Button Callback Arguments

[author <millward Ms UManitoba CA>]

I'm just a newbie and I'm puzzled by the limitations on
arguments to callbacks triggered by a simple button.
It is true that you can only use 2 arguments as in:
void button_callback(GtkWidet * widget, gpointer * data)  ?

I want to write a callback, triggered by a simple button click,
that will:
1) There is an array buffer in main with 6 char strings
     each of which will be displayed in a label
     which has been created in main.
2) obtain the present state of this label
    gtk_label_get(GTK_LABEL(label), &str);
3) Detect  if it is at the end of the array buffer and needs to
      be reset to the the front of the buffer ( index = 0 ).
4) Change the character string on the label to another
     held in the array buffer.
This is simple stuff but I keep getting 'segmentation default'
whenever I try to use one of the label functions inside the callback.
I have to import into the callback
  1) GtkWidget * widget   for the button
   2) gint array_size    for the number of strings in the
                                   array buffer
   3) GtkWidget * label    the label to be altered
   4) char buffer[][26]     the array buffer that holds the strings.
I suspect this might be impossible using a simple button
since every example I see using a button callback only
has 2 arguments.   I hope this isn't true. I can't see how
a button would be of any practical use if it was limited to
2 arguments for its callback function. Everything would
have to be defined as global. 
Here is my buggy code:
#include <stdio.h>
#include <gtk/gtk.h>

void button_callback(GtkWidget * widget, GtkWidget * label,
                                 gint array_size,  char buffer[][26] )
{
   static int i = 0;
   char * str = NULL;
   gtk_label_get(GTK_LABEL(label), &str);
   if ( strcmp( str, "Today + 2")==0 )
    {
      **** do something no yet defined ****
   }
   if(  i >=  array_size )
   {
         i = 0;
         gtk_label_set_text(GTK_LABEL(label),  buffer[ i ++] );
   }
    else
   {
          gtk_label_set_text(GTK_LABEL(label), buffer[ i ++] );
    }                            
}

  In Main the following is defined ( plus a lot of other stuff )
  
static  char  buffer[6][26] = { "Yesterday","Today","Tomorrow",
               "Today + 2 ","Today + 3 ","Today + 4"};

button = gtk_button_new_with_label("Change the Day");
gtk_signal_connect(GTK_OBJECT(button), "clicked",
                      GTK_SIGNAL_FUNC(button_callback),
                      & buffer[0] );