[squeak-dev] Save as new image -> ModificationForbidden!

Thiede, Christoph Christoph.Thiede at student.hpi.uni-potsdam.de
Tue Mar 24 17:33:29 UTC 2020

Hi Marcel,

I cannot reproduce this using a fresh Trunk image (Update 19541, VM 201912311458), because privateKeyPair is nil by default, but the following looks suspicious to me:


No idea how your image can have this, as #loadOLPCOwnerKeys has no senders in Trunk, but maybe we should fix this defect via #copy and write an update script ...



Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von Taeumel, Marcel
Gesendet: Dienstag, 24. März 2020 11:43:30
An: John Pfersich via Squeak-dev
Betreff: Re: [squeak-dev] Save as new image -> ModificationForbidden!

Hi Torge.

Thanks. I know how to workaround that debugger in my image. I was asking for a general fix for Trunk.


Am 24.03.2020 11:04:48 schrieb Torge Husfeldt <torge.husfeldt at gmx.de>:

• create a weak reference to said bigInt
• remove last hard reference
• call gc
• verify that weak reference points to reclaimed object
You will have to do that one step down the stack, though

Von meinem iPhone gesendet

Am 24.03.2020 um 09:39 schrieb Marcel Taeumel <marcel.taeumel at hpi.de>:

Hi, there.

I just wanted to save a 32-bit image (Update 19541, VM 202003021730, Windows 10) under a new filename.

Boom! ModificationForbidden!

Here is the interesting stack:

SecurityManager class>>shutDown
SecurityManager class(Behavior)>>shutDown:
[] in SmalltalkImage>>send:toClassesNamedIn:with:

Well, that code tries to change a LargePositiveInteger:

SecurityManager >> flushSecurityKey: aKey
"Flush a security key"
| n |
n := aKey first.
1 to: n basicSize do:[:i| n basicAt: i put: 0].
n := aKey second.
1 to: n basicSize do:[:i| n basicAt: i put: 0].

How to fix that without breaking security measures or the underlying concept?


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