[Freeciv-Dev] possible segfault and help!

[Mike Kaufman <mkaufman@xxxxxxxxxxxxxx>]

I've been working on a new dialog for civworld, and have run into this
segfault condition. It is easily caught for what I want to do, and since
the dialog is similar to the create_races_dialog(), in
client/gui-gtk/dialogs.c, it _might_ happen there.

below is a program similar to the dialog (without the cruft) that
reproduces the problem.
The problem: activating the zeroth button does not signal the
"toggled" callback the first time.

The question is why does this happen?

An workaround is to active a non-zero button before creating the signal
(see below and attached patch), but I'd like to know if there's a direct 
fix. Anybody?

--mike

/* gcc radio_test.c `gtk-config --libs --cflags` */

#include<gtk/gtk.h>
#include<stdio.h>

struct dlg {
  GtkWidget *shell;
  GtkWidget **races_toggles;
  int i;
};

/*****************************************************************/
static void races_toggles_callback( GtkWidget *w, struct dlg *en)
{
  printf("into callback\n");fflush(stdout);/* DEBUG */
  en->i = 1;  /* valid array index */
}

/*****************************************************************/
static void select_random_race(struct dlg *en)
{
  /* setting en->races_toggles[0] -> en->races_toggles[1] cures it */
  /* otherwise we get a segfault because of bad array index        */

  gtk_toggle_button_set_state(GTK_TOGGLE_BUTTON(en->races_toggles[0]),
TRUE );
  gtk_toggle_button_set_state(GTK_TOGGLE_BUTTON(en->races_toggles[en->i]),
TRUE );
  printf("%d\n",en->i);fflush(stdout);/* DEBUG */
}

/*****************************************************************/
int main(int argc, char **argv)
{
  int i;
  char buffer[3];
  struct dlg *en;
  GSList *group = NULL;

  gtk_init(&argc,&argv);

  en        = (struct dlg *)malloc(sizeof(struct dlg));
  en->i     = -1;              /* invalid array index */
  en->shell = gtk_dialog_new();

  en->races_toggles = (GtkWidget**)malloc(5*sizeof(GtkWidget*));

  for(i=0; i < 5 ; i++) {
    sprintf(buffer,"%d",i);

    en->races_toggles[i] = gtk_radio_button_new_with_label(group, buffer);

    /* setting FALSE -> TRUE cures it */
    gtk_toggle_button_set_state(GTK_TOGGLE_BUTTON(en->races_toggles[i]),
FALSE);
    group =
gtk_radio_button_group(GTK_RADIO_BUTTON(en->races_toggles[i]));

    gtk_box_pack_start(GTK_BOX(GTK_DIALOG(en->shell)->vbox),
      en->races_toggles[i],FALSE,FALSE,0);
  }

  for(i=0; i< 5 ; i++)
     gtk_signal_connect(GTK_OBJECT(en->races_toggles[i]), "toggled",
       races_toggles_callback, (gpointer)en );

  select_random_race(en);

  gtk_widget_show_all(en->shell);
  gtk_main();
  return 0;
}

dialogs_patch
Description: Text document