[Cuis-dev] Using OSProcess package

[Juan Vuletich]

Hi Dave,

On 12/9/2022 2:33 PM, David T. Lewis via Cuis-dev wrote:
>
> Hi Juan,
>
> I have not had time to look in detail, but something is badly broken. I see
> "Bad file descriptor" errors in the console, and UnixProcessAccessorTestCase
> crashes the VM.
>
> I'll try to look at it this weekend and give a better answer.
>
> Dave

The problem is that what used to be instances of String, that can be 
sent directly to the C world, only needing a zero byte at the end, are 
now instances of UnicodeString. UnicodeString is a regular class (with 
instance variables) and it can't be sent to the C world in the same way. 
Something like UnicodeString that uses encapsulation to protect its 
encoding is much better for the Smalltalk world. But unfortunately it 
breaks the assumptions of code that deals with the external world. 
Apologies for that.

I did some experiments:

If I add #asByteString to these methods like this:

AttachableFileStream >> name: aSymbolOrString attachTo: anIOHandle 
writable: readWriteFlag
     "Attach to an existing file handle, assumed to have been previously 
opened by the underlying operating system."
     name _ aSymbolOrString asByteString.
     fileID _ anIOHandle.
     readWriteFlag ifTrue: [self readWrite] ifFalse: [self readOnly].
     self ascii.
     self register.

UnixProcess >> forkJob: executableFile arguments: arrayOfStrings 
environment: stringDictionary descriptors: arrayOf3Streams
     "Call Unix vfork() and execve() to create a child process, and 
answer the child process.
     Delegate this to the singleton OSProcess>>thisOSProcess."
     ^ self forkAndExec: executableFile asByteString
         arguments: (arrayOfStrings collect: [ :s | s asByteString ])
         environment: stringDictionary
         descriptors: arrayOf3Streams

and then evaluate:
OSProcessAccessor initialize
AttachableFileStream initialize
OSProcess initialize
ThisOSProcess initialize

then this appears to work on my Mac
OSProcess command: 'ls -l /etc'

However I think it would be much better to send the #bytes of the 
UnicodeString. This is a ByteArray that holds the UTF-8 bytes of the 
Unicode String. Still, it looks like the Plugin needs stuff to be actual 
instances of String, so perhaps a hacked string that actually holds 
UTF-8 bytes would be best. I think that's what the Clipboard gives us, 
and we need to convert to a proper UnicodeString in the image.

I would suggest an adaptor message like #asZeroTerminatedBytes or 
similar, that builds and answers what the plugin needs (avoiding the 
explicit concatenation of `Character numericValue: 0`).

I didn't move beyond that experiment, because this is your code, and it 
is also for other Smalltalk dialects, and you know better.

Thank you!

-- 
Juan Vuletich
cuis.st
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