Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com Message-ID: <00d001c427a4$c51e3eb0$66fda287@docbill002> From: "Bill C. Riemers" To: "Bill C. Riemers" , , References: <000e01c4274e$2fcca690$73aa4142 AT arda> <009a01c427a2$ed1184b0$66fda287 AT docbill002> Subject: Re: Emulating hard links on FAT et al. Date: Wed, 21 Apr 2004 09:30:03 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Ack. I do wish Outlook Express had grammar checking abilities, or I would at least remember to proof read after correcting the spelling... Bill ----- Original Message ----- From: "Bill C. Riemers" To: ; Sent: Wednesday, April 21, 2004 9:16 AM Subject: Re: Emulating hard links on FAT et al. > You can't expect me to just admit I was completely wrong... :) It turns out > the only version of Unix I can remember that allowed separate permissions > for hard linked files was Apollo DomainOS. In DomainOS, separate hidden ACL > files where used to override and extend permissions. Because the ACL's were > stored in a separate file, the net result is each hardlink could and often > did have different permissions. The Apollo DomainOS were truly fantastic > machines, at least ten years ahead of their times in terms of usability > features. For example, it is the only version of Unix I know of that > allowed SYSV or BSD syntax to be selected at runtime. Unfortunately, the > hardware itself was expensive to maintain. The maintained contracts where > $20,000 per year per node. So if you wonder the halls at CERN you might > still find one of the old Apollo machines, but chances are it is being used > as a coffee table or such. > > The cause of my original error is I vaguely remember using the separate > permissions trick on TitanOS to avoid problems if the owner decided to > restrict a directory later. However, I later remembered it wasn't separate > permissions on the file, but separate permissions on the file path that I > would take advantage of. > > i.e. I would do something like: > mkdir ~/cool-program > ln cool-program/* ~/cool-program/. > > So later if the owner did something like: > chmod go-rwx cool-program > -or- > rm -rf cool-program > > I would still be able to run the program without using up part of my disk > quota with a copy. > > At the time I wrote my original post all I remembered was I used separate > permissions for hard-links to cheat quotas. I didn't remember that it was > the separate permissions on the path, not the file, that I used. > > Bill > > > ----- Original Message ----- > From: "Dennis McCunney" > To: "'Bill C. Riemers'" > Sent: Tuesday, April 20, 2004 11:10 PM > Subject: RE: Emulating hard links on FAT et al. > > > > > -----Original Message----- > > > From: cygwin-owner AT cygwin DOT com > > > [mailto:cygwin-owner AT cygwin DOT com]On Behalf > > > Of Bill C. Riemers > > > Sent: Tuesday, April 20, 2004 5:37 PM > > > To: cygwin AT cygwin DOT com > > > Subject: Re: Emulating hard links on FAT et al. > > > > > > I stand corrected. Only some flavors of Unix allow hardlinks to carry > > > separate permissions. I imagine the list of UNIX platforms which > support > > > this *feature* have greatly reduced in recent years since this trick was > > > commonly used to cheat quota systems. > > > > Er, what versions did this? I've dealt at one time or another with AT&T > > Systen V Release 2, 3, and 4, in ports for Intel, Motorola, and WE32000 > > CPUs, SunOS on SPARC, IBM's AIX on RS/6000, Red Hat and Suse Linux on > Intel, > > and Solaris 7, 8, and 9. > > > > None of them allowed seperate permissions on different hard links to a > file. > > > > Given the way hard links are implemented (and Corrina has it exactly > right), > > I don't believe it's *possible*. A link is simply a pointer to an inode, > > where the actual permissions are stored, and links to the same inode > *must* > > carry the same permissions. > > > > I suppose someone could hack a *nix kernel to store seperate permissions > > entries for each hard link to an executable, but I've never heard of it > > being done. > > > > Pointers, please? > > ______ > > Dennis > > > > > > -- > Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple > Problem reports: http://cygwin.com/problems.html > Documentation: http://cygwin.com/docs.html > FAQ: http://cygwin.com/faq/ > -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/