Subject: Re: Removing GNU tar and GNU cpio from src?
To: NetBSD Userlevel Technical Discussion List <firstname.lastname@example.org>
From: Greg A. Woods <email@example.com>
Date: 01/25/2003 22:24:16
[ On Saturday, January 25, 2003 at 17:25:32 (-0500), der Mouse wrote: ]
> Subject: Re: Removing GNU tar and GNU cpio from src?
> > A backup tool that knowingly produces corrupt backups without exiting
> > with a non-zero error code is buggy -- pure and simple.
> Pure, yes. Simple, no. Who gets to decide what counts as corrupt?
Yes, actually it is very simple in this case. If the st_mtime value for
the file changes from the time it was first opened to the time its
"last" buffer was written to the backup then the backup is obviously
corrupt. Any program which (often) writes to slow media, and which is
(often) intended for doing backups (especially "live" backups), and
which doesn't do such a check is clearly buggy. Obviously a lot more
could be done to better verify the integrity of the backup copy, but
this one check is so obvious and simple and low-cost that not doing it,
at least by default, is a bug, pure and simple.
Now of course we're talking about NetBSD here, and NetBSD is open source
and so anyone truly annoyed at this kind of behaviour can easily modify
their copy of the source (or have someone do it for them), perhaps
adding a new command-line flag which turns off the last-modified check
for those cases where it just gets in the way (eg. backing up a live
Greg A. Woods
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