Subject: Re: bug#7113: 23.2; Crash on invalid path argument to dbus-introspect-xml

From: Thomas Fitzsimmons <[email-masked]>
Date: Sat, 02 Oct 2010 21:58:47 -0700

Michael Albinus <[email-masked]> writes:

> Thomas Fitzsimmons <[email-masked]> writes:
>
>>> The crash happens because DBUS uses fatal warnings. Setting the
>>> environment variable DBUS_FATAL_WARNINGS to 0 helps:
>>>
>>>   DBUS_FATAL_WARNINGS=0 emacs -Q --eval "(require 'dbus)" --eval
>>>   '(dbus-introspect-xml :session "org.freedesktop.DBus" "")'
>>>
>>> This way the warning message is still printed but Emacs doesn't crash.
>>
>> OK, that does improve the situation for me but it doesn't solve the
>> problem in general.  By default an unsuspecting user developing D-Bus
>> Lisp code (e.g. in ielm) can easily crash their Emacs session.  Is there
>> a way for the Emacs D-Bus bindings to disable fatal warnings and/or to
>> intercept their causes and report the errors?
>
> I've committed a patch to the emacs-23 branch, unsetting
> $DBUS_FATAL_WARNINGS during initialization:
>
> *** /home/albinus/src/emacs-23/src/dbusbind.c.~100061~	2010-09-27 10:41:33.251159798 +0200
> --- /home/albinus/src/emacs-23/src/dbusbind.c	2010-09-27 10:41:33.315137500 +0200
> ***************
> *** 2132,2137 ****
> --- 2132,2139 ----
>     Vdbus_debug = Qt;
>   #else
>     Vdbus_debug = Qnil;
> +   /* We do not want to abort.  */
> +   unsetenv ("DBUS_FATAL_WARNINGS");
>   #endif
>
>     Fprovide (intern_c_string ("dbusbind"), Qnil);

This putenv is only run when initialization is not skipped (e.g.,
running src/temacs).  When initialization is skipped (e.g., running
src/emacs) the putenv is not executed and D-Bus warnings are fatal as
before.

Thomas