List the URL schemes supported by QNetworkAccessManager

Introducing a new method which allows us to know before hand if an URL
scheme will be supported by QNetworkAccessManager. It is especially useful in
combination with QFileDialog URL based methods to pass this list as the
allowed schemes the user can select in the dialog.

Change-Id: If625b045e87959bfd78fea2c9213b69caf506886
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

src/network/access/qnetworkaccessbackend.cpp

@@ -47,6 +47,7 @@
 #include "qnetworkreply_p.h"
 #include "QtCore/qhash.h"
 #include "QtCore/qmutex.h"
+#include "QtCore/qstringlist.h"
 #include "QtNetwork/private/qnetworksession_p.h"
 
 #include "qnetworkaccesscachebackend_p.h"
@@ -110,6 +111,22 @@ QNetworkAccessBackend *QNetworkAccessManagerPrivate::findBackend(QNetworkAccessM
     return 0;
 }
 
+QStringList QNetworkAccessManagerPrivate::backendSupportedSchemes() const
+{
+    if (QNetworkAccessBackendFactoryData::valid.load()) {
+        QMutexLocker locker(&factoryData()->mutex);
+        QNetworkAccessBackendFactoryData::ConstIterator it = factoryData()->constBegin();
+        QNetworkAccessBackendFactoryData::ConstIterator end = factoryData()->constEnd();
+        QStringList schemes;
+        while (it != end) {
+            schemes += (*it)->supportedSchemes();
+            ++it;
+        }
+        return schemes;
+    }
+    return QStringList();
+}
+
 QNonContiguousByteDevice* QNetworkAccessBackend::createUploadByteDevice()
 {
     if (reply->outgoingDataBuffer)

src/network/access/qnetworkaccessbackend_p.h

@@ -62,6 +62,7 @@ class QAuthenticator;
 class QNetworkProxy;
 class QNetworkProxyQuery;
 class QNetworkRequest;
+class QStringList;
 class QUrl;
 class QUrlInfo;
 class QSslConfiguration;
@@ -219,6 +220,7 @@ class QNetworkAccessBackendFactory
 public:
     QNetworkAccessBackendFactory();
     virtual ~QNetworkAccessBackendFactory();
+    virtual QStringList supportedSchemes() const = 0;
     virtual QNetworkAccessBackend *create(QNetworkAccessManager::Operation op,
                                           const QNetworkRequest &request) const = 0;
 };

src/network/access/qnetworkaccessdebugpipebackend.cpp

@@ -42,6 +42,7 @@
 #include "qnetworkaccessdebugpipebackend_p.h"
 #include "QtCore/qdatastream.h"
 #include <QCoreApplication>
+#include <QStringList>
 #include <QUrlQuery>
 #include "private/qnoncontiguousbytedevice_p.h"
 
@@ -54,6 +55,11 @@ enum {
     WriteBufferSize = ReadBufferSize
 };
 
+QStringList QNetworkAccessDebugPipeBackendFactory::supportedSchemes() const
+{
+    return QStringList(QStringLiteral("debugpipe"));
+}
+
 QNetworkAccessBackend *
 QNetworkAccessDebugPipeBackendFactory::create(QNetworkAccessManager::Operation op,
                                               const QNetworkRequest &request) const

src/network/access/qnetworkaccessdebugpipebackend_p.h

@@ -102,6 +102,7 @@ private:
 class QNetworkAccessDebugPipeBackendFactory: public QNetworkAccessBackendFactory
 {
 public:
+    virtual QStringList supportedSchemes() const Q_DECL_OVERRIDE;
     virtual QNetworkAccessBackend *create(QNetworkAccessManager::Operation op,
                                           const QNetworkRequest &request) const;
 };

src/network/access/qnetworkaccessfilebackend.cpp

@@ -49,6 +49,17 @@
 
 QT_BEGIN_NAMESPACE
 
+QStringList QNetworkAccessFileBackendFactory::supportedSchemes() const
+{
+    QStringList schemes;
+    schemes << QStringLiteral("file")
+            << QStringLiteral("qrc");
+#if defined(Q_OS_ANDROID)
+    schemes << QStringLiteral("assets");
+#endif
+    return schemes;
+}
+
 QNetworkAccessBackend *
 QNetworkAccessFileBackendFactory::create(QNetworkAccessManager::Operation op,
                                          const QNetworkRequest &request) const

src/network/access/qnetworkaccessfilebackend_p.h

@@ -88,6 +88,7 @@ private:
 class QNetworkAccessFileBackendFactory: public QNetworkAccessBackendFactory
 {
 public:
+    virtual QStringList supportedSchemes() const Q_DECL_OVERRIDE;
     virtual QNetworkAccessBackend *create(QNetworkAccessManager::Operation op,
                                           const QNetworkRequest &request) const;
 };

src/network/access/qnetworkaccessftpbackend.cpp

@@ -43,6 +43,7 @@
 #include "qnetworkaccessmanager_p.h"
 #include "QtNetwork/qauthenticator.h"
 #include "private/qnoncontiguousbytedevice_p.h"
+#include <QStringList>
 
 #ifndef QT_NO_FTP
 
@@ -61,6 +62,11 @@ static QByteArray makeCacheKey(const QUrl &url)
                        QUrl::RemoveFragment);
 }
 
+QStringList QNetworkAccessFtpBackendFactory::supportedSchemes() const
+{
+    return QStringList(QStringLiteral("ftp"));
+}
+
 QNetworkAccessBackend *
 QNetworkAccessFtpBackendFactory::create(QNetworkAccessManager::Operation op,
                                         const QNetworkRequest &request) const

src/network/access/qnetworkaccessftpbackend_p.h

@@ -111,6 +111,7 @@ private:
 class QNetworkAccessFtpBackendFactory: public QNetworkAccessBackendFactory
 {
 public:
+    virtual QStringList supportedSchemes() const Q_DECL_OVERRIDE;
     virtual QNetworkAccessBackend *create(QNetworkAccessManager::Operation op,
                                           const QNetworkRequest &request) const;
 };

src/network/access/qnetworkaccessmanager.cpp

@@ -1159,6 +1159,57 @@ QNetworkReply *QNetworkAccessManager::createRequest(QNetworkAccessManager::Opera
     return reply;
 }
 
+/*!
+    \since 5.2
+
+    Lists all the URL schemes supported by the access manager.
+
+    \sa supportedSchemesImplementation()
+*/
+QStringList QNetworkAccessManager::supportedSchemes() const
+{
+    QStringList schemes;
+    QNetworkAccessManager *self = const_cast<QNetworkAccessManager *>(this); // We know we call a const slot
+    QMetaObject::invokeMethod(self, "supportedSchemesImplementation", Qt::DirectConnection,
+                              Q_RETURN_ARG(QStringList, schemes));
+    schemes.removeDuplicates();
+    return schemes;
+}
+
+/*!
+    \since 5.2
+
+    Lists all the URL schemes supported by the access manager.
+
+    You should not call this function directly; use
+    QNetworkAccessManager::supportedSchemes() instead.
+
+    Reimplement this slot to provide your own supported schemes
+    in a QNetworkAccessManager subclass. It is for instance necessary
+    when your subclass provides support for new protocols.
+
+    Because of binary compatibility constraints, the supportedSchemes()
+    method (introduced in Qt 5.2) is not virtual. Instead, supportedSchemes()
+    will dynamically detect and call this slot.
+
+    \sa supportedSchemes()
+*/
+QStringList QNetworkAccessManager::supportedSchemesImplementation() const
+{
+    Q_D(const QNetworkAccessManager);
+
+    QStringList schemes = d->backendSupportedSchemes();
+    // Those ones don't exist in backends
+#ifndef QT_NO_HTTP
+    schemes << QStringLiteral("http");
+#ifndef QT_NO_SSL
+    if (QSslSocket::supportsSsl())
+        schemes << QStringLiteral("https");
+#endif
+#endif
+    schemes << QStringLiteral("data");
+    return schemes;
+}
 
 /*!
     \since 5.0

src/network/access/qnetworkaccessmanager.h

@@ -97,6 +97,9 @@ public:
     explicit QNetworkAccessManager(QObject *parent = 0);
     ~QNetworkAccessManager();
 
+    // ### Qt 6: turn into virtual
+    QStringList supportedSchemes() const;
+
     void clearAccessCache();
 
 #ifndef QT_NO_NETWORKPROXY
@@ -153,6 +156,9 @@ protected:
     virtual QNetworkReply *createRequest(Operation op, const QNetworkRequest &request,
                                          QIODevice *outgoingData = 0);
 
+protected Q_SLOTS:
+    QStringList supportedSchemesImplementation() const;
+
 private:
     friend class QNetworkReplyImplPrivate;
     friend class QNetworkReplyHttpImpl;

src/network/access/qnetworkaccessmanager_p.h

@@ -124,6 +124,7 @@ public:
 #endif
 
     QNetworkAccessBackend *findBackend(QNetworkAccessManager::Operation op, const QNetworkRequest &request);
+    QStringList backendSupportedSchemes() const;
 
 #ifndef QT_NO_BEARERMANAGEMENT
     void createSession(const QNetworkConfiguration &config);