Problems with drag and drop in Gtk - c

Question

I'm building an application that uses drag and drop using GTK in C language but I have a problem with this part of code
void view_onDragDataReceived(GtkWidget *wgt, GdkDragContext *context, int x, int y,GtkSelectionData *seldata, guint info, guint time,gpointer userdata)
{
GtkTreeModel *model;
GtkTreeIter iter;
model = GTK_TREE_MODEL(userdata);
gtk_list_store_append(GTK_LIST_STORE(model), &iter);
gtk_list_store_set(GTK_LIST_STORE(model), &iter, COL_URI,(gchar*)seldata->data, -1);
pathh=(char*)seldata->data;
}
I call this Function from this line of code
g_signal_connect(view, "drag_data_received",G_CALLBACK(view_onDragDataReceived), liststore);
the problem i'm having is that when i try to use that pathh variable in an other function i find it empty even though it's declared a global variable type char*

Answer 1

Try this way
struct SelectionData
{
GtkListStore *listStore;
gchar *path;
}
and then in the caller function
struct SelectionData *data;
data = malloc(sizeof(*data));
if (data == NULL)
handleMallocFailureAndPleaseDoNotContinue();
data->listStore = liststore;
data->path = NULL;
g_signal_connect(view, "drag_data_received",G_CALLBACK(view_onDragDataReceived), data);
and then
void view_onDragDataReceived(GtkWidget *wgt, GdkDragContext *context, int x, int y,GtkSelectionData *seldata, guint info, guint time, gpointer userdata)
{
GtkTreeModel *model;
GtkTreeIter iter;
SelectionData *selectionData;
size_t length;
selectionData = (SelectionData *)userdata;
model = GTK_TREE_MODEL(selectionData->liststore);
gtk_list_store_append(GTK_LIST_STORE(model), &iter);
gtk_list_store_set(GTK_LIST_STORE(model), &iter, COL_URI,(gchar*)seldata->data, -1);
length = strlen((char*)seldata->data);
if (selectionData->path != NULL) /* for subsequent calls */
free(selectionData->path);
selectionData->path = malloc(1 + length);
if (selectionData->path != NULL)
memcpy(selectionData->path, seldata->data, 1 + length);
}
and then you can access selectionData somewhere else and thus it's path field, which must be freed after you finish using it.
Try to avoid global variables as much as possible.
You can also use the same technique to copy seldata->data into your pathh global variable, but rethink your design and try not to use pathh global variable, since you are going to use malloc to allocate space for the string, and the global variable will be a pointer to it, so it will be very dificult to understand where and how you must free it.