Probleme with structure, string anf gtkwidget - c

Question

I'm trying to create a diaporama in c using gtk. I have a button "previous", which show the previous image. So I connect my button to a function and I pass it to a structure. But when I try to print an element of my array I have weird characters, and I don't know why. Plus, I got this warning for my gtk image :
GLib-GObject-WARNING **: 19:12:16.442: invalid uninstantiatable type '(null)' in cast to 'GtkImage'
Gtk-CRITICAL **: 19:12:16.442: IA__gtk_image_set_from_file: assertion 'GTK_IS_IMAGE (image)' failed
Here's my structure :
struct ButtonsArg {
GtkWidget *image;
char *img[];
};
Here's my code for the initialisation of my structure in the main :
GtkWidget *image = gtk_image_new();
char *images[nbImages];
//I get the name of all my image in this function
getImageList(images);
//This print work fine
printf("%s\n", images[0]);
struct ButtonsArg * arg;
arg = malloc(sizeof(struct ButtonsArg) + nbImages*sizeof(char*));
for(int i = 0; i < nbImages; i++) {
arg->img[i] = malloc(strlen(images[i])+1);
strcpy(arg->img[i], images[i]);
}
arg->image = image;
g_signal_connect(precedent, "clicked", G_CALLBACK(event_precedent), &arg);
Here's the function where the problems occur:
static void event_previous(GtkWidget *widget, gpointer data) {
g_print ("previous\n");
struct ButtonsArg *arg = data;
//Print weird charac
for(int i = 0; i < nbImages; i++) {
printf("%s\n", arg->img[i]);
}
GtkWidget *image = arg->image;
if(currentImage == 0) {
currentImage = nbImages - 1;
gtk_image_set_from_file (GTK_IMAGE (arg->image), arg->img[1]);
} else {
currentImage--;
gtk_image_set_from_file (GTK_IMAGE (arg->image), arg->img[2]);
}
}
If you have any advice, help or link that could help, thanks for sharing it with me.

Answer 1

Can you show the part of code where you try to change GtkImage variable? Seems like program was trying to set the null-value to GtkImage-type variable. In this cause any expression with this variable (like image->value) can raise segementation fault.
UPD: Ok. I see it. You should be check the arg-structure. I think, some attribute of this structure can have null-value.