Writing a Custom File Handler

When writing a custom file handler you must ensure that it:

• conforms to the standard Micro Focus Call Handler interface. See the section Calling the File Handler for more information.

  Additionally, once a custom file handler has determined whether or not it will perform the I/O operations for a file, it must set the RETURN-CODE to 1 (to indicate that it will perform the file's I/O operations) or to 0 (to indicate that it will not).

  If a custom file handler sets RETURN-CODE to 0, the next specified custom file handler is tried. If no other custom file handler has been specified, the file's I/O operations are processed by the File Handler.

• is compiled with CALLFH(EXTFH), CALLFH(MFFH) or CALLFH(FHREDIR). See The CALLFH Directive for more information.
• does not call the Micro Focus File Handler (in order to avoid problems with recursion).