From: ts <decoux@...>
Date: 2004-03-07T23:49:09+09:00
Subject: Re: freeze, frozen? in extensions

>>>>> "d" == daz  <dooby@d10.karoo.co.uk> writes:

d> As a Ruby String points to a C string, it would easily be possible for
d> an ext just to overwrite part of the C string even if it had been frozen
d> but (you made me think) Ruby objects *always* are/should be modified via
d> the API rather than directly which allows Ruby to check things such as
d> /frozen/ status.

 well, I can give you an exception. In plruby you have

        vid = INT2NUM(typoid);
        klass = rb_hash_aref(plruby_classes, vid);
        if (NIL_P(klass)) {
            klass = rb_hash_aref(plruby_conversions, vid);
            if (NIL_P(klass)) {
                st_insert(RHASH(plruby_classes)->tbl, vid, Qfalse);
            }
            else {
                klass = rb_const_get(rb_cObject, NUM2INT(klass));
                st_insert(RHASH(plruby_classes)->tbl, vid, klass);
            }
        }

 It's trying to search if it exist a class associated with a postgres type,
 to call a conversion method.

 Now there is rb_hash_aref() but it use st_insert() rather than
 rb_hash_aset(). The reason is simple, plruby can run with $SAFE >= 4 and
 in this case ruby will give an error

svg% ruby -e 'a = {}; $SAFE = 4; a[12] = 24'
-e:1:in `[]=': Insecure: can't modify hash (SecurityError)
        from -e:1
svg% 

 because I'm *sure* that it don't exist a security problem in this case it
 use st_insert() rather than the standard API function to bypass the
 security mechanism


Guy Decoux