cgi - a pointer to a CGI struct allocated with cgi_init
form_name - the form name that the file was uploaded as
(not the filename) (if NULL, we're asking for the
file handle for the PUT upload)
DESCRIPTION
cgi_filehandle will return the stdio FILE pointer
associated with a file that was uploaded using
multipart/form-data. The FILE pointer is positioned at
the start of the file when first available.