Cellular: Fix CellularContext destructor memory leak

Author: Ari Parkkila

UNITTESTS/features/cellular/framework/AT/at_cellularcontext/at_cellularcontexttest.cpp

@@ -109,16 +109,20 @@ class my_stack : public AT_CellularStack {
 class my_AT_CTX : public AT_CellularContext {
 public:
     my_AT_CTX(ATHandler &at, CellularDevice *device, const char *apn = MBED_CONF_NSAPI_DEFAULT_CELLULAR_APN) :
-        AT_CellularContext(at, device, apn), _st(at, *get_device())
+        AT_CellularContext(at, device, apn)
     {
         AT_CellularDevice_stub::supported_bool = false;
     }
     virtual ~my_AT_CTX() {}
 
     virtual NetworkStack *get_stack()
     {
-        return &_st;
+        if (!_stack) {
+            _stack = new my_stack(_at, *get_device());
+        }
+        return _stack;
     }
+
     virtual uint32_t get_timeout_for_operation(ContextOperation op) const
     {
         return 10;
@@ -137,24 +141,23 @@ class my_AT_CTX : public AT_CellularContext {
     {
         deactivate_non_ip_context();
     }
-
-    my_stack _st;
 };
 
 class my_AT_CTXIPV6 : public AT_CellularContext {
 public:
     my_AT_CTXIPV6(ATHandler &at, CellularDevice *device, const char *apn = MBED_CONF_NSAPI_DEFAULT_CELLULAR_APN) :
-        AT_CellularContext(at, device, apn), _st(at, *get_device()) {}
+        AT_CellularContext(at, device, apn) {}
     virtual ~my_AT_CTXIPV6() {}
     virtual NetworkStack *get_stack()
     {
-        return &_st;
+        if (!_stack) {
+            _stack = new my_stack(_at, *get_device());
+        }
     }
     virtual uint32_t get_timeout_for_operation(ContextOperation op) const
     {
         return 10;
     }
-    my_stack _st;
 };
 
 class def_AT_CTX : public AT_CellularContext {

features/cellular/framework/API/CellularContext.h

@@ -17,6 +17,7 @@
 #ifndef _CELLULARCONTEXT_H_
 #define _CELLULARCONTEXT_H_
 
+#include "NetworkStack.h"
 #include "CellularInterface.h"
 #include "CellularDevice.h"
 #include "CellularUtil.h"
@@ -117,7 +118,15 @@ class CellularContext : public CellularInterface {
     // friend of CellularDevice, so it's the only way to close or delete this class.
     friend class CellularDevice;
     CellularContext();
-    virtual ~CellularContext() {}
+    virtual ~CellularContext()
+    {
+#if !NSAPI_PPP_AVAILABLE
+        if (_stack) {
+            delete _stack;
+        }
+#endif
+    }
+
 public: // from NetworkInterface
     virtual nsapi_error_t set_blocking(bool blocking) = 0;
     virtual NetworkStack *get_stack() = 0;