PATHWORKS File System 4.0

This document is a DRAFT COPY specification of the PATHWORKS File System (PFS) and its standard file system libraries, developed by the Personal Computer Systems Group at Digital Equipment Corporation in June 1993.

Key aspects summarized:

1. Purpose: The specification details the functional and structural components of the PATHWORKS File System (PFS) for Hydra Servers, providing a comprehensive description of its design and library interfaces.
2. Core Functionality: PFS offers a single, abstracted interface to multiple host file systems, aiming for both Network Operating System (NOS) independence and PATHWORKS platform independence. It handles operations like file creation, deletion, renaming, attribute management, and data transfer.
3. Supported Environments: It specifically supports the semantics and syntax of MSDOS and Macintosh clients, with VMS being the underlying host file system. The document delves into how filenames, paths, data formats, and file attributes are mapped and handled across these different namespaces.
4. Design Principles: Key design requirements include:
   • Tightly coupling all file-related information.
   • Compatibility with Microsoft LanManager for Unix (LMU) server software.
   • Achieving performance comparable to existing PATHWORKS products.
   • Operating effectively in a distributed VAXCluster environment, necessitating distributed file caches.
   • Maintaining independent NOS and host security models, often leading to distinct file attributes for different NOS types.
   • Requiring data presented to the cache interface to be in stream format, limiting write access to stream files.
5. Architecture: PFS is logically divided into two main components:
   • PATHWORKS File Interface (PFS): The top-level interface that performs argument checking and dispatches requests to the appropriate file system library.
   • File System Library (FSLIB): A collection of routines that implement the actual file system functions, potentially supporting "variant" file systems within a single library. Additional supporting libraries include PATHLIB (for path manipulation) and TIMELIB (for time conversions).
6. Data Structures: The document defines numerous data structures (e.g., PFSPATHID, PFSFID, PFSATTR, PFSSTAT) used to pass information and cache data, noting that many fields are file system-specific.
7. Security: PFS manages NOS-specific security data and supports host security checks based on configurable modes (HOST, CREATOR, NOS).

The document is highly detailed, including extensive tables of contents, revision history, definitions of terms, design requirements, and a summary of all PFS and FSLIB routines, along with appendices describing the VMS ODS2, MSDOS FAT, and Macintosh HFS file systems for context.