installable file system

operating system (IFS or "File System Driver", "FSD") An

API that allows you to extend OS/2 to access files stored

on disk in formats other than FAT and HPFS, and access

files that are stored on a network file server.

For example an IFS could provide programs running under OS/2

(including DOS and Windows programs) with access to files

stored under Unix using the Berkeley fast file system.

The other variety of IFS (a "remote file system" or

"redirector") allows file sharing over a LAN, e.g. using

Unix's Network File System protocol. In this case, the

IFS passes a program's file access requests to a remote file

server, possibly also translating between different file

attributes used by OS/2 and the remote system.

Documentation on the IFS API has been available only by

special request from IBM.

An IFS is structured as an ordinary 16-bit DLL with entry

points for opening, closing, reading, and writing files, the

swapper, file locking, and Universal Naming Convention. The

main part of an IFS that runs in ring 0 is called by the

OS/2 kernel in the context of the caller's process and

thread. The other part that runs in ring 3 is a utility

library with entry points for FORMAT, RECOVER, SYS, and

CHKDSK.

EDM/2 article .

(1999-04-07)