im_mmapinrw - memory maps a VASARI image file with read and write
im_mmapinrw(3) works exactly as im_mmapin but the entered file_name is
memory mapped with read and write permissions. This is useful for some
applications, like writing lines onto an existing file. Since the user
might change accidentally the context of the original file, great care
should taken when handling a file with this routine.
im_open(3) is generally more convenient.
The function returns the image descriptor on success and NULL on error.
im_close(3), im_open(3), im_makerw(3).
N. Dessipris - 11/04/1990
22 April 1991