readCdfHeader <- function(filename) {

   # Expand '~' pathnames to full pathnames.
   filename <- file.path(dirname(filename), basename(filename));
   if (!file.exists(filename))
     stop("Cannot read CDF header. File not found: ", filename);
 

   res <- .Call("R_affx_get_cdf_file_header", filename, PACKAGE="affxparser");
 

   # Sanity check
   if (is.null(res)) {
     stop("Failed to read CDF file header: ", filename);
   }
 

   # Adding backward compatibility for now. /HB 2006-09-07
   res$rows <- res$nrows;
   res$cols <- res$ncols;
   res$probesets <- res$nunits;
   res$qcprobesets <- res$nqcunits;
   res$reference <- res$refseq;
 

   # Workaround for a bug in Fusion SDK. /HB 2008-12-04
   # If the CDF file is on a Windows share, then the from
   # pathname inferred chip type contains a path as well.
   # Reference: See aroma.affymetrix thread on Dec 4, 2008.
   res$chiptype <- basename(res$chiptype);
 

   res;

 } # readCdfHeader()
 
 
 ############################################################################
 # HISTORY:
 # 2011-11-18
 # o ROBUSTNESS: Added sanity check that the native code did not return NULL.
 ############################################################################