Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!yale!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.unix.internals
Subject: Re: How do you find the symbolic links to files.
Message-ID: <10960:Dec507:07:4190@kramden.acf.nyu.edu>
Date: 5 Dec 90 07:07:41 GMT
References: <25146@adm.brl.mil> <1990Dec5.052124.28435@erg.sri.com>
Organization: IR
Lines: 12

In article <1990Dec5.052124.28435@erg.sri.com> zwicky@erg.sri.com (Elizabeth Zwicky) writes:
> Unfortunately, you
> have to get pretty intimate with the disk to tell that the 20 meg of
> nulls aren't there

Hardly. You just look at the file size. Other than the file size, there
is no way a portable program can tell the difference between a hole and
an allocated block of zeros. If an archiver knows the block size and
sees that a file has N holes, it can just squish the first N holes it
finds, and write explicit zeros in the remaining zero-filled blocks.

---Dan