[Vm-dev] FilePlugin>>primitiveFileStdioHandles fails incorrectly?

[Denis Kudriashov]

2018-08-09 17:34 GMT+01:00 Eliot Miranda <eliot.miranda at gmail.com>:

>
> Hi Alistair,
>
> On Thu, Aug 9, 2018 at 1:37 AM, Alistair Grant <akgrant0710 at gmail.com>
> wrote:
>
>>
>> Hi Eliot,
>>
>> On Wed, 8 Aug 2018 at 21:31, Eliot Miranda <eliot.miranda at gmail.com>
>> wrote:
>> >
>> >
>> > Hi Alistair,
>> >
>> > On Sun, Aug 5, 2018 at 1:02 PM, Alistair Grant <akgrant0710 at gmail.com>
>> wrote:
>> >>
>> >>
>> >> Hi Everyone,
>> >>
>> >> FilePlugin>>primitiveFileStdioHandles is responsible for opening stdio
>> >> in the VM.  The basic behaviour is to call sqFileStdioHandlesInto()
>> >> which does the actual work and returns a mask indicating which streams
>> >> were successfully opened (stdin, stdout, stderr).
>> >>
>> >> However primitiveFileStdioHandles regards a mask of 0, i.e. no files
>> >> available, as a primitive failure:
>> >>
>> >>
>> >> sHFAfn ~= 0 ifTrue:
>> >>     [(self cCode: ' ((sqInt (*)(void))sHFAfn)()' inSmalltalk: [true])
>> ifFalse:
>> >>         [^interpreterProxy primitiveFailFor: PrimErrUnsupported]].
>> >> self cCode: '' inSmalltalk: [fileRecords := Array new: 3].
>> >> validMask := self sqFileStdioHandlesInto: fileRecords.
>> >> validMask = 0 ifTrue:
>> >>     [^interpreterProxy primitiveFailFor: PrimErrUnsupported].
>> >>
>> >>
>> >> This doesn't cause a problem in squeak since all primitive errors are
>> >> handled by simply assuming that the stdio files can't be opened and
>> >> ignoring any other errors.
>> >>
>> >> Pharo currently raises an unhandled exception.
>> >>
>> >> On Windows not having stdio available is a normal condition, so
>> >> I think the correct behaviour is for the primitive to succeed, but
>> >> return an array of 3 nils, i.e. successfully determined that none of
>> the
>> >> stdio files are available (this is effectively what happens in the
>> >> Squeak image anyway).
>> >>
>> >> It would then mean that a primitive failure can be treated as something
>> >> going wrong, rather than the normal (on Windows) situation of no stdio
>> >> files being available.
>> >>
>> >> The other (minor) benefit is that at the moment there are two
>> situations
>> >> in which the primitive fails with PrimErrUnsupported: sHFAfn ~= 0 and
>> >> validMask = 0.  This change would make it easier to interpret the
>> >> failure.
>> >>
>> >> Any objections?
>> >
>> >
>> > No, but I think the right thing to do is to fail if
>> sqFileStdioHandlesInto answers a value less than zero.  That would;d still
>> allow the subsystem to communicate some serious error, while allowing the
>> system also to report that no streams are available (e.g. when not attached
>> to a console).
>>
>> Wouldn't it  be better for sqFileStdioHandlesInto to flag the
>> primitive as failing itself as it could then provide a reason, e.g.
>> primitiveFailFor or primitiveFailForOSError? (the platform support
>> file is already doing this in other support routines).
>>
>>
>> > BTW, is there any image level source code available for accessing the
>> FileAttributesPlugin's primitives?  This is lazy of me, but if there is
>> could you email me a pointer to the code or the code itself asap?  TIA
>> >
>> > P.S> I'm specifically looking for code to implement testing directory
>> writability in Squeak.
>>
>> OK, just a warning in advance: The code (VM and image) works fine on
>> Linux and Windows.  I didn't know about the Mac file encoding quirks
>> until recently, so need to change the plugin to work properly on Mac
>> OS.  But I haven't got the VM to compile on my Mac virtualbox machine,
>> so the changes are still local to my PC.  This won't affect you unless
>> you've got non-ascii characters in your file names.  I should have
>> fixed this by now, but the problems compiling on Mac have frustrated
>> me, and I've had very little time (personal reasons).
>>
>
> I develop on the Mac so feel free to email me a change set and tests (e.g.
> just doit in a workspace) and IO can test for you.
>
>
>>
>> The main repository for the image side file attributes code is at:
>> https://github.com/akgrant43/pharo/tree/21368-Integrate-File
>> AttributesPlugin.
>>
>
> OK, I'll see if I can grab this wen I have time. Today is taken :-)
>
>
>>
>> If you're not comfortable with git I think figuring out the changes
>> will be difficult.  I've got a .cs from a slightly earlier revision
>> which I can email you - probably directly, it's 93Kb.
>>
>> I'll try and put together a change set which just includes enough code
>> to get file attributes.
>>
>
> I've got myself going.  I have the R_OK, W_OK, E_OK accessors in place so
> don't need source code.  I do suggest however that primitiveFileAttribute
> would be nicer to use if it took its arguments in reverse order.  i.e.
>
>     attribute: attributeNumber forPath: path
>
> is less clumsy than
>
>     attributeForPath: path numbered: attributeNumber
>

It can be with more traditional #at:

     attributeForPath: path at: attributeNumber


>
>
>> Any other questions, of course please let me know.
>>
>> Cheers,
>> Alistair
>>
>
>
> _,,,^..^,,,_
> best, Eliot
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.squeakfoundation.org/pipermail/vm-dev/attachments/20180809/cb3935ee/attachment-0001.html>