Check for lock file in non-writable directoriesv5.4.0-rc1

On some linux systems /var/lock is not writable by users which are not
root and not in the uucp or dialout group.
If the root user acquires a lock and you are trying to access the same
port with a non-root user it will not check for the lock but creates a
new lock file in /tmp instead.
This change checks in readable directories for lock files.

Change-Id: Ia308fd344d2fe9d3c699f7a428ff620ea101eff3
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/src/serialport/qserialport_unix.cpp b/src/serialport/qserialport_unix.cpp
index 99792561..eb71e86b 100644
--- a/src/serialport/qserialport_unix.cpp
+++ b/src/serialport/qserialport_unix.cpp
@@ -72,13 +72,21 @@ QString serialPortLockFilePath(const QString &portName)
 #endif
     ;
 
+    QString fileName = portName;
+    fileName.replace(QLatin1Char('/'), QLatin1Char('_'));
+    fileName.prepend(QStringLiteral("/LCK.."));
+
     QString lockFilePath;
 
     foreach (const QString &lockDirectoryPath, lockDirectoryPaths) {
+        const QString filePath = lockDirectoryPath + fileName;
+
         QFileInfo lockDirectoryInfo(lockDirectoryPath);
-        if (lockDirectoryInfo.isReadable() && lockDirectoryInfo.isWritable()) {
-            lockFilePath = lockDirectoryPath;
-            break;
+        if (lockDirectoryInfo.isReadable()) {
+            if (QFile::exists(filePath) || lockDirectoryInfo.isWritable()) {
+                lockFilePath = filePath;
+                break;
+            }
         }
     }
 
@@ -89,11 +97,6 @@ QString serialPortLockFilePath(const QString &portName)
         return QString();
     }
 
-    QString replacedPortName = portName;
-
-    lockFilePath.append(QStringLiteral("/LCK.."));
-    lockFilePath.append(replacedPortName.replace(QLatin1Char('/'), QLatin1Char('_')));
-
     return lockFilePath;
 }