Delete subsystem instances *before* plugin unload

BZ: 208504

Before this patch there was a crash in CElement destructor in Ubuntu upon
destuction of parameter framework instance.
The crash was caused by the attempt to call unmapped code: The subsystem
plugin libraries were getting unloaded before the execution of the subsystem
destructors.
Note:
In Android the issue is not seen since library unload is not implemented.

This patch ensures SystemClass destructor destroys the subsystems explicitely
unloading the plugins.

Change-Id: I19dad262b384bdbd63c7c319a41a5d547d0e75e9
Signed-off-by: Patrick Benavoli <patrick.benavoli@intel.com>

2 files changed, 12 insertions, 7 deletions

diff --git a/parameter/SystemClass.cpp b/parameter/SystemClass.cpp
index effc573..6169223 100644
--- a/parameter/SystemClass.cpp
+++ b/parameter/SystemClass.cpp
@@ -71,11 +71,16 @@ CSystemClass::~CSystemClass()
 {
     delete _pSubsystemLibrary;
 
-    // Close all previously opened libraries
-    while (!_subsystemLibraries.empty())
-    {
-      dlclose(_subsystemLibraries.back());
-      _subsystemLibraries.pop_back();
+    // Destroy child subsystems *before* unloading the libraries (otherwise crashes will occur
+    // as unmapped code will be referenced)
+    clean();
+
+    // Close all previously opened subsystem libraries
+    list<void*>::const_iterator it;
+
+    for (it = _subsystemLibraryHandleList.begin(); it != _subsystemLibraryHandleList.end(); ++it) {
+
+        dlclose(*it);
     }
 }
 
@@ -238,7 +243,7 @@ bool CSystemClass::loadPlugins(list<string>& lstrPluginFiles, list<string>& lstr
         }
 
         // Store libraries handles
-        _subsystemLibraries.push_back(lib_handle);
+        _subsystemLibraryHandleList.push_back(lib_handle);
 
         // Get plugin symbol
         string strPluginSymbol = getPluginSymbol(strPluginFileName);
diff --git a/parameter/SystemClass.h b/parameter/SystemClass.h
index 3ffbf25..b5bce45 100644
--- a/parameter/SystemClass.h
+++ b/parameter/SystemClass.h
@@ -111,6 +111,6 @@ private:
 
     // Subsystem factory
     CSubsystemLibrary* _pSubsystemLibrary;
-    std::list<void*> _subsystemLibraries; /**< Contains the list of all open plugin libs. */
+    std::list<void*> _subsystemLibraryHandleList; /**< Contains the list of all open plugin libs. */
 };