Not so random state

[JesterSks]

I recently used UUID in a compiled project using SBCL and found that the random state does not get changed when the application launches causing repeated v4 UUIDs. The following code recreates the error:

(sb-ext:save-lisp-and-die "uuid-static-random"
    :executable t
    :purify t
    :toplevel (lambda ()
        (unwind-protect
            (format t "uuid: ~A~%" (uuid:print-bytes nil (uuid:make-v4-uuid)))
            (sb-ext:exit))))

I can work around the issue by doing the following:

(sb-ext:save-lisp-and-die "uuid-random"
    :executable t
    :purify t
    :toplevel (lambda ()
        (unwind-protect
            (let ((uuid::*uuid-random-state* (make-random-state t)))
                (format t "uuid: ~A~%" (uuid:print-bytes nil (uuid:make-v4-uuid))))
            (sb-ext:exit))))

Which works but it feels wrong having to violate the implied private nature of uuid-random-state.

[tuscland]

I have reproduced this problem on LispWorks with both hcl:save-image and deliver. Wouldn't it be a solution if *uuid-random-state* was lazily bound at runtime, instead of being initialized as a global variable? This is a pretty serious problem as any delivered application will generate the same UUIDs on each consequent launch.

[tuscland]

Works fine, thanks!

[dardoria]

Thanks for the feedback!