[C][Client] Check the pointer before deleting operation to avoid core dump label:"Client C" (#5626)

* [C-libcurl] Check the pointer before deleting operation to avoid core dump

* [C-libcurl] Check the pointer before deleting operation, update sample

modules/openapi-generator/src/main/resources/C-libcurl/list.c.mustache

@@ -88,8 +88,10 @@ void list_iterateThroughListBackward(list_t *list,
 }
 
 void list_free(list_t *list) {
-    list_iterateThroughListForward(list, listEntry_free, NULL);
-    free(list);
+    if(list){
+        list_iterateThroughListForward(list, listEntry_free, NULL);
+        free(list);
+    }
 }
 
 void list_addElement(list_t *list, void *dataToAddInList) {

modules/openapi-generator/src/main/resources/C-libcurl/model-body.mustache

@@ -205,6 +205,9 @@ char* {{name}}{{classname}}_ToString({{projectName}}_{{classVarName}}_{{enumName
 
 
 void {{classname}}_free({{classname}}_t *{{classname}}) {
+    if(NULL == {{classname}}){
+        return ;
+    }
     listEntry_t *listEntry;
     {{#vars}}
     {{^isContainer}}

samples/client/petstore/c/model/api_response.c

@@ -23,6 +23,9 @@ api_response_t *api_response_create(
 
 
 void api_response_free(api_response_t *api_response) {
+    if(NULL == api_response){
+        return ;
+    }
     listEntry_t *listEntry;
     free(api_response->type);
     free(api_response->message);

samples/client/petstore/c/model/category.c

@@ -21,6 +21,9 @@ category_t *category_create(
 
 
 void category_free(category_t *category) {
+    if(NULL == category){
+        return ;
+    }
     listEntry_t *listEntry;
     free(category->name);
     free(category);

samples/client/petstore/c/model/order.c

@@ -46,6 +46,9 @@ order_t *order_create(
 
 
 void order_free(order_t *order) {
+    if(NULL == order){
+        return ;
+    }
     listEntry_t *listEntry;
     free(order->ship_date);
     free(order);

samples/client/petstore/c/model/pet.c

@@ -46,6 +46,9 @@ pet_t *pet_create(
 
 
 void pet_free(pet_t *pet) {
+    if(NULL == pet){
+        return ;
+    }
     listEntry_t *listEntry;
     category_free(pet->category);
     free(pet->name);

samples/client/petstore/c/model/tag.c

@@ -21,6 +21,9 @@ tag_t *tag_create(
 
 
 void tag_free(tag_t *tag) {
+    if(NULL == tag){
+        return ;
+    }
     listEntry_t *listEntry;
     free(tag->name);
     free(tag);

samples/client/petstore/c/model/user.c

@@ -33,6 +33,9 @@ user_t *user_create(
 
 
 void user_free(user_t *user) {
+    if(NULL == user){
+        return ;
+    }
     listEntry_t *listEntry;
     free(user->username);
     free(user->first_name);

samples/client/petstore/c/src/list.c

@@ -88,8 +88,10 @@ void list_iterateThroughListBackward(list_t *list,
 }
 
 void list_free(list_t *list) {
-    list_iterateThroughListForward(list, listEntry_free, NULL);
-    free(list);
+    if(list){
+        list_iterateThroughListForward(list, listEntry_free, NULL);
+        free(list);
+    }
 }
 
 void list_addElement(list_t *list, void *dataToAddInList) {