1 files changed, 292 insertions, 176 deletions

diff --git a/src/corelib/io/qwindowspipereader.cpp b/src/corelib/io/qwindowspipereader.cpp
index b525e88282..bf03737c39 100644
--- a/src/corelib/io/qwindowspipereader.cpp
+++ b/src/corelib/io/qwindowspipereader.cpp
@@ -1,6 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2021 Alex Trotsenko <alex1973tr@gmail.com>
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -38,58 +39,63 @@
 ****************************************************************************/
 
 #include "qwindowspipereader_p.h"
-#include "qiodevice_p.h"
-#include <qelapsedtimer.h>
 #include <qscopedvaluerollback.h>
+#include <qcoreapplication.h>
+#include <QMutexLocker>
 
 QT_BEGIN_NAMESPACE
 
 static const DWORD minReadBufferSize = 4096;
 
-QWindowsPipeReader::Overlapped::Overlapped(QWindowsPipeReader *reader)
-    : pipeReader(reader)
-{
-}
-
-void QWindowsPipeReader::Overlapped::clear()
-{
-    ZeroMemory(this, sizeof(OVERLAPPED));
-}
-
-
 QWindowsPipeReader::QWindowsPipeReader(QObject *parent)
     : QObject(parent),
       handle(INVALID_HANDLE_VALUE),
-      overlapped(this),
+      eventHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
+      syncHandle(CreateEvent(NULL, FALSE, FALSE, NULL)),
+      waitObject(NULL),
       readBufferMaxSize(0),
       actualReadBufferSize(0),
-      bytesPending(0),
+      pendingReadBytes(0),
+      lastError(ERROR_SUCCESS),
       state(Stopped),
       readSequenceStarted(false),
-      notifiedCalled(false),
       pipeBroken(false),
       readyReadPending(false),
+      winEventActPosted(false),
       inReadyRead(false)
 {
-    connect(this, &QWindowsPipeReader::_q_queueReadyRead,
-            this, &QWindowsPipeReader::emitPendingReadyRead, Qt::QueuedConnection);
+    ZeroMemory(&overlapped, sizeof(OVERLAPPED));
+    overlapped.hEvent = eventHandle;
+    waitObject = CreateThreadpoolWait(waitCallback, this, NULL);
+    if (waitObject == NULL)
+        qErrnoWarning("QWindowsPipeReader: CreateThreadpollWait failed.");
 }
 
 QWindowsPipeReader::~QWindowsPipeReader()
 {
     stop();
+
+    // Wait for thread pool callback to complete, as it can be still
+    // executing some completion code.
+    WaitForThreadpoolWaitCallbacks(waitObject, FALSE);
+    CloseThreadpoolWait(waitObject);
+    CloseHandle(eventHandle);
+    CloseHandle(syncHandle);
 }
 
 /*!
     Sets the handle to read from. The handle must be valid.
+    Do not call this function while the pipe is running.
  */
 void QWindowsPipeReader::setHandle(HANDLE hPipeReadEnd)
 {
     readBuffer.clear();
     actualReadBufferSize = 0;
-    bytesPending = 0;
+    readyReadPending = false;
+    pendingReadBytes = 0;
     handle = hPipeReadEnd;
     pipeBroken = false;
+    lastError = ERROR_SUCCESS;
 }
 
 /*!
@@ -98,8 +104,7 @@ void QWindowsPipeReader::setHandle(HANDLE hPipeReadEnd)
  */
 void QWindowsPipeReader::stop()
 {
-    state = Stopped;
-    cancelAsyncRead();
+    cancelAsyncRead(Stopped);
 }
 
 /*!
@@ -108,16 +113,27 @@ void QWindowsPipeReader::stop()
  */
 void QWindowsPipeReader::drainAndStop()
 {
-    state = Draining;
-    cancelAsyncRead();
+    cancelAsyncRead(Draining);
+
+    // Note that signals are not emitted in the call below, as the caller
+    // is expected to do that synchronously.
+    consumePending();
 }
 
 /*!
     Stops the asynchronous read sequence.
  */
-void QWindowsPipeReader::cancelAsyncRead()
+void QWindowsPipeReader::cancelAsyncRead(State newState)
 {
+    if (state != Running)
+        return;
+
+    QMutexLocker locker(&mutex);
+    state = newState;
     if (readSequenceStarted) {
+        // This can legitimately fail due to the GetOverlappedResult()
+        // in the callback not being locked. We ignore ERROR_NOT_FOUND
+        // in this case.
         if (!CancelIoEx(handle, &overlapped)) {
             const DWORD dwError = GetLastError();
             if (dwError != ERROR_NOT_FOUND) {
@@ -125,11 +141,37 @@ void QWindowsPipeReader::cancelAsyncRead()
                               handle);
             }
         }
-        waitForNotification(-1);
+
+        // Wait for callback to complete.
+        do {
+            locker.unlock();
+            waitForNotification(QDeadlineTimer(-1));
+            locker.relock();
+        } while (readSequenceStarted);
     }
 }
 
 /*!
+    Sets the size of internal read buffer.
+ */
+void QWindowsPipeReader::setMaxReadBufferSize(qint64 size)
+{
+    QMutexLocker locker(&mutex);
+    readBufferMaxSize = size;
+}
+
+/*!
+    Returns \c true if async operation is in progress, there is
+    pending data to read, or a read error is pending.
+*/
+bool QWindowsPipeReader::isReadOperationActive() const
+{
+    QMutexLocker locker(&mutex);
+    return readSequenceStarted || readyReadPending
+           || (lastError != ERROR_SUCCESS && !pipeBroken);
+}
+
+/*!
     Returns the number of bytes we've read so far.
  */
 qint64 QWindowsPipeReader::bytesAvailable() const
@@ -145,6 +187,7 @@ qint64 QWindowsPipeReader::read(char *data, qint64 maxlen)
     if (pipeBroken && actualReadBufferSize == 0)
         return 0;  // signal EOF
 
+    mutex.lock();
     qint64 readSoFar;
     // If startAsyncRead() has read data, copy it to its destination.
     if (maxlen == 1 && actualReadBufferSize > 0) {
@@ -155,6 +198,7 @@ qint64 QWindowsPipeReader::read(char *data, qint64 maxlen)
         readSoFar = readBuffer.read(data, qMin(actualReadBufferSize, maxlen));
         actualReadBufferSize -= readSoFar;
     }
+    mutex.unlock();
 
     if (!pipeBroken) {
         if (state == Running)
@@ -166,197 +210,268 @@ qint64 QWindowsPipeReader::read(char *data, qint64 maxlen)
     return readSoFar;
 }
 
+/*!
+    Returns \c true if a complete line of data can be read from the buffer.
+ */
 bool QWindowsPipeReader::canReadLine() const
 {
+    QMutexLocker locker(&mutex);
     return readBuffer.indexOf('\n', actualReadBufferSize) >= 0;
 }
 
 /*!
-    \internal
-    Will be called whenever the read operation completes.
+    Starts an asynchronous read sequence on the pipe.
  */
-void QWindowsPipeReader::notified(DWORD errorCode, DWORD numberOfBytesRead)
+void QWindowsPipeReader::startAsyncRead()
 {
-    notifiedCalled = true;
-    readSequenceStarted = false;
-
-    switch (errorCode) {
-    case ERROR_SUCCESS:
-        break;
-    case ERROR_MORE_DATA:
-        // This is not an error. We're connected to a message mode
-        // pipe and the message didn't fit into the pipe's system
-        // buffer. We will read the remaining data in the next call.
-        break;
-    case ERROR_BROKEN_PIPE:
-    case ERROR_PIPE_NOT_CONNECTED:
-        pipeBroken = true;
-        break;
-    case ERROR_OPERATION_ABORTED:
-        if (state != Running)
-            break;
-        Q_FALLTHROUGH();
-    default:
-        emit winError(errorCode, QLatin1String("QWindowsPipeReader::notified"));
-        pipeBroken = true;
-        break;
-    }
+    QMutexLocker locker(&mutex);
 
-    // After the reader was stopped, the only reason why this function can be called is the
-    // completion of a cancellation. No signals should be emitted, and no new read sequence should
-    // be started in this case.
-    if (state == Stopped)
+    if (readSequenceStarted || lastError != ERROR_SUCCESS)
         return;
 
-    if (pipeBroken) {
-        emitPipeClosed();
+    state = Running;
+    startAsyncReadLocked();
+
+    // Do not post the event, if the read operation will be completed asynchronously.
+    if (!readyReadPending && lastError == ERROR_SUCCESS)
         return;
-    }
 
-    actualReadBufferSize += numberOfBytesRead;
-    readBuffer.truncate(actualReadBufferSize);
+    if (!winEventActPosted) {
+        winEventActPosted = true;
+        locker.unlock();
+        QCoreApplication::postEvent(this, new QEvent(QEvent::WinEventAct));
+    } else {
+        locker.unlock();
+    }
 
-    // Read all pending data from the pipe's buffer in 'Draining' state.
-    if (state == Draining) {
-        // Determine the number of pending bytes on the first iteration.
-        if (bytesPending == 0)
-            bytesPending = checkPipeState();
-        else
-            bytesPending -= numberOfBytesRead;
+    SetEvent(syncHandle);
+}
 
-        if (bytesPending == 0) // all data received
-            return; // unblock waitForNotification() in cancelAsyncRead()
+/*!
+    Starts a new read sequence. Thread-safety should be ensured
+    by the caller.
+ */
+void QWindowsPipeReader::startAsyncReadLocked()
+{
+    // Determine the number of bytes to read.
+    qint64 bytesToRead = qMax(checkPipeState(), state == Running ? minReadBufferSize : 0);
 
-        startAsyncReadHelper(bytesPending);
-        if (readSequenceStarted)
-            notifiedCalled = false; // wait for more data
+    // This can happen only while draining; just do nothing in this case.
+    if (bytesToRead == 0)
         return;
+
+    while (lastError == ERROR_SUCCESS) {
+        if (readBufferMaxSize && bytesToRead > (readBufferMaxSize - readBuffer.size())) {
+            bytesToRead = readBufferMaxSize - readBuffer.size();
+            if (bytesToRead <= 0) {
+                // Buffer is full. User must read data from the buffer
+                // before we can read more from the pipe.
+                return;
+            }
+        }
+
+        char *ptr = readBuffer.reserve(bytesToRead);
+
+        // ReadFile() returns true, if the read operation completes synchronously.
+        // We don't need to call GetOverlappedResult() additionally, because
+        // 'numberOfBytesRead' is valid in this case.
+        DWORD numberOfBytesRead;
+        DWORD errorCode = ERROR_SUCCESS;
+        if (!ReadFile(handle, ptr, bytesToRead, &numberOfBytesRead, &overlapped)) {
+            errorCode = GetLastError();
+            if (errorCode == ERROR_IO_PENDING) {
+                Q_ASSERT(state == Running);
+                // Operation has been queued and will complete in the future.
+                readSequenceStarted = true;
+                SetThreadpoolWait(waitObject, eventHandle, NULL);
+                return;
+            }
+        }
+
+        if (!readCompleted(errorCode, numberOfBytesRead))
+            return;
+
+        // In the 'Draining' state, we have to get all the data with one call
+        // to ReadFile(). Note that message mode pipes are not supported here.
+        if (state == Draining) {
+            Q_ASSERT(bytesToRead == qint64(numberOfBytesRead));
+            return;
+        }
+
+        // We need to loop until all pending data has been read and an
+        // operation is queued for asynchronous completion.
+        // If the pipe is configured to work in message mode, we read
+        // the data in chunks.
+        bytesToRead = qMax(checkPipeState(), minReadBufferSize);
     }
+}
 
-    startAsyncRead();
-    if (!readyReadPending) {
-        readyReadPending = true;
-        emit _q_queueReadyRead(QWindowsPipeReader::QPrivateSignal());
+/*!
+    Thread pool callback procedure.
+ */
+void QWindowsPipeReader::waitCallback(PTP_CALLBACK_INSTANCE instance, PVOID context,
+                                      PTP_WAIT wait, TP_WAIT_RESULT waitResult)
+{
+    Q_UNUSED(instance);
+    Q_UNUSED(wait);
+    Q_UNUSED(waitResult);
+    QWindowsPipeReader *pipeReader = reinterpret_cast<QWindowsPipeReader *>(context);
+
+    // Get the result of the asynchronous operation.
+    DWORD numberOfBytesTransfered = 0;
+    DWORD errorCode = ERROR_SUCCESS;
+    if (!GetOverlappedResult(pipeReader->handle, &pipeReader->overlapped,
+                             &numberOfBytesTransfered, FALSE))
+        errorCode = GetLastError();
+
+    pipeReader->mutex.lock();
+
+    pipeReader->readSequenceStarted = false;
+
+    // Do not overwrite error code, if error has been detected by
+    // checkPipeState() in waitForPipeClosed(). Also, if the reader was
+    // stopped, the only reason why this function can be called is the
+    // completion of a cancellation. No signals should be emitted, and
+    // no new read sequence should be started in this case.
+    if (pipeReader->lastError == ERROR_SUCCESS && pipeReader->state != Stopped) {
+        // Ignore ERROR_OPERATION_ABORTED. We have canceled the I/O operation
+        // specifically for flushing the pipe.
+        if (pipeReader->state == Draining && errorCode == ERROR_OPERATION_ABORTED)
+            errorCode = ERROR_SUCCESS;
+
+        if (pipeReader->readCompleted(errorCode, numberOfBytesTransfered))
+            pipeReader->startAsyncReadLocked();
+
+        if (pipeReader->state == Running && !pipeReader->winEventActPosted) {
+            pipeReader->winEventActPosted = true;
+            pipeReader->mutex.unlock();
+            QCoreApplication::postEvent(pipeReader, new QEvent(QEvent::WinEventAct));
+        } else {
+            pipeReader->mutex.unlock();
+        }
+    } else {
+        pipeReader->mutex.unlock();
     }
+
+    // We set the event only after unlocking to avoid additional context
+    // switches due to the released thread immediately running into the lock.
+    SetEvent(pipeReader->syncHandle);
 }
 
 /*!
-    \internal
-    Starts an asynchronous read sequence on the pipe.
+    Will be called whenever the read operation completes. Returns \c true if
+    no error occurred; otherwise returns \c false.
  */
-void QWindowsPipeReader::startAsyncRead()
+bool QWindowsPipeReader::readCompleted(DWORD errorCode, DWORD numberOfBytesRead)
 {
-    if (readSequenceStarted)
-        return;
+    // ERROR_MORE_DATA is not an error. We're connected to a message mode
+    // pipe and the message didn't fit into the pipe's system
+    // buffer. We will read the remaining data in the next call.
+    if (errorCode == ERROR_SUCCESS || errorCode == ERROR_MORE_DATA) {
+        readyReadPending = true;
+        pendingReadBytes += numberOfBytesRead;
+        readBuffer.truncate(actualReadBufferSize + pendingReadBytes);
+        return true;
+    }
 
-    state = Running;
-    startAsyncReadHelper(qMax(checkPipeState(), minReadBufferSize));
+    lastError = errorCode;
+    return false;
 }
 
 /*!
-    \internal
-    Starts a new read sequence.
+    Receives notification that the read operation has completed.
  */
-void QWindowsPipeReader::startAsyncReadHelper(qint64 bytesToRead)
+bool QWindowsPipeReader::event(QEvent *e)
 {
-    Q_ASSERT(bytesToRead != 0);
+    if (e->type() == QEvent::WinEventAct) {
+        consumePendingAndEmit(true);
+        return true;
+    }
+    return QObject::event(e);
+}
 
-    if (pipeBroken)
-        return;
+/*!
+    Updates the read buffer size and emits pending signals in the main thread.
+    Returns \c true, if readyRead() was emitted.
+ */
+bool QWindowsPipeReader::consumePendingAndEmit(bool allowWinActPosting)
+{
+    mutex.lock();
 
-    if (readBufferMaxSize && bytesToRead > (readBufferMaxSize - readBuffer.size())) {
-        bytesToRead = readBufferMaxSize - readBuffer.size();
-        if (bytesToRead <= 0) {
-            // Buffer is full. User must read data from the buffer
-            // before we can read more from the pipe.
-            return;
-        }
+    // Enable QEvent::WinEventAct posting.
+    if (allowWinActPosting)
+        winEventActPosted = false;
+
+    const bool emitReadyRead = consumePending();
+    const DWORD dwError = lastError;
+
+    mutex.unlock();
+
+    // Disable any further processing, if the pipe was stopped.
+    // We are not allowed to emit signals in either 'Stopped'
+    // or 'Draining' state.
+    if (state != Running)
+        return false;
+
+    if (emitReadyRead && !inReadyRead) {
+        QScopedValueRollback<bool> guard(inReadyRead, true);
+        emit readyRead();
     }
 
-    char *ptr = readBuffer.reserve(bytesToRead);
-
-    readSequenceStarted = true;
-    overlapped.clear();
-    if (!ReadFileEx(handle, ptr, bytesToRead, &overlapped, &readFileCompleted)) {
-        readSequenceStarted = false;
-
-        const DWORD dwError = GetLastError();
-        switch (dwError) {
-        case ERROR_BROKEN_PIPE:
-        case ERROR_PIPE_NOT_CONNECTED:
-            // It may happen, that the other side closes the connection directly
-            // after writing data. Then we must set the appropriate socket state.
-            pipeBroken = true;
-            emit pipeClosed();
-            break;
-        default:
-            emit winError(dwError, QLatin1String("QWindowsPipeReader::startAsyncRead"));
-            break;
-        }
+    // Trigger 'pipeBroken' only once.
+    if (dwError != ERROR_SUCCESS && !pipeBroken) {
+        pipeBroken = true;
+        if (dwError != ERROR_BROKEN_PIPE && dwError != ERROR_PIPE_NOT_CONNECTED)
+            emit winError(dwError, QLatin1String("QWindowsPipeReader::consumePendingAndEmit"));
+        emit pipeClosed();
     }
+
+    return emitReadyRead;
 }
 
 /*!
-    \internal
-    Called when ReadFileEx finished the read operation.
+    Updates the read buffer size. Returns \c true, if readyRead()
+    should be emitted. Thread-safety should be ensured by the caller.
  */
-void QWindowsPipeReader::readFileCompleted(DWORD errorCode, DWORD numberOfBytesTransfered,
-                                           OVERLAPPED *overlappedBase)
+bool QWindowsPipeReader::consumePending()
 {
-    Overlapped *overlapped = static_cast<Overlapped *>(overlappedBase);
-    overlapped->pipeReader->notified(errorCode, numberOfBytesTransfered);
+    if (readyReadPending) {
+        readyReadPending = false;
+        actualReadBufferSize += pendingReadBytes;
+        pendingReadBytes = 0;
+        return true;
+    }
+
+    return false;
 }
 
 /*!
-    \internal
     Returns the number of available bytes in the pipe.
-    Sets QWindowsPipeReader::pipeBroken to true if the connection is broken.
  */
 DWORD QWindowsPipeReader::checkPipeState()
 {
     DWORD bytes;
     if (PeekNamedPipe(handle, nullptr, 0, nullptr, &bytes, nullptr))
         return bytes;
-    if (!pipeBroken) {
-        pipeBroken = true;
-        emitPipeClosed();
-    }
+
+    lastError = GetLastError();
     return 0;
 }
 
-bool QWindowsPipeReader::waitForNotification(int timeout)
+bool QWindowsPipeReader::waitForNotification(const QDeadlineTimer &deadline)
 {
-    QElapsedTimer t;
-    t.start();
-    notifiedCalled = false;
-    int msecs = timeout;
-    while (SleepEx(msecs == -1 ? INFINITE : msecs, TRUE) == WAIT_IO_COMPLETION) {
-        if (notifiedCalled)
+    do {
+        DWORD waitRet = WaitForSingleObjectEx(syncHandle, deadline.remainingTime(), TRUE);
+        if (waitRet == WAIT_OBJECT_0)
             return true;
 
-        // Some other I/O completion routine was called. Wait some more.
-        msecs = qt_subtract_from_timeout(timeout, t.elapsed());
-        if (!msecs)
-            break;
-    }
-    return notifiedCalled;
-}
+        if (waitRet != WAIT_IO_COMPLETION)
+            return false;
 
-void QWindowsPipeReader::emitPendingReadyRead()
-{
-    if (readyReadPending) {
-        readyReadPending = false;
-        QScopedValueRollback<bool> guard(inReadyRead, true);
-        emit readyRead();
-    }
-}
+        // Some I/O completion routine was called. Wait some more.
+    } while (!deadline.hasExpired());
 
-void QWindowsPipeReader::emitPipeClosed()
-{
-    // We are not allowed to emit signals in either 'Stopped'
-    // or 'Draining' state.
-    if (state == Running)
-        emit pipeClosed();
+    return false;
 }
 
 /*!
@@ -366,22 +481,12 @@ void QWindowsPipeReader::emitPipeClosed()
  */
 bool QWindowsPipeReader::waitForReadyRead(int msecs)
 {
-    if (readyReadPending) {
-        if (!inReadyRead)
-            emitPendingReadyRead();
-        return true;
-    }
-
-    if (!readSequenceStarted)
-        return false;
-
-    if (!waitForNotification(msecs))
-        return false;
+    QDeadlineTimer timer(msecs);
 
-    if (readyReadPending) {
-        if (!inReadyRead)
-            emitPendingReadyRead();
-        return true;
+    // Make sure that 'syncHandle' was triggered by the thread pool callback.
+    while (isReadOperationActive() && waitForNotification(timer)) {
+        if (consumePendingAndEmit(false))
+            return true;
     }
 
     return false;
@@ -393,15 +498,26 @@ bool QWindowsPipeReader::waitForReadyRead(int msecs)
 bool QWindowsPipeReader::waitForPipeClosed(int msecs)
 {
     const int sleepTime = 10;
-    QElapsedTimer stopWatch;
-    stopWatch.start();
+    QDeadlineTimer timer(msecs);
+
+    while (waitForReadyRead(timer.remainingTime())) {}
+    if (pipeBroken)
+        return true;
+
+    if (timer.hasExpired())
+        return false;
+
+    // When the read buffer is full, the read sequence is not running,
+    // so we need to peek the pipe to detect disconnection.
     forever {
-        waitForReadyRead(0);
         checkPipeState();
+        consumePendingAndEmit(false);
         if (pipeBroken)
             return true;
-        if (stopWatch.hasExpired(msecs - sleepTime))
+
+        if (timer.hasExpired())
             return false;
+
         Sleep(sleepTime);
     }
 }