list.c

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         lhandle->beginptr = lhandle->currptr->next ;
         lhandle->beginptr->prior = NULL;
         free(lhandle->currptr) ;                        /* free the node */
         lhandle->currptr = lhandle->beginptr ;          /* current pointer stays at he beginning of the list */
         lhandle->currno = 1L ;                          /* update current item's number */
      }
      else
      {
         tmpl1 = lhandle->currptr->prior ;
         tmpl2 = lhandle->currptr->next ;
         tmpl1->next = tmpl2 ;
         tmpl2->prior = tmpl1 ;
         free(lhandle->currptr) ;                          /* free the node */
         lhandle->currptr = tmpl2 ;
         /* Note! lhandle->currno does not change */
      }
       return( LIST_OK ) ;
   }

}

/* ===================================
*
* ListReturn() - Return the actual data stored in the current entry
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*   LIST_ERR_NO_CURR
*
* ===================================*/
int ListReturn(HNDLIST *lhandle, void **buf, unsigned long *buflen)
{
   
   *buf = NULL ;
   *buflen = 0L ;

   if (lhandle == NULL)
       return( LIST_ERR_BAD_POINTER );

   if(lhandle->currptr == NULL)
      return( LIST_ERR_NO_CURR ) ;

   *buf = lhandle->currptr->buf ;
   *buflen = lhandle->currptr->buflen ;
   return( LIST_OK ) ;
}

/* ===================================
*
* ListOverwrite() - Set the actual data stored in the current node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*   LIST_ERR_NO_CURR
*
* ===================================*/

int ListOverwrite(HNDLIST *lhandle, void *buf, long buflen)
{
void *tmpbuf ;

   if (lhandle == NULL)
       return( LIST_ERR_BAD_POINTER ) ;

   if(lhandle->currptr == NULL)
      return(LIST_ERR_NO_CURR) ;
      
   if ((tmpbuf = calloc(1, (size_t) buflen)) != NULL)       /* reserve memory for actual data */
   {
      memcpy(tmpbuf, buf, (size_t) buflen) ;              /* store data in reserved memory block */
      free(lhandle->currptr->buf) ;                       /* free old data in node */
      lhandle->currptr->buf = tmpbuf ;                    /* set current node to point to the correct buffer */ 
      lhandle->currptr->buflen = buflen ;                 /* set size of data */
   }
   else
      return( LIST_ERR_MEMORY_ALLOCATION ) ;
}

/* ===================================
*
* ListFirst() - Set the current pointer to the first node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*
* ===================================*/

int ListFirst(HNDLIST *lhandle)
{
   if (lhandle == NULL)
       return( LIST_ERR_BAD_POINTER ) ;

   if( lhandle->itemscount == 0L)
      return( LIST_ERR_END_LIST ) ;
       
   lhandle->currptr = lhandle->beginptr ;
   lhandle->currno = 1 ;

   return(LIST_OK) ;
}

/* ===================================
*
* ListLast() - Set the current pointer to the last node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*
* ===================================*/

int ListLast(HNDLIST *lhandle)
{
   if (lhandle == NULL)
       return( LIST_ERR_BAD_POINTER ) ;
       
   if( lhandle->itemscount == 0L)
      return( LIST_ERR_END_LIST ) ;

   lhandle->currptr = lhandle->endptr ;
   lhandle->currno = lhandle->itemscount ;

   return(LIST_OK) ;
}

/* ===================================
*
* ListForward() - Set the current pointer forward node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*
* ===================================*/

int ListForward(HNDLIST *lhandle, long forward)
{
long l ;
   if (lhandle == NULL)
       return( LIST_ERR_BAD_POINTER ) ;

   if (lhandle->currptr == lhandle->endptr)
      return( LIST_ERR_END_LIST ) ;

   for (l = 0L; l < forward; l++)
   {              
      if (lhandle->currptr == lhandle->endptr)
         return( LIST_ERR_END_LIST ) ;

      lhandle->currptr = lhandle->currptr->next ;
      lhandle->currno ++;

      /* Is this correct ??? */
      if (lhandle->currptr == NULL)
         return(LIST_ERR_BAD_POINTER) ;
   }
   return(LIST_OK) ;
}

/* ===================================
*
* ListNext() - Set the current pointer to next node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*
* ===================================*/

int ListNext(HNDLIST *lhandle)
{
   return( ListForward(lhandle, 1L) );
}

/* ===================================
*
* ListBackward() - Set the current pointer backward node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*   LIST_ERR_BEG_LIST,    when at the beginning of the list
*
* ===================================*/

int ListBackward(HNDLIST *lhandle, long backward)
{
long l ;
   if (lhandle == NULL)
       return( LIST_ERR_BAD_POINTER ) ;

   if (lhandle->currptr == lhandle->beginptr)
      return( LIST_ERR_BEG_LIST ) ;


   for (l = 0L; l < backward; l++)
   {     
      if (lhandle->currptr == lhandle->beginptr)
         return( LIST_ERR_BEG_LIST ) ;

      lhandle->currptr = lhandle->currptr->prior ;
      lhandle->currno -- ;

      /* Is this correct ??? */
      if (lhandle->currptr == NULL)
         return(LIST_ERR_BAD_POINTER) ;
         
   }

   return(LIST_OK) ;
}

/* ===================================
*
* ListPrior() - Set the current pointer to the prior node.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*   LIST_ERR_BEG_LIST,    when at the beginning of the list
*
* =================================== */

int ListPrior(HNDLIST *lhandle)
{
   return( ListBackward(lhandle, 1L) ) ;
}

/* ===================================
*
* ListGetPos() - returns pointer to the current item.
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*
* ===================================*/

LIST_ENTRY *ListGetPos(HNDLIST * lhandle, int *actioncode, long *currno)
{
   *actioncode = LIST_OK ;
   *currno = 0L ;
   
   if (lhandle == NULL)
   {
       *actioncode = LIST_ERR_BAD_POINTER ;
       return( NULL ) ;
   }
   *currno = lhandle->currno ;
   return(lhandle->currptr) ;
}



/* ===================================
*
* ListSetPos() - returns current item pointer to a value returned earlier
* ListGetPos().
* This function can return one of the following error codes:
*   LIST_ERR_BAD_POINTER
*
* ===================================*/

int ListSetPos(HNDLIST * lhandle, LIST_ENTRY *newcurrptr, long newcurrno)
{

   if (lhandle == NULL)
      return( LIST_ERR_BAD_POINTER ) ;

   lhandle->currptr = newcurrptr ;
   lhandle->currno = newcurrno ;
   return( LIST_OK ) ;
}