[Vm-dev] bugs in DeflatePlugin?

[Eliot Miranda]

_,,,^..^,,,_ (phone)

> On Jan 11, 2022, at 3:22 AM, Marcel Taeumel <marcel.taeumel at hpi.de> wrote:
> 
> 
> Hi Florin, hi Fabio --
> 
> Fixed via VMMaker.oscog-mt.3135.

I just generated the plug-in.

> 
> Thanks for reporting this!

+1

> 
> Best,
> Marcel
>> Am 10.01.2022 19:39:46 schrieb Florin Mateoc <florin.mateoc at gmail.com>:
>> 
>> Also now MCSerializationTest>>#testMczSerialization is succeeding for me, 
>> it was failing before (in JsSqueak) 
>> 
>> On Mon, Jan 10, 2022 at 3:42 AM Fabio Niephaus wrote: 
>> 
>> > 
>> > Hi Florin, 
>> > 
>> > Happy new year and thanks for the bug report! PNGReadWriterTest seems 
>> > to pass on TruffleSqueak (although I remember some bug fixing a while 
>> > ago). Anyway, I looked into #primitiveZipSendBlock which seems to be 
>> > the only sender of #loadZipEncoderFrom:. 
>> > 
>> > While #loadZipEncoderFrom: reads from writeStreamInstSize + 1 and + 2, 
>> > which is off by one as you mentioned, #primitiveZipSendBlock stores at 
>> > readStreamInstSize + 1 and + 2. And as it happens, readStreamInstSize 
>> > seems to be 4 while writeStreamInstSize is 5, which compensates for 
>> > the off-by-one error. However, I don't understand why reading from the 
>> > wrong positions does not cause the tests to fail. Anyway, I cleaned 
>> > this up in TruffleSqueak (see [1]). 
>> > 
>> > Fabio 
>> > 
>> > [1] 
>> > https://github.com/hpi-swa/trufflesqueak/commit/5b6066b54e03e19ec4c4d2b22550ff081e46f6e6 
>> > 
>> > On Mon, Jan 10, 2022 at 4:33 AM Florin Mateoc 
>> > wrote: 
>> > > 
>> > > 
>> > > I should have also mentioned that PNGReadWriterTest also has 18 failures 
>> > for SqueakJS, and I think I remember them failing in TruffleSqueak as well 
>> > > 
>> > > On Sun, Jan 9, 2022 at 10:18 PM Florin Mateoc 
>> > wrote: 
>> > >> 
>> > >> Hi all, and Happy New Year! 
>> > >> 
>> > >> I think I just found a couple of bugs in the DeflatePlugin. They were 
>> > causing errors in my JsSqueak, I don't fully understand why they don't seem 
>> > to cause problems in Squeak. Anyway, after I fixed them, the primitives 
>> > work and the PNGReadWriterTest tests are all succeeding for me. 
>> > >> 
>> > >> One is in #loadZipEncoderFrom: 
>> > >> The method checks and then determines the writeStreamInstSize and then 
>> > fetches the bitBuffer and bitPosition (the first two instvars of 
>> > ZipEncoder, a direct subclass of WriteStream) from offsets 
>> > writeStreamInstSize + 1 and writeStreamInstSize + 2, although the fetches 
>> > are 0-based 
>> > >> 
>> > >> The other is in #primitiveZipSendBlock 
>> > >> The method, still working on a ZipEncoder, at the end stores the 
>> > modified values for bitBuffer and bitPosition at offset readStreamInstSize 
>> > + 1 and readStreamInstSize + 2, which is just wrong. 
>> > >> 
>> > >> As I said, I don't quite get why this does not cause at least 
>> > image-side errors if not VM crashes in Squeak, but they should probably be 
>> > fixed anyway :) 
>> > >> 
>> > >> All the best, 
>> > >> Florin 
>> > 
>> Also now MCSerializationTest>>#testMczSerialization is succeeding for me, it was failing before 
>> (in JsSqueak) 
>> 
>> 
>> On Mon, Jan 10, 2022 at 3:42 AM Fabio Niephaus <lists at fniephaus.com> wrote:
>>>  
>>> 
>>> Hi Florin,
>>> 
>>> 
>>> 
>>> Happy new year and thanks for the bug report! PNGReadWriterTest seems
>>> 
>>> to pass on TruffleSqueak (although I remember some bug fixing a while
>>> 
>>> ago). Anyway, I looked into #primitiveZipSendBlock which seems to be
>>> 
>>> the only sender of #loadZipEncoderFrom:.
>>> 
>>> 
>>> 
>>> While #loadZipEncoderFrom: reads from writeStreamInstSize + 1 and + 2,
>>> 
>>> which is off by one as you mentioned, #primitiveZipSendBlock stores at
>>> 
>>> readStreamInstSize + 1 and + 2. And as it happens, readStreamInstSize
>>> 
>>> seems to be 4 while writeStreamInstSize is 5, which compensates for
>>> 
>>> the off-by-one error. However, I don't understand why reading from the
>>> 
>>> wrong positions does not cause the tests to fail. Anyway, I cleaned
>>> 
>>> this up in TruffleSqueak (see [1]).
>>> 
>>> 
>>> 
>>> Fabio
>>> 
>>> 
>>> 
>>> [1] https://github.com/hpi-swa/trufflesqueak/commit/5b6066b54e03e19ec4c4d2b22550ff081e46f6e6
>>> 
>>> 
>>> 
>>> On Mon, Jan 10, 2022 at 4:33 AM Florin Mateoc <florin.mateoc at gmail.com> wrote:
>>> 
>>> >
>>> 
>>> >
>>> 
>>> > I should have also mentioned that PNGReadWriterTest also has 18 failures for SqueakJS, and I think I remember them failing in TruffleSqueak as well
>>> 
>>> >
>>> 
>>> > On Sun, Jan 9, 2022 at 10:18 PM Florin Mateoc <florin.mateoc at gmail.com> wrote:
>>> 
>>> >>
>>> 
>>> >> Hi all, and Happy New Year!
>>> 
>>> >>
>>> 
>>> >> I think I just found a couple of bugs in the DeflatePlugin. They were causing errors in my JsSqueak, I don't fully understand why they don't seem to cause problems in Squeak. Anyway, after I fixed them, the primitives work and the PNGReadWriterTest tests are all succeeding for me.
>>> 
>>> >>
>>> 
>>> >> One is in #loadZipEncoderFrom:
>>> 
>>> >> The method checks and then determines the writeStreamInstSize and then fetches the bitBuffer and bitPosition (the first two instvars of ZipEncoder, a direct subclass of WriteStream) from offsets writeStreamInstSize + 1 and writeStreamInstSize + 2, although the fetches are 0-based
>>> 
>>> >>
>>> 
>>> >> The other is in #primitiveZipSendBlock
>>> 
>>> >> The method, still working on a ZipEncoder, at the end stores the modified values for bitBuffer and bitPosition at offset readStreamInstSize + 1 and readStreamInstSize + 2, which is just wrong.
>>> 
>>> >>
>>> 
>>> >> As I said, I don't quite get why this does not cause at least image-side errors if not VM crashes in Squeak, but they should probably be fixed anyway :)
>>> 
>>> >>
>>> 
>>> >> All the best,
>>> 
>>> >> Florin
>>> 
>> 
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