Date: Wed, 7 Jun 2000 02:24:34 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: tms2@mail.ptd.net (Thomas M. Sommers) Cc: freebsd-chat@FreeBSD.ORG Subject: Re: Why encourage stupid people to use *BSD WAS:Re: IE Message-ID: <200006070224.TAA06462@usr08.primenet.com> In-Reply-To: <3939A4B5.C62DF7F8@mail.ptd.net> from "Thomas M. Sommers" at Jun 03, 2000 08:37:09 PM
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> > What's wrong with having an undelete command, if someone can implement > > one? > > Nothing, *if* it can be implemented without affecting the integrity of > the system. But coming up with an implementation is not easy. Actually, there already is one; it uses the "whiteout" option; this construct "removes" the file without actually removing it; it's a "no-see-um", rather than a delete. > There are security concerns. Not really. The inode is still allocated to the file; the entries for the file are simply not returned by "getdirentries(2)" or "getdents(2)". The ownership of the file and permissions remain unchanged. Security issues for files that you really want deleted so that the police don't get you because you're a criminal are why there is a "-P" option to "rm". > How do undeleteable files interact with disk quotas? They are accounted against your quota, until purged. > How do they interact with multiple hard links? How does deleting a file that has other hard links interact with hard links? Whiteout interacts by _not_ reducing the link count, and setting the "whiteout" flag on the directory entry. > That, in the 30 years since its creation, Unix has not come > up with undelete strongly suggests that either it can't be > done or that there is no real need for it. It's been done many times for UNIX; visit the comp.sources.unix archives; many implementations predate the ArpaNet. As we used to say: "If VMS can do it, UNIX can do it better". Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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