Fix usage of QString::toUtf8(). Fixes #2299

Desktop runtime has a couple bugs using already freed memory supplied to embedded python leading to occasional crashes and failures to start maintenance processes (VACUUM, ANALYZE, REINDEX, CLUSTER).

This is caused by incorrect usage of QString::toUtf8() which returns newly created QByteArray which is automatically destroyed once closing context; e.g.
Py_SetPythonHome(pythonHome.toUtf8().data());

runtime/Server.cpp

@@ -59,16 +59,19 @@ Server::Server(quint16 port, QString key)
     m_port = port;
     m_key = key;
     m_wcAppName = NULL;
+    m_wcPythonHome = NULL;
 
     // Initialise Python
     Py_NoSiteFlag=1;
     Py_DontWriteBytecodeFlag=1;
 
+    PGA_APP_NAME_UTF8 = PGA_APP_NAME.toUtf8();
+
     // Python3 requires conversion of char  * to wchar_t *, so...
 #ifdef PYTHON2
-    Py_SetProgramName(PGA_APP_NAME.toUtf8().data());
+    Py_SetProgramName(PGA_APP_NAME_UTF8.data());
 #else
-    char *appName = PGA_APP_NAME.toUtf8().data();
+    char *appName = PGA_APP_NAME_UTF8.data();
     const size_t cSize = strlen(appName)+1;
     m_wcAppName = new wchar_t[cSize];
     mbstowcs (m_wcAppName, appName, cSize);
@@ -171,15 +174,16 @@ Server::Server(quint16 port, QString key)
              << "\nPython Home: " << pythonHome;
     if (!pythonHome.isEmpty())
     {
+        pythonHome_utf8 = pythonHome.toUtf8();
 #ifdef PYTHON2
-        Py_SetPythonHome(pythonHome.toUtf8().data());
+        Py_SetPythonHome(pythonHome_utf8.data());
 #else
-        char *python_home = pythonHome.toUtf8().data();
+        char *python_home = pythonHome_utf8.data();
         const size_t cSize = strlen(python_home) + 1;
-        wchar_t* wcPythonHome = new wchar_t[cSize];
+        m_wcPythonHome = new wchar_t[cSize];
         mbstowcs (wcPythonHome, python_home, cSize);
 
-        Py_SetPythonHome(wcPythonHome);
+        Py_SetPythonHome(m_wcPythonHome);
 #endif
     }
 
@@ -208,6 +212,9 @@ Server::~Server()
     if (m_wcAppName)
         delete m_wcAppName;
 
+    if (m_wcPythonHome)
+        delete m_wcPythonHome;
+
     // Shutdown Python
     Py_Finalize();
 }
@@ -269,6 +276,7 @@ void Server::run()
     PyRun_SimpleString(QString("PGADMIN_KEY = '%1'").arg(m_key).toLatin1());
 
     // Run the app!
+    QByteArray m_appfile_utf8 = m_appfile.toUtf8();
 #ifdef PYTHON2
     /*
      * Untrusted search path vulnerability in the PySys_SetArgv API function in Python 2.6 and earlier, and possibly later
@@ -276,11 +284,11 @@ void Server::run()
      * which might allow local users to execute arbitrary code via a Trojan horse Python file in the current working directory.
      * Here we have to set arguments explicitly to python interpreter. Check more details in 'PySys_SetArgv' documentation.
      */
-    char* n_argv[] = { m_appfile.toUtf8().data() };
+    char* n_argv[] = { m_appfile_utf8.data() };
     PySys_SetArgv(1, n_argv);
 
-    PyObject* PyFileObject = PyFile_FromString(m_appfile.toUtf8().data(), (char *)"r");
+    PyObject* PyFileObject = PyFile_FromString(m_appfile_utf8.data(), (char *)"r");
-    int ret = PyRun_SimpleFile(PyFile_AsFile(PyFileObject), m_appfile.toUtf8().data());
+    int ret = PyRun_SimpleFile(PyFile_AsFile(PyFileObject), m_appfile_utf8.data());
     if (ret != 0)
         setError(tr("Failed to launch the application server, server thread exiting."));
 #else
@@ -290,7 +298,7 @@ void Server::run()
      * which might allow local users to execute arbitrary code via a Trojan horse Python file in the current working directory.
      * Here we have to set arguments explicitly to python interpreter. Check more details in 'PySys_SetArgv' documentation.
      */
-    char *appName = m_appfile.toUtf8().data();
+    char *appName = m_appfile_utf8.data();
     const size_t cSize = strlen(appName)+1;
     wchar_t* wcAppName = new wchar_t[cSize];
     mbstowcs (wcAppName, appName, cSize);
@@ -298,8 +306,8 @@ void Server::run()
     PySys_SetArgv(1, n_argv);
 
     int fd = fileno(cp);
-    PyObject* PyFileObject = PyFile_FromFd(fd, m_appfile.toUtf8().data(), (char *)"r", -1, NULL, NULL,NULL,1);
+    PyObject* PyFileObject = PyFile_FromFd(fd, m_appfile_utf8.data(), (char *)"r", -1, NULL, NULL,NULL,1);
-    if (PyRun_SimpleFile(fdopen(PyObject_AsFileDescriptor(PyFileObject),"r"), m_appfile.toUtf8().data()) != 0)
+    if (PyRun_SimpleFile(fdopen(PyObject_AsFileDescriptor(PyFileObject),"r"), m_appfile_utf8.data()) != 0)
         setError(tr("Failed to launch the application server, server thread exiting."));
 #endif
 

runtime/Server.h

@@ -40,7 +40,12 @@ private:
 
     quint16  m_port;
     QString m_key;
+    // Application name in UTF-8 for Python
     wchar_t *m_wcAppName;
+    QByteArray PGA_APP_NAME_UTF8;
+    // PythonHome for Python
+    wchar_t *m_wcPythonHome;
+    QByteArray pythonHome_utf8;
 };
 
 #endif // SERVER_H