Pharo.image and the VM simulator

>
> 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
>

>
>
> 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
> >
>
>

> On Oct 7, 2018, at 11:18 PM, Alistair Grant <[hidden email]> wrote:
>
>
> 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?

>
> 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

>
>
> Hi Alistair,
>
> > On Oct 7, 2018, at 11:18 PM, Alistair Grant <[hidden email]> wrote:
> >
> >
> > 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?
>
> Look at VMClass>>#strncpy:_:_: et al.  All the machinery for string copying is already there.  cwdString and buffer are integer indices into memory, the LittleEndianBitmap that holds the entire state of the simulation’s heap. In the JIT memory also holds the stack zone and the method zone.

> > 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