I don't know what the failure mode was on Windows (file system full?
something else?). Regardless of the underlying failure, if you write
the image file and the write does not successfully complete, then
you almost certainly have a junk file that cannot be fixed.

But to your other question, could we check for the failure and not
exit the image, that's definitely worth looking into.

Take a look at SmalltalkImage>>snapshotEmbeddedPrimitive and
SmalltalkImage>>snapshotPrimitive. If the method comments are
right, then a nil result would indicate a write faiure. I don't
know if the actual primitives in the VM behave this way (if not
they could be fixed). But if that is how the primitives behave,
then it should be possible to add a check for nil to prevent
exiting the image after a failed write.

I do not see any such check in SmalltalkImage>>snapshot:andQuit:withExitCode:embedded:
so it would be worth looking at this to see if a nil check could
be added to protect against the kind of failure you saw.

Dave

On Fri, Sep 03, 2021 at 10:04:18PM +0000, Thiede, Christoph wrote:
> Truncate? It has still a very usual file size ... But when I try to open it, the VM asks me for another image file, so apparently, it cannot read it. No idea what's going on here ...
> 
> 
> Best,
> 
> Christoph
> 
> ________________________________
> Von: Squeak-dev <squeak-dev-bounces at lists.squeakfoundation.org> im Auftrag von David T. Lewis <lewis at mail.msen.com>
> Gesendet: Samstag, 4. September 2021 00:01:54
> An: The general-purpose Squeak developers list
> Betreff: Re: [squeak-dev] Image damaged due to IO error while saving
> 
> On Fri, Sep 03, 2021 at 09:02:07PM +0000, Thiede, Christoph wrote:
> > Or is there maybe, just maybe some kind of automatic image repair tool? One that does not require in-depth knowledge of the file format internals of .image files? :-)
> >
> 
> No, if you truncate the image file, it's junk.
> 
> Dave
> 
> 

>