[Vm-dev] Pharo.image and the VM simulator

[David T. Lewis]

The primitive answers a Smalltalk String (cwdString). The rest of the
logic is there to instantiate the String and populate its data area with
the results of the getcwd() call.

For purposes of simulation, anything that answers a reasonable looking
String might be good enough. Possibly it could just end up being something
like this:

primitiveGetCurrentWorkingDirectory
    interpreterProxy pop: 1 thenPush: 'My Current Working Directory';



>
> Hi Everyone,
>
> I'm trying to get a Pharo image running in the VM simulator (as part of
> working towards writing a FileAttributesPluginSimulator).  My image
> happens to use UnixOSProcessPlugin>>getCurrentWorkingDirectory during
> startup, and this isn't yet supported in the simulator (there's no
> UnixOSProcessPluginSimulator class).
>
> For reference, the method is:
>
>
> UnixIOProcessPlugin>>primitiveGetCurrentWorkingDirectory
> "Answer a string containing the current working directory."
>
>     | cwd cwdString bufferSize incrementBy maxSize buffer |
>     <export: true>
>     <var: 'buffer' type: #'char *'>
>     <var: 'cwd' type: #'char *'>
>
>     bufferSize := 100.
>     incrementBy := 100.
>     maxSize := 5000.
>
>     [cwdString := interpreterProxy
>         instantiateClass: interpreterProxy classString
>        indexableSize: bufferSize.
>     buffer := interpreterProxy arrayValueOf: cwdString.
>     cwd := self get: buffer cwd: bufferSize. "getcwd(buffer, bufferSize)"
>     (cwd = 0
>     and: [bufferSize < maxSize])]
>         whileTrue:
>             [bufferSize := bufferSize + incrementBy].
>         cwd = 0
>             ifTrue:
>                 [interpreterProxy primitiveFail]
>             ifFalse:
>                 [cwdString := self stringFromCString: cwd.
>                 interpreterProxy pop: 1 thenPush: cwdString]
>
>
> In the simulator, cwdString and buffer are both SmallIntegers (the
> Oop and begining of the string data respectively).
>
> How can I write the contents of the string in to buffer as part of
> the #get:cwd: simulation?
>
> For reference I'd also like to have the answer given the oop
> (cwdString).
>
> From Clement's answer to Ben in
> http://forum.world.st/Exploring-the-simulator-was-Re-REPL-image-for-simulation-td4896870.html
> it seems like it may not be possible.  In that case I'd have to re-write
> the primitive to avoid this type of code.
>
> The only other similar code I could find used an uninitialised buffer on
> the stack, so had something like:
>
> self cCode: '' inSmalltalk:[ buffer := ByteArray new: 256 ].
>
> and so passed the actual object to the function simulation.
>
>
> Thanks,
> Alistair
>