360 lines
10 KiB
C++
360 lines
10 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2016 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 3 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL3 included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 3 requirements
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** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
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**
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** GNU General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU
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** General Public License version 2.0 or (at your option) the GNU General
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** Public license version 3 or any later version approved by the KDE Free
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** Qt Foundation. The licenses are as published by the Free Software
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** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
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** included in the packaging of this file. Please review the following
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** information to ensure the GNU General Public License requirements will
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** be met: https://www.gnu.org/licenses/gpl-2.0.html and
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** https://www.gnu.org/licenses/gpl-3.0.html.
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "qwindowspipereader_p.h"
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#include "qiodevice_p.h"
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#include <qelapsedtimer.h>
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QT_BEGIN_NAMESPACE
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QWindowsPipeReader::Overlapped::Overlapped(QWindowsPipeReader *reader)
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: pipeReader(reader)
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{
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}
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void QWindowsPipeReader::Overlapped::clear()
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{
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ZeroMemory(this, sizeof(OVERLAPPED));
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}
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QWindowsPipeReader::QWindowsPipeReader(QObject *parent)
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: QObject(parent),
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handle(INVALID_HANDLE_VALUE),
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overlapped(nullptr),
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readBufferMaxSize(0),
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actualReadBufferSize(0),
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stopped(true),
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readSequenceStarted(false),
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notifiedCalled(false),
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pipeBroken(false),
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readyReadPending(false),
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inReadyRead(false)
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{
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connect(this, &QWindowsPipeReader::_q_queueReadyRead,
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this, &QWindowsPipeReader::emitPendingReadyRead, Qt::QueuedConnection);
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}
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QWindowsPipeReader::~QWindowsPipeReader()
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{
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stop();
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delete overlapped;
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}
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/*!
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Sets the handle to read from. The handle must be valid.
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*/
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void QWindowsPipeReader::setHandle(HANDLE hPipeReadEnd)
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{
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readBuffer.clear();
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actualReadBufferSize = 0;
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handle = hPipeReadEnd;
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pipeBroken = false;
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}
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/*!
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Stops the asynchronous read sequence.
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If the read sequence is running then the I/O operation is canceled.
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*/
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void QWindowsPipeReader::stop()
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{
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stopped = true;
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if (readSequenceStarted) {
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overlapped->pipeReader = nullptr;
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if (!CancelIoEx(handle, overlapped)) {
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const DWORD dwError = GetLastError();
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if (dwError != ERROR_NOT_FOUND) {
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qErrnoWarning(dwError, "QWindowsPipeReader: CancelIoEx on handle %p failed.",
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handle);
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}
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}
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overlapped = nullptr; // The object will be deleted in the I/O callback.
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readSequenceStarted = false;
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}
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}
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/*!
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Returns the number of bytes we've read so far.
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*/
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qint64 QWindowsPipeReader::bytesAvailable() const
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{
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return actualReadBufferSize;
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}
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/*!
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Copies at most \c{maxlen} bytes from the internal read buffer to \c{data}.
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*/
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qint64 QWindowsPipeReader::read(char *data, qint64 maxlen)
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{
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if (pipeBroken && actualReadBufferSize == 0)
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return 0; // signal EOF
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qint64 readSoFar;
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// If startAsyncRead() has read data, copy it to its destination.
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if (maxlen == 1 && actualReadBufferSize > 0) {
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*data = readBuffer.getChar();
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actualReadBufferSize--;
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readSoFar = 1;
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} else {
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readSoFar = readBuffer.read(data, qMin(actualReadBufferSize, maxlen));
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actualReadBufferSize -= readSoFar;
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}
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if (!pipeBroken) {
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if (!readSequenceStarted && !stopped)
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startAsyncRead();
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if (readSoFar == 0)
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return -2; // signal EWOULDBLOCK
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}
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return readSoFar;
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}
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bool QWindowsPipeReader::canReadLine() const
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{
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return readBuffer.indexOf('\n', actualReadBufferSize) >= 0;
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}
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/*!
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\internal
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Will be called whenever the read operation completes.
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*/
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void QWindowsPipeReader::notified(DWORD errorCode, DWORD numberOfBytesRead)
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{
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notifiedCalled = true;
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readSequenceStarted = false;
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switch (errorCode) {
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case ERROR_SUCCESS:
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break;
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case ERROR_MORE_DATA:
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// This is not an error. We're connected to a message mode
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// pipe and the message didn't fit into the pipe's system
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// buffer. We will read the remaining data in the next call.
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break;
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case ERROR_BROKEN_PIPE:
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case ERROR_PIPE_NOT_CONNECTED:
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pipeBroken = true;
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break;
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case ERROR_OPERATION_ABORTED:
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if (stopped)
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break;
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Q_FALLTHROUGH();
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default:
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emit winError(errorCode, QLatin1String("QWindowsPipeReader::notified"));
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pipeBroken = true;
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break;
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}
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// After the reader was stopped, the only reason why this function can be called is the
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// completion of a cancellation. No signals should be emitted, and no new read sequence should
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// be started in this case.
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if (stopped)
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return;
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if (pipeBroken) {
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emit pipeClosed();
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return;
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}
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actualReadBufferSize += numberOfBytesRead;
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readBuffer.truncate(actualReadBufferSize);
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startAsyncRead();
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if (!readyReadPending) {
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readyReadPending = true;
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emit _q_queueReadyRead(QWindowsPipeReader::QPrivateSignal());
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}
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}
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/*!
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\internal
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Reads data from the pipe into the readbuffer.
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*/
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void QWindowsPipeReader::startAsyncRead()
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{
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const DWORD minReadBufferSize = 4096;
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qint64 bytesToRead = qMax(checkPipeState(), minReadBufferSize);
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if (pipeBroken)
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return;
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if (readBufferMaxSize && bytesToRead > (readBufferMaxSize - readBuffer.size())) {
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bytesToRead = readBufferMaxSize - readBuffer.size();
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if (bytesToRead <= 0) {
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// Buffer is full. User must read data from the buffer
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// before we can read more from the pipe.
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return;
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}
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}
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char *ptr = readBuffer.reserve(bytesToRead);
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stopped = false;
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readSequenceStarted = true;
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if (!overlapped)
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overlapped = new Overlapped(this);
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overlapped->clear();
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if (!ReadFileEx(handle, ptr, bytesToRead, overlapped, &readFileCompleted)) {
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readSequenceStarted = false;
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const DWORD dwError = GetLastError();
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switch (dwError) {
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case ERROR_BROKEN_PIPE:
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case ERROR_PIPE_NOT_CONNECTED:
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// It may happen, that the other side closes the connection directly
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// after writing data. Then we must set the appropriate socket state.
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pipeBroken = true;
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emit pipeClosed();
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break;
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default:
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emit winError(dwError, QLatin1String("QWindowsPipeReader::startAsyncRead"));
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break;
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}
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}
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}
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/*!
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\internal
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Called when ReadFileEx finished the read operation.
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*/
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void QWindowsPipeReader::readFileCompleted(DWORD errorCode, DWORD numberOfBytesTransfered,
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OVERLAPPED *overlappedBase)
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{
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Overlapped *overlapped = static_cast<Overlapped *>(overlappedBase);
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if (overlapped->pipeReader)
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overlapped->pipeReader->notified(errorCode, numberOfBytesTransfered);
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else
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delete overlapped;
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}
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/*!
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\internal
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Returns the number of available bytes in the pipe.
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Sets QWindowsPipeReader::pipeBroken to true if the connection is broken.
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*/
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DWORD QWindowsPipeReader::checkPipeState()
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{
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DWORD bytes;
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if (PeekNamedPipe(handle, NULL, 0, NULL, &bytes, NULL)) {
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return bytes;
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} else {
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if (!pipeBroken) {
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pipeBroken = true;
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emit pipeClosed();
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}
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}
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return 0;
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}
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bool QWindowsPipeReader::waitForNotification(int timeout)
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{
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QElapsedTimer t;
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t.start();
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notifiedCalled = false;
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int msecs = timeout;
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while (SleepEx(msecs == -1 ? INFINITE : msecs, TRUE) == WAIT_IO_COMPLETION) {
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if (notifiedCalled)
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return true;
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// Some other I/O completion routine was called. Wait some more.
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msecs = qt_subtract_from_timeout(timeout, t.elapsed());
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if (!msecs)
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break;
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}
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return notifiedCalled;
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}
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void QWindowsPipeReader::emitPendingReadyRead()
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{
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if (readyReadPending) {
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readyReadPending = false;
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inReadyRead = true;
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emit readyRead();
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inReadyRead = false;
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}
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}
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/*!
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Waits for the completion of the asynchronous read operation.
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Returns \c true, if we've emitted the readyRead signal (non-recursive case)
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or readyRead will be emitted by the event loop (recursive case).
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*/
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bool QWindowsPipeReader::waitForReadyRead(int msecs)
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{
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if (!readSequenceStarted)
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return false;
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if (readyReadPending) {
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if (!inReadyRead)
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emitPendingReadyRead();
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return true;
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}
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if (!waitForNotification(msecs))
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return false;
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if (readyReadPending) {
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if (!inReadyRead)
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emitPendingReadyRead();
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return true;
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}
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return false;
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}
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/*!
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Waits until the pipe is closed.
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*/
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bool QWindowsPipeReader::waitForPipeClosed(int msecs)
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{
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const int sleepTime = 10;
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QElapsedTimer stopWatch;
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stopWatch.start();
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forever {
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waitForReadyRead(0);
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checkPipeState();
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if (pipeBroken)
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return true;
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if (stopWatch.hasExpired(msecs - sleepTime))
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return false;
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Sleep(sleepTime);
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}
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}
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QT_END_NAMESPACE
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