From bug-octave-request at bevo dot che dot wisc dot edu  Tue Nov 18 22:52:48 1997
Subject: saving undefined variables in functions
From: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
To: Maximilian Pitschi <Maximilian dot Pitschi at ofw dot pr dot siemens dot de>
Cc: bug-octave at bevo dot che dot wisc dot edu
Date: Tue, 18 Nov 1997 22:46:28 -0600

On 18-Nov-1997, Maximilian Pitschi <Maximilian dot Pitschi at ofw dot pr dot siemens dot de> wrote:

| Bug report for Octave 2.0.9 configured for hppa1.1-hp-hpux10.20
| 
| Trying to (implicitly or explicitly) save variables with the save 
| command that are not defined causes octave to dump the core.
| 
| Repeat-By:
| ---------
| 
| f and g are functions, the second arguments a2 of which are optional 
| arguments.
| 
| f.m:
| 
| function f(a1, a2)
| save('vars.mat', 'a1', 'a2');
| 
| g.m:
| 
| function g(a1, a2)
| save('vars.mat');
| 
| Now, calling f with two arguments is o.k., whereas calling f with
| one argument terminates octave:
| 
| /opt/pubdom/bin/octave 
| Octave, version 2.0.9 (hppa1.1-hp-hpux10.20).
| Copyright (C) 1996, 1997 John W. Eaton.
| This is free software with ABSOLUTELY NO WARRANTY.
| For details, type `warranty'.
| 
| octave:1> f(1,2)
| octave:2> f(1)
| error: illegal instruction -- stopping myself...
| attempting to save variables to `octave-core'...
| 
| In the above situtation the problem --- saving an undefined
| variable --- is more or less obvious.  Unfortunately, function g,
| which is supposed to save all defined variables, behaves 
| the same way.

Please try the following patch.

Thanks,

jwe


Tue Nov 18 04:27:55 1997  John W. Eaton  <jwe at bevo dot che dot wisc dot edu>

	* load-save.cc (do_save): Avoid dereferencing NULL pointers.


*** /home/jwe/src/octave-releases/octave-2.0.9/src/load-save.cc	Mon May 19 19:55:53 1997
--- load-save.cc	Tue Nov 18 22:42:05 1997
***************
*** 2238,2243 ****
--- 2238,2247 ----
    string help = sr->help ();
    int global = sr->is_linked_to_global ();
    tree_fvc *tmp = sr->def ();
+ 
+   if (! tmp)
+     return;
+ 
    octave_value tc = tmp->eval (0);
  
    if (tc.is_undefined ())