QAbstractSocket: Don't pretend pause and resume is a stack

It only stores one layer of state, and pausing twice in a row will just
overwrite the previous state. This doesn't happen often but can happen,
especially on Windows if a certificate needs to be looked up in the system
certificate stores (socket gets paused) and then a recoverable error
occurs in QNAM (socket gets paused again).

Fixes: QTBUG-100362
Fixes: QTBUG-63196
Fixes: QTBUG-98476
Pick-to: 6.3 6.2 5.15
Change-Id: Ie524c48e11b6fa8010b78cc1bf3931efe2ce3351
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

2 files changed, 41 insertions, 14 deletions

diff --git a/src/network/socket/qabstractsocket.cpp b/src/network/socket/qabstractsocket.cpp
index 08e6b8c77d..b5228981fc 100644
--- a/src/network/socket/qabstractsocket.cpp
+++ b/src/network/socket/qabstractsocket.cpp
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2022 The Qt Company Ltd.
 ** Copyright (C) 2016 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
@@ -1346,12 +1346,29 @@ void QAbstractSocketPrivate::pauseSocketNotifiers(QAbstractSocket *socket)
     QAbstractSocketEngine *socketEngine = socket->d_func()->socketEngine;
     if (!socketEngine)
         return;
-    socket->d_func()->prePauseReadSocketNotifierState = socketEngine->isReadNotificationEnabled();
-    socket->d_func()->prePauseWriteSocketNotifierState = socketEngine->isWriteNotificationEnabled();
-    socket->d_func()->prePauseExceptionSocketNotifierState = socketEngine->isExceptionNotificationEnabled();
-    socketEngine->setReadNotificationEnabled(false);
-    socketEngine->setWriteNotificationEnabled(false);
-    socketEngine->setExceptionNotificationEnabled(false);
+    bool read = socketEngine->isReadNotificationEnabled();
+    bool write = socketEngine->isWriteNotificationEnabled();
+    bool except = socketEngine->isExceptionNotificationEnabled();
+
+#ifdef QABSTRACTSOCKET_DEBUG
+    qDebug() << socketEngine->socketDescriptor()
+             << "pause notifiers, storing 'true' states, currently read:" << read
+             << "write:" << write << "except:" << except;
+#endif
+    // We do this if-check to avoid accidentally overwriting any previously stored state
+    // It will reset to false once the socket is re-enabled.
+    if (read) {
+        socket->d_func()->prePauseReadSocketNotifierState = true;
+        socketEngine->setReadNotificationEnabled(false);
+    }
+    if (write) {
+        socket->d_func()->prePauseWriteSocketNotifierState = true;
+        socketEngine->setWriteNotificationEnabled(false);
+    }
+    if (except) {
+        socket->d_func()->prePauseExceptionSocketNotifierState = true;
+        socketEngine->setExceptionNotificationEnabled(false);
+    }
 }
 
 void QAbstractSocketPrivate::resumeSocketNotifiers(QAbstractSocket *socket)
@@ -1359,9 +1376,19 @@ void QAbstractSocketPrivate::resumeSocketNotifiers(QAbstractSocket *socket)
     QAbstractSocketEngine *socketEngine = socket->d_func()->socketEngine;
     if (!socketEngine)
         return;
-    socketEngine->setReadNotificationEnabled(socket->d_func()->prePauseReadSocketNotifierState);
-    socketEngine->setWriteNotificationEnabled(socket->d_func()->prePauseWriteSocketNotifierState);
-    socketEngine->setExceptionNotificationEnabled(socket->d_func()->prePauseExceptionSocketNotifierState);
+    QAbstractSocketPrivate *priv = socket->d_func();
+#ifdef QABSTRACTSOCKET_DEBUG
+    qDebug() << socketEngine->socketDescriptor()
+             << "Maybe resume notifiers, read:" << priv->prePauseReadSocketNotifierState
+             << "write:" << priv->prePauseWriteSocketNotifierState
+             << "exception:" << priv->prePauseExceptionSocketNotifierState;
+#endif
+    if (std::exchange(priv->prePauseReadSocketNotifierState, false))
+        socketEngine->setReadNotificationEnabled(true);
+    if (std::exchange(priv->prePauseWriteSocketNotifierState, false))
+        socketEngine->setWriteNotificationEnabled(true);
+    if (std::exchange(priv->prePauseExceptionSocketNotifierState, false))
+        socketEngine->setExceptionNotificationEnabled(true);
 }
 
 QAbstractSocketEngine* QAbstractSocketPrivate::getSocketEngine(QAbstractSocket *socket)
diff --git a/src/network/socket/qabstractsocket_p.h b/src/network/socket/qabstractsocket_p.h
index 83a8afe36d..d2a1378874 100644
--- a/src/network/socket/qabstractsocket_p.h
+++ b/src/network/socket/qabstractsocket_p.h
@@ -1,6 +1,6 @@
 /****************************************************************************
 **
-** Copyright (C) 2016 The Qt Company Ltd.
+** Copyright (C) 2022 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtNetwork module of the Qt Toolkit.
@@ -159,9 +159,9 @@ public:
 
     QAbstractSocket::NetworkLayerProtocol preferredNetworkLayerProtocol;
 
-    bool prePauseReadSocketNotifierState;
-    bool prePauseWriteSocketNotifierState;
-    bool prePauseExceptionSocketNotifierState;
+    bool prePauseReadSocketNotifierState = false;
+    bool prePauseWriteSocketNotifierState = false;
+    bool prePauseExceptionSocketNotifierState = false;
     static void pauseSocketNotifiers(QAbstractSocket*);
     static void resumeSocketNotifiers(QAbstractSocket*);
     static QAbstractSocketEngine* getSocketEngine(QAbstractSocket*);