Add property to set exclusivity

Disabling the serial port driver's exclusive mode is necessary for
pseudo serial ports and some USB/serial adapters to work correctly.

Change-Id: I74d45feed619817b61e265b00aec8b0ebfae7a33
Reviewed-by: Sergey Belyashov <Sergey.Belyashov@gmail.com>
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>

9 files changed, 129 insertions, 24 deletions

diff --git a/src/serialport/qserialport.cpp b/src/serialport/qserialport.cpp
index 96f06d4..d90b48d 100644
--- a/src/serialport/qserialport.cpp
+++ b/src/serialport/qserialport.cpp
@@ -73,6 +73,7 @@ QSerialPortPrivateData::QSerialPortPrivateData(QSerialPort *q)
     , stopBits(QSerialPort::UnknownStopBits)
     , flow(QSerialPort::UnknownFlowControl)
     , policy(QSerialPort::IgnorePolicy)
+    , exclusiveMode(QSerialPort::FullyExclusive)
     , settingsRestoredOnClose(true)
     , q_ptr(q)
 {
@@ -320,6 +321,27 @@ int QSerialPortPrivateData::timeoutValue(int msecs, int elapsed)
     \sa QSerialPort::error
 */
 
+/*!
+    \enum QSerialPort::ExclusiveModeFlag
+
+    This enum describes the level of exclusivity to set on the serial port.
+
+    \value NotExclusive      The serial port may be opened elsewhere even if it
+                             is open here. This flag only has effect on Unix.
+    \value LockFileExclusive A lock file prevents the serial port from being
+                             opened elsewhere while it is open here. This flag
+                             only has effect on Unix.
+    \value DriverExclusive   The serial port driver prevents the serial port
+                             from being opened elsewhere while it is open here.
+                             This flag only has effect on Unix if the ioctl
+                             request TIOCEXCL is available.
+    \value FullyExclusive    Both the serial port driver and, if on Unix, a
+                             lock file prevent the serial port from being opened
+                             elsewhere while it is open here.
+
+    \sa QSerialPort::exclusiveMode
+*/
+
 
 
 /*!
@@ -489,6 +511,28 @@ void QSerialPort::close()
 }
 
 /*!
+    \property QSerialPort::exclusiveMode
+    \brief the exclusivity of this object's claim on the serial port
+
+    If the setting is successful, returns true; otherwise returns false. Serial
+    ports are set to QSerialPort::FullyExclusive by default.
+
+    This flag is always QSerialPort::FullyExclusive on Windows and Symbian and
+    cannot be changed.
+*/
+bool QSerialPort::setExclusiveMode(ExclusiveMode exclusiveMode)
+{
+    Q_D(QSerialPort);
+    return d->setExclusiveMode(exclusiveMode);
+}
+
+QSerialPort::ExclusiveMode QSerialPort::exclusiveMode() const
+{
+    Q_D(const QSerialPort);
+    return d->exclusiveMode;
+}
+
+/*!
     \property QSerialPort::settingsRestoredOnClose
     \brief the flag which allows to restore the previous settings while closing
     the serial port.
diff --git a/src/serialport/qserialport.h b/src/serialport/qserialport.h
index c193bcd..6ec8e25 100644
--- a/src/serialport/qserialport.h
+++ b/src/serialport/qserialport.h
@@ -65,10 +65,11 @@ class Q_SERIALPORT_EXPORT QSerialPort : public QIODevice
     Q_PROPERTY(bool dataTerminalReady READ isDataTerminalReady WRITE setDataTerminalReady NOTIFY dataTerminalReadyChanged)
     Q_PROPERTY(bool requestToSend READ isRequestToSend WRITE setRequestToSend NOTIFY requestToSendChanged)
     Q_PROPERTY(SerialPortError error READ error RESET clearError NOTIFY error)
+    Q_PROPERTY(ExclusiveMode exclusiveMode READ exclusiveMode WRITE setExclusiveMode)
     Q_PROPERTY(bool settingsRestoredOnClose READ settingsRestoredOnClose WRITE setSettingsRestoredOnClose NOTIFY settingsRestoredOnCloseChanged)
 
     Q_ENUMS(BaudRate DataBits Parity StopBits FlowControl DataErrorPolicy SerialPortError)
-    Q_FLAGS(Directions PinoutSignals)
+    Q_FLAGS(Directions PinoutSignals ExclusiveMode)
 
 public:
 
@@ -160,6 +161,14 @@ public:
         UnknownError
     };
 
+    enum ExclusiveModeFlag {
+        NotExclusive = 0,
+        LockFileExclusive = 1,
+        DriverExclusive = 2,
+        FullyExclusive = LockFileExclusive | DriverExclusive
+    };
+    Q_DECLARE_FLAGS(ExclusiveMode, ExclusiveModeFlag)
+
     explicit QSerialPort(QObject *parent = 0);
     explicit QSerialPort(const QString &name, QObject *parent = 0);
     explicit QSerialPort(const QSerialPortInfo &info, QObject *parent = 0);
@@ -173,6 +182,9 @@ public:
     bool open(OpenMode mode) Q_DECL_OVERRIDE;
     void close() Q_DECL_OVERRIDE;
 
+    bool setExclusiveMode(ExclusiveMode exclusiveMode);
+    ExclusiveMode exclusiveMode() const;
+
     void setSettingsRestoredOnClose(bool restore);
     bool settingsRestoredOnClose() const;
 
@@ -252,6 +264,7 @@ private:
 
 Q_DECLARE_OPERATORS_FOR_FLAGS(QSerialPort::Directions)
 Q_DECLARE_OPERATORS_FOR_FLAGS(QSerialPort::PinoutSignals)
+Q_DECLARE_OPERATORS_FOR_FLAGS(QSerialPort::ExclusiveMode)
 
 QT_END_NAMESPACE
 
diff --git a/src/serialport/qserialport_p.h b/src/serialport/qserialport_p.h
index abd9cb6..b74cda6 100644
--- a/src/serialport/qserialport_p.h
+++ b/src/serialport/qserialport_p.h
@@ -80,6 +80,7 @@ public:
     QSerialPort::DataErrorPolicy policy;
     bool dataTerminalReady;
     bool requestToSend;
+    QSerialPort::ExclusiveMode exclusiveMode;
     bool settingsRestoredOnClose;
     QSerialPort * const q_ptr;
 };
diff --git a/src/serialport/qserialport_symbian.cpp b/src/serialport/qserialport_symbian.cpp
index 2bba5a4..3e904ab 100644
--- a/src/serialport/qserialport_symbian.cpp
+++ b/src/serialport/qserialport_symbian.cpp
@@ -158,6 +158,12 @@ void QSerialPortPrivate::close()
     descriptor.Close();
 }
 
+bool QSerialPortPrivate::setExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode)
+{
+    Q_UNUSED(exclusiveMode);
+    return false;
+}
+
 QSerialPort::PinoutSignals QSerialPortPrivate::pinoutSignals() const
 {
     QSerialPort::PinoutSignals ret = QSerialPort::NoSignal;
diff --git a/src/serialport/qserialport_symbian_p.h b/src/serialport/qserialport_symbian_p.h
index 7f9eadd..1b235f5 100644
--- a/src/serialport/qserialport_symbian_p.h
+++ b/src/serialport/qserialport_symbian_p.h
@@ -84,6 +84,7 @@ public:
     bool setStopBits(QSerialPort::StopBits stopBits);
     bool setFlowControl(QSerialPort::FlowControl flowControl);
     bool setDataErrorPolicy(QSerialPort::DataErrorPolicy policy);
+    bool setExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode);
 
     bool notifyRead();
     bool notifyWrite();
diff --git a/src/serialport/qserialport_unix.cpp b/src/serialport/qserialport_unix.cpp
index 2f6c8cc..0e19d05 100644
--- a/src/serialport/qserialport_unix.cpp
+++ b/src/serialport/qserialport_unix.cpp
@@ -139,11 +139,7 @@ QSerialPortPrivate::QSerialPortPrivate(QSerialPort *q)
 
 bool QSerialPortPrivate::open(QIODevice::OpenMode mode)
 {
-    QByteArray portName = portNameFromSystemLocation(systemLocation).toLocal8Bit();
-    const char *ptr = portName.constData();
-
-    bool byCurrPid = false;
-    if (QTtyLocker::isLocked(ptr, &byCurrPid)) {
+    if (isLockedByFile()) {
         q_ptr->setError(QSerialPort::PermissionError);
         return false;
     }
@@ -169,17 +165,13 @@ bool QSerialPortPrivate::open(QIODevice::OpenMode mode)
         return false;
     }
 
-    ::fcntl(descriptor, F_SETFL, FNDELAY);
-
-    QTtyLocker::lock(ptr);
-    if (!QTtyLocker::isLocked(ptr, &byCurrPid)) {
+    if (!changeExclusiveMode(exclusiveMode)) {
+        ::close(descriptor);
         q_ptr->setError(QSerialPort::PermissionError);
         return false;
     }
 
-#ifdef TIOCEXCL
-    ::ioctl(descriptor, TIOCEXCL);
-#endif
+    ::fcntl(descriptor, F_SETFL, FNDELAY);
 
     if (::tcgetattr(descriptor, &restoredTermios) == -1) {
         q_ptr->setError(decodeSystemError());
@@ -217,10 +209,6 @@ void QSerialPortPrivate::close()
 #endif
     }
 
-#ifdef TIOCNXCL
-    ::ioctl(descriptor, TIOCNXCL);
-#endif
-
     if (readNotifier) {
         readNotifier->setEnabled(false);
         readNotifier->deleteLater();
@@ -239,19 +227,24 @@ void QSerialPortPrivate::close()
         exceptionNotifier = 0;
     }
 
-    ::close(descriptor);
-
-    QByteArray portName = portNameFromSystemLocation(systemLocation).toLocal8Bit();
-    const char *ptr = portName.constData();
+    changeExclusiveMode(QSerialPort::NotExclusive);
 
-    bool byCurrPid = false;
-    if (QTtyLocker::isLocked(ptr, &byCurrPid) && byCurrPid)
-        QTtyLocker::unlock(ptr);
+    ::close(descriptor);
 
     descriptor = -1;
     isCustomBaudRateSupported = false;
 }
 
+bool QSerialPortPrivate::setExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode)
+{
+    if (descriptor != -1 && !changeExclusiveMode(exclusiveMode)) {
+        q_ptr->setError(QSerialPort::PermissionError);
+        return false;
+    }
+    this->exclusiveMode = exclusiveMode;
+    return true;
+}
+
 QSerialPort::PinoutSignals QSerialPortPrivate::pinoutSignals() const
 {
     int arg = 0;
@@ -1340,4 +1333,41 @@ QList<qint32> QSerialPortPrivate::standardBaudRates()
     return standardBaudRateMap().keys();
 }
 
+bool QSerialPortPrivate::isLockedByFile()
+{
+    QByteArray portName = portNameFromSystemLocation(systemLocation).toLocal8Bit();
+    const char *ptr = portName.constData();
+    bool byCurrPid;
+
+    return QTtyLocker::isLocked(ptr, &byCurrPid);
+}
+
+bool QSerialPortPrivate::changeExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode)
+{
+    QByteArray portName = portNameFromSystemLocation(systemLocation).toLocal8Bit();
+    const char *ptr = portName.constData();
+    bool byCurrPid;
+
+    if (exclusiveMode & QSerialPort::LockFileExclusive) {
+        QTtyLocker::lock(ptr);
+        if (!QTtyLocker::isLocked(ptr, &byCurrPid))
+            return false;
+    } else {
+        if (QTtyLocker::isLocked(ptr, &byCurrPid) && byCurrPid)
+            QTtyLocker::unlock(ptr);
+    }
+
+#ifdef TIOCEXCL
+    if (exclusiveMode & QSerialPort::DriverExclusive) {
+        if (::ioctl(descriptor, TIOCEXCL) < 0) {
+            QTtyLocker::unlock(ptr);
+            return false;
+        }
+    } else
+        ::ioctl(descriptor, TIOCNXCL);
+#endif
+
+    return true;
+}
+
 QT_END_NAMESPACE
diff --git a/src/serialport/qserialport_unix_p.h b/src/serialport/qserialport_unix_p.h
index ce70c24..3d96ecb 100644
--- a/src/serialport/qserialport_unix_p.h
+++ b/src/serialport/qserialport_unix_p.h
@@ -91,6 +91,7 @@ public:
     bool setStopBits(QSerialPort::StopBits stopBits);
     bool setFlowControl(QSerialPort::FlowControl flow);
     bool setDataErrorPolicy(QSerialPort::DataErrorPolicy policy);
+    bool setExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode);
 
     bool readNotification();
     bool writeNotification(int maxSize = INT_MAX);
@@ -149,6 +150,8 @@ private:
 #endif
     qint64 readPerChar(char *data, qint64 maxSize);
 
+    bool isLockedByFile();
+    bool changeExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode);
 };
 
 QT_END_NAMESPACE
diff --git a/src/serialport/qserialport_win.cpp b/src/serialport/qserialport_win.cpp
index e8d4d62..4da1d1d 100644
--- a/src/serialport/qserialport_win.cpp
+++ b/src/serialport/qserialport_win.cpp
@@ -310,6 +310,12 @@ void QSerialPortPrivate::close()
 
 #endif // #ifndef Q_OS_WINCE
 
+bool QSerialPortPrivate::setExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode)
+{
+    Q_UNUSED(exclusiveMode);
+    return false;
+}
+
 QSerialPort::PinoutSignals QSerialPortPrivate::pinoutSignals() const
 {
     DWORD modemStat = 0;
diff --git a/src/serialport/qserialport_win_p.h b/src/serialport/qserialport_win_p.h
index a59ea9a..02810c0 100644
--- a/src/serialport/qserialport_win_p.h
+++ b/src/serialport/qserialport_win_p.h
@@ -97,6 +97,7 @@ public:
     bool setStopBits(QSerialPort::StopBits stopBits);
     bool setFlowControl(QSerialPort::FlowControl flowControl);
     bool setDataErrorPolicy(QSerialPort::DataErrorPolicy policy);
+    bool setExclusiveMode(QSerialPort::ExclusiveMode exclusiveMode);
 
     bool processIoErrors(bool error);
 #ifndef Q_OS_WINCE