Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!oliveb!amiga!cbmvax!jesup From: jesup@cbmvax.UUCP (Randell Jesup) Newsgroups: comp.sys.amiga.tech Subject: Re: Soft links vs hard links (was Re: yet another 1.4 request) Message-ID: <7227@cbmvax.UUCP> Date: 6 Jul 89 18:18:30 GMT References: <8906302004.AA16719@postgres.Berkeley.EDU> <18191@usc.edu> <1092@sas.UUCP> Reply-To: jesup@cbmvax.UUCP (Randell Jesup) Organization: Commodore Technology, West Chester, PA Lines: 36 In article <1092@sas.UUCP> toebes@sas.UUCP (John Toebes) writes: >I hate to pop your bubble on this, but from the standpoint of writing an >AmigaDos filing system (and experience to back it :-) softlinks are >*SIGNIFICANTLY* more difficult to implement than hardlinks. With >softlinks, the file system needs to be able to communicate with other >filing systems *ASYNCHRONOUSLY*. This is an important point because >of the problem where a file may be linked to another device which in >turn is a link back to a different place on the original device. We >haven't even started to scratch the surface of handling details such >as links from filesystems to handlers which support a subset of packet >types or even worse handling any newly defined packets. John is making an incorrect assumption here: that soft links will be implemented by the filesystems. What is planned is for the dos library to implement them (note that this may have some gotchas for people using packet interfaces right now, depending on how we implement it). There are two obvious ways to implement links: one with files with a link bit set, the other using a couple of new packets to deal with links and opening files. Both will affect asych packet io people (if they Lock/Open using asych - Read/Write/etc won't be affected); one requires no modification to filesystems (and therefor can be used on OFS floppies, over NFS, etc immediately), the other is a bit more robust in dealing with asynch IO and old dir/delete/etc programs. Comments? >Look at how long it took Bill Hawes to get Pathman correct - there are >many loopholes to be handled and some subtle interactions. One reason we don't plan on having a path-handler ala Bill's in 1.4. -- Randell Jesup, Keeper of AmigaDos, Commodore Engineering. {uunet|rutgers}!cbmvax!jesup, jesup@cbmvax.cbm.commodore.com BIX: rjesup Common phrase heard at Amiga Devcon '89: "It's in there!"