*BSD News Article 13893


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From: tinguely@plains.NoDak.edu (Mark Tinguely)
Subject: Re: File Truncation Philosophy
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Date: Fri, 2 Apr 1993 04:10:50 GMT
References: <C4tJ6C.C17@ns1.nodak.edu> <CGD.93Apr1173018@eden.CS.Berkeley.EDU>
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In article <CGD.93Apr1173018@eden.CS.Berkeley.EDU> cgd@eden.CS.Berkeley.EDU (Chris G. Demetriou) writes:
>In article <C4tJ6C.C17@ns1.nodak.edu> tinguely@plains.NoDak.edu (Mark Tinguely) writes:
>no.  if you're using a program to backup/restore the contents
>of your hard disk, use one that's smart enough to do it right.
>
>despite all the attempts to make it so, GNU tar is *not*
>a valid backup/restore tool.

fact, replacing the binaries of a executing program will lead to a core.
one SMALL example is rsh of a running rrestore. another example is the install
step if the program is running. fact, unlinking the executing program before
replacing the program prevents this. (the kernel and init are started
differently, and have to be handled differently).

the request is ideas how many problems will be introduced by changing this?
If it is changed, where should it be change? maybe executing program can
have it's inode protected from truncation, or other low changes to how
truncation of a inode.

on the other hand how important is it for other processes having the inode
open to react to a truncation on the inode? Do a minor partial fix to the
patchkit scripts that only for the patchkits?

A side question is how much ease of use do you want? I know how to work around 
problem, it will can make sure it doesn't bother me, but this problem will be a
FAPIA (frequently asked pain in the ass).

--mark.