Fix using QNetworkReply with custom url schemesv6.2.6-lts-lgpl

Sequential QIODevices are allowed to report atEnd() when they have no
data to read, but add more data later.

To avoid a regression with our own tests, treat a read error from a
sequential device at end, as end-of-data.

Fixes: QTBUG-106461
Change-Id: Iac1233e6daa978c827c37a7fd3131e2fce764111
Reviewed-by: Michal Klocek <michal.klocek@qt.io>
(cherry picked from commit aefd389bfdf7efcaf787d2cfb4683d7018cb377c)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

2 files changed, 60 insertions, 8 deletions

diff --git a/src/core/net/custom_url_loader_factory.cpp b/src/core/net/custom_url_loader_factory.cpp
index d607da656..892f21dac 100644
--- a/src/core/net/custom_url_loader_factory.cpp
+++ b/src/core/net/custom_url_loader_factory.cpp
@@ -416,13 +416,20 @@ private:
             m_totalBytesRead += bytesRead;
             m_client->OnTransferSizeUpdated(m_totalBytesRead);
 
-            if (m_device->atEnd() || (m_maxBytesToRead > 0 && m_totalBytesRead >= m_maxBytesToRead)) {
+            const bool deviceAtEnd = m_device->atEnd();
+            if ((deviceAtEnd && !m_device->isSequential())
+                || (m_maxBytesToRead > 0 && m_totalBytesRead >= m_maxBytesToRead)) {
                 OnTransferComplete(MOJO_RESULT_OK);
                 return true; // Done with reading
             }
 
             if (readResult == 0)
                 return false; // Wait for readyRead
+            if (readResult < 0 && deviceAtEnd && m_device->isSequential()) {
+                // Failure on read, and sequential device claiming to be at end, so treat it as a successful end-of-data.
+                OnTransferComplete(MOJO_RESULT_OK);
+                return true; // Done with reading
+            }
             if (readResult < 0)
                 break;
         }
diff --git a/tests/auto/widgets/qwebengineprofile/tst_qwebengineprofile.cpp b/tests/auto/widgets/qwebengineprofile/tst_qwebengineprofile.cpp
index c09f3b51a..ee4f5990e 100644
--- a/tests/auto/widgets/qwebengineprofile/tst_qwebengineprofile.cpp
+++ b/tests/auto/widgets/qwebengineprofile/tst_qwebengineprofile.cpp
@@ -66,6 +66,7 @@ private Q_SLOTS:
     void urlSchemeHandlerFailRequest();
     void urlSchemeHandlerFailOnRead();
     void urlSchemeHandlerStreaming();
+    void urlSchemeHandlerStreaming2();
     void urlSchemeHandlerRequestHeaders();
     void urlSchemeHandlerInstallation();
     void urlSchemeHandlerXhrStatus();
@@ -289,10 +290,12 @@ public:
     QList<QPointer<QBuffer>> m_buffers;
 };
 
-class StreamingIODevice : public QIODevice {
+// an evil version constantly claiming to be at end, similar to QNetworkReply
+class StreamingIODeviceBasic : public QIODevice
+{
     Q_OBJECT
 public:
-    StreamingIODevice(QObject *parent) : QIODevice(parent), m_bytesRead(0), m_bytesAvailable(0)
+    StreamingIODeviceBasic(QObject *parent) : QIODevice(parent), m_bytesRead(0), m_bytesAvailable(0)
     {
         setOpenMode(QIODevice::ReadOnly);
         m_timer.start(100, this);
@@ -303,12 +306,11 @@ public:
         const std::lock_guard<QRecursiveMutex> lock(m_mutex);
         return m_bytesAvailable;
     }
-    bool atEnd() const override
+protected:
+    bool internalAtEnd() const
     {
-        const std::lock_guard<QRecursiveMutex> lock(m_mutex);
         return (m_data.size() >= 1000 && m_bytesRead >= 1000);
     }
-protected:
     void timerEvent(QTimerEvent *) override
     {
         const std::lock_guard<QRecursiveMutex> lock(m_mutex);
@@ -329,7 +331,7 @@ protected:
             memcpy(data, m_data.constData() + m_bytesRead, len);
             m_bytesAvailable -= len;
             m_bytesRead += len;
-        } else if (atEnd())
+        } else if (internalAtEnd())
             return -1;
 
         return len;
@@ -339,14 +341,26 @@ protected:
         return 0;
     }
 
-private:
     mutable QRecursiveMutex m_mutex;
+private:
     QByteArray m_data;
     QBasicTimer m_timer;
     int m_bytesRead;
     int m_bytesAvailable;
 };
 
+// A nicer version implementing atEnd
+class StreamingIODevice : public StreamingIODeviceBasic
+{
+public:
+    StreamingIODevice(QObject *parent) : StreamingIODeviceBasic(parent) {}
+    bool atEnd() const override
+    {
+        const std::lock_guard<QRecursiveMutex> lock(m_mutex);
+        return internalAtEnd();
+    }
+};
+
 class StreamingUrlSchemeHandler : public QWebEngineUrlSchemeHandler
 {
 public:
@@ -361,6 +375,20 @@ public:
     }
 };
 
+class StreamingUrlSchemeHandler2 : public QWebEngineUrlSchemeHandler
+{
+public:
+    StreamingUrlSchemeHandler2(QObject *parent = nullptr)
+        : QWebEngineUrlSchemeHandler(parent)
+    {
+    }
+
+    void requestStarted(QWebEngineUrlRequestJob *job) override
+    {
+        job->reply("text/plain;charset=utf-8", new StreamingIODeviceBasic(job));
+    }
+};
+
 void tst_QWebEngineProfile::urlSchemeHandlers()
 {
     RedirectingUrlSchemeHandler lettertoHandler;
@@ -502,6 +530,23 @@ void tst_QWebEngineProfile::urlSchemeHandlerStreaming()
     QCOMPARE(toPlainTextSync(view.page()), QString::fromLatin1(result));
 }
 
+void tst_QWebEngineProfile::urlSchemeHandlerStreaming2()
+{
+    StreamingUrlSchemeHandler2 handler;
+    QWebEngineProfile profile;
+    profile.installUrlSchemeHandler("stream", &handler);
+    QWebEngineView view;
+    QSignalSpy loadFinishedSpy(&view, SIGNAL(loadFinished(bool)));
+    view.setPage(new QWebEnginePage(&profile, &view));
+    view.settings()->setAttribute(QWebEngineSettings::ErrorPageEnabled, false);
+    view.load(QUrl(QStringLiteral("stream://whatever")));
+    view.show();
+    QTRY_COMPARE_WITH_TIMEOUT(loadFinishedSpy.count(), 1, 30000);
+    QByteArray result;
+    result.append(1000, 'c');
+    QCOMPARE(toPlainTextSync(view.page()), QString::fromLatin1(result));
+}
+
 class ExtraHeaderInterceptor : public QWebEngineUrlRequestInterceptor
 {
 public: