[Vm-dev] Bug in #instVarAt:put: for read-only objects

[Eliot Miranda]

Hi Norbert,


> On Jan 5, 2018, at 7:53 AM, Clément Bera <bera.clement at gmail.com> wrote:
> 
> 
> 
>> On Fri, Jan 5, 2018 at 4:05 PM, Norbert Hartl <norbert at hartl.name> wrote:
>>  
>> You mean
>> 
>> 	<primitive: 174 error: ec>
>> 	self isReadOnlyObject 
>> 		ifTrue: [(ModificationForbidden for: self atInstVar: index with: anObject) signal]
>> 		ifFalse: [ self primitiveFailed ]
>> ?
>> 
>> Norbert

The index and bounds validation should also occur, probably first.  So something like

Object>>instVarAt: index put: anObject
    <primitive: 174 error: ec>
    (index isInteger
    and: [index between: 1 and: self class instSize + self basicSize]) ifFalse:
        [self badIndexError: index].
    self isReadOnlyObject ifTrue:
         [^(NoModificationError for: self atInstVar: index with: anObject) signal].
    self primitiveFailed

> 
> yes something like that.
> 
> 
> Same thing for Object>>#at:put:, floatAt:put: and so on.
>  
>> 
>>> Am 05.01.2018 um 14:22 schrieb Clément Bera <bera.clement at gmail.com>:
>>> 
>>> Hi,
>>> 
>>> No this is not a bug.
>>> 
>>> This needs to be handled in the primitive failure code in the image, the method should be something like that :
>>> 
>>> Object>>instVarAt: index put: anObject
>>> 	<primitive: 174 error: ec>
>>>         self isReadOnlyObject ifTrue: [(ModificationForbidden for: self atInstVar: index with: anObject) signal]
>>> 	self primitiveFailed
>>> 
>>> All primitive fall-back code triggering object mutation should be rewritten this way, especially primitives such as #at:put:, #instVarAt:put:, etc.
>>> 
>>> Cheers
>>> 
>>>> On Fri, Jan 5, 2018 at 1:42 PM, Norbert Hartl <norbert at hartl.name> wrote:
>>>>  
>>>> If I do 
>>>> 
>>>> (#foo -> #bar)
>>>> 	beReadOnlyObject;
>>>> 	value: #baz
>>>> 
>>>> it throws
>>>> 
>>>> ModificationForbidden:  #foo->#bar is read-only, hence its field 2 cannot be modified with #baz
>>>> 
>>>>  which is as expected. But if I do
>>>> 
>>>> (#foo -> #bar)
>>>> 	beReadOnlyObject;
>>>> 	instVarNamed: #value put: #baz
>>>> 
>>>> I get
>>>> 
>>>> PrimitiveFailed: primitive #instVarAt:put: in Association failed
>>>> 
>>>> I think this a bug, no?
>>>> 
>>>> Norbert
>>>> 
>>> 
>>> 
>>> 
>>> -- 
>>> Clément Béra
>>> Pharo consortium engineer
>>> https://clementbera.wordpress.com/
>>> Bâtiment B 40, avenue Halley 59650 Villeneuve d'Ascq
>> 
>> 
> 
> 
> 
> -- 
> Clément Béra
> Pharo consortium engineer
> https://clementbera.wordpress.com/
> Bâtiment B 40, avenue Halley 59650 Villeneuve d'Ascq
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