(QLocalServer);
    if (isListening()) {
        qWarning("QLocalServer::listen() called when already listening");
        return false;
    }
 
    d->serverName.clear();
    d->fullServerName.clear();
 
    if (!d->listen(socketDescriptor)) {
        return false;
    }
 
    return true;
}
 
/*!
    Returns the maximum number of pending accepted connections.
    The default is 30.
 
    \sa setMaxPendingConnections(), hasPendingConnections()
 */
int QLocalServer::maxPendingConnections() const
{
    Q_D(const QLocalServer);
    return d->maxPendingConnections;
}
 
/*!
    \fn void QLocalServer::newConnection()
 
    This signal is emitted every time a new connection is available.
 
    \sa hasPendingConnections(), nextPendingConnection()
*/
 
/*!
    Returns the next pending connection as a connected QLocalSocket object.
 
    The socket is created as a child of the server, which means that it is
    automatically deleted when the QLocalServer object is destroyed. It is
    still a good idea to delete the object explicitly when you are done with
    it, to avoid wasting memory.
 
    \nullptr is returned if this function is called when there are no pending
    connections.
 
    \sa hasPendingConnections(), newConnection(), incomingConnection()
 */
QLocalSocket *QLocalServer::nextPendingConnection()
{
    Q_D(QLocalServer);
    if (d->pendingConnections.isEmpty())
        return nullptr;
    QLocalSocket *nextSocket = d->pendingConnections.dequeue();
#ifndef QT_LOCALSOCKET_TCP
    if (d->pendingConnections.size() <= d->maxPendingConnections)
#ifndef Q_OS_WIN
        d->socketNotifier->setEnabled(true);
#else
        d->connectionEventNotifier->setEnabled(true);
#endif
#endif
    return nextSocket;
}
 
/*!
    \since 4.5
 
    Removes any server instance that might cause a call to listen() to fail
    and returns \c true if successful; otherwise returns \c false.
    This function is meant to recover from a crash, when the previous server
    instance has not been cleaned up.
 
    On Windows, this function does nothing; on Unix, it removes the socket file
    given by \a name.
 
    \warning Be careful to avoid removing sockets of running instances.
*/
bool QLocalServer::removeServer(const QString &name)
{
    return QLocalServerPrivate::removeServer(name);
}
 
/*!
    Returns the server name if the server is listening for connections;
    otherwise returns QString()
 
    \sa listen(), fullServerName()
 */
QString QLocalServer::serverName() const
{
    Q_D(const QLocalServer);
    return d->serverName;
}
 
/*!
    Returns the full path that the server is listening on.
 
    Note: This is platform specific
 
    \sa listen(), serverName()
 */
QString QLocalServer::fullServerName() const
{
    Q_D(const QLocalServer);
    return d->fullServerName;
}
 
/*!
    Returns the type of error that occurred last or NoError.
 
    \sa errorString()
 */
QAbstractSocket::SocketError QLocalServer::serverError() const
{
    Q_D(const QLocalServer);
    return d->error;
}
 
/*!
    Sets the maximum number of pending accepted connections to
    \a numConnections.  QLocalServer will accept no more than
    \a numConnections incoming connections before nextPendingConnection()
    is called.
 
    Note: Even though QLocalServer will stop accepting new connections
    after it has reached its maximum number of pending connections,
    the operating system may still keep them in queue which will result
    in clients signaling that it is connected.
 
    \sa maxPendingConnections(), hasPendingConnections()
 */
void QLocalServer::setMaxPendingConnections(int numConnections)
{
    Q_D(QLocalServer);
    d->maxPendingConnections = numConnections;
}
 
/*!
    Waits for at most \a msec milliseconds or until an incoming connection
    is available.  Returns \c true if a connection is available; otherwise
    returns \c false.  If the operation timed out and \a timedOut is not
    \nullptr, *timedOut will be set to true.
 
    This is a blocking function call. Its use is ill-advised in a
    single-threaded GUI application, since the whole application will stop
    responding until the function returns. waitForNewConnection() is mostly
    useful when there is no event loop available.
 
    The non-blocking alternative is to connect to the newConnection() signal.
 
    If msec is -1, this function will not time out.
 
    \sa hasPendingConnections(), nextPendingConnection()
 */
bool QLocalServer::waitForNewConnection(int msec, bool *timedOut)
{
    Q_D(QLocalServer);
    if (timedOut)
        *timedOut = false;
 
    if (!isListening())
        return false;
 
    d->waitForNewConnection(msec, timedOut);
 
    return !d->pendingConnections.isEmpty();
}
 
/*!
    Sets the backlog queue size of to be accepted connections to \a
    size. The operating system might reduce or ignore this value.
    By default, the queue size is 50.
 
    \note This property must be set prior to calling listen().
 
    \since 6.3
 
    \sa listenBacklogSize()
*/
void QLocalServer::setListenBacklogSize(int size)
{
    Q_D(QLocalServer);
    d->listenBacklog = size;
}
 
/*!
    Returns the backlog queue size of to be accepted connections.
 
    \since 6.3
 
    \sa setListenBacklogSize()
*/
int QLocalServer::listenBacklogSize() const
{
    Q_D(const QLocalServer);
    return d->listenBacklog;
}
 
QT_END_NAMESPACE
 
#include "moc_qlocalserver.cpp"