[XForms] Segfault after fl_finish and fix

[Steven G. Messervey]

Hello,
  From my understanding, if you call fl_finish in a callback, fl_do_forms
should return.
Instead, tt segfaults.

Debian Wheezy 64-bit on x86_64.


  Simple program to demonstrate the issue:
#include <forms.h>

void callback(FL_OBJECT *obj, long data) {
  fl_finish();
}

int main(int argc, char **argv) {
  FL_FORM *form;
  FL_OBJECT *btn;

  fl_initialize(&argc, argv, "TEST", 0, 0);
  form = fl_bgn_form(FL_UP_BOX,320,120);
  btn = fl_add_button(FL_NORMAL_BUTTON,40,70,80,30,"Click me");
  fl_set_object_callback(btn,callback,0);
  fl_end_form();

  fl_show_form(form, FL_PLACE_MOUSE, FL_TRANSIENT, "FOO");
  fl_do_forms();

  return 0;
}

  My proposed fix:
In lib/events.c - fli_object_qread():
replace all occurrences of fli_context = <some value>; with:
if (fli_context)
  fli_context = <some_value>.

After applying the fix and recompiling, the above program works.

I discovered it while making XForms bindings to javascript (Duktape).

Thanks,
  Steve M.