[cffi-devel] CFFI-USER: Dereferencing an address to a pointer array ... ?

[Frank Goenninger]

Hi all:

I have in C  in a library:

typedef struct  __tsPMDevInfo
{
    ... some slots in here; don't matter ...

} tsPMDevInfo, *ptsPMDevInfoPtr;

//  
------------------------------------------------------------------------
// nFindPMs -- Find PM Devices on all available serials
//  
------------------------------------------------------------------------ 
-

int nFindPMs( ptsPMDevInfoPtr **pppsPMDevInfoArray,
                           int *pnNrPMsFound )
{
   int nRC = 0;

   ptsPMDevInfoPtr *ppsPMDevInfoArray = NULL;

  .... Here, memory gets allocated and
  ppsPMDevInfoArray points to an array of
pointers to struct tsPMDevInfo !

   if( pppsPMDevInfoArray != NULL )
     *pppsPMDevInfoArray = ppsPMDevInfoArray;

   if( pnNrPMsFound != NULL )
     *pnNrPMsFound = nNrPMs;

   if( nNrPMs > 0 )
     nRC = PMIO_RC_OK;
   else
     nRC = PMIO_RC_NO_PM_FOUND;

   return nRC;
}

In Lisp-land I do (simplified):

(defcfun ("nFindPMs" %nFindPMs) pmio-rc
   (ppsPMDevInfoPtr :pointer)
   (pnNrPMs         :pointer))

(defun find-pms (ppsPMDevInfoPtr pnNrPMs)
   (%nFindPMs ppsPMDevInfoPtr pnNrPMs))

I do get a valid value for the nr of PMs back with

(mem-ref pnNrPMs :int 0)

But I am unable to get a valid foreign pointer back for  
ppsPMDevInfoPtr :

(mem-ref ppsPMDebInfoPtr :pointer 0)

always returns an invalid value (no valid memory address). So, the  
question is: How do I return a pointer to an array of pointers ?
In C land everything is OK and the pointer array is valid: check via  
ppsPMDebInfoPtr[0] -> This is the pointer to a valid struct tsPMDevInfo.

Thx for any pointers ;-) !!!

Frank


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