startupscreen: enable usb mode switch

The USB button can be used switch the USB Ethernet driver mode
between cdcecm and rndis to work with Linux, Windows and macOS
host machines.

Task-number: QTBUG-87857
Change-Id: Iab54d7582bdd9c39fca95dfa0bb8637d5ea14e81
Reviewed-by: Rami Potinkara <rami.potinkara@qt.io>

1 files changed, 126 insertions, 0 deletions

diff --git a/startupscreen/settingsmanager.cpp b/startupscreen/settingsmanager.cpp
new file mode 100644
index 0000000..4f5f217
--- /dev/null
+++ b/startupscreen/settingsmanager.cpp
@@ -0,0 +1,126 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples of Qt for Device Creation.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "settingsmanager.h"
+
+#include <QDebug>
+#include <QDir>
+#include <QFile>
+#include <QTemporaryFile>
+
+#include <sys/reboot.h>
+#include <unistd.h>
+
+const QString QdbdFileName(QStringLiteral("/etc/default/qdbd"));
+const char *ProtocolSetting("USB_ETHERNET_PROTOCOL=");
+
+SettingsManager::SettingsManager(QObject *parent) : QObject(parent) {}
+
+bool SettingsManager::hasQdb()
+{
+    return QFile::exists(QdbdFileName);
+}
+
+QString SettingsManager::usbMode()
+{
+    static bool initialized = false;
+    if (!initialized) {
+        QFile file(QdbdFileName);
+        if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
+            QByteArray line;
+            while (!(line = file.readLine()).isEmpty()) {
+                if (line.startsWith(ProtocolSetting))
+                    m_usbMode =
+                            QString::fromLatin1(line.last(line.length() - strlen(ProtocolSetting)))
+                                    .trimmed();
+            }
+        } else {
+            qWarning() << "Failed to open file" << QdbdFileName;
+        }
+        initialized = true;
+    }
+    return m_usbMode;
+}
+
+void SettingsManager::setUsbMode(const QString &usbMode)
+{
+    QFile file(QdbdFileName);
+    QTemporaryFile newFile(QdbdFileName);
+    newFile.setAutoRemove(false);
+    if (!newFile.open()) {
+        qWarning() << "Failed to save qdbd settings:" << newFile.errorString();
+        return;
+    }
+
+    if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
+        QTextStream out(&newFile);
+        QByteArray line;
+        while (!(line = file.readLine()).isEmpty()) {
+            if (line.startsWith(ProtocolSetting))
+                out << ProtocolSetting << usbMode.toLatin1() << '\n';
+            else
+                out << line;
+        }
+
+        file.remove();
+        if (!newFile.rename(QdbdFileName))
+            qWarning() << "Failed to save qdbd settings:" << newFile.errorString();
+
+    } else {
+        qWarning() << "Failed to save qdbd settings:" << file.errorString();
+    }
+}
+
+void SettingsManager::reboot()
+{
+    sync();
+    ::reboot(RB_AUTOBOOT);
+    qWarning("reboot failed");
+}